Hey all,
Sorry I was gone so long ....Life moves on and the project sort of burnt me out for a bit :roll: . A few of you had questions, so I thought that I could start a discussion about the project.
Alexander
So you have a turbo on your GS?
was that your bike in the wof?, if so, im kinda curious about 1, costs, who made parts,, 2. needed engine mods (if any) btw wow!! :cheers: :mrgreen:
yeah, that's my black suzuki...
roughly, the cost was about 3500-4000 but I used a lot of top of the line parts. You could probably do the same for 1500-2k.
My team made most of the parts by hand.
Alexander
Are you gonna post the info? For 2K I'd turbo my GS just for kicks!! I even got a spare motor in the garage for when I blow it up! Hook a brotha up! :thumb:
man that is wild!!!!, could you at least tell us where to get parts, or share any info, id be most appreciative, (as i am sure a lot of others here would be) :cheers: :thumb: Thanks!!!
You're still pissin' on the flag man!
ok who cares how much the damn thing costs. i wanna know how much fun it is and what your performance ratings are now and if it is street legal (doubt it)
I dig the fact that you could ride a little bike as fast as some of the SuperSports out there.
Bling,
Do you have any stats? 1/4 mile? Top speed?...
the stats on the bike are as follows: The bike can run 30 psi for a few secs, but i usually turn it down to 10 to 15 psi. This is to protect the stock, I repeat, Stock motor. No special balancing, titanium do hickeys and what not. Before you guys jump my case, remember that the engine does not run at a higher rpm than stock; it is simply running at a higher BMSP (brake mean specific pressure) in the cylinder. Provided you keep your engine well oiled, and only stay on the boost for a few seconds, you're fine. Where people get in trouble is when they have overboosted an engine and then over rev it. Ouch. $$.
Besides...8 seconds of boost and you're well into triple digits.
The Turbo is a GT-15 with a ceramic turbine. It spins about 200K RPM and was originally desinged for a 1.4 L diesel engine. You could buy something similiar to this for new for about $800. You could also find one on ebay with few hours on it for much less. The rest of the parts are between $1000 and $1500 depending on how many gauges you want.
My riding impressions: It's a lot of fun to ride, but the turbo can get a little hot. Boost is available from 3000 rpm to 11k, and from 50 feet away, the whistle of the turbo drowns out the exhaust note. Note: a turbo acts as an exhaust by dispeling the majority of the exhaust pulse into the compressor. As a result, the pipe is quiet, but the turbine whisles like a jet engine....200,000 rpm remember? The bike is balanced and above 3K RPM the turbo is seamless. 3/4 throttle under boost is still a problem, with some hesitation and coughing. Blame the Carburetors. Besides, you don't build a turbo for 3/4 throttle, right?
I built most of the other items by hand. The plenum is 1/4" aluminum pipe with a 6 in diameter and welded in Velocity Stacks. The carbs are sealed and the caps are bolted down with a reinforment bar. The exhaust and intake are pretty basic tube work in Aluminum and 304 Stainless, with a little 317 stainless thrown in for the exhaust flanges. Gaskets are made of Copper, by hand and are .010 thick. The intercooler is a cut down version meant for the CBR1100 XX and I formed end caps and mounts for it. The turbo rides the exhaust manifold and is supported by a single floating mount common to the engine mounting bolts.
Street legal? Yes. With the exception that I run non-insulated sparkplug wires that fuzz out the TV's when I really get on it. He he.
More Later...
Bling!
OH yeah,
I can now send some files in large format. Please check if you can down load a 10 Mb file. If you can, I will develop a list and see if I can batch file some information.
Bling!
PS, I just sold my other bike, a PC800, for an Aprilia Falco. I think it is the perfect move up for anyone who likes the GS. Fantastico!
PLEASE put me on the list!!
me too, me too
can i b on the list to please. your gs sounds amazingly awsome. now i really want a turbo but knowing myslf i would prob. die in "8" seconds.
pics? intercooled? interested in seeing how you routed all the piping.
Id love to be on the list. This is a project Im really considering!!
:cheers:
Octane wrote:
QuoteYou're still pissin' on the flag man!
Sorry about that, oversight on my part. didnt mean to offend anyone :nono: :(
Have you put that bike on a dyno? I'm curious how much power it makes. (maybe you van give an estimate??)
You maybe able to get someone to host that file and just provide the link
I can host it if John can't.
Someone asked about power. I dynoed the GS at 42 Hp stock at 14.7~ psi(Rear wheel SAE Horsepower, adjusted to sea level). Since horsepower is directly porportional to intake pressure for a given compression ratio, and I have increased the ABSOLUSTE pressure to ~45 psi (30 psi gauge), the engine should produce in the area of 120 hp at the rear wheel. :mrgreen:
HOWEVER, friction loads increase with higher compression...so I will estimate that I am probably getting about 105-110 hp. For a few seconds. ;)
If you guys do want to turbo your bikes, I would suggest you stick to 10-15 psi (gauge). My team and I did quite a bit of stress anaysis on the shape of the plenum, and the associated parts to handle that psi, Unless you had our exact model and built it just the way we did, you might end up cracking your plenum or worse. 10-15 psi will get you 65 to 80 Hp. :cheers:
My seat of the pants dyno says that this is about right for the bike. I haven't dynoed it with the turbo on...maybe I should do that sometime. Anyway, the thermodynamics are correct (They gave the team our sheepskins, right?) and I would be very suprised if the bike didn't make those numbers. :dunno:
And Last: I run 105 octane in the bike. I mix a blend of Toulene and Xylene with 93 octane and this gives me at least 103~105 octane. Don't try to run 15 psi without a much higher octane. I'm not kidding, unless you want to paste your ass to the moon, on the back of your skyrocketing heads. :nono:
I will check my files and maybe send a test file in a couple of days. Please give me time as these documents are big, hairy, and have my name on them.
:thumb:
Bling!
if your running the hight boost like that why wouldnt you want to run race gas? i guess my question is why cant you run the higher octaine with 15psi of boost?
turbo boost isn't the same as increasing compresson in the cylinder...turbo engines don't require race gas but engines with high cylinder compression have to use race gas
i'm still not understanding why it is so bad to run the high octane gas in this situation.
I can host the files.. PM me..
you don't have to run race gas to increase turbo boost....i'm not a turbo guru but i know some thing about turbos....me and my friend took his VOLVO turbo and increased the boost from 5 to 24 PSI and he was running 91 octane gas....it would backfire from time to time but it ran good
There's a good chance that the compression in that Volvo wasn't too high.
If the GS makes more compression (without the turbo) it will need race gas or else it starts knocking. The Turbo pumps more mixture in the cylinder wich means that the compression will also get higher. If it gets too high the engine will start knocking. That's why the standard compression on Turbo-engines is often a bit lower.
you *do* need to run higher octane gas with more boost, otherwise you will get knock. the reason your friend could get away with using 91 octane is because his car had a knock sensor, which can retard the timing automatically to reduce knock. if he were to run higher octane gas, he would be able to run more advance and make more power safely.
it's NOT bad to run high octane gas. in fact, what he's saying is you NEED to run higher octane gas.
and for whoever asked about race gas, toulene and xylene are common components in race gas. you can pick them up at most hardware or paint stores. they both have octanes in the 114-117 range i believe. if you were to mix one of those with 94 octane in a 1:1 ratio, you'd end up with about 104-105 octane, though personally i wouldn't do more than 3:1 gasoline to toulene/xylene. also, they have a tendency to make rubber gaskets and hoses deteriorate much faster than regular gasoline.
fwiw, i OWN a turbo car, and i run about 18-20psi. stock was ~14psi. and yes, there is a noticible difference when running 93 octane vs. ~96 octane. i haven't tried anything higher than that.
Quote from: LarsThere's a good chance that the compression in that Volvo wasn't too high.
If the GS makes more compression (without the turbo) it will need race gas or else it starts knocking. The Turbo pumps more mixture in the cylinder wich means that the compression will also get higher. If it gets too high the engine will start knocking. That's why the standard compression on Turbo-engines is often a bit lower.
good point but volvos compression is 8:1 and gs500's is 9:1
not a big difference but probobly makes a lot of difference
Hey all,
Sorry I can't reply as often as I like, but I do have to work :)
Two things. One: compression is compression. Since turbos provide pressure by compressing the flow of air, this must be multiplied by the engine compression to get true compression. Ex: a turbo blowing 15 psi gives a compression of ~ 2:1. This goes into an engine that compresses the mix 9:1. Therefore, the true compression is 2/1 x 9/1 = 18/1 or 18:1 compression.
Since this vapor pressure of fuels is dependent upon the absolute pressure, and atmospheric is 14.7 then 18:1 compression gives a before ignition pressure of roughly 260 psi absolute. AND using the approximation of the Ideal gas law (yes I know air is not ideal, but close enough) this also gives a temperature of the mix, prior to ignition, of approximately 600 deg F. This is localized temperature within the gas cloud, and is only an ESTIMATE. I am not going to get into an arguement about the Gauss-Seidel iteration process required to find the true temperature and pressure.......Whew!.
Okay. So a higher octane fuel does nothing other than resist knock by resisting spontaneous combustion at higher temperature. Higher octane = Higher knock resistance. Easy. Turbos create lots of heat and pressure, see above, and as a result, to avoid knock you must use high octane fue. Q.E.D.
Second, the formula's work backward. If you have the specs on your engine, you can estimate the octane you need. There are a couple of places on the net where you can get formulas for high octane. The basics are this: A large portion of actual fuel, mixed with Toulene which is an accelerant, not a fuel, and a portion of Xylene which is a "light fraction" of the fuel. The trick here is that the toulene increases the flame front propogation across the head, allow normal combustion to occur before knock can start. As a hard example of this, in the 80's formula one teams used to get 1500hp from their turbo engines by running 70 PSI and using tremendous amounts of toulene. This "rocket fuel" was later banned, and now the engines are in the 900-1000 hp area.
I think the formula I use requires 4 oz. of toulene for 1 gal of 93 octane.
Jiggersplat was right.
Bling!
Where'd you learn all this crap Bling? I can turn wrenches like nobody's business, but you start throwing equations and shaZam! at me like that and I get a frickin' headache!
Also the volvo was water cooled wasn't it. Air cooled is basically like playiing roulette compared to water cooled. Steady temp, no uneven hot/cold spots and a well defined range of temperature.
Cool.
Srinath.
Ah. Well....I'm a mechanical engineer with a specialy in dynamic systems of pneumatics and hydraulics. I work for an Aerospace company as a manufacturing engineer. But, mainly I trained under Proffessor Bob Woods at University of Texas at Arlington. An outstanding professor with an drive for racing. Under his guide, the UTA racing team has won more of the Formula SAE competitions than the rest of the world combined.
Enough said?
Bling!
Bling- What is the ideal gas law approximation that you used to find the temp... I follow you through the explanation, I just want to know the formula.
So what temp is the exhaust gas? And doesn't that temp effect the the temp of the compressed air (reasoning behind intercoolers) which enters the engine?
later,
Hi-t
Without refering to my books, the Ideal gas law is PV=NRT or expressed in word form, pressure times volume = the numbers of moles x the universal gas constant x the temperature. With a given quantity of gas, it can be summarized as PV=RT. (a mole is a quantity of molecules, not a ground rodent)
Please note this is an approximation which closely resembles air and other gases, but is not specific. There are adjustments to the formula for each gas: air, nitrogen, helium, etc. but for this type of discussion it's fine.
Hi-T, I think that there may be some confusion about intercoolers. In a turbo system, intercoolers work as an Air to Air heat exchanger, flowing compressed and hot INTAKE air inside, and cooling air outside...much like a radiator, only intake air instead of water.
The heat of exhaust is usually between 1200 and 1500 deg, depending on the original fuel/air ratio. Most turbo systems make big efforts to keep that heat from affect the relatively cooler intake air. The biggest heat transfer occurs at the turbocharger, itself, through the casing and through the turbine spindle shaft. This amount of heat is minor when you consider that compression of the intake air alone causes temps to climb to 350 Deg F or higher.
In a thermodynamic sense, heat and pressure are interchangable. A turbocharger thus exchanges pressure and heat of the spent exhaust gases for pressure and heat of the incoming gases. When doing this turbochargers can commonly see efficiencies of 50 to 60%. Quite high.
Bling!
Holy cow ... what an edumacation we are getting! Just kidding! It's a refreshing change from talking about carburator jets. Sounds like you know what you're talking about Bling! Thanks.
Rob
I would also imagine you have a Cap on the octane you can run, higher the octane the hoter the burn yes? Figure there is a point to which its the pistons start mushrooming, and heads start drooping do to heat.
The higher the Octane the hotter the burn = NO. High Octane does not burn at higher temperature. In fact, High Octane fuels have a greater portion of the "light fractions" of fuel, or in other words, have a greater portion of the fuels that evaporate faster, thereby igniting at lower temperatures.
These ligher portions are known mainly as the "Aromatics" because they are the ones you normally smell the most. They increase octane by vaporizing faster and allowing the burn to occur faster.
Gasoline is a chemical mixture of up 23 different chemicals. Refineries mix each fraction of chemical to suit the climate and law of the state or town that the fuel is going to. Also, the Petroleum pulled from the ground is much different from site to site. Therefore, the 93 octane I get from the station is NOT the same formula you may be getting. In fact, since most gas stations do not have octane testers, unsruptulous companies make profit by providing 91 octane instead of 93. Buyer Beware.
An Octane Limit? Short answer: I don't know.
However, since high octane fuels cost lots of $$$, this is usually not a problem.
"The higher the octane, the hotter the burn" comes from the fact that many racers who run high octane also have high compression engines, thus encouraging engine knock and higher cylinder temps. And THAT leads to holed pistons and toasted valves.
Bling!
So simply put, gas is gas (from the pump)- regardless of the octane # it should burn and produce the same amount of heat or energy. As compression increases, the temp inside the cylinder increases meaning that a higher octane gas will withstand the higher temp resulting from the higher compression/pressure and have a higher flash point.
So, an engine that runs lower octane and higher compression risks a trip to the moon because detonation can occur before the engine is ready for it... and with a higher compression you're dealing with more than just an average knock.
Now a gas molecule can only store so much potential energy- so by increasing the compression, we increase the number of potential booms (or molecules) that can fit in the cylinder... then by increasing the octane we control at what temp the boom occurs and make it more likey that all the booms occur simultanueosly.
Do I get it? ( really... Is this a sound understanding?)
So an intercooller is primarily used to cool the intake air into the engine. How much difference does this make? At what temperatures are there significant changes in air density? I assume there is a differance considering must turbos do have an intercooller.
Thanks Hi-T
i believe the of BTU's released during combustion per unit of fuel is what determines how much power you get out of gas, not the octane, but the rest sounds more or less correct to me. i'm sure our expert, bling, will chime in though.
Quote from: Hi-T...so by increasing the compression, we increase the number of potential booms (or molecules) that can fit in the cylinder...
Not really no. The compression is defined by the shape and dimentions of the combustion chamber (stroke, bore, crown and head essentialy). That volume doesn't change. You can change the density of the mixture going in with a turbo, super charger or other things, but this is not related to compression in this sense. Higher compression simply means that the pre-ignition temp is higher and thus easier to ignite and that all of the fuel molecules are as close together and ready to ignite each other (flame front and flame propagation).
Hi-T, it sounds like you got it for the most part, but that one point seemed to need a bit of clarification.
Wrencher - that makes sense to me- But...
A turbo/super charger is a forced induction system. It's purpose is to provide (ie, force) more air into the engine. If more air is added to the equation, then more gas is added too (espescially if we are refering to an 8 to 15 psi boost). That would increase the volume of gas in the cylinder and immediately increase the pressure felt within the cylinder.
So it seemed to me that with the added gas in the cylinder we are increasing the compression ratio (more gas in the same amount of space = higher pressure). So I think I just used the wrong wording.... let's try:
"So by using a turbo we are increasing the number of molecules (potential booms) in the cylinder. As a result the compression ratio increases. As compression increases, pressure increases. As pressure increases temperature increases. As temp increases the risk of preignition increase requiring the use of a higher octane fuel..."
or something.
Seriously, thanks for the input,
Dathan
Engines are mass flow machines. The more mass we can flow in a given time, the more power we can get out of them. More fuel and air at one time gives us more horsepower. There are two ways we can do this: increase displacement or increase the mass flow. Turbos increase the mass flow by compressing a large volume of air into a smaller area. Thus our 250cc turbocharged cylinder now has more mass of fuel and air that it has any right to and delivers more power.
Wrencher wrote:
QuoteHigher compression simply means that the pre-ignition temp is higher and thus easier to ignite and that all of the fuel molecules are as close together and ready to ignite each other
Wrencher is right that pre-ignition temps are higher. BUT, a denser fuel charge actually slows the flame front. While turbo engines have a higher effective pressure in the cylinder, they also have a MUCH longer burn impulse. This is another reason why Toulene in the fuel is so important (see prior postings).
Wrencher wrote:
QuoteThe compression is defined by the shape and dimentions of the combustion chamber (stroke, bore, crown and head essentialy). That volume doesn't change.
Wrencher....see my earlier post: Compression is Compression. Whether it happens in the turbo or the engine, the pre-ignition temperature and pressure are the same.
Hi-t wrote:
Quote"So by using a turbo we are increasing the number of molecules (potential booms) in the cylinder. As a result the compression ratio increases. As compression increases, pressure increases. As pressure increases temperature increases. As temp increases the risk of preignition increase requiring the use of a higher octane fuel..."
Correct. This is an accurate but very simplified expression of what is going on.
Bling!
Quote from: Bling!Wrencher....see my earlier post: Compression is Compression. Whether it happens in the turbo or the engine, the pre-ignition temperature and pressure are the same.
I did read the earlier post, and we seem to be saying the same thing. I was trying to point out the difference between the intake density (variable) and the combustion chamber's volume (fixed). :cheers:
Sweet!!! (I decided this year to go for MEEN- I might have a chance at making it after all) thanks Bling.
So that takes care of the "why" it works... so how about a little more on the how you got it to work. I'd like to see your turbo set up a little closer- some the part that were fabricated for the manifold and intake.
Later and thanks again,
Dathan
Intercoolers.
Intercoolers make a huge difference in the temperature of the intake charge. Because air from the turbo is heated from compression to 300 to 350 Deg F, unless we want to run extremely high octane, we try to cool it before the cylinder sees it. We do this with intercoolers.
An intercooler can drop the intake temperature from 350 deg to 160 or lower with the given conditions. They are dependant on the outside environmental air to soak away all that excess heat.
Here's the catch: as the temperature drops, so does the pressure. Then you have to increase boost pressure to make up for what you lost...and the temperature rises...etc...
What happens in reality, is that the temp and pressure increase simultaneously together. The turbo and the intercooler find an equilibrium which is determined by the amount of boost you have proscribed for the turbo. This simultaneous solution of the equations is known as a Gauss-Seidel iteration process. With it we approximate a solution for 3 equations and 2 unkowns. However, we just keep re-iterating until our values have more decimal places than we require or use.
Isn't it great that mother nature does this so easily?
Bling!
Dang- I had no idea that the intercooler could drop the temp that dramatically.
Do you use one on the bike?
Good Point Wrencher.
The great thing about turbos is that we CAN vary the amount of boost. We don't always want to run 15 psi, when 5 will do.
Hi-T: the cylinder is always moving, but the basics of science is that if you take a snapshot of one period, and another of a second period, you could draw a line between the two that describes the behavior pretty well.
So, more snapshots mean more lines, until you have a perfect replica of the behavior. This is what we do for engineering. take lots of snapshots.
Bling!
PS. Hi-T, how was that for your first Calculus class?
PPS. What's a MEEN?
Yes, its on the left side,
(http://www.gstwin.com/gallery/view_photo.php?set_albumName=member_bikes&id=abb)
Its the long silve rectangle near the cylinders.
i think this is the deepest most informational topic gstwin has ever seen. :cheers: At lest from my experience :dunno:
Ok, now, im not that savvy on CV carbs, Does not vacume raise the slides in thecarbs in relation to throtle plate position? if so, how do you keep the +boost pressure from compressing the diaphrams to into the the caps? i understood you haveing to reinforce them with tie downs do to the pressure. is the waste gate manualy controled by throttle or just spring pressure? would not Standard Av Gas have sufficed for your needs? it is a fuel designed for high compression engines.(namely Aircraft) How much over stock did you have to Richen the jetting?
so a simple home made kit say like a 1Liter Mitsu turbo from local junkyard, home made plumbing and oil feeder for bearing on turbo. running some Cam2 purple in theory would yeild some interesting results, makeing it reliable and predictable would require alot more homework and refining of the numbers. sound about right?
Blueknyt,
I don't have a lot of time today, but here goes...
Yes, Av Gas would work fine, It's just higher octane with more refining. The waste gate is controlled by boost feedback from the plenum. I have put a controlled leak into the feedback loop. This controlled leak makes the turbo think there is less pressure than there actually is in the plenum. This controlled leak is called a Dial-a-boost.
The carbs are sealed from outside air, so as far as they are concerned, the carbs are seeing regular pressure, and work normally. Under boost, though, the Density of air passing through is higher, and thus my need for jets that are 4 times larger than stock. I have needles from Factory and larger jets, and am still running leaner than I should...As a result I am considering converting to FI. FI would solve all this.
Quoteso a simple home made kit say like a 1Liter Mitsu turbo from local junkyard, home made plumbing and oil feeder for bearing on turbo. running some Cam2 purple in theory would yeild some interesting results, makeing it reliable and predictable would require alot more homework and refining of the numbers. sound about right?
Correct. That is basically what I did. A little more detailed though....
Bling!
Gotta go to work.... :)
Even without the turbo, we would all like to see an F.I. conversion. Figure an SV650 Based rig would be nice. Just outa curiousity, if a split plenum manifold was made for the GS wouldnt ONE 34mm carb not feed both just fine? Truth be told, only one cyl is drawing from the carb at a time anyway. i know the Rebel 250 works this way. but if talking FI or turbo, this would simplify a few things yes? instead of draw pulse being every other 720* it would be every 360* but still only feeding each cyl every 720* which would work better, piping and syncing 2 carbs/TBI's or 1?
(instead of draw pulse being every 720* it would be every 360* but still only feeding each cyl every 720*)
Do it yourself EFI info:
software - http://megasquirt.sourceforge.net/
computer - http://www.bgsoflex.com/megasquirt.html
Dana Goulston is in the process of adapting the Megasquirt system to his GS450 land speed racer. Unfortunately, he sent the system to someone for some tuning help and it has disappeared.
Anyway, if you want to learn EFI retrofit, join the yahoo group:
http://autos.groups.yahoo.com/group/megasquirt/
Lol. Dana Goulston and I have talked quite a bit... I have sent him everything I have on the turbo system....I think that is one of the reasons he was looking at EFI. He's a really nice guy...
There's a bit of an technical arguement about running 1 or 2 carbs. In theory, yes, 1 carb would serve both cylinders. However, when the 1st cylinders draws intake, the plenum pressure drops before the boost can recover, and the 2nd cylinder doesn't see quite as much mass flow into it. Therefore, the since the jets would be the same for both cylinders, the second cylinder is running slightly rich.
There's arguements both ways, and successful turboengines have been built both ways. The preference in the industry today is to have a separate carb for each cylinder to make tuning easier.
In truth though, ALL big engine builders prefer EFI with separate throttle bodies...It is much easier to tune with. EFI has it's own demons, though, that's why some manufacturers still use carbs.
Bling!
i'm not sure i follow your argument on the 2nd cylinder business. what happens when the first cylinder fires again? suddenly, it's firing after the second cylinder, and now it's got the same A/F mixture. unless i'm missing something about the phase between the two cylinders.
on a side note, a lot of turbo cars just use bigger plenums, so the pressure doesn't drop as much, and you allegedly get better throttle response.
Since most twins fire in an asymetrical order "1,2, wait, wait, 1,2...", the plenum can suffer a slight pressure drop for the second cylinder and the 1st cylinder gets a chance to recharge.....Remember that air has some inertia and takes that split milli-second to get moving and fill the plenum.
To answer the question about the plenum, simply take the idea to extremes...if the plenum was the size of a soda can, even filling of one cylinder will drop the pressure substantially, but turbo lag vanishes. Conversly, if the plenum was the size of a living room, filling a small cylinder would not dramatically drop the pressure, and turbo lag is monumental. For road racing, smaller plenums are preferred, while drag racers prefer larger plenums. The industry trend right now is for the plenum to be 3 to 5 times the displacment of the turbo.
Remember that throttle response is NOT, repeat, NOT the same as turbolag. The throttle response how long the engine takes to respond to the pressure already inside the plenum, while turbo lag is the time it takes for the turbo to bring the plenum up to pressure again. NOTE: there is a critical engine RPM required before the turbo will be able to pressurize the plenum AT ALL. This is the "critical boost RPM" or the "Boost Threshhold" when plenum pressure is more than atmospheric pressure.
This also leads me into the little known fact that on a standard turbo system running at less than the critical boost RPM, the plenum can actually be at a lower pressure than atmospheric, because the turbo is acting as a restiction of the intake (much like a closed throttle). Advanced turbo systems have a 1-way opening to allow atmopheric air into the plenum at low idles.
(http://www.gstwin.com/albums/member_bikes/abb.jpg)
(http://www.gstwin.com/albums/member_bikes/aba.jpg)
Are you talking about this bike, from the WOF?
yes. thats my bike.[/url]
MEEN = Mechanical engineering. It's the coding that the schools here in Utah use. Actually, I've taken calc a couple times now. And the deeper I get into it the more I can see that it has real word apps... go figure.
Thanks for the lesson in turbo charging physics. If you have a picture of the plennum, that'd be nice too.
Later,
Dathan
bling,
quick ? about intakes in general. would it be better to have a intake that is fed from the side(most cars) or straght through and branch out into individual runners. Kind of like a header(4-2-1) but in the opposite.
also, In your opinion should the Pent. be the same size all the way across. I've seen some that tapper at the other side. I had two ideas on this last ccylinder will not get as much as the other/ it's smaller becuase it'll force the air into the cilinder because it has no where to go.
sorry if it's too off topic.
thanks in advance....
albert
Shapes of Plenums:
Generally the best plenums are those that allow the intake flow to maintain its momentum and flow directly into the cylinder. While the "Best" shape is a subject of long debate, one fact is clear: the intake should never blow across the inlet of the carbs or throttle body. This would have a venturi effect and substantially reduce the pressure seen by that carb. Much like the old laboratory vacuums that worked by flowing water by a small hole hooked to a hose. The carbs would suffer the same effect to some extent.
I should say that I have seen plenums that taper and those that don't. While a tapered plenum would stand a better chance of being correct, only flow testing can tell the truth. Generally, even with flow prediction software, airflows are a little tricky and can be potentially unpredictable....Just ask the Aviation Industry..:)
Bling!
I've got a few questions now, after reading along for awhile!
How does the system keep at a certain pressure? Is there some sort of blow out valve that only works when a certain pressure is reached? Without this i would assume the turbo could just over pressureize and explode things :( .
Another thing, while we're on the topic of air and whatnot. Would adding a ram air intake do anything at all? Probably does the same stuff as the turbo only just at high speeds. (I think I just awnsered my question)!
Oh well, I'll think of more!
The system maintains a certain pressure two ways: by using a waste gate and a blow off valve.
The waste gate is a short cut for the exhaust to avoid going into the turbo. The waste gate receives a pressure feedback from the plenum and a small pressure diaphragm opens the waste gate at a preset pressure (set by the amount of spring force upon the diaphragm). The exhaust's heat and pressure energy is wasted...thus the name.
The blow off valve is a secondary protection. It is simply a pressure valve like a radiator cap set to a couple of PSI over the desired boost pressure. It normally does nothing. However, when the engine is at high RPM and the throttle is shut, pressure builds up quicker than the waste gate can dispose of it. When that happens the blowoff valve pops open and vents. This normally happens when a highly tuned car or bike is at WOT and shifts gears....you hear the engine whine up and then a "pfooshhissstle". Some of the more trendy tuners put a horn on the waste gate to make more noise. :roll:
To compare Ram Air to Turbos, a turbo system typically adds 5 to 15 psi to the intake pressure. At 150 MPH Ram Air effect is 0.5 psi. The reason it has become so popular with bikes is that the new 600s and 1000s are so closely matched in engines and powermaking that the 0.5 psi can mean 1 or 2 more horsepower at high speed. It also looks cool, and sounds good in the Ads, which sells more bikes. "He's got it, So I gotta have it, too"
Bling!
this is a little off topic, but what do you know about pop-off valves? i've got a blow off valve on my turbo supra, but am looking for something that will give me more protection from overboosting. there's an adjustment spring on the blow-off valve, but no real way to set to a specific PSI. know any good ones?
thought up another one!
What would happen if you had 2 turbos? (Or one for each cylinder) Would it not get enough exhaust pressure/speed to spin up enough to create pressure? Would it eliminate the little bit of pressure loss for the 2nd cylinder?
Do they just do twin turbos on cars because they have lots more cylinders and the pressure would drop too much? Sidenote on that: Do the turbos both feed all the cylinders or do they each feed half? ect.....
What else..... I guess thats all for now! :mrgreen:
Im currently (well on winter break still) going to school to become either Mechanical Engineer or Aerospace Engineer (both are same till like 4th or 5th year). And yes, its a 5 year program here because we get co-op added into half the 4th and 5th years! I really like learning about anything mechanical, I've been itching at buying an old engine or something and tearing it down to see if i can get it back togeather and working!
most twin turbo setups, in fact, all the ones i know of, both turbos feed all the cylinders. you see a lot of twin turbos on v-configuration engines because it's easier to route the piping. the twin turbo setup on my supra is sequential, which means the one turbo comes on first for quick response, the other comes on at higher rpm for more top end power. most twin turbo setups, the two turbos just run in parallel.
two turbos on a 500cc engine would probably be a bad idea. more displacement spools the turbos quicker. you would need two VERY small turbos to be worth while on a gs. as far as i know, there isn't any real advantage to twin turbo setups over a comparable single turbo, unless it is a sequential setup, or you can't find a single turbo that is big enough for your needs.
Ok, still pinballing the Megasquirt FI bit around in the brainpan. thinking of what to use for the Thottle bodies. was thinking of some Guted stock carbs, basicly pluging over all air/fuel porting save for air bleed for idle. working a custom top cap to hold an injector and having it aim down where the neddle slide would be. OR make a manifold and bolt a 2bbl tbi from a small car engine engine. Could use a single TBI and a custom plentum box. still, no coolent temp, unless one is rigged to run off oil temp. O2 sens woudlnt be an issue. hmmm, Bling? any free radicals shorting amungst your nuerons?
I' try to respond to all the Q's today, from easiest to hardest.
For fuel injection, you could convert a carburetor. Certainly, many people have. However, if you look, there are a ton of throttle bodies available already. What does the SV650 use? Injector placement is easy, just drill a hole where you want it, and reinforce the mounting....The hardest part will be routing and mounting the pressurized fuel rail. The easiest set up i could think of would be an injector after the throttle body, and use an electronic system to measure O2 and exhaust temp. (that's what you really want to know, anyway.)
Twin turbos serve several purposes on a big engine. The foremost is the reduction of turbo lag: it is faster to spin up to little turbos than one large one. The cost is that the twins usually peter out at the higher engine RPMs where a large turbo would just be hitting it's efficiency zone. Thus the preference in drag racing for super large turbos. Problem is, it can take forever to spin them up; this is not good for street applications.
Second, two smaller turbos working in tandem at, say, 65% efficiency, are better than a larger turbo handling the same volume at 55% efficiency.
Optimum, for multiple setups, is the sequential system where one small turbo works for low RPM and a slightly larger one joins in for the High RPM. You need more advanced controls for this, and special gates and valves for this setup. Usually, only the pro builders can afford to spend this sort of money.
Some engines separate the sides into mini turbo systems, with one turbo feeding each side. This is really more of a packaging issue, and doesn't really add a whole lot to the system.
There are some VERY small turbos out there, but since they are hard to find, and the graphs for them are even harder to find, most small engines use a larger, more common turbo - like the Garrett series I have.
Now, Pop-off valves are typically, but not always, set by a spring on the inside to blow off at a certain pressure. If your blow off (pop off) valve is set too high, you can either reset or cut the spring to adjust. Some valves can be screwed in or out to set the pressure. Turbonetics, Inc. makes a really nice one for about $100. Also, not only must the valve open at the right pressure, it must vent enough air to decompress the system. If the valve is not big enough, then some big turbos can open the valve and STILL pressurize the system. Dangerous. Make sure that your blow off valve is big enough. There usually is some flow rating for them. They should at least match the flow of the turbo at highest efficiency.
WheW! I'll check back later.
Bling!.
PS. Lots more can be said about EFI and Blow off. This is just a light touch.
gonna have to disagree with you about the twin vs. single turbo setups. it is true that you *could* have a twin turbo set that spools faster than a single turbo setup. it's also true that you could have a single turbo setup that spools faster than a twin setup.
i think we can agree that two small turbos, that are less than half the size of one larger turbo has less inertia, and therefore quicker spool. let's say they have half the inertia (which we can agree is NOT true, they would have less, but it makes my math easier). now you are splitting the exhaust gas in half to spool two turbos, you would get identical spool. if you made those turbos any bigger, they would spool slower than a "double" sized single.
anyway, this argument could go on and on, but i don't feel it's accurate to say that a twin setup will outspool a single setup. that's too broad a statement.
on sequential systems... optimal would be truly sequential unequal sized turbos but that is extremely complicated (one turbo comes on first, and as the second comes on, the first shuts off). the stock turbo setup on the supra has two equal sized turbos in a quasi-sequential arrangement. (one turbo comes on first, then both) it's not as good for high end power or low end spool as an unequal sized setup, but the tradeoff is, it only requires one (maybe two) valve(s) to operate. for anyone that interested in a true sequential, unequal sized turbo setup, there's a good thread somewhere over at supraforums. if i can find it i'll post a link.
next... the pop-off valve. maybe i've got my terminology wrong, but you seem to be using the term blow off valve and pop off valve interchangeably. the blow off valve i have is not actuated by boost pressure. it's either vaccuum actuated or actuated by the change in pressure, and so adjusting the spring doesn't <edit>change</edit> at what pressure it blows off. (hks super sequential BOV) i'm looking for something more like a wastegate, only for the compressor side, not the exhaust side.
Jiggersplat,
The rotating inertia of an object increases with the square of its radius. This is the reason two smaller turbos spin up faster than a larger single one blowing the same volume and pressure . For a quick example, the moment of inertia of a sphere is I=2/5 x Mass x Radius squared. Thus, in the two turbos, the moment if intertia is double, in the second larger turbo, it is squared. I realize we agree, but I wanted to support my statement.
"Pressure is pressure" whether positive or negative. the blow off valve is simply a pressure differential system. Vacuum operated blow off valves have a lead to the intake after the throttle and before the valves, to draw off the vaccum there. the differential pressure in the valve works against a spring inside to open the valve. Trust me, there is a spring in there, whether it is metal or just a stiff rubber diaphram, there must be a force to return the valve to close. (no use having a valve that opens at just 1 psi differential, either) Another type of blow off is simply a static pressure valve as part of the plenum, and uses outside air. This is an absolute pressure blow off. This is what i was talking about. They are both the same thing, just receive pressure (or lack of it) from different sources.
Corky Bell, a renowned Turbo Engineer, has written a book called "Maximun Boost". Corky has laid out the basics very well, based on true science. He also has a website where you can glean more info. For a pictoral explanation of what I'm talking about, I suggest that everyone go pick it up. It's about $22 at barnes & Noble. I don't mean to Hawk the book, but it really is the best source of general information in one place.
Bling!
i think the SV 650 uses a larger diameter TB. main reason i was thinking Moded carbs, they are perfect fit, airflow is designed for that engine, plumbing shouldnt take up any more space then standardlines already do.
i think i have a trashed set that i can play with, wouldnt need a hardline for fuel rail. perhaps (depending on pump) 2 threaded injectors with braided lines.
ok yea but i thought you were goin to post up some vids of your bike.
on the twin turbo versus single turbo issue.
In the case of a two cylinder motor. Two turbochargers in parallel would not be a good idea. Exhaust timing is a big factor in getting turbochargers to spin up and stay that way.
In the case of a harley davidson. With it's odd (from an exhaust builders standpoitn) exhaust timing. It's possiable to actually have air in the plenum stall and even reverse the spin on the turbocharger. The more even the exhaust pulses, the less time the turbo has to coast on it's own. And the faster it will spin up, and stay up.
If you had two turbos on a gs500. You'd have ages between exhaust pulses. At that point I might even considder using a flapper valve to prevent backflow from the pleanum into the turbo.
Sequential turbos "might" have a place. But unless you need instant boost responce I can't see it being a real issue on a gs500. I mean, look at our example. 45psi, single turbo. How's the lag? I have this funny feeling out engineer friend matched his turbo right so there's almost no lag whatsoever. Between that and a properly sized pleanum you're sitting pretty.
Staged turbos.... Well if you want 150psi manifold pressure, that's the only way to get it ;-)
Course, if your biggest concern is boost responce, your best bet is to run a small pelanum. And run multiple throttle bodies. One on each side of the turbocharger. This stalls the compressor when you shift. Stalled compressors use less energy than one actively compressing so the turbo doesn't spool down as much in the meantime. Blow off valves are often rigged to simmilar effect. By dumping pleanum air between shifts you can reduce energy lost as well. (turbo isn't trying to pump against 15-45 psi...)
Isn't the rate of spooling effected by the angle of the vanes, and to prevent overspooling at low rpm's you increase the angle so the turbine is essentially less effecient at lower rpm's and only reach their maximun effeciency at the desired rpm?
Quote from: BlueknytOk, still pinballing the Megasquirt FI bit around in the brainpan. thinking of what to use for the Thottle bodies. was thinking of some Guted stock carbs, , Bling? any free radicals shorting amungst your nuerons?
I believe Dana used throttle bodies from a 550cc (or thereabouts) snowmobile.
FWIW Dana doesn't park here anymore...
Quote from: DomIsn't the rate of spooling effected by the angle of the vanes, and to prevent overspooling at low rpm's you increase the angle so the turbine is essentially less effecient at lower rpm's and only reach their maximun effeciency at the desired rpm?
Yes, no, no. :-) Yes, the "vane angle" Actually A/R ratio of the turbine housing changes the efficancy and gas flow required to spin the compressor up.
No, the turbine housing isn't changed to alter compressor speed. Though it can be used to rig a turbo setup that won't overspeed. But usually the wastegate is used to to prevent compressor overspeed. And more importantly to control boost pressure.
Overall system efficancy is affected in part by the A/R ratio. By incresing backpresure on the engine or reducing backpressure. But that's a byproduct, not a primary function.
a lot of the new turbodiesel cars here use turbo's with variable vanes. It's used to let the turbo spin up at lower speeds. Maybe they're even usable on GS500's. The turbodiesel engines for cars here are mostly 1900 cc, but they operate at much lower rpm. The turbo works really well at 2000 rpm, so it will probably work also on the GS when it's at a higher rpm.
Quote from: Blueknyti think the SV 650 uses a larger diameter TB. main reason i was thinking Moded carbs, they are perfect fit, airflow is designed for that engine, plumbing shouldnt take up any more space then standardlines already do.
i think i have a trashed set that i can play with, wouldnt need a hardline for fuel rail. perhaps (depending on pump) 2 threaded injectors with braided lines.
You're right, SV650 has 39mm throttle bodies... If you figure out how to convert the carbs, please let us know! :)
I think I'll be looking out for soma carbs on E-Bay! :)
D.
Hmm, Kawasaki Z750 is using 34mm throttle bodies... If they are individual they could be usefull.
D.
i know honda produced the CX500 turbo, 500 twin, dont remember what they used for fuel deliveery, what about making a plug to take the place of the slide/needle but not extending down infront of the butterfly, caping off the "Jets" effectively making the carbs JUST throttlebodies, and then mounting 2 injectors in a angled plenum box.
I hope somebody does this and we dont just keep talkign about it
Hi Guys,
Although this is quite an old thread I found it irresistible to respond, I even became a member for this purpose. ;)
I've built a Suzuki GSX 1168 Turbo a while ago, (which is technically really double a GS500) and solved the carburation issues you people have perfectly. And no, the solution was invented by someone else, so don't turn me into some kind of guru cos' I'm not. See my webpage for full report. :thumb:
The basics of a turbo are quite clear to you. Put a turbo on, build a plenum, connect them, then what?
:dunno:
You need a fuel pump and regulator to keep the fuelpressure of the carbs above boostpressure. I used these off of a Yamaha 650 turboseca, they are all over ebay and cost next to nothing.
You have to make a connection to the inlet of the plenum with the open end of the tube facing the airstream, so you get a ram-air boost compensation. This connects to the T of the floatbowls and pressurises them. You will want to replace the o-rings on the T-s because they will leak making the engine run really bad.
Now, you can run the bike with standard ignition, compression and even standard neeldes and jets. Put an A/F meter in the exhaust to monitor fuelling, you will see a slightly rich mixture, which is good. Put a turbo on it off of the same Yamaha XJ turbo if you can get one or maybe one off of a Ford Fiesta RS turbo (a Garrett T2) and run it no higher than 7 psi boost. Now you have a bike that will run as sweet as a babies behind and make serious power. :cheers:
Greetz, Marco.
http://home.wanadoo.nl/marcovandevelde/turbo%20GSX.htm
need to dispel some myths that SOME PEOPLE on forums are pounding into your head. peep this:
"turbo boost isn't the same as increasing compresson in the cylinder...turbo engines don't require race gas but engines with high cylinder compression have to use race gas"
-what the hell ever gave you that idea? Think about that realistically and see if it makes sense? This is why forums are dangerous. People who are stupid listen to people like you that don't know what they are talking about. If you want to learn so you can spout bullshit, read a book!!! Learn the stuff, don't say it if you don't know....
Assume = Ass U Me
"you don't have to run race gas to increase turbo boost....i'm not a turbo guru but i know some thing about turbos....me and my friend took his VOLVO turbo and increased the boost from 5 to 24 PSI and he was running 91 octane gas....it would backfire from time to time but it ran good"
-Lol, aside from the knock sensor retarding timing and the fact that it probably has an electronic boost controller to let off bost after 7 or 8 psi when knock is detected (if you were looking at the stock guage just shut up righ now, you weren't even running 24PSI) you won't make any power running that far out of the efficiency range of the turbo, in fact you will probably make LESS horsepower heating the turbo up so much and doing all kinds of horrible things to it. Shame on you!!!!
"Two things. One: compression is compression. Since turbos provide pressure by compressing the flow of air, this must be multiplied by the engine compression to get true compression. Ex: a turbo blowing 15 psi gives a compression of ~ 2:1. This goes into an engine that compresses the mix 9:1. Therefore, the true compression is 2/1 x 9/1 = 18/1 or 18:1 compression.
Since this vapor pressure of fuels is dependent upon the absolute pressure, and atmospheric is 14.7 then 18:1 compression gives a before ignition pressure of roughly 260 psi absolute. AND using the approximation of the Ideal gas law (yes I know air is not ideal, but close enough) this also gives a temperature of the mix, prior to ignition, of approximately 600 deg F. This is localized temperature within the gas cloud, and is only an ESTIMATE. I am not going to get into an arguement about the Gauss-Seidel iteration process required to find the true temperature and pressure.......Whew!. "
-Just flat out wrong! you forgot to take into account the turbo when you wrote that. Hmm.... lets see! different turbos have different compressor wheels efficiency ranges (re: PSI and engine size). TD05-12A 15PSI = 320CFM TD05-19C = something like 600CFM at 15PSI.
Dammit, RTFM!!!!!!!
Dammit, RTFM!!!!!!!
Dammit, RTFM!!!!!!!
Dammit, RTFM!!!!!!!
"Also the volvo was water cooled wasn't it. Air cooled is basically like playiing roulette compared to water cooled. Steady temp, no uneven hot/cold spots and a well defined range of temperature. Cool. Srinath."
-Nope, F watercooling. water does not compress like gases do, you get enough CCs of water in there and your piston will stop moving, but your crankshaft won't (get the picture)? A good intercooler such as a PWR unit will do much better on a turbo engine than just water cooling.,
"Ah. Well....I'm a mechanical engineer with a specialy in dynamic systems of pneumatics and hydraulics. I work for an Aerospace company as a manufacturing engineer. But, mainly I trained under Proffessor Bob Woods at University of Texas at Arlington. An outstanding professor with an drive for racing. Under his guide, the UTA racing team has won more of the Formula SAE competitions than the rest of the world combined. "
-Did you say you had a degree? Jesus, I learned all this from reading books and working on turbo cars. Wait, you work on hydraulics not turbo cars.... oh yeah... that makes sense why you know so much about turbos!!! (not shooting on you, just showing people that you can't listen to forums)
"In a thermodynamic sense, heat and pressure are interchangable. A turbocharger thus exchanges pressure and heat of the spent exhaust gases for pressure and heat of the incoming gases. When doing this turbochargers can commonly see efficiencies of 50 to 60%. Quite high. "
- hope you bought that turbo off ebay and you plan on getting it rebuilt! I 15 year old turbo volvo sees higher efficiency ranges than that (funny thing is you make it sound as though this efficiency range is a constant however it depends on the PSI created by the turbo and what RPM the motor is at as well as the actual flow of motor components and the CFM needed to keep the motor running at the specified RPM)
"The higher the Octane the hotter the burn = NO. High Octane does not burn at higher temperature. In fact, High Octane fuels have a greater portion of the "light fractions" of fuel, or in other words, have a greater portion of the fuels that evaporate faster, thereby igniting at lower temperatures.
These ligher portions are known mainly as the "Aromatics" because they are the ones you normally smell the most. They increase octane by vaporizing faster and allowing the burn to occur faster. "
- you contradicted your previous statements about high octane fuel. this is the opposite of what it was intended to do. The high octane fuel is made specifically to be HARDER to ignite inhibiting pre-ignition aka DETONATION which is the *only* factor that will melt pistons
*exceptions being things such as not putting oil in your car and running 25 psi on a turbo that stops being efficient after 15psi
"Not really no. The compression is defined by the shape and dimentions of the combustion chamber (stroke, bore, crown and head essentialy). That volume doesn't change. You can change the density of the mixture going in with a turbo, super charger or other things, but this is not related to compression in this sense. Higher compression simply means that the pre-ignition temp is higher and thus easier to ignite and that all of the fuel molecules are as close together and ready to ignite each other (flame front and flame propagation). "
-wrong again man..... compression has NOTHING to do with the "pre-ignition temp" being higher and eaiser to ignite! A turbo is an air pump which delivers a large amount of compresed air allowing you to burn more fuel in a (hopefully) controlled way, although if people keep listeing to you, i am going to dive out of the way whenever i see a bike on this forum going by.
"Wrencher - that makes sense to me- But...
A turbo/super charger is a forced induction system. It's purpose is to provide (ie, force) more air into the engine. If more air is added to the equation, then more gas is added too (espescially if we are refering to an 8 to 15 psi boost). That would increase the volume of gas in the cylinder and immediately increase the pressure felt within the cylinder.
So it seemed to me that with the added gas in the cylinder we are increasing the compression ratio (more gas in the same amount of space = higher pressure). So I think I just used the wrong wording.... let's try:
"So by using a turbo we are increasing the number of molecules (potential booms) in the cylinder. As a result the compression ratio increases. As compression increases, pressure increases. As pressure increases temperature increases. As temp increases the risk of preignition increase requiring the use of a higher octane fuel..."
or something.
Seriously, thanks for the input,
Dathan"
-Beautiful, starting to get it....
"The great thing about turbos is that we CAN vary the amount of boost. We don't always want to run 15 psi, when 5 will do. "
- if you only understood a turbo you would see why this statement is just plain incorrect. Sure you can run 5 psi of boost, but you will see a 30efficiency range versus 60-70 at 10psi (depending on turbos)
" The waste gate is controlled by boost feedback from the plenum. I have put a controlled leak into the feedback loop. This controlled leak makes the turbo think there is less pressure than there actually is in the plenum. This controlled leak is called a Dial-a-boost. "
-LOL, ever hear of boost spike?
I am sorry, i CANNOT read anymore. It's hurting my head from hearing so much crap spewed from other forums. If you want help making a turbo system work let me know. I can do it for you in a jiffy and it won't be engineered by someone who got their degree online! LOL. if you have any questions or flames, PM me so i can help you.
this place is like initial D, you can't downshift into every turn 50 times! there are only 4-6 gears!!!
Wow that was a long post. First part seemed interesting but Im to tired to read all that, lol.
I understand your response. I agree there is a whole lot of waste that is inherent in the very structure of a forum. Get 100 people together, 95 won't know whether what the other 5 are saying is correct or not.
"Also the volvo was water cooled wasn't it. Air cooled is basically like playiing roulette compared to water cooled. Steady temp, no uneven hot/cold spots and a well defined range of temperature. Cool. Srinath."
-Nope, F watercooling. water does not compress like gases do, you get enough CCs of water in there and your piston will stop moving, but your crankshaft won't (get the picture)? A good intercooler such as a PWR unit will do much better on a turbo engine than just water cooling.,
I agree with you on the water vs air intercooling, but Srinath there was talking about a WATER-COOLED BLOCK. NOT water injection/INTERcooling vs air to air methods.
Just thought I would point out that Srinath was in fact correct in his statements.
EDIT:Fixed grammatical errors.