Hey guys, as some of you may remember I am currently designing and building a turbo-kit for the GS for my senior design project. Most of the fabrication is complete, however, I still need to run the oil lines, re-jet the carb, and tune it. The link below shows some pics that I took today. Let me know what you guys think. Also looking for feedback for running the oil inlet line. Thanks guys, Enjoy!
http://pg.photos.yahoo.com/ph/bobbygianfagna/album?.dir=/e702
-Bob
Very cool, how does you knee fit in there though?
My knee is about 5-6" at closest from the downpipe. I am either going to make a heat shield or wrap the exhaust
pretty sweet. that thing should haul ass when your done. don't know if you are gonna be able to lean that far in turns though. keep us posted. would love to see a clip of her in action. nice work. :thumb:
Handling will most likely be hindered...though the turbo should make up for that with its "cool" factor...jk
Anyway, I'm still looking for some pointers on jetting and oiling the turbo. Any input welcome!
Jetting? Can't help you there, but I like.
GS Turbo. Crazy.
I'd do a 8 inch over swing arm, lower the back with longer dog bones, and slide those forks down in the trees and you'd have a bona fide GS drag bike like nobody has ever seen!!!
Se7enty7 knew of a place to plumb that oil line. He may have already told you about it when you first posted a couple months ago. I seem to recall him posting a photo of a place that has oil presure that you could run the oil line from or maybe he just told you. He sold his GS though, so he may have taken his knowledge with him and gone home. . .
a couple of questions....
why did you go with suck thru instead of blow thru?
why did you stay with the TINY GS stock carb?
what kind of pressure are you expecting?
BOV set at?
what turbo did you use? (it looks big)
what power did you design into it....expected power?
where did you get the flex pipe?
otherwise....kewl project
Nice progress.
Werase brings up a good question with the suck v.s. blow. With the blow-thru you are likely to get a more predictable mix, whereas with the suck through you are more at the mercy of unexpected turbulence and air volume/mix changes that will vary due to the ram-air effect. The ram-air effect might work in your favor at higher speeds, though working in the capacity of a supercharger.
Cool. Another turbo GS. heh
Have you adjusted the compression ratio? I think I'd cut down the piston face or make some new rods and run boost to bring the BMEP back up. More power due to a change in slope of the expansion pressure curve, no increase in peak stresses on the head / bottom end. Low boost / high volume is easy to regulate too.
Running increased cylinder volume could cause some exhaust valve torching / flamelets out the stack though but that's easily fixed. Might talk like a Merlin with transport heads and 10 less cylinders too. That could be a good thing. :mrgreen:
Keep us posted! :)
he wanted to keep it simple.
i can see the logic but having a hard time discribing so here it goes.
only so much air will flow into a Naturaly asperated engine at one time its messured in CFM (Cubic Feet per Min)
to get more air to pass through you either have to open the hole or setup a pressurized source.
the atmosphere is like what 14.7psi at sealevel?
so in truth right off the bat you have 14.7 psi flowing IN and size of opening allows so much CFM when the piston creates the vacume into the cyl.
now, with a turbo pulling air from outside, its still only 14.7psi pushing through the carb, i dont think the CFM increases (but could be wrong)
i dont know if jetting would change all that much in relation at this point.
IF however the turbo is Blowing through, By increasing the pressure you can increase the CFM flowing through same size hole, but being as it IS more air you have to increase the Fuel to keep the Mixture proper
ok, i think i have reached the end of my Pneumatics physics knowledge and shaky at that, someone with more Turbo knowledge step up and correct my mistakes please. I will be taking notes.
Suck thru set-ups are a lot easier to fab up. You don't have to worry about equalization of pressures in the carbs and you don't have to worry about supplying extra fuel pressure to overcome the difference in ambient and compressed air. As for the lube to the turbo you could maybe tap into the gallery used for checking oil pressure? And then maybe tap into the rockerbox for a return...or maybe return it directly to the oil cooler, I would think that might be best. I wonder if you could use an electric pump for the turbo, with it's own supply tank and cooler? That way, when you shut off the bike you could continue circulating oil to the turbo till it cooled somewhat to prevent coking of the oil in the turbo itself. Could maybe use a temp switch to shut off the pump when it cooled down. Should be a Great White Owl when it's finished. Love the little GS bikes and this forum.
C.......
Answering these questions
a couple of questions....
why did you go with suck thru instead of blow thru? simple, much cheaper
why did you stay with the TINY GS stock carb? the carb issue will be trial and error I believe, drawing through the carb it is possible to run the same size carb or smaller. I am reading as much as I can. Taking the cross sectional areas of both stock carbs you'd need one 48mm carb to cover the same area. This seems very excessive and drawing through it is easy to "over" carburete engines
what kind of pressure are you expecting? the internal wastegate is set at 8 psi
BOV set at? the system does not have a BOV, remember you're drawing air and fuel through the intake piping
what turbo did you use? (it looks big)-IHI RHB52, with a smaller turbine housing that has been bored and the radius has been changed to not interfere with the original impeller. This will lower the A/R and help the turbo spool quicker
what power did you design into it....expected power? @8lbs, somewhere approximately 70hp
where did you get the flex pipe?-this was actually fabricated by this Lanco's Machine Shop where the rest of the piping was fabbed. If anyone needs anywork done at all I have been EXTREMELY pleased and impressed by the detail, ability, and price that this shop (Lance Corsi) has to offer and I'd be glad to recommend him to anyone needing various fabrication, machining, or welding done. He really knows his stuff!
What is BOV?
Blow Off Valve, it makes it so the turbo can only push so much boost into the engine by opening when a certain pressure is reached. Also it helps keep the common shaft from breaking when letting off the throttle during shifts and the such. The turbo will spool up and keep creating boost even after letting off the throttle, only for a second, the boost then has nowhere to go as the engine is now "closed" so the pressure basically goes backward and will try to spin your turbo the wrong way and can break the shaft.
if you did decide you need a BOV then you could put it after the head on the way to the exhaust side of the turbo, that way you wouldnt have to worry about blowing out the fuel air mixture.
so your basicly going to rely on just the throttle plate and wastegate to govern the turbo? your setting the throttle up as push/pull i hope.
just an afterthought, might want to run the valves alittle on the loose side of the specs for the extra heat. Taping into the Main oil galley below the clutch sidecover, (not the oilpresure sending unit) would work, i would also add in a small oil cooler to help keep the beast from melting.
Did you do anything to decrease compression, ie., thick stainless head gasket?
If you can restore the lean angle I will be more interested, but since I am a knee drager, it just wouldent make sense.
Sure love the idea of a turbo GS!!
The engine and drivetrain are being left stock. Our stock compression ratio is 9:1, I've calculated the effective compression ratio to be 11.5:1. This is reasonable, will obviously at least require 93 octane though. [/list]
I know for cars the cap for compression ratio on blowers and turbos is 9:1 with 6:1 being widely agreed upon as the "magic number" so 11.5:1 seems a little high, but singe our bikes redline at 10k the ideal compression ratio might be bumped up a bit as well.
Just wondering why you didn't utilize any of the space behind the carbs? Without the airbox it's pretty much empty. Understood that when plumbing the intake manifold running pipes back any further than you did you would risk some leg burns, but that could have been alleviated with some pipe wrap. I imagined running the headers down each side into the turbo which would be placed directly behind the engine, but then again, you proly thought of this all and came to the conclusion that it was unfeasable to mount the turbo anywhere other than where you did.
Mounting the turbo on the right side was not my original plan. Originally I had wanted to mount the turbo in original location of the airbox. However, there simply is not enough room. The space narrows to about 6.5" there, which is not much more than the turbo. Also you'd have a very very hot turbo right under your seat and next to the battery, not exactly ideal. Also, I wanted to keep the manifold as short as possible, the longer then manifold and more bends, there would be more pressure, friction, and temperature losses. I believe you could mount the turbo right in front of the engine, but you'd have to modify the frame to fit it, and probably use a smaller turbo.
Like I said before, this is for my senior design projecttat for school. Being that it will determine if I get to become a real mech engineer, if there aren't calculations showing my reasoning, there are at least logical explanations.
Anyway, still looking for help with jetting and oiling!!
Quote from: 94gsriderThe engine and drivetrain are being left stock. Our stock compression ratio is 9:1, I've calculated the effective compression ratio to be 11.5:1. This is reasonable, will obviously at least require 93 octane though. [/list]
(14.7 PSI + 8 PSI)(9.0) = 204.3 PSI
204.3 / 14.7 = 13.9
13.9:1 is the equivalent compression, which is on it's way into Diesel territory. 13.9:1 will autoignite gasolines.
Another thought comes to mind in deciding how high to run this thing. At an effective compression ratio of 13.9:1 you're seriously eating into the safety factor of the cylinder head bolts and main bearing cap bolts, which I wouldn't suspect is over 2:1 anyway. I'd be worried about plastic deformation of the bolts or their threaded holes leading to a blown gasket or thrown crank. In fact, I wouldn't assume that the threaded holes for the cylinder head bolts are capable of bringing the bolts to plastically deform. There may not be enough thread engagement there.
Just curious.