Custom Motorcycle turbo

[Billy Golightly]

I'm thinkin about trying to buy and plumb a turbo onto something that was never intended to have one :-laf Its 500cc Honda CR500 dirtbike engine it produces about 60-65hp stock. I've looked at the Garrett GT-12 online and its about the closest thing I've found to what I need. Are there any other models about that same size from the different brands, preferably not with a waste gate setup?



Also, any thoughts or input from anyone on how to go about plumbing a carb in? From what I've read there is pretty much two ways. The first is the blow through where the turbo pushes air into the carb and from the carb into the intake. Carb would be a pain to tune with the constantly changing volume of airflow. It would be impossible to jet it where it was at the right AFR all the time.



Or, the suck through method where the carb is first in line and more or less mixes the fuel and air into the turbo. It doesnt atomize well though and the fuel/air seperate alot, I've even read stories of the raw fuel puddling in the turbo.



Does anyone have any experience or information on a project like this? Couple of books on the theory if nothing else I guess?

 

[nickleinonen]

Carb would be a pain to tune with the constantly changing volume of airflow. It would be impossible to jet it where it was at the right AFR all the time.

it should be ok to tune a turbo/carb setup... blow through is a better design i think, but the carb needs to be completely sealed in a box so the boost pressure is outside the carb and down through the barrels

It doesnt atomize well though and the fuel/air seperate alot, I've even read stories of the raw fuel puddling in the turbo.

i think the turbocharger compressor wheel would atomize/mix the fuel/air very well. . ?

 

[Rman]

Some friends of mine have turbo'd 4 wheelers and fuel injection becomes a must. Carbs simply can't supply enough fuel. The carbs on bikes are just too small, you can empty the fuel bowl pretty quick, with gravity fed fill up it's just not going to work. There's lots of stuff on 4 wheelers, maybe try researching some of that first. I have a Yz426 and I know I couldn't turbo it without difficulty the compression is already too high.



Good luck though, post if you get this thing working, 500's already have huge power. Turboing that would be awesome. All my buds ride tricked sport quads, I can't even come close to hill climbing with them. I can take em on the bumpy stuff though

 

[Stake Man]

Turboing a 2 stroke can be done, but you need a sealed bearing turbo or a oiling setup. I don't know about the specific turbo you mentioned, but have you looked at the older VNT turbos that Garret had? There was no wastegate and the vane actuation can be done manually(by vacuum/boost) verses the computer controlled version on the late 80's/early 90's turbo dodges. I do remember seeing a Shadetree Mechanic episode where they installed one of these "kits" on a Harley.

 

[Billy Golightly]

I have a friend of mine that had drag raced sleds (snowmobiles). He had a turbo on his arctic cat tripple engine, and it was carbed. So I'm sure it can be done. Difference is he shelled out the money for a kit and I'm making my own Thats what I'm doing with the CR500 engine actually, drag racing. I converted it into a three-wheeler and I race it occasionally at the ATV dirt drag races. Its good for flat 5's and high 4s already in 300ft but thats just not fast enough against the highly modded Yamaha banshees.



Oiling the journals is something else I had thought of too. I figured I'll either have to have an external sump or use some sort of an electrical pump with an extra resivoir and recycle the transmission oil from the engine that also lubes the clutch. I'll check into the VNT line and see if I can find one small enough for my use. Thanks for the input so far guys.

 

[rubberneck]

Shoot Ted Janetty a PM, there was a video on here a while ago of him racing his turbo charged sled. Wicked fast compared to the others in the video. I remember him saying he has turboed a couple of 2 strokes.

 

[Billy Golightly]

Thanks rubberneck. Just sent Ted a PM.

 

[SDancy]

Billy,is it kind of hard on snowmobile parts here in Suwannee County?

 

[Rman]

Bill, the carbs on snowmobiles are much larger than on dirtbikes. They can support the fuel flow, and turboing has been going on with snowmobiles for some time now. with the tiny 39mm opening on a dirtbike carb, and the tiny fuel bowl with gravity feed fueling, it's just not a good combo. Fitting a larger carb is most certainly going to be the answer. Like I said all my buddies with quads that turbo'd HAD to switch to fuel injection. IF you could rig up a carb from a snowmobile I think you'd be set.



Is this going to be strictly a racing bike? Because all those tricked out quads and dune runners sure do spend a lot of downtime with maintenance. Seems like they never get them running right. But man when they do, it's insane. Were you planning on running a better fuel? Or just pump gas?



Sorry I just re-read that it is a race bike. That's better, I'd definitly look into a larger side mounted carb and intake. The poor intake and design of the standard bike system can be elminated if you want a drag machine. A nice fat tire would help too! hehee

 

[HoleshotHolset]

http://video.google.com/videosearch?q=turbo+snowmobile



:--)



Matt

 

[Billy Golightly]

Billy,is it kind of hard on snowmobile parts here in Suwannee County?

Hahaha your right not much in the line of sled parts down here. My friend with the turbo setup lives in WI. It started as a ZRT800 block and ended up as a 1300cc big bore with a turbo kit from PSI. Made almost 300hp.



I didn't know there was anyone else on here from around here, much less right in town. Thats pretty cool. Only half of what you read about me in the newspaper is true, I swear! :-laf

Bill, the carbs on snowmobiles are much larger than on dirtbikes. They can support the fuel flow, and turboing has been going on with snowmobiles for some time now. with the tiny 39mm opening on a dirtbike carb, and the tiny fuel bowl with gravity feed fueling, it's just not a good combo. Fitting a larger carb is most certainly going to be the answer. Like I said all my buddies with quads that turbo'd HAD to switch to fuel injection. IF you could rig up a carb from a snowmobile I think you'd be set.



Is this going to be strictly a racing bike? Because all those tricked out quads and dune runners sure do spend a lot of downtime with maintenance. Seems like they never get them running right. But man when they do, it's insane. Were you planning on running a better fuel? Or just pump gas?



Sorry I just re-read that it is a race bike. That's better, I'd definitly look into a larger side mounted carb and intake. The poor intake and design of the standard bike system can be elminated if you want a drag machine. A nice fat tire would help too! hehee

Lectron makes up to a 50mm intake end carb, and a custom intake shouldn't be much of a problem. I've seen guys take aluminum plate and then cut and weld on a tube in relation to the carb size. A rubber hose, usually like radiator hose, joins the 2 of them together. I can probably use a vacume driven fuel pump to make sure the bowl doesnt run out of fuel.



Heres a picture of it now: #ad


Not a dirtbike anymore



This will definetly be strictly a race bike after the turbo and will probably only get ran once a month, if even that. I dont have a problem running Race gas. Alot of the guys on the drag banshee's are running alcohol. I want to keep mine some what of a sleeper, if thats possible with a turbo hanging off the side of it Thanks for the suggestions so far guys.