turbo project

Thanx for answering all my questions about the turbo setup, but I still have many unanswered questions. I know the 750 turbo would be a better platform but i already have a motor and the project has begun. I have been convinced that a single carb setup would be the best. What kind of carb would be able to feed the motor under boost and high rpm? and also, when designing the intake manifold could i just make an open box type manifold connecting to all four cylinders, with the carb placed on one end? Or would the intake manifold have to be evenly seperated into all four cylinders? Also, how would a fuel pump be setup, and does anybody know how I could circulate oil through the turbo? Maybe you can help me with this Lorcan

Mikuni flat slide 40mm-ish
dont put the carb on the intake. put it on the turbo inlet for a draw thru setup. this way you dont need a blow off valve. or rising rate fuel pressure regulator IIRC. make the intake box so the inlet from the turbo is in the middle. look at a kit for a busa for ideas on this specific piece
not sure about pump.:pinch:
if you dont have an oil cooler, you could get oil from where you would connect a cooler(oil galley under points cover). if you go with a draw thu setup, you dont need a scavange pump as the oil will gravity dran back to the engine cases(where you would connect the second cooler line, or mod your oil filler cap)

If you are doing a draw through, dosen't the turbo have have to be carbon sealed or something. And how would you tell if it is carbon or dynamic sealed

Yes the turbo has to be carbon sealed. A turbo off a car that is blow-through uses something similar to a piston ring for a seal. It only seals one way, when it has pressure (boost) on it. This is a "dynamic" seal. If you use a blow-through turbo in a draw through application when you shut the throttle the vacuum will draw oil from the centre section of the turbo into the compressor housing, and from there into the engine. One of the reasons Rajay turbos are popular on bikes is that they are carbon sealed from new. You can get other turbos sealed by the manufacturer if you are ordering a new one. You would have to ask a nice friendly turbo company to do it for you on a used item.

The best draw through carb for big bikes is the Mikuni HSR42. I don't know how well this would work on a 750 though. It would probably be ok.

My preference for oil supply is to drill and tap the plug at the rear of the front-to-back oil galley and use that as a feed. If you are placing the turbo behind the block you should have no problems draining back to the cases, just make sure they are well vented.

Well then our turbo from an eagle talon is most likely not carbon sealed, right? We will prolly just do the blow-through setup instead then. How would you set up a regulator to supply more fuel as boost increases?

You need a boost-compensating "3 port" regulator linked to boost pressure at the throttle bodies. You also need to link the float bowls of the carbs to boost pressure. I've seen this done quite successfully using pitot tubes but from what I've read it takes a bit of setting up to get it right. Sorry I can't give you specifics, injection is my thing, not carbs.

And yes your car turbo most likely won't be carbon sealed.

jordan wrote:

Thanx for answering all my questions about the turbo setup, but I still have many unanswered questions. I know the 750 turbo would be a better platform but i already have a motor and the project has begun. I have been convinced that a single carb setup would be the best. What kind of carb would be able to feed the motor under boost and high rpm? and also, when designing the intake manifold could i just make an open box type manifold connecting to all four cylinders, with the carb placed on one end? Or would the intake manifold have to be evenly seperated into all four cylinders? Also, how would a fuel pump be setup, and does anybody know how I could circulate oil through the turbo? Maybe you can help me with this Lorcan

I've been reading a lot about turbos and oil flow. The concensus I've come to is that while a separate pump, cooler and filter aren't needed to make it run. They really should be put in place for longevity. Pumping oil debris throught the turbo can toast bearings. Gravity drain is fine only as long as the drain doesn't clog. The Oldkawman lists a good cooler that works well, fits well and can be plumbed in line with your turbo oil supply. I'm thinking a deep sump pan can be made and a tapped in the bottom. An oil feed line from here can use an electric pump+filter to suplly your turbo. A separate timed relay can ensure good flow for a minute or so once the key is turned off to keep things cool. Check valves will restrict flow and prevent oil from remaining in the turbo and being coked.

hope this helps...(and I hope I made sense)

sam