motorcycle turbo blow thru carb

[rascalion]

looking for advice with a blow thru carb set up for a turbo salt flat runner,,,any help would be greatly appreciated
 

[Dean Los Angeles]

This has been discussed:
http://www.landracing.com/forum/index.php/topic,4333.0.html
http://www.landracing.com/forum/index.php/topic,5833.0.html

[Rchop]

I don't see a lot in those links that apply to your situation rascalion. Why don't you go into some more detail about what you want to set-up and why you want to use a blow-thru. I think if you are more specific, you will get some more detailed responses.

[1212FBGS]

my advice don't do it.....
Kent

[McRat]

Turbos can generate a lot of heat if you aren't intercooled, I wouldn't be surprised if you boil the fuel in the floatbowl.  Pre-turbo is going to be easier to jet across the whole boost range.

But if you must, pretty much all you need to do is run the float bowl vent line into the boosted air side, not atmosphere.  Make it secure, as the factory vent tube can pop off when boosted.  Oh, and you need to make a vent fitting on top of the slide or it will go WOT when you hit boost.   Plumb that into boost too.  For safety reasons, I'd only use a carb that was "push-me-pull-you" or whatever the right name is.  A CV carb would probably be a bad idea as well.

[John Noonan]

Some guy named Toy did pretty good with one..and it was a kawapookie too..

John

[Dakzila]

looking for advice with a blow thru carb set up for a turbo salt flat runner,,,any help would be greatly appreciated
 

What bike is involved?  Lots of info available on the older model Kawasaki and Suzuki four cylinder engines and blow thru turbo.
Even through you can go this way (blow thru carb) using either electronic or mechanical injection seems to be a  better way to go...

Hilborn still sales the injectors for making the conversion on the above mentioned engines..

Buzz

[rascalion]

wow thanks to all for the responses,,,my limited knowledge of fuel injection and budget make using injection difficult for my first attempt...the bike in progress is based on an 883 sportster,,,am in the process of modifying/altering the frameand doing the headwork,,have pistons on order from Dan at nhrs,,a gt15 turbo to plumb and a dream.....any help is greatly appreciated
am not against fuel injection but am old school and kind of leary of it

[rascalion]

could y'all recommend basic books on fuel injection,,,maybe reading a bit will help remove my apprehension

[McRat]

Some guy named Toy did pretty good with one..and it was a kawapookie too..

John

The only benefit I can think of is you can use a smaller carb post-charger, (or use the factory carb(s) in the stock location) and save a little money.  Not a lot of money, because you can sell you stock carb(s) to defray the cost of buying a single carb.  Back when I had a turbo KZ650, we just bought a used Harley carb and made a manifold to replace the stock carbs.  It gave more room, and the main jet was adjustable with a simple knob.

[firemanjim]

Rascallion, not too hard to do on a Sportster,I ran blow thru on one of my Buells. Used a 42 Mikuni,ran boost lines to bowl vent and carb body. Had an Aerocharger on it,worked well--190 HP. Need a boost referenced fuel pressure regulator, an electric fuel pump that will put out at least 5 psi more than your projected boost. Fuel return line from regulator to tank. Is the GT-15 a ball bearing turbo--as HD engines do not have enough oil pressure for a plain bearing turbo--being a ball bearing engine.Carb had a special needle and seat for pressure available from Mikuni.And an intercooler would be good!

[rascalion]

Firemanjim: did you have any problems with the float collapsing under boost pressure?  plan to only run about 10 lb. at first,,,do you recall the specs on the needle and seat....plan on using a separate oil pump system for the turbo,,unfortunately gt15 is not ball bearing,,,plan on intercooler and considering the possibility of water injection,not convinced about water yet.

[John Noonan]

From what I recall you need a #2.3 needle and seat for the HSR 42 Mikuni and the "A" needle as well, I seem to remember that is what I used on mine..and it worked great..call up Steve at Mikuni in sales/tech and he will get you what you need.

John

[Rchop]

rascalion, do you have an intercooler yet?

[Glen]

WOW.....John has recall