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Dual Weber blow through Engine for Speedsters

FM Former Member
I just finished a customers 78x94 2165cc engine with our new dual 44idf weber blow through turbo kit. The engine was built for high rpm power but can be built for lower rpm power also. At 6300 rpm's power output was 325 flywheel horsepower and 320ft.lbs of torque at 4700. This engine used one of our BIGGER turbo cams but had very low lift, I dont like high lift turbo engines unless they are drag race only engines. This engine is going into an autocross car and needs reliability. There was no intercooler used but if there was add another 40-50 horsepower. Turbo was one of our custom T04b's with a smaller .59 exhaust housing. Turbo spooled very fast and the Weber carbs worked better than I ever expected. Power was smooth without any rich spots or stumbles. We have invested many hours into these carbs and I am glad we did, they work awsome! If any of you guys have any questions, give me a call at CB and I will fill you in more.

Pat Downs
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FM Former Member
I just finished a customers 78x94 2165cc engine with our new dual 44idf weber blow through turbo kit. The engine was built for high rpm power but can be built for lower rpm power also. At 6300 rpm's power output was 325 flywheel horsepower and 320ft.lbs of torque at 4700. This engine used one of our BIGGER turbo cams but had very low lift, I dont like high lift turbo engines unless they are drag race only engines. This engine is going into an autocross car and needs reliability. There was no intercooler used but if there was add another 40-50 horsepower. Turbo was one of our custom T04b's with a smaller .59 exhaust housing. Turbo spooled very fast and the Weber carbs worked better than I ever expected. Power was smooth without any rich spots or stumbles. We have invested many hours into these carbs and I am glad we did, they work awsome! If any of you guys have any questions, give me a call at CB and I will fill you in more.

Pat Downs
Gordon NicholsGordon NicholsMassachusetts 1993 CMC Supporting Member
Yeah, I'm interested in how "streetable" it is, too. My bet is it'll be pretty sane on the street.

My son (Chris, on here, too) has a wildly turbo'd, intercooled, 2 liter Eclipse putting out over 425 HP on a wheel dyno and running mid-11's in the quarter, and every time I drive it I am awed at how tame it is on the street. Nice, smooth idle, reasonable low-end torque and nothing to let on what it's capable of. It acts like a strong stock engine until, of course, you really put your foot in it and then all hell breaks loose and it goes beyond crazy to Plaid!

Hope Nic Rupert reads Pats post.........Looks like just what he's looking for.

gn
FM Former Member
Ron, There is no strength difference between 90.5mm and 94mm cylinders. Both have close to the same wall thickness. The 90.5 will run cooler than the 94, but things can be done to keep a 94 bore engine cool enough for the street using a turbo. Shorter stroke cranks stress the engine case less, but also make less power. I like long stroke turbo engines, they are power animals. When our new case is done this summer, 82 and 84mm stroke turbo engines will become very popular. A properly built engines reliability is governed by the owner. Maintanence is an issue with 300+ horsepower. Oil changes, valve adjustments need extra attention. If you want a hundred- thousand mile engine, dont buy a turbo engine. If you want an engine that can eat up anything on the street and I say anything, with about a forty thousand mile lifespan, get a turbo.
FM Former Member
There are problems that must be dealt with when using this much power in a light street Speedster replica.

Primary consideration is the transaxle - a "built" VW transaxle is too weak to take over 300 BHP for any reasonable amount of time, so a 901 5-speed (or the stronger 901 4-speed) or later Porsche transaxle will be necesary, and a torque-biased LSD would probably be a very good idea.

A car with this power will also require some suspension modifications and probably 225 series tires to use the power effectively.

Finally, experience driving cars or bikes with similar BHP to weight ratios might help keep you from killing yourself.

Just some things to think about before taking the plunge...
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