CJV,

I think if you DON'T go for choice B you will regret. If I'm not mistaken, the k24/gt35 hybrids are the turbos your currently using. These turbos were good for the stock internal engine, as well as the built 4.0L motor that never got completed, but I thought that your goal with the current motor was in the 1200+ hp range.

I feel that if you don't go this route, you may regret it. Have you thought about other turbo options? Ideally you would want something that produces as much boost as possible up until redline. If you use the k24s, you will have absolutely no need for the last 1500 rpm till redline, and all the extra effort it to produce a high reving engine will of gone to waste.

I possible solution to the low boost until 5000 rpm could be using the nitrous. I know that previously you used your nitrous setup to fill in a void in your powerband. Maybe now you could use the nitrous progressively up to 4500 rpms, and then let the turbos take over. From my experience, there IS a perfect turbo for every engine setup, it's just a matter of research and finding the right one for you.

I can't imagine an off-the-shelf turbo (Garrett GT35R) is the 'perfect' turbo for your setup. And I'm sure if you look into other hybrids you may find exactly what you want. There are companies that build application specific turbos, such as Innovative turbo

And most importantly, at the end of it all, it's what YOU want, it's how you want the car to perform.

With your current engine being able to output 1200hp+ (I wonder what the maximum output it could reach would be ) you may want to browse forums such as Supra Forums. There are many people that are running twin turbo setups and making numbers similar to yours.

Keep up the good work Chad

 

Frosty,

Rob at S Car Go Racing recomendation is to go with "A" first. Then if I don't like it go with "B." His reasoning is you are not so prone to think about what gear or rpm you are in when you need the power. He says for street and most tracks "A" would be the quicker turbo. He also believes for top speed, fast ovals and the quarter "B" would be faster. His question to me was ............ is this for the street or the track? He followed it by saying if it is for the track then figure on getting her down to about 2400 pounds. His opinion is it is a choice about the full rpm range driveability.

I spoke with sharkster today and he somewhat agrees saying if he doesn't have the proper rpm's then there is await. He also said when it comes on in a turn it can be a little tricky as to how the power comes on. He offered to let me drive his car as see for myself as he is running the GT35R's.

I guess the question is can a 1200 hp car car excell in the twisties? I don't believe so. Maybe I'm wrong.

 

If you think that you're going to track it, go with the first choice. Out on the track, you need power and you need it right now. Too many twists and turns on a track would mean that you'll barely be able to get on boost before having to brake and set-up for the corner. You don't need 900 horses to go play on the track so it's a completely different setup compared to the street. Even your car Chad, can't be jack of all trades.

In all honesty, I don't see any of the choices above as suitable for your purposes. You might need to talk to Kevin and see if he has something more suited to your unique engine. But if I had to make a decision based on just these two turbo choices? I'd go with choice number one based on my street/track usage.

It's nearly a catch 22 situation. Go with the quick spinning turbos and you, somehow, negate your high revving engine's capability. Go with the large, more high revving choice and you loose some drivability.

 

Time to develope a good variable vain technology. It would be nice to have the best of both worlds.

 

03-turbo911,

I have taken it to the track from time to time. What I really enjoy doing most is deserted winding mountain roads.

I realize these cars can't be the best in all catagory's. However, I don't want to kill one catagory at the expense of another. Lately, the mods have focused on the motor, however the prior chassis mods are a match for this motor. On the flip side, with "A" she will be very quick coming out of the turns and this motor could cruise @ 8000 rpm's all day long.

Your last sentence is exactly what S Car Go keeps saying........... go with the driveability. We are going to to look at some impeller options with "A" that shift the curve a little. In addition, I do want to see how sharkster's turbo's react in the twisties.

We also have another consideration ............... gearing. All six gears have been revised. First and second has been lengthened very similar to the CGT's ratio's. Actually a tad longer, while third through sixth has been shortened. Years ago we sacrificed top speed when we first modified third through sixth.

I think this is becoming too complicated.

 

just 2 questions:
how expensive are the "choice a" and "choice b" turbos each?

and

does your car have rwd or 4wd?

 

My cost is just under 5K a pair "a" or "b." That doesn't include the labor for cleaning them up or coating. The cost of the tuning is more than the turbo's.

The car has awd.

 

and have you considered k26 or k27 turbos?

 

Yes, we have thanks. A friend Elliot750 had TTP build a motor for him. He went with Ruf titanium rods, shuffle pinned the crank, GT3 Oil Pump, Ported/polished head and larger valves and TTP tuning. They installed the K26's. The last time I spoke with him, he was removing the K26's. He said the car simply wasn't drivable in the lower and mid rpm's. He said it was good above 5000, but took too much time to gain power in the lower levels.

 

i would take the k24 hybrids due to driveability...

worst case would be that you are not satisfied with them, have to buy the t35 and sell the used k24 hybrids for 3-4k $.

btw. have you considered kevin's zero clearence turbos from ultimatemotorwerks?

 

If it were me it would be "A" without hesitation. You always said your building a road car therefore you want as flat a power curve as possible which "B" will not give you. "A" will be far more enjoyable on the street. "B" will sacrifice too much driveability for peak HP.

 

CJV,

In all honesty, I don't think you're going to be happy with either of these turbos. If your pushing the envelope, why don't you go all the way and use one of each. Small turbo for low RPM, big turbo for the upper range.

 

that would be nearly impossible to realize.
you would need the build a very "unique" exhaust system. and you would need a valve system, which allows you to switch between both turbos depending on the rpm.
and don't forget, on this porsche each turbo is working with and for three cylinders (on each side). if you have two different turbos, you would need to get all the exhaust gases from both sides to each turbo. that means long ways for the gases, obviously more backpreassure, more heat and so on....

i doubt that it would be possible to realize it due to the available space and heat issues.

 

That might be a slight understatement.

 

Your probably right, just for some reason, given the extent of this build-up, both options seem to be a compromise. Either the quick spool and limited power, or lots of power but lag. Just seems like there is something else better out there that just hasn't been found yet.