Brought my car to Prototech of Fort Lauderdale, FL and delt with David Hart. http://www.prototechonline.com

Decided to step up to a more free flowing exhaust system that eliminated my old muffler thereby further reducing back pressure. The exhaust note carries a little more rumble than my previous system (without any resonance) but surprisingly, is a bit quieter than I expected.

Here are a few photos of the design - the bridge in the center and the design of the pipes actually keep the exhaust note at a level that isnt bothersome.








60-130 mph runs:

To determine as to wether or not the exhaust helped performance any, I set out for a few 60-130 passes to see if I picked up any improvements.

Low Boost Setting (1.0 bar) - Old exhaust system vs. new exhaust system both got 6.8's (60-130 mph). It just seems that the 6.8 with the new system took more runs to acheieve. Bottom line, it seems that the performance package thats in place on my car currently likes the higher back pressure of the old exhaust system that had the muffler in place. Its evident that back pressure is important to some extent on lower boost/ stock turbo cars.

High Boost Setting (1.4 bar) - New Exhaust system works better at higher boost pressures. With that said, I hit a new best of 5.42 seconds from (60-130 mph) compared to my previous best of 5.78.

Here is the chart that I sent in for approval:





I also had a chance to run my car at the 1/4 mile track. I was only able to get in 2 passes since my crank pulley came loose after pulling though on the second pass. Since the belt drives a number of important components (steering, clutch, etc etc.) my car was done for the night. With that said, I didnt achieve the trap speed goal of 140.00 mph I was shooting for.

Nevertheless, I achieved 2 back to back 139's. Keep in mind I do not want to break my car so I always launch conservatively - thus my ETs are on the slow side. Here is a copy of a slip with my highest trap.




Its possible if I had a few more opportunities, I may have hit a 140, but nevertheless, it didnt happen that night. (BTW, the driftbox was in my car during my passes and showed 142.0 & 142.1 respectively)

One point I wanted to make is that according to my dyno sheets, my car makes peak power around 6200 rpms. I was passing through the traps in 4th gear at about 7500 rpm. At this rpm, my power is down nearly 100 awhp. With that said, I wanted to try a run shifting into 5th gear on my 3rd pass but couldnt since my car was down. If I was able to shift into 5th without losing any boost pressure, I feel I would hit a 140-142. But zero boost loss between shifts isnt possible with a 6 speed car. I have a suspicion that if I shifted to 5th, the time my car would take to build back boost again would actually end up yielding a lower trap than 139. So, I think staying in 4th is the winning ticket....

As for my overall feeling on the exhaust. Low boost hp gain - loss of HP negligible if any at all. High boost hp gain is noticable. Overall - the exhaust upgrade was a good compromise.

Let me know what you think!


Keith

 

congrats!!!Protomotive is best to go!!

 

Congrads...very good results on race !!! but pump gas 60-130 are not too impressive...considering that SPI VTG kit runs 6.55 on race...at simular power levels...

 

very strong. What temps were the runs at? Dr Jitsu's Protomotive GT2 is now up to ~680 rwhp and runs about a 5.7 60-130 IIRC, so your runs are very impressive for a heavier platform.

 

WOW...congrats man great times proto rocks!!
tim

 

Congrats, awesome times...and the 1.0 bar pump gas run of 6.8 is VERY impressive considering that at that boost level you could put 100K on your motor.

You are running GT 3071's, yes?

 

Congratulations Keitha

BTW....A friend of mine went from Milltek 100cells to Prototech exhaust on VTG's and he saw HUGE DIFFERENCE EVERYWHERE!!!

 

Very nice results!!
What is also very impressive is that you picked up 35mph on the last 1/8th mile, which means the car is really pulling hard.
With a quicker 60', that car will definitely be in the low 140's!!
Very nice!

 

Keith, I think you'd be surprised but shifting into 5th will likely slow you down...at 130+ mph you are covering LOTS of ground and by simply interrupting acceleration at that speed (to shift) you will lose a couple mph and will cover lots of distance. In any event, sick set-up, definately a 10 second and 140 mph car...
Peter

 

Good trap speed.

 

Thanks and Yes. Im running standard spec 3071s with .63 ARs.

Keith

 

keith, congrats on the runs. it will be tough to beat on the street from a roll!

 

True Peter. From past experience I was sure I Id end up losing mph if I shifted. Especially since the car had to build back boost with so little distance remaining before the end of the track.

I ran this test to reinforce this assumption on a milder boost level:

I ran 2 passes from 85-141 on the driftbox staying in 4th. (I ran 2 back to back 5.4's)
I ran 2 passes from 85-141 on the driftbox power shifting into 5th at 6800. (5.7 & 5.9 seconds)

I laid the 2 graphs over each other. When I shift to 5th (6800 rpm) at around 125 mph, the 4th gear graph jumps ahead by 5 mph! But since shifting into 5th puts my car in a better power band, by 141 the 5th gear graph comes back 2.5 mph. Good, but still not enough to recover and make up the lost ground.

I could try to run the car at the strip again to see if I can hit the 140 staying in 4th again, but figured Id back off and cut my losses. Dont want to keep beating the hell out of the car.

All and all Im sure if I get the right shift points in and launch, the car is capable of a 140 staying in 4th gear if I make enough passes. But for now 139.52 is it.

Keith

 

Keith awsome dave did a great job on my 997TT yours is just another level now ! enjoy it whats next ?

 

Congrats Keith. Very well done. Did you achieve that 60-130 of 5.4 with those 19" wheels and bodykit? That car is a beast. Have you weighed it? Very nice!!!