akisman1

Hi,

I have a 2001 C5 coupe with:

Custom remote 72mm turbo
M&H racemasters 26 11.50 16
Stock A4
Stock converter
With Pcs tcu
3.15 gears

At 8 Psi I got 430 rwhp

I went on the strip today and the best et I got was 12.58 with 2.122 60ft and 116mph.
No wheel spin at all.
The question is, why I couldn't get any lower than 12.58?

Thank you.

LS1LT1

That stock converter is really hurting you, you might even have 'too much tire' for it. That sixty foot should be down around the 1.6x - 1.7x range (which would put you right into the high-mid 11s), not 2.1s with that kind of power and tire.
Even your trap speed is a bit low for that power so you might need to check your tuning/log some passes at the track etc.

Also, what were the weather conditions/temps when you ran.

akisman1

Thank you very much for your reply.
So you think a higher stall converter would get me lower 60ft?
The temperature at the track was 26C.
I checked the tune and there was no KR, fueling was great so was timing.
What else do you suggest?

LS1LT1

Oh I don't think it will, I know that it will LOL. As long as you still hook just as well of course, which you should easily be able to do on those tires.
I assume that those are the bias ply M&Hs and not the drag radials?
A drag radial might be better for your current combo but if you ever go bigger boost, high stall converter and/or steeper gears the bias plies/slicks could possibly still be the better choice.




Ok, a little warm but not too bad either depending on the other factors (physical elevation of the track, barometer etc.).




You could try really stalling it up hard at the line in an attempt to build some boost (again, not easy with a stock converter) but be careful not to push through the beams while doing it. In fact, make sure that you are very shallow staged (ie: just barely light up the 2nd bulb while staging) as rolling too far forward can also hurt your sixty foots.
Other things you can try is some weight reduction, maybe take out the floor mats, any extra stuff in the back hatch or glove/center boxes, run only 1/3 of a tank of fuel and even pump the front tires up higher than normal.

akisman1

Ok then! Converter is on the way!

The M&Hs are the Cheater Slicks.

Barometer i think is 1017.9 and physical elevation 600ft.

I will try tommorow exactly what you suggested and i will report

Thank you very very much!!

383vett

What was the tranny shifting at? Were the shift points at the optimal rpms? Were you stalling the converter or leaving at idle?

LS1LT1

That's important as well, shift points set even just a few hundred RPMs too low could really steal some ET and MPH.
I had assumed that if he was logging/checking A/F and timing that he was also monitoring shift points too.

4DRUSH

Get a supercharger, small turbo builds aren't worth it.

akisman1

I have the Pcs Tcu(Transmission controller, manual to auto swap) controlling the transmission, and the the shift points are correct as it seems from the log.

I did stall the converter a bit at 1300-1400 rpm with foot braking.

I did this build because it cost me lower than 2000$, i couldn't find any supercharger for that money.

pcguy2u

Try this link for calculating an optimum differential. You only need to fill in the columns on the left. You'll need flywheel HP, RPM of the engine at the end, weight of the vette and the diameter of the tires.

Short of changing the gears, you could try a smaller diameter tire???

http://www.assassinracing.com/tech/drag_calc.html

383vett

It sounds like you do need a looser converter and/or gears. Can you stall the thing higher without pushing? Do you have a linelock? At the end of my burnout, I put some pressure on the brake pedal to heat up the rear pads which helps with holding the car on the line while I stall up the converter.

RonSSNova

You need a converter. Your turbo needs some rpm to spool a bit, and the stock converter stalls at 1400.....maybe. Something around 3000 would be good. And don't buy a cheap one. Get a good Yank, PTC, Circle D etc 9.5" unit.

You won't believe the difference.

Ron

robert miller

Really bad 60ft.Also what gear are you pulling off the line in, Where are you shifting at also...Robert

akisman1

I don't have a linelock, only foot bracking for burnout and of the line.




At the last run i did, i noticed the boost gauge, it seems that boost comes after 80ft... So a looser converter could help a lot spooling the turbo off the line.
I will buy a Yank one i just wait a dyno run tommorow so i could buy the right one.







I did test pulling through 3 and D but made no difference.
The auto is shifting at redline around 6050rpm.

cv67

as said bias ply can run a little slower than a regular DR.

Converter as said will drop your times substabtially
3000 will really wake it up, 3600 well-