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#693 - 02/28/01 10:51 PM 2nd test of Rebel at drag strip  
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This was the 2nd round of testing the 1999 Mallett 435 C5.
Keep in mind ( or review the chassie dyno results on this forum) that rear wheel HP is about 380 with about 370 ft/lbs of torque at rear wheels.

The first test day at the dragstrip was on a cold day ( about 50 degrees) with a cold track surface and no sticky put on the track surface.

With 3 passes on the 1/4 mile I found there was no way to really get this car launched with any decent E.Ts for the following outcome:

1. With a 30 series tire (335/30/18) the limited sidewall just does not have any give (even wth only 25 lbs cold air pressure) and tires do not conform to high torque off the line traction.

2. As the 6 speed trannie built up internal temps, the shifting became rougher, seemed to need more effort to make the shift happen or would jam into a gear. This was worst when attempting to shift into 3rd gear.

3. Even with a full tank of gas as added rear end weight, the C5 suffers from real bad wheel hop and "snaking" even more so as you increase the torque and HP of the engine.

This ended the first tests, things had to change to better the performance of this C5 under drag race conditions.

First I changed the stock 6 speed shifter, it was junk for under high load/RPMs it would jam as you attempted to shift from one gear to another. I replaced the stock shifter with a Kirbin. This is a better designed product but it is notchy, has more rattle sound and requires more force but the 2nd testing at the drag strip showed the stock shifter indeed was a bad problem.

2nd is in the 1st tests I used Pzero tires, they are noisy tires that I have ever used. These tires were breaking loose badly in first 3 gears giving lousy E.Ts.
They did though allow the car to launch straight and true off the line and not much snaking when shifting into 2nd and 3rd gears.

For 2nd tests I switched to the street pilot tires. they are more quite then the other brand was. But for off the line launching, they were worse, car snaked much more but they did not break loose going into 3rd gear as Pzeros did but 2nd gear snaking was as bad as it was in first gear.

BTW, the 2nd tests where done at the same dragstip with about the same outside temps ( around 50 degrees, road surface cold)

I made 3 pasees down the 1/4 mile.
All three had E.Ts of 13.4s at 115 MPH with 2.6 second 60 foot times :-(

1. All three had lousy 60 foot times of 2.6 seconds, which should have been around 2.0 which shows the drivetrain out powered the tires badly, even with a full tank of gas, the front shocks set to soft and rear shocks set to stiff. That 6 tenths of a second really reared its head to the E.Ts which where 13.4s.
Being the rear end ratio is a 3.73, it required an ectra shift to 4th gear ( which costs about 3 tenths to make the shift) at about the 1,000 foot mark which did not give 4th gear much distance to pull at it's best.

The better part of this test showed that the MPH was at 115 MPH and shows the HP is there if the car would treat the tires better and the tires maintained traction.

If the extra .6 was taken off the 60 foot time, the E.Ts would be about right for the HP and under warmer outside and road temps I can see the car can pull about 120 MPH, which would verify the HP nummber.

Using a non stock wheel size, a tire with better sidewall give, and the right tire makeup like a Hoosier race tire, I can say the E.Ts would be a low 12.

On another note of testing, I had installed a heat exchanger to use the radiator water flow to cool the engine oil. It worked quite well for oil temps stayed around 205 degrees max even under the high load of making the runs.
This then leaves me to a compare of this C5 and the '94 ZR-1 I owned and raced for 5 years. The LT-5 reacts much better when you hit the rev limiter then the LS1, the LT-5 recovers more quickly.

With a totally stock LT-5 it ran 12.2 at 118 MPH using stock wheels and tires. It did this time and time again, year after year and again leaves me to say the C5 is not the king of the hill, the ZR-1 still owns that crown for as a stock driver it still can perform as good and in most cases better then a modified C5.
In dollar amounts a '94 ZR-1 would cost about half of what a highly modified C5 is and although after more testing and tuning I will get this C5 into the low 12s, but it will take a lot more work then it did with the ZR-1 to get to the same perforamce levels.

John

[This message has been edited by teamzr1 (edited 03-01-2001).]


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#694 - 03/01/01 02:19 PM Re: 2nd test of Rebel at drag strip  

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John, figure each 60 foot tenth equals 1.5 tenths on the top end - so if you can get them to sub 2.0, you're under 12.5 now.

I agree with you on C5 wheel hop. Having run a couple C4s over the last few years, and over 500 miles of seat time in a C5, the C5 has a much greater propensity to bounce the rear wheels than the C4.Mr. Bardahl Haven't gotten any Z06 time yet to see if it's the same.

Joe

#695 - 03/01/01 03:53 PM Re: 2nd test of Rebel at drag strip  
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Quote
<font face="Verdana, Arial" size="2">Originally posted by muttvette:
John, figure each 60 foot tenth equals 1.5 tenths on the top end - so if you can get them to sub 2.0, you're under 12.5 now.

I agree with you on C5 wheel hop. Having run a couple C4s over the last few years, and over 500 miles of seat time in a C5, the C5 has a much greater propensity to bounce the rear wheels than the C4. Haven't gotten any Z06 time yet to see if it's the same.

Joe
</font>


Your right about the numbers Joe, I also see the car should be able to do a high 11.
I wonder if since the frame is stiffer it prevents better off the line whereas the C4 gave a little and allowed rear to flex downward easier.
I thought the ZR-1 was hard to launch, but once I learned how to con it off the line, it was easier then this C5 is.


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#696 - 11/28/01 10:51 AM Re: 2nd test of Rebel at drag strip  

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I believe mine has no wheel hop to speak of. At least that may be due to the A4. Take offs are very easy with 60ft usually around 2.0 or better on stock tires.

George

#697 - 03/24/02 01:43 AM Re: 2nd test of Rebel at drag strip  

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my zr1 makes 372 (uncorrected) 354 (80 deg correction) at the wheels. I've had fits launching with the 4.10 gears and finally got a 2.0 60 foot leaving at idle and "walking" out.

anything more and the car spins bad (2.3 60 foot). I'm not gonna bother again until I get some stickies. what RPM and technique should I try for best results. thanks.


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