Track results

[Dave Vince]

Ran a test and tune on my 95Z last night 5/21/05. 1/8th mile track, Results:

RT - .612 - Has nothing to do with other times, but the new LED bulbs take some getting used to. I am used to the .400 Pro Tree anyway.
My car: Opponent, a chevy S-10 drag car:

60' - 2.088 1.598

330' - None at this track

1/8th mile - 8.944 7.529

Speed - 84.26mph 91.09

Small speed difference of 7mph, large ET difference of 1.4 Sec.

This indicates a 1/4 mile time of approximately 13.90 - 14.00, and a speed of 100-102mph.
Modifications include: MT drag radials, comp cam, mildly ported heads, 2.02 1.60 valves, 1.6 roller rockers, shorty coated headers, flomaster, cold air intake, 160 therm. reprogramed computer by madz28.
This car is an automatic with a stock converter. It was in need of some stall as the best ET was achieved by leaving at idle, and letting the converter flash. Trying to bring the motor up on the converter would only slide the front tires thru the beams, and would slow the 60'.
The speed is real close to my own prediction of 85mph, but the ET, and 60' is pretty sad. To give and example, a car ran a similar ET to mine, but it was a full 12mph slower in speed. Obviously this car was much better set up for the drags than mine. I was hoping for a 1.90 60', and 8.50 ET which the speed the car ran could easily support. There was a snag that I ran into that maybe someone can explain. The shift point is set at 6200 which on the street has never been a problem. However at the track it was starting to cut out near the shift point, on one pass the motor completely fell on its face, (as if it hit a rev limiter), and then came back on strong when I lifted, and re hit it. The best ET came when I blipped the throttle to make it shift earlier than 6200. Is fuel pressure a problem here?? On the last run something in the suspension gave up the ghost. I think the rubber piece that supports the front of the long arm from the rear end, (looks like a long ladder bar), broke. Is there an aftermarket replacement? Any ideas, help, laughs, suggestions, threats, etc. I have raced on the drag strip for a long time, but I am ignorant as to what makes these cars run. This car is a snail compared to what I am used to, but I can drive this on the street.

[Dave Vince]

For some reason the other cars times did not show:

60' -1.598

ET -7.529

MPH -91.09

[Injuneer]

I'd guess that an 8.94@84.26 would convert to roughly 13.9@105mph. With that MPH, you could be running very low 13's with a good launch.

The big long arm that connects the rear axle assembly to the tailshaft of the tranny is the "torque arm". Its the only thing that prevents the pinion from rotating upward and smashing into the body.

There is a rubber bushing in a clamshell-type housing attached to the tailshaft of the tranny. That bushing is on the soft side, and after 10 years, might have crumbled, but that's not usually the problem. Usually, its the tranny mount that breaks. The tranny will bang on the floor under hard load.

Both the torque arm bushing and the tranny mount can be replaced with Energy Suspension polyurethane mounts. The poly tranny mount can cause a lot of vibration, but its worth living with. There is some concern that the ES poly trans mount is a shade too tall, so some people go with a GM piece called the "1LE" trans mount. Better height, but its still rubber. Alternatively, Spohn Performance has a poly trans mount that is the correct height.

[fastTa]

This car is an automatic with a stock converter. It was in need of some stall as the best ET was achieved by leaving at idle, and letting the converter flash. Trying to bring the motor up on the converter would only slide the front tires thru the beams, and would slow the 60'.

You are absolutely correct. Lots of people just assume that the best way to launch a "stock" converter is to hold it at the stall speed and then go. The way you did it is the best way hands down.

I'm sure with a cam, ported heads, and DR's, you will most likely and significantly improve your times with a litte seat time.

BTW how big of a cam if you don't mind?

[Dave Vince]

Reply

Thanks for the reply's. The rear trans mount is new, but it is a stocker. The front Torque arm rubber looks OK, but that is only looking at it, (same for the trans mount). I will have to do some further checks on this one.
Cam specs are @ .050 218 Int. 224 Ex., gross lift I .528 E .530 calculated with the 1.6 roller rockers. Yes, the launch was superior letting the converter flash. The MT drag radials hooked pretty good. I think a high 1.9's is possible with this setup, after I play with the suspension a bit. I had no idea what pressure to run at. We used to run between 4 & 5.5 lbs in our drag slicks, but thats a whole different world. I agree with the times you indicate it might run if the power can be put to the track more efficiently. I will need to get used to running this kind of car, as seat time in other vehicles does not always translate.

[Joe 1320]

A vigilante 2800 stall speed would work wonders.

[Dave Vince]

Stall

Agreed, it was deperate for some stall. I just repalced the converter. Unfortunately I was not thinking, since it was going to be a daily driver I went with the stocker forgeting that this has a lock up converter in it. There is no doubt that it would have made a world of difference in ET. We were always trying different Converters in our race car. One change from a motor converter, to a Nitrous converter netted .6 tenth's of a second in ET. The converter was being blown thru badly.

[Formulaboy95]

Hmmm... Makes me wonder what my car would/shoud be running without the knock.

R/T -.016
60' 2.079
330' 5.724
1/8 8.705
MPH 82.78
1000' 11.288
1/4 13.466
MPH 103.85

Pulled 6* at 93 MPH to 105 through the traps w/just the stuff in my sig. Stock 3.23's, stock stall... Sorry to hijack the thread, but it is on topic. Based on the 8th, what would my run be?

[Dave Vince]

Times

Thanks for posting your times, it makes me wonder what is going on with my car, as our 60' and 1/8 mile mph are similar, but your ET is over .2 tenth faster. I was having a problem with it dying just before it shifted, so I would pedal the throttle to make it shift earlier. This would account for some of the difference in ET. Is 6200 too high a shift point for this motor? It has the beehive springs that Comp Cams recomended installed, with new Hydraulic rollers, (stock type). It would nose over when it hit around 5800rpm. It completely cut out on one run... I was looking at some times from a drag car that I had about 11 years ago, which was running similar mph in the 1/8th mile. This car was running ET's as quick as 8.18, and the slowest was 8.29, with 60' times of 1.826 - 1.895 That car had a 4.56 gear with 10.5 slicks, and a mild 2500 rpm converter. No tranny brake either. I notice from my old notes that one of the best 60' times with this mild converter was achieved by leaving at idle.

[Joe 1320]

I wouldn't trust the factory tach for one. Next, a scanner would be helpful in observing if there were any knock retard. It could be real knock or false knock due to rocker noise, tailpipe rattle or any one of a number of things. If you are going to start playing with these cars, a scanner will save you lots of diagnostic headaches.