I am going to a test and tune with my local Corvette Club, Looking Glass Corvette Club, at Gateway International tomorrow night and I have never drag raced before. My car is a 1985 Corvette with a stock L98 and a 4+3 Transmission that has never given me any trouble. I assume I should run with the overdrive off. I don't know what rear axle the car has. The car is in good operating condition and the only modification is a Borla cat back exhaust. Can someone tell me a conservative launch RPM and what RPM to shift at. I just want to have some fun and not break anything. Also, about what should the car run ET & MPH.

 

I would think shifting it is the same as any manual car. Each gear is different and will stop pulling at different points so there is no set RPM. Just shift when you feel her not pulling as hard. As for launch RPM good luck with that because that depends on your tires. Lower your air pressure in your rears just a bit and it will help you get off the line.

 

Lower your REAR tire pressure to around 25 PSI

yes, keep OD off!

Have you ever launched the car on the street to where the tires spin? Thats what you DON'T want. Since the tracks are usually pretty level, once you stage, you can let off the brake. Keep the clutch all the way in and rev it up to, say, 1200RPM (or whatever you feel comfortable with). Once the light goes green, let the clutch out, and see if she spins, if not, then mash the gash to the floor. The launch is really all about how YOU are able to drive YOUR car... and the traction it has (tires and track prep) and a few other factors. Just keep making runs until you have it down.

Shift points are different for each car. I usually shift mine around the top of the tach's curve or just a tad before. You can experiment around with this to find the best place. I can't recall the RPM I run, but it doesn't matter because I have a 6spd and you haev a 4+3.

You can find your gearing by looking under the arm rest cover at the RPO codes. Just google search Corvette RPO codes and you can look at the list to see which codes refer to the gears, then figure it out from there.

Some things that will help times.... take out the spare tire and any other heavy crap you have in the car.
Run the gas tank down to just enough to get to the track and back, or leave enough to get to a gas station on the way home. Try to stay under 1/4 tank.
Make sure you have the AC turned OFF when you run down the track (the compressor robs HP).

Other than that, just have fun. Don't be embarrassed to run high times at first, remember you are out there to have FUN. Lower times come with practice. Once you master it, and if you really get into it, start modding it. Theres many cheap mods that can get some nice HP gains that won't hurt the car's daily drive-ability or gas milage.

 

I believe your axle ratio is 3.07. Launch at least at 1500 rpm. Shift about 4500 rpm.

 

Last time I was at the track, I raced my friend's "newly purchased" 85 Vette with a 4+3 and got the best ETs launching at 1600 and shifting it at 4200 rpm. I'm not gonna say I'm the best driver in the world, but I was impressed with the very strong low-end performance.

You will only run worse ETs if you shift higher than that. I was able to run a 14.02 that day and trapped at 95.1 mph. I tried shifting it higher like at 5000 and I ran a 14.6. The motor didn't feel like it was making anymore power up there. Just more noise.

 

I did the same thing and my best was 14.2 @ 95 mph. Some good advice there.

 

Thanks all for the help. I hope to have a good time and your suggestions will give me a good place to start. I will post the out come Wednesday morning. Again thanks! It is nice to have a place to get answers to Corvette questions.

 

Ya know, the corvette is a road car, not a drag racer.
Yea it's nice to know how fast it is, but you should be doing road courses instead of straight line.
You have very stiff springs and sway bars for that. For a drag car, your shocks are all wrong, and the weight distribution is poor. The car needs sticky tires to launch, and If you launch that hard, the trans or clutch is gonna blow.
I am not saying gloom and doom, but your car is 23 years old, and rubber bushings, shocks, springs, mounts, all the soft goods are the same age, and aging.
The trans is readily available, but it's a pita to change. so is the clutch. I don't know anything about you or your car, and I hope it hangs together. but to me, it's a shame not to do the twisties with a car that begs to kick asphalt in the face of porsches, mustangs, camaros, jaguars, and other legendary corner carvers.
just my 2c

 

Overdrive off. (although some have used 3+OD in place of 4th gear)

Drive around the water box, do not get the rear tires wet.

Drop the clutch and spin the wheels, very briefly, only a few revolutions, just enough to clean them off. Hot/smoking street tires do not grip.

Pull up to the staging lights quickly and get pre-staged. Get staged when the other guy starts pulling up. This will give you PLENTY of time to concentrate on holding your launch rpm and watching the third yellow. Hold the clutch in and rpms at about 2000 rpm. This will vary depending on the traction available and how grippy your tires are. If they're old, they won't grip for sh** and you'll soon realize racing on cheap/old tires is a waste of time.

Let off the clutch quickly at half throttle and quickly go to full throttle, if you get wheel spin, modulate the throttle a bit to try and get it back.

Shift at 4200-4300. Keep in mind the tach lags especially in 1st gear, so pay attention to the engine pitch as well.

Make damn sure you don't let off before the finish lights, some people do. There's plenty of shut-down room so stay in it until you're absolutely sure.


You'll probably spin the tires on launch nearly every time on your first trip out. If you spin em at 2200 rpm on your first launch, and you're smart, you'll adjust and drop it from 1500 rpm. Then when you bog the engine down, drop the clutch from 2000 rpm... until you narrow in on the window.

Expect 2.20 60' on a poorly prepped track with street tires. With that launch, I'd expect about 14.3-14.5 1/4 et at 96 mph.

 

good post central. i haven't been to the track but plan on going at some point. while i'm sure that nothing beats experience and the feel of going through the motions at the track your post gives a good insight into launching the 4+3

 

I agree with all expect the shift points, I'd try some different RPMs but I think you'll be closer to 47-4900 rpm for da best times. 42-43 is too close to peak HP to shift at.

 

Alot of guys Drag Race with automatic's. The 4+3 is a different ball of wax. It is much tougher to launch, however it is alot more enjoyable ripping the gears down the track.

You will find out there is a sweet spot. Too much gas, and the tires will spin up, and not enough rpm's, and the motor will bog. This is how it goes with my car. To compare when my 88 was stock I went to the track for a few runs. The best was a 14.21@98.5 with I believe a 2.05 60 foot. Goodluck!

This might be hard to do, but try shifting at 4300 the whole way down the 1/4 mile, then bring it up to 4500, and then finally too 4700, and then compare your times. I believe my 98.5 MPH trap speed was shifting at 4500.

 

I tend to rev mine a little higher, or about 2500-3000rpm, and use more clutch to keep from spinning the tires. Using this technique, I pulled a 2.1 60" my first try ever with Sumitomos

As far as shifting my 4+3, It felt best shifting at around 5000 on the stock tach. This may be slightly higher because I have a TPIS big mouth, but I have always felt that it's faster when you error on the high side.

Be careful not to get wheel hop, as that is what kills transmissions. With my h/c l98, that 2.1 60" got me a 13.3 @ 106mph. Doesn't seem to be much to gain with the TPI intake, but I may go back some day with some drag radials just to pull that 12 second slip.

 

Slipping the clutch can work, but it's risky and will get you a smoked clutch before it'll get you consistent runs.

The tach is slow to respond, so if you shift when it says 4200-4300, you'll already be closer to 4500, which is ideal, IMO.

I put in a shift light for this reason, because the tach is worthless, especially in 1st gear, I think I have it set at 4500 rpm right now.



Don't be a noob and spin the tires every time out. Experiment, spin them once, ease up and bog it the next time out, and narrow in on that sweet spot where you get a little squeal from the tires without bogging it or breaking loose.

 

Try to remember that you aren't going to break any records your first time out. Make your first pass at 80% or so. That'll give you a chance to see where the finish line is, where the return road is, how to stage, and all kinds of things. Here's some track etiquette and the things that tripped me up my first time:

Staging. You don't stage at the tree, it's actually about 30 feet behind the tree. There are 2 light beams about 6 inches apart running on the ground. When you break the first beam with the front tire, the top light on the tree will light up. Creep forward until the second bulb on the tree lights up, that means you've broken the second beam. Once you and your opponent have done this, the amber lights will begin to light in sequence down to the green.

The finish line. My first time at the track, I let out at the 1000 foot mark, 320 feet shy of the finish line. The 1/4 mile stripe is quite aways out there.

The return road. If the road at the end of the track that brings you back to the pits is on the left, the car in the left lane should always exit first. If you are in the right lane, and are much faster than the car in the left lane, use your brakes and slow down to wait for him. Come to a stop if you have to. Never pull in front of a moving car to exit the track. Always wait if you are in the far lane and must cross traffic to get to the return road. Conversely, if you are in the near lane, be aware that not everyone knows this little jewel of information, and they may turn in front of you at any time.

Have a good time man, we were all new once.

 

Well, again thanks to all for the good advise. I had a great time at the Test and Tune and hope to go again soon. The car hung in there with no problems and I made nine runs. The best I could do was 15.7 at 87 MPH. There could be some problem with the car but it starts and runs great so I believe the problem was the driver (me). I was running against faster cars for the most part. When we hand the Corvettes only runs I ran against C5s and C6s - they are faster. I did have the oportunity to run against a 1988 C4 (40,000 miles a very nice car!) but I killed the engine on the line. All in all I feel I will do much better next time. After my first run of 16.8 I just wanted to get in the 15s which I did. I can see I have a lot to learn and only trial and error will help. I have only road raced once and that was with my Miata in 2000. Yes road racing is fun but very expensive, I believed I payed $250 for the day and was on the track 3 or 4 times. At the test and tune I paid $15for the evening and the track is about 15 minutes from my home. I could have hade more runs but wanted to take it a little easy on the car. For a 23 year old car it is tough machine.

 

Well, again thanks to all for the good advise. I had a great time at the Test and Tune and hope to go again soon. The car hung in there with no problems and I made nine runs. The best I could do was 15.7 at 87 MPH. There could be some problem with the car but it starts and runs great so I believe the problem was the driver (me). I was running against faster cars for the most part. When we hand the Corvettes only runs I ran against C5s and C6s - they are faster. I did have the oportunity to run against a 1988 C4 (40,000 miles a very nice car!) but I killed the engine on the line. All in all I feel I will do much better next time. After my first run of 16.8 I just wanted to get in the 15s which I did. I can see I have a lot to learn and only trial and error will help. I have only road raced once and that was with my Miata in 2000. Yes road racing is fun but very expensive, I believed I payed $250 for the day and was on the track 3 or 4 times. At the test and tune I paid $15for the evening and the track is about 15 minutes from my home. I could have hade more runs but wanted to take it a little easy on the car. For a 23 year old car it is tough machine.

 

Good info!

 

Bill, what were your 60' times for each run?

What tires are you using and how old are they?


I think the "run it 80%" is bad advice. Maybe for some monster build up the first trip out, but not for a stock vette. Go all out, you don't want to waste a run.