Ok, I've got a question regarding 60' times, 1/8 mile times & 1/4 mile times.

Is there a way to guess-timate what a 1/4 mile time/mph should have been, based on a 60' time and 1/8 mile ET/mph???

When I had my old '81 Z28 with the 383, I took it to the track twice, and came home pi$$ed off both times. For some strange reason (that I never figured out because I sold the car not long after) at the track, the motor was leaning out big time, so at 4000-4500rpm, it began "bucking" so I had to shift to the next gear by 4500rpm instead of 6200rpm where that motor (usually) liked to shift at (anytime except at the track ).

Anyway, here's what my best run looked like:

• 60' - 2.067
• 1/8th - 9.176 @ 78.21 mph
• 1/4 - 14.124 @ 97.43 mph

IMO, my 60' time was really good (and that was running street tires! Dunlop Qualifer GT's) but I don't think that the 1/8th mile time, and especially not the 1/4 mile time, are in line with what the 60' time was headed for. Like I said, the car kept leaning out at the track, so a lot of time was wasted at the top of 1st gear, and again at the top of 2nd gear, since I couldn't rev the motor to ~6000rpm. Based on my 60' time (which was still within the time the motor was running good), what times/speeds do you think that car should have been capable of???

Thanks for any response............I know there's no exact "science" to my question.

 

If you were short shifting by ~ 1500 rpm, you would have definitely ran faster if you could have pulled the motor to 6k. However, the 60' is not a good indicator (at all really) of what you would have run. I've seen guys cut 2.0xx short times and run in the 11s and some guys cut 2.0xx 60' and run in the 15s. The 60' marker tells you how well you are getting out of the hole...the car could fall on its face after the 60' or it could pull like crazy w/either yielding totally different results, even though the 60's are the same.

Every tenth off the 60' will give you ~ .15 in the quarter. So, given your time, if you would have cut a 1.967 60'...hypothetically you would have ran a ~ 13.974. This doesn't take into account shift points etc. In other words, your 60' wouldn't be affected by shifting early and inversly, wouldn't be affected by you shifting later...although shifting later would have yielded a quicker ET on the same 60'.

 

I see in your sig that you ran 13.2 w/a 2.0 60' time. Is it safe to say that there's sort of an "average" ET that a car will run based on 60' times?? The thing is, my car came out of the hole great, and it did pull like crazy (although only around home ). It was sorta like the LS1 is --- it pulled good upto ~3000rpm, then from ~3500-6000rpm it pulled like a bat out of hell! My new car though, ran a best of 14.008 @ 102.99mph, with a 2.129 60' time, and that's running at its peak. Therefore, I figure with (obviously) better traction, a lower 60', and comparible 1/4 mile times, the old car "theoretically" should have run at least mid 13's.

Well, any more opinions would be great.

 

In reality,that 60' time is about average for the et's.
I ran 13.88@100 with a 2.0 60',and next pass it went 13.81@101 with a 1.98 60'.
When i was running 13.2's my 60's were in the 1.8 range. Now that i'm running 12.3's n/a my 60's are around 1.66-1.7. On the bottle it really gets the power down and runs low 11's with a 1.51 60(killer for the et).

 

Your 1/8 to 1/4 times seem allright by this chart http://www.highperformancecars.com/p...to_quarter.jpg

As for 60' times... first, you haven't mentioned what gear you are running, I expect it's not alot of gear, you need alot of gear to get it hard out of the hole... gear and converter (assuming it's automatic).

How did you determin it was leaning out?

You might have had a detonation problem.

Hope this helps a little

 

I was also wondering about "leaning out".

Based on your 9.176 1/8 mile ET, you should be able to run 14.3 in the 1/4. Since you ran much quicker than that I'd say you had more problems in the first 1/8 mile (shifting rpms) than you did in the last 1/8 mile (brute HP pull).

Bucking isn't really a good description of what might be wrong. Yes there's a possibility that the engine was running out of fuel for any number of reasons. Low fuel pressure at high rpm, too small of fuel line preventing enough fuel from reaching the carb, jets too small, float level set too low. Even something simple as a pinched or kinked fuel line will prevent enough fuel from reaching the carb.

Another possibility is that the valve springs were worn out and will really limit the rpm range of an engine when the valves start floating.

I've also see worn out distributor weights. The distributor won't go to full advance because the weights are worn out or even seized.

Maybe the ignition coil was breaking down under load.

Just too many variables as to why it ran the way it did.

 

330', 660', and 1/4m times have a pretty predictable relationship for a given type of car. IOW, if you are trying to compare two NA 4th gens with similar tires the comparison will be valid.

But if you spend time watching different types of cars run at the track, you will see major variations. In my case, the runs are fairly typical of a SC car with small tires and a street suspension. Relatively high trap speed v. ET compared to a more traditional drag setup running similar times. If I were to line up at test and tune against a tubbed out, NA, carbureted car that runs a similar ET (mid 10's) he would have a much better 60', 330', and would still be ahead at the 1/8mi. But I would be catching him and we might finish with comparable ET's. But my mph might be 10-15mph faster. The first part of track is all about traction, the second part about hp. Even with similar cars, the 60' is basically a function of traction and can't be used to predict the ET. The further you get down the track, the more the equation simplifies.

Rich Krause

 

Mezmorized: the car I'm talking about is my '81 Z28 listed in my sig. It was an automatic (TH350) with factory stall, and a 3.42 posi rearend. I had trac-bars on the car to help with traction, which they did quite well - considering I ran with street tires and didn't deflate them whatsoever, the car hardly spun off the line, and was able to pull 2.0 60's, which IMO, isn't bad for a daily driver on street tires.

The "leaning out" problem, or whatever I had going on, was very confusing. Note: it never occurred when I was driving (testing ) the car around home, but happened every run at the track - from the 1st to the last. What was actually happening??? Well, once the motor started to rev over 4000rpm, it felt like a "rev-limiter" kicked in and either killed the ignition, or cut the fuel off (which seemed to make more sense). If I held my foot to the floor the whole time, the engine would surge, then die, then surge, then die - almost the same sensation as "chugging" a car that's a standard when you're learning to drive it. If I let off the gas, immediately the engine would run normal, and I could "drive" down the track, but if I stepped on the gas again, it would nose-dive and start surging.

I was p'd after the 1st night at the track when the problem occurred, so that week my dad and I checked out different stuff (electrical connections, fuel connections, etc.) and road tested the car, and the problem never repeated itself. So I went back to the track the next week (we even trailered it down so the motor wouldn't be hot or anything) and still the problem occurred from 1st to last run.

My conclusion: the track I went to (Cayuga) is at a slightly higher elevation (I believe) than where I live, therefore I wonder if the elevation had an effect on the fuel/air mixture (I know from snowmobiling that larger jets are required for higher elevations) and so my Q-Jet wasn't jetted quite big enough to allow the motor to run at its full potential?? Otherwise, why would the car run perfect (no ) around home, but F-up at the track, then run fine at home again????

Like I said, even at the track, it pulled hard up to 4000rpm, but should have pulled all the way to 6000rpm (at least - I usually would shift around ~6200rpm). So with that in mind, running 3.42's, good traction and all, I think it should have been a ~13.5 second car, if not a little quicker?!

Thx for any more feedback..................sorry for the long post!?

 

Did you change anything at all at the track? Like timing?

What temp were you running the car at?

Oh, as a foot note: I'm not 100% sure you have to lean out at higher altitudes... At higher alt. there is less air (which would make the car run richer). That's the way I think it goes... I could be wrong, I'll try to look it up.

 

Now I can't remember if we messed around with stuff or not --- really, I don't think we touched anything once we got to the track, ie: timing, carb adjustments, etc. - basically just showed up and ran.

I believe I had a 160* thermostat because in stop-and-go traffic I did have overheating issues sometimes, but as long as I was moving there were no problems. It was really weird though - how it would work perfect at home, then at the track screw up every time --- I couldn't even get ONE good run --- I mean, why couldn't it have run good at least once?!

Now I'm pi$$ed at my new car cause it only ran a best of 14.008 @ 102.99.............................I mean, I was only 9 thousandths of a second off of a 13!!!!!...............................apparen tly I'm destined to have 14-second "13-second cars"?! --- don't worry though, next year my new car WILL run 13's!! By Hell or high water!