Tuning Question (help please)

[6SENSE]

Will achieving a faster 1/8 mile give you a higher overall mph in the 1/4?

I decided to look at tonights timeslips a little differently. I noticed that my 2nd halves of the 1/4, the car was moving pretty darn well. I would gain 20-22 mph in 4.9 seconds. I compared these averages to some other cars that ran faster than me and faired very well [in the second half]. In fact my mph gain often was better. The time I gained over 22 mph equaled a car I ran against that went 108mph.

So back to the question. Looking at it this way, the first half is where I am lacking. Its not that Im moving out real slow, its that I am spinning like crazy anytime I try to hold a pound of boost at the line. I had to let off the pedal a couple times because I was spinning through the whole 60ft and bouncing (wheelhop). A couple times it got bad enough that it was setting off my audible knock sensor. I would get off the pedal just to be safe, and when I got back on, it was back to spinning.
IF I EVER GET MY TRACTION TOGETHER SHOULD I EXPECT TO SEE MORE THAN 991/2 MPH 1/4 MILES?? Or does that have nothing to do with the overall 1/4 mph?

Thanks.

P.S. Oh yeah, almost forgot. From Tlink data on one of the runs I know that I could have gone WOT at least 106mph with no KR. Now if I could just get there before the 1/4 was over .

 

[6SENSE]

Maybe "Tuning Question (help please) " wasnt the right title for this thread. Just thought about it

 

[boostmaster]

for more detailed help please post times -i.e. 60ft, mph, 1/8, 1000ft, 1/4 etc. also if you know it weight of vehicle. convertor locked or unlocked.

 

[cool 84]

Contrary to what a lot of people think, if you're spinning for most of the 1/8 mile, it's going to lower your mph quite a bit. On my 110mph run I couldn't hook until past the 1/8 mile and a few friends I regularly beat on the street, even from a roll trapped 112-116mph at the track. Difference is, my car somewhat hooked on the street but at the track it took until I was in third.

With that said, you really can't compare the second 1/8 times with a car that was already going faster than you in the first 1/8. I have a friend with a Porsche and even though he ran a 15 something to the other guy's 11 something, they both picked up roughly the same mph in the second half. The 11 second car still had 20mph on him through the traps but my friend still believes from a freeway roll he could pull an 11 second car. I just gave up trying to argue.

 

[6SENSE]

Originally posted by boostmaster
for more detailed help please post times -i.e. 60ft, mph, 1/8, 1000ft, 1/4 etc. also if you know it weight of vehicle. convertor locked or unlocked.

All six of my runs had problems early on, a few worse than the others. Here are a few examples:

60ft: 2.344, 1/8: 9.689@77.46, 1000: 12.4, 1/4: 14.665@99.53
Let off the pedal because of wheelspin/bad wheel hop which set off the audible KR sensor. 15.2 degrees of false KR@24mph. Rest of run no problem with KR.

60ft: 2.649, 1/8: 9.721@78.91, 1000: 12.395, 1/4: 14.653@99.30
Let off again, same reason. This time KR never got above 2@19mph (must have got off it quicker ).

60ft: 2.492, 1/8: 9.947@76.92, 1000: 12.674, 1/4: 14.947@99.23
Let off again, same reason again. Set off audible sensor. 19.4degrees of KR@29mph. No KR rest of run.

Wheel hop was bad! This is on 255/50x16 BFG DR's. O2s were never under 810. Usually between 820 and 860! Was running the alky inj on these runs (straight methanol for the first time), 93 octane gas.

Any more info that would help, just let me know. I am open for suggestions of what direction to go next. With the mph I shouldnt have any trouble going at least mid 13's. I feel that I should see more mph though.
Thanks.

 

[6SENSE]

Originally posted by cool 84
...........With that said, you really can't compare the second 1/8 times with a car that was already going faster than you in the first 1/8. I have a friend with a Porsche and even though he ran a 15 something to the other guy's 11 something, they both picked up roughly the same mph in the second half. The 11 second car still had 20mph on him through the traps but my friend still believes from a freeway roll he could pull an 11 second car. I just gave up trying to argue.

I hear what your saying. I was thinking the same thing. That is why when I compared I also compared to slower cars aswell and did notice that the slower cars would gain less mph during that 2nd 1/8 and the faster cars would gain more. I fell into the "faster" cars. This is why I took the time to take a look because I was curious if their was a difference or if every car just gained about the same amount at the point. But indeed there seemed to be a difference of how each car pulled at that point, so I was thinking well hey my car seems to pull pretty well at that point, maybe I need to just work on the first half and the whole thing will come together. Of course (probably) my thinking could be way off, but Im eager to learn Must go faster!

 

[boostmaster]

From what I see the average of those 3 runs 9.786@ 77.76 MPH combine for an average ET of 15.26. But the problem is not in your 60 ft times. Your are primarily within your first 1/8 of the mile. I don't know if wheel hop wheel cause false kr at least I've never heard of it before. I've experianced wheel hop and 60's similar to yours on 225-60-15's and still at that trapp speed hit an E.T. of 13.5-13.7 with trapp speeds between 77-80 mph in the 1/8 and 97-99mph in the 1/4. But don't give up hope that sucker is pullin like a motha on the top end. Deal with your low end Issues, wich could be KR or bog from too much alky or both, and you will soon see low 13.1-13.5 qtr runs, get your 60's down to the 1.7-1.8 range and you'll see some 12.70-12.90 runs. These cars make so much torque it's hard to get them to hook without practice and the proper set up. Last time I took my T to the track I ran my best of 13.28@104 mph on street radials.

 

[cool 84]

You might want to look into the suspension. I sort of had the same problem. When I bought my car it hooked hard. I basically added just an intercooler, and went 13.9. I pulled high 1.8 60' on an open rear and DRs. Then the car sat for a year and a half. Once up and running again it never hooked even close to how it once did. The only thing I could think of is the rubber bushings in the front suspension deteriorated badly so maybe the front was binding and not transferring weight. After watching videos of my car at the streetraces, I noticed my headlights stayed pretty much perfectly level. The front end didn't rise at all.

EDIT: I totally missed the wheelhop part. I would seriously take a look at those rear control arm bushings. Your problem most likely lies there. The car should never wheelhop no matter how much you spin unless something's worn out. It does cause false KR also, like you said. I broke my axle from a bad wheelhop experience.

My dad went 14.0@100mph with stock everything with the exceptions of a K&N, chip, 20psi, and AFPR. Your combo probably has a lot more in it once you get it sorted out. I can't imagine it not going at least 105mph with it running right.

Not to jack your thread, but how do you like the F-bod radiator, and was it a drop in?

 

[b4black]

Pinion snubber?

 

[6SENSE]

Thanks for the replies everyone. You are all so encouraging .

Im gonna take a look at the rear suspension. Way back when I thought I had it covered, but obviously not. Passenger side is air bagged, I boxed the LCA's, swapped out the peg-leg rear for a factory posi from a donor '87T, and added an aftermarket poly pinion snubber. Bilsteins and new springs all around. I re-did the front suspension/steering linkage with exception of A-arm bushings which were in good shape.
b4black, next time at the track I may go ahead and take off the snubber. Ive been talking about trying that for awhile now. The guys on the General tech forum have been debating on that topic for ever. Is it safe to just take the thing off completely? Or must I get ahold of a stock rubber one? Wheel hop has consistantly been getting worse, especially as the car has seemed to be making more power. I get bad wheel hop in the burnout box and have to let off. Ive set the audible sensor off doing a burnout .
Ive never seen anything better than a 2.0 60ft, and that was a loooong time ago. My best this year may be a 2.3 (maybe one 2.2, dont remember).

cool84, the Fbody rad is coool . Fits in like stock. Just move over the rubber mounts at the bottom if youve got a stock rad. I already had a V8 rad so I didnt have to move anything. Wish I knew about it a long time ago. $117.99 at AutoZone w/ lifetime warranty (part#433918 from '90 IROC w/5.7). RC fans didnt fit as easily between the tanks, but a little shaving off the sides [of the fans] took care of that (no big deal). The AL rad is much lighter and definately runs cooler. Temps have got to be about 10 degrees cooler.