went to the local 1/4mile track today, just thought i'd post my experience for discussion.

it seems like i was blessed with a fairly lame L98 in my '91. I only got in two passes (the third was botched), both of which were 14.9's at 93mph with a 2.3 60ft. I was powerbraking to about 1800rpm and then rolling into the throttle.

Pretty dissapointing considering I was hoping for at least a mid 14.

As for the mods - catback and a 9.5" 2400rpm stall converter, that's all. I don't know what I could have done to improve my 60ft time - I'm guessing that if I could run a 2.0 60ft, the car would do a mid 14. When it's said that the stock l98's are mid-low 14 second cars, is that presuming a sub-2 second 60ft time?

You guys who are running L98's in the low 14's, what kind of 60ft times are you running?

 

Your mph shows enough power for mid 14's, just practice your launch some more. My car only went 15.1's bone stock, though yours should be faster than mine anyway.

nick

I Pm'd you about the convertor.

 

Im kind of new at racing too. Ive made 6 passes with my 91 Formula L98 WS6 at an 1/8 mile track. 60' times varied between 2.19 and 2.09, and 1/8 mile times between about 9.36 and 9.06. MY car is mostly stock, I have an airfoil, open filter element, MSD Blaster GM coil and Ed Wright Fastchip. My times varied a lot depending on how much I spun the tires. If I really jump on it I spin a lot. Im considering buying some MT ET Drag slicks just for the track (see my thread "What about slicks just for the track" on this board. Did you spin your tires some? Since I was racing test and tune, I could be racing literally anything up to a methanol dragster. I raced against very loud cars, and found it difficult to tell how much I was spinning my tires. It seems to me the slicks would be the fastest, most direct way to faster times tho.

Im told a 2.0 60' time relates to a low 14 sec 1/4mile

 

No, I wasn't spinning the tires. I'm thinking it's possible that I actually wasn't agressive enough off the line in terms of rolling into the throttle (maybe it could have taken more without spinning). I suppose it could be in part tires too - i have yokohama s306's, which are a run of the mill all season tire. With only getting two good runs it's hard to tell. I was trying to avoid spinning off the line, but everyone was spinning for at least a few feet, so maybe that's just part of being agressive enough to lower the 60ft time?

 

YEah I guess it just takes practice. Of course no spinning is best, but as close to breaking loose as possible. I think you are need to be more agressive to find out where that point is, then you can back off a little. I have the Goodyear GSC 245 50 ZR16 tires that come stock with the WS6. I think they are a pretty good tire for a street tire on the strip because they are fairly soft, but the slicks would be a lot better. What kind of Toque converter do you have, I see you are selling one too, im interested but kind of broke. I was told that a hi performance TC is a really good mod for the strip.

 

93 MPH is low for a L98 with exhuast. I run that trap with a 305. Something is very wrong here, tuning or other wise.

 

As for the trap speed, I'm wondering if it could have simply been the air (it was warm) and all the sitting/idling in the lanes. My dad was there with his 88 iroc L98 and both of his runs were also 93mph. There was a stock GTA there but he coudln't make any runs, otherwise I would have had a pretty good comparison. I'm thinking if I could get down to a 2.1 60ft, and with better air, the car might have done a 94 or 95mph trap speed?

What's a typical trap speed for an L98 auto car?

 

I have the L98, check my sig for times. I can't manage better than a 2.1 60', and I have a few hundred in the rear suspension.

If you're running at a high altitude, your trap speed will actually be a little higher corrected. My trap is around 93 mph at 3100 feet.

 

A higher than stock stall converter is best used with other mods, and not the best for a stock l98 motor. It can drop your mph a little, and decrese your gas mileage. A higher stall speed is great for higher reving engines, especially on cars with suspension mods. Are you shifting, or letting the auto do it? I would recomend opening up the intake with a superram, or miniram if you can afford it, then go with some suspension mods. If you can't, try putting the stock torque converter in untill you do some more upgrades.

 

my converter is pretty mild, it is a 2400rpm stall. I think it actually helps, because I can launch smoother and firmer instead of just blowing the tires away. Judging by pure feel, i can launch harder with it than i could on the stock converter. With the stock converter, basically just touching the gas would spin the tires and it was impossible to get traction. On a stock converter I have to really backpedal for the first 2-3 seconds (and the launch feels totally lame), on this one i can hold a good bit more throttle those first few seconds (and i can feel the car is pulling harder) before i go WOT. The car leaves the line a lot better.
Has anyone ever bolted on a mildly higher stall converter and actually lost 60ft time? i've seen several people gain a few tenths...
I am shifting because my governer is currently set too low (4800 from 1-2 and 4500 2-3). I am shifting about 300rpm higher at both points (5100 1-2, and about 4900 2-3). My TPI hits "the wall" right at 5000 so i shift 2-3 right before it lays down.

I think I just need to practice some more and maybe in better weather. drawing any major concluscions from my first two dragstrip runs ever, is probably asking too much. (My R/T was about 1.1 seconds so that shows i'm a beginner!)

Not quite ready to drop a few thousand on suspension and intake mods, not until i can at least get a decent R/T and 60ft. I think the car can do better than 2.3 in the 60ft.

edit: i'm running at sea level. weather conditions last night were about 80F, 8% humidity, 29.95 baro, and i was leaving the line with the engine around 210F.

 

Something seems fishy to me,

I pulled 2.0x 60'ers with a tired 305 on the stock converter. Has a tuneup been done recently? What was the engine temp? I rigged a fan switch so I could run the fans while staging. That helped my MPH a little bit.

It also seems strange to me that you are having LESS traction problems with a higher stall converter. The pedal should feel softer, but the tires should be spinning more.

Some converters like to be flashed off idle instead of powerbraking. Maybe you should try that a few times. Just hammer it off idle on the 3rd yellow and see what happens.

I'd definetly look into basic stuff (plugs/cap/rotor/timing/wires) and see if that helps.

-Doug

 

Yeah, something seems a bit fishy to me too, I'll have to try different launch techniques. My dad's 88 IROC (5.7 auto stock) was doing 2.2 60ft's also on run of the mill street tires. He was just punching it and spinning for about 15-20 feet.

Engine has new NGK plugs, new MSD 8.5mm wires, timing at 6*, haven't replaced cap/rotor yet but they look good. Engine temp leaving the line both times was right at 100C (212F).

as for the traction and stall converter. If I just punched it, the converter would DESTROY the tires. the higher stall gives me an area where I can still get power to the rear without going up in smoke. Come to think of it, I logged both of my runs, and since I know my 60ft time.... Well here's the data:

Run 1
RPM__MPH_Throttle %
2125 - 0.0 - 22
2025 - 1.0 - 17
1850 - 3.0 - 22
2025 - 4.0 - 36
2950 - 12.0 - 54
3850 - 24.0 - 100
4000 - 26.0 - 100
4225 - 27.0 - 100
4600 - 31.0 - 100 (60ft marker)
4950 - 35.0 - 100
5150 - 36.0 - 100 (start of 1-2)
3800 - 43.0 - 100 (end of 1-2)
3950 - 48.0 - 100
...and so on through the gears

Run 2 (EDIT: had to fix the RPMs, typed them wrong)
RPM__MPH_Throttle %
2250 - 0.0 - 38
2800 - 11.0 - 37 (spinning, it looks like?)
2800 - 13.0 - 26
2475 - 13.0 - 29
2550 - 11.0 - 85
3350 - 16.0 - 100
3750 - 22.0 - 100
4175 - 28.0 - 100
4675 - 32.0 - 100 (60ft marker)
4850 - 33.0 - 100
4925 - 34.0 - 100 (start of 1-2)
5200 - 37.0 - 100 (end of 1-2)
3950 - 41.0 - 100
...and so on through the gears

If anyone would like to see the whole run, let me know.

Well, I guess I'm just going to have to go back and try some different techniques for launching. It's either a traction or technique problem. Judging by the data above, it's both!

As for the tad low MPH (93), i think i'll ignore that for now it might come around with better air (94) and a better launch (95?).

 

Your mph will most likely go down or stay the same with a better launch.

nick

 

I see your problem.

Get some sticky tires (nitto or BFG drag radials) or slicks (M/T ET streets) and go back to the track. Then you'll be able to give full throttle on the launch. I am sure that is what is hurting your 60' times, MPH, and ET.

I thought you were giving her all she had off the line when I read this thread for the first time.

I'll bet you can cut some 1.8 60'ers with drag radials. Just be sure to heat them up (burnout) for a good 4 seconds or so.

-Doug

 

raising the ride height of the car a couple of inches always helps some.

 

My 87 IROC L98 ran these numbers with trans problems making me pedal it to shift 2-3 and pedaling it further to hold 3rd gear....

60 ft.- 1.969

1/8- 9.222

1/4- 14.52 @ 93MPH

Now remember, this is running at about 50% throttle in 3rd gear crossing the traps. This year I am hoping for a high-to-mid 13 second run.

A few pointers:

Footbraking the TQ is good. Hold it @ 1500-1600 RPM's and roll into the gas just short of breaking the tires loose. On the street you can practice this by listening for the tires to chirp. You want to hear them just barely....

What octane fuel are you running at the track?

Your base timing of 6* btdc is not the best for performance if you're running a stock EPROM. Run premium fuel and advance the timing to 8*-12* (depending on detonation)

Where is your tire pressure at? You should run 40-45 psi in the front and 25 psi in the rear.

Are you doing a burnout with the street tires? One good smokey burnout the first run of the day is all you need to make them tacky. The remainder of runs just drive around the burnout box and forget about it.....

Adjust your TV cable in one click and it should help your shift points. There are technical advice topics that will give you the correct method of setting the TV cable. Do a search on this site and you will find it.

Good luck next time. I'm sure you can run in the mid 14"s or better with ease.

 

iroc57tpi -
what mods if any were you running that would help with your 60ft time?

to answer your questions:

i'm running the best pump gas available in california, but that's only 91 octane. they no longer even sell the 92 stuff let alone 93 that you guys in a lot of the country get.

I'd increase the timing, but I'm already getting 3-4 degrees of retard in the computer (i have a data logger and logged each run). I'm working through addressing that on the TPI board and on my own. It may be that I need to run octane booster just to be able to use all of the stock timing - california fuel is really crappy.

tire pressure was as off the steet...32psi all around. wasn't doing any burnouts, just rolled around the burnout box.

as for the shift points, i'm not going to tweak the TV cable since it's set right. I will be tweaking the governor though, so that I can get my shift points where they are supposed to be in full automatic, instead of shifting manually (since that's inconsistent). The biggest problem right now is I HAVE to start in first manually, because when i pedal it to prevent wheelspin, the tranny goes into 2nd (which is what you'd expect when you get out of the gas). So have to manually hold it back in 1st at least until I finally get to WOT after the launch.

thanks for the input, after a day or two of living with the dissapointment, I think i'm going to figure it out and make it better!

 

For no faster than what your running drop tire pressure down. When I ran my 14.8's & 9's my short times were 2.01-2.07. Running street radials aired down to 18psi anything higher I'd go up in smoke. Unless you get some sort of full blown slick or cheater slick your not going to see the cars full potential at launch or on the big end. As far as 60 foot times goes if you can go 1.9 or better that's a bad!#@ launch. Buddies big block Chevelle (3980lbs.) pulls 1 tire and his short times are 1.7 and let me tell ya-If you've never felt it-WOW!!

 

Oops! I forgot my sig in that post up there ^

The tires that day were General XP2000Z's that were almost bald. The burnout helped me go from a 2.01 60ft. to the 1.969...

EDIT:
My sig shows up in the preview window but disappears when I post

 

my friend has a 70 nova with a built 355 and is pulling 1.30's 60 ft
thats with slicks, 5.13 gears and a 4-link suspension.

now talking about a launch. the front tires come off the ground by about 3-4 feet.

 

Back when my car was mostly stock with a few boltons (airfoil, crank pulley, Flowmaster, K&N, Hyperjunk) it went 14.125 @ 96.96 MPH on street tires, rest of the car stock and I also run at sea level and the car weighed in at 3700 lbs aprox and this was in good weather. With that converter I hope youre running a cooler, if not theres your next mod ASAP but coupled with a drag radials theres no reason why you cant cut sub 1.9 60fts if your car is in a good state of tune, maybe even sub 1.8s but make sure you have SFCs before running a sticky tire.

As for my car I was having problems trapping at 94. x MPH recently even if I hooked in the upper 1.7s or 2.1s but I finally got headed in the right direction last Fri as I posted a 13.758 at 99.7 MPH (finally!) on a 1.905 60ft on street tires with my current set up which includes a 2k stall converter and a few more boltons above and beyond what I listed above. If youre interested heres a page I have with my slips and mods for each run with a similar car and what my results were...Timeslips

 

When I raced my dad's '69 LeMans, my times improved when I spun JUUUUST a little bit off the line than when I just launche really hard, try gettin the tires to spin about a 1/2 a turn

 

I think theoretically no spin is better than any spin at all. However if you dont' spin at all you may be farther under you capacity than you would be over optimum point if you spun a little, which would give you a worse time. If you don't ever spin, then you dont' know where that point is.

 

Any time your car spins or twists(chasis) that's losing momentum resulting in slower ET's. All the energy that could be transfered into foward momentum is lost to those little things.

 

I see you live in California,I here the elevation at LACR really hurts
performance.

 

Have you tried letting it shift earlier?