What am I doing wrong (dragstrip question)

40th GT · Nov 10, 2009

So I've made a total of 19 passes down the strip and I still can't get my 60' down from the 2.3x range.
For the last 9 runs I had the rear tires pressures down to 25psi and even then I found myself breaking traction at any launch rpm above 2700.
I was slipping the clutch as much as I can without bogging the car.
My car is completely stock and I'm running the stock 18" BFGs. (400 treadwear)

I've been running mid to high 14s at 97-99mph, which seems to be a whole new issue.
Is it my shifting? Is it fair to blame the weather? (the DA was at 3000-3200)

Here's a timeslip:
r/t: .515
60': 2.348
330': 6.44
1/8: 9.69 @ 75.77mph
1000': 12.49
1/4: 14.82 @ 97.24

Any help is appreciated.

autumn_again · Nov 10, 2009

try basically taking off like your taking off fast from a light on the street. thats when i get my best launches basically. otherwise i just bog or spin.

40th GT · Nov 10, 2009

autumn_again said:
try basically taking off like your taking off fast from a light on the street. thats when i get my best launches basically. otherwise i just bog or spin.

That's a new one. I'll try that next time, thanks.

edit: so wait at the light with the engine idling and then do the see-saw action with my feet when it goes green?

fallenauthority · Nov 10, 2009

Ive found it works for me to act like im a noob at driving a stick, rev it to like 3000 and slip the clutch while adding more gas, it slips the clutch quite a bit but the car will take off quite quick if you can hold traction.

gmantheman · Nov 10, 2009

Tires aren't helping any. 400 treadwear tire is a harder compound which not ideal for the strip.

ViperNuge · Nov 11, 2009

Besides the 60 ft are you shifting at the proper peak rpm for HP/torque? Shifting too soon will hurt your times a lot.

patrick

J.Cagle · Nov 11, 2009

Don't feel bad 40th gt, my best time in my gt 5speed is 14.5. I hit 100mph but my 0-60 times were terrible. I still havent gotten a chance to go back and try it again.

40th GT · Nov 11, 2009

ViperNuge said:
Besides the 60 ft are you shifting at the proper peak rpm for HP/torque? Shifting too soon will hurt your times a lot.

patrick

I'm shifting at 5800-6000. Haven't taken any higher because I can feel the power dropping off after 5500 or so.
Is that right?

BennyBlown2v · Nov 11, 2009

40th GT said:
I'm shifting at 5800-6000. Haven't taken any higher because I can feel the power dropping off after 5500 or so.
Is that right?

Rev it out! Think about it this way - when you reach the end of a gear if you shift too early you'll end up being at an RPM in the next gear making less power than if you let it rev yo

40th GT · Nov 11, 2009

BennyBlown2v said:
Rev it out! Think about it this way - when you reach the end of a gear if you shift too early you'll end up being at an RPM in the next gear making less power than if you let it rev yo

But 6k is the redline?

autumn_again · Nov 11, 2009

i shift at 6200. before my tune i shifted at 6. even sometimes i'll shift at 6500.

Ken04 · Nov 11, 2009

40th GT said:
But 6k is the redline?

shifting will help your quarter mile time, but it won't do a thing for your 60' time. There's a couple different ways you can launch. Holding your rpm at a constant and dumping the clutch, which you have to try a few different rpms to do finding which gives you the best traction without bogging or wheelspin. Or sliding the clutch at different rpms. Very, very hard to be consistent sliding the clutch. This is why so many drag racers run an automatic. Try some different tire pressures and different rpms to launch with. Obviously some drag radials will help out because you'll be able to launch at a higher rpm even if you use the dump the clutch method. Bottom line is it takes practice to fine tune your launch to be quick and consistent. So many people think drag racing is easy, but you're finding out it takes more skill and paractice than just mashing the gas and going straight.

J.Cagle · Nov 11, 2009

When I ran for the first time I did the hold and dump method. I held it at 2,000rpm and dumped. LOTS of wheels spin. The best run I had I just took off as if I was leaving a stop sign. I still need lots of practice but the strip is closed

SpartaPerformance · Nov 12, 2009

The best E.T.'s I got where with a bit of clutch skip and a little bit of tire spin. How do you shift? If you shift like an old lady that will most likely explain the slow times. Even with a 2.3 60' you should still be in the low 14's

40th GT · Nov 12, 2009

tommyroc said:
The best E.T.'s I got where with a bit of clutch skip and a little bit of tire spin. How do you shift? If you shift like an old lady that will most likely explain the slow times. Even with a 2.3 60' you should still be in the low 14's

I'm shifting as quickly as I can without powershifting. (i.e. I'm going sideways in the 1-2 shift and chirping the 2-3. But then again I do have 400 treadwear tires.)
Though I have "accidentally" powershifted once during a pass and it felt awesome..No pause in acceleration whatsoever. I'm not sure if I want to do it every time though, since this is my DD and I need it to last.

88Koupe · Nov 14, 2009

Three things.

1. Are you racing at Bristol Motor Speedway? Bristol simply is a high altitude slow track. I love racing there, but compare your car to other cars around you when ther, not what you read on this board. I have seen plenty of stock sn197s running very similar times to what you are running. When my car was stock the best I ran was 14.6 and the car was bone cold. Most of the passes were 14.7-14.9. With 19 passes your car must have been heatsoaked for several of those passes.

With a CAI and Doug's tune it went 13.8 @ 102

2. I use the emergency brake to hold the car on the line. Lets me not be so jerky with the transition.

3. These cars love rpms. Get the tune, raise the limter and twist it. 6300-6400 and my car is screaming.

J.Cagle · Nov 14, 2009

How do you raise the limiter?

ViperNuge · Nov 14, 2009

You raise it via the tune.

patrick

40th GT · Nov 14, 2009

88Koupe said:
Three things.

1. Are you racing at Bristol Motor Speedway? Bristol simply is a high altitude slow track. I love racing there, but compare your car to other cars around you when ther, not what you read on this board. I have seen plenty of stock sn197s running very similar times to what you are running. When my car was stock the best I ran was 14.6 and the car was bone cold. Most of the passes were 14.7-14.9. With 19 passes your car must have been heatsoaked for several of those passes.

With a CAI and Doug's tune it went 13.8 @ 102

2. I use the emergency brake to hold the car on the line. Lets me not be so jerky with the transition.

3. These cars love rpms. Get the tune, raise the limter and twist it. 6300-6400 and my car is screaming.

1) No sir. I'm racing at Atlanta Dragway, which has a altitude of 1000 ft and the DA at the time was in the 3000 ft area.
As for comparisons, a s197 GT500 with 315 DRs was running mid to high 13s, a 460whp Terminator running the same times, a stock Harley F-150 (the blown one) matching my times, and I saw a LS2 GTO in the low 14s.
And no, the 19 runs is the total number of passes I made with my car over the course of 2 track days (10 on one day, 9 on another). I gave my car a 15 minute rest at the 5th or 6th run, so there shouldnt've been any heatsoaking. The fan didn't kick in once.

2) Is your track not flat?

3) OK. More RPM it is.

88Koupe · Nov 14, 2009

1. Your car is slower than it should be then, but I cannot help as to why. Alot of times a slower 60ft will make a lot higher mph on the big end. At mustangweek, my quickest run was actually my slowest 60ft. I would begin with a cai & tune and see what that does.
Some of the other guys on here may know better than me, but my car takes more than 15 minutes to get an optimun run. these cars need to be cold.

2. Bristol is not flat--infact it is uphill. I always have to hold a brake to stage where I want to. I have always done this from local 1/8 mile tracks to Rockingham.

3. Will need the tune to get the benefit of the rpms.

Nice looking car btw

What am I doing wrong (dragstrip question)

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