More mods=slower times

2003_GT · 06-04-2009

Ok so last year when i went to the track before they closed i ran a 1/4 time of 15.2, at the time my car only had the CAI, tb/plenum, and flowmaster mufflers, and some really really bad 245/45/17 kumho ast tires. i just came back form the track and my fastes time(ran it 6 times) was a 15.3, since then i have added 3.90 gears and the predator 93 oct tune, and nitto 275/40/17 drag radials in the rear, i thought that the gears alone should have gotten me alteast into the 14's since after that i felt a huge difference in accelaration on the street, so why am i getting a slower tim than before?

i do do a good burn out to warm up the radials before every run, so again can somebody help me understand what the problem is

here are my times from this last time i went to the track

60'=2.380
1/8=9.919 @72.661 mph
E/T=15.370 @89.896

2Manystangs · 06-04-2009

60' time looks high, how does it hook? Is the air temp the same? If it's hotter, that will not help, it might help to shift manually, if it's hitting overdrive and not staying in 4th that could be a factor...

MUSTANG_220 · 06-04-2009

Wow that is really really strange bro IDK whats happening with your stang... I remember when motortrend did there test on an 04 GT with an automatic transmission bone stock no mods straight from Ford the thing ran a 14.0 which isnt too common for an auto. But usually automatic GTs run a 14.3-14.6.

You should get some upper intake work done and maybe some head/cam work that should definetely liven her up. Then for sure you'll be running I'd say low 14's FOR SURE.

Good luck bro and sorry to hear about your stangs times...

Yea and like 2manystangs said what elevation and temps are you running at because that can affect your times A LOT.

**EagleAutosports** · 06-04-2009

Don't worry about your previous time because that was a different time of year. The air was different, and the weather/atmosphere conditions have a huge impact on your times.
Are you getting any traction, or are you spinning the tires off the line?

**RLG34750** · 06-04-2009

it appears by the 60' you are having a major traction problem

nitto's are not the great with regard to traction....

couple that with the new gears .....

what other if any suspension upgrades do you have,,,,,,,

dodgestang · 06-04-2009

Those tires need to be at 15-17 PSI for best results in my experience. Based on that 60' you were above 20 psi.

You added the gearing which increases your acceleration potential and attempted to compensate with a stickier tire, but if you are not managing your air pressure properly you will not see a gain in your 60' and therefor your overall time. Compare the 60' on your new time slip with that of your old timeslip and tell us what they are.

shinerstang · 06-04-2009

You have really bad 60fts as all the other guys have mentioned. I'm curious if your trap speeds have changed. If you went with a lower gear and changed your tire height, you gain nothing.......

Cheer up, we'll help you figure it out......

BKid · 06-05-2009

The heat can really slow these cars down. Did you run your last run when the air was cold that would do it. Let you car cool before you run it. These motors do not run well heat soaked. If you ran your car last time out and it was 30 degrees or so , and now go and run at 100 degrees that would do it. The cold air makes the car run easier and faster. Not sure that is the case here, you need Mickey Thompson drag radials which hook. Slippage can cost you a lot of time. Think about it ,you slip for say a second ,and then you finally move.

2003_GT · 06-05-2009

Quote:

Originally Posted by 2Manystangs

60' time looks high, how does it hook? Is the air temp the same? If it's hotter, that will not help, it might help to shift manually, if it's hitting overdrive and not staying in 4th that could be a factor...

I ran it with the overdriveoff should i run it with it on?

Quote:

Originally Posted by MUSTANG_220

Wow that is really really strange bro IDK whats happening with your stang... I remember when motortrend did there test on an 04 GT with an automatic transmission bone stock no mods straight from Ford the thing ran a 14.0 which isnt too common for an auto. But usually automatic GTs run a 14.3-14.6.

You should get some upper intake work done and maybe some head/cam work that should definetely liven her up. Then for sure you'll be running I'd say low 14's FOR SURE.

Good luck bro and sorry to hear about your stangs times...

Yea and like 2manystangs said what elevation and temps are you running at because that can affect your times A LOT.

Yeah those seem to be the normal numbers for these cars with what i hear from you guys, but at the same time supercharged cobras and GT's and procharged ones around here only seem to be hitting on average 13.9's so maybe its a slow track

or bad drivers!!! The track is at around (really not sure) 5200-5500 ft in elevation

and at night the temp around the track is usually at around 50-65 degrees

Quote:

Originally Posted by EagleAutosports

Don't worry about your previous time because that was a different time of year. The air was different, and the weather/atmosphere conditions have a huge impact on your times.
Are you getting any traction, or are you spinning the tires off the line?

I am getting a little traction but really not much, if this is the issue should i invest in some LC's and subframe connectors?

Quote:

Originally Posted by RLG34750

it appears by the 60' you are having a major traction problem

nitto's are not the great with regard to traction....

couple that with the new gears .....

what other if any suspension upgrades do you have,,,,,,,

I currnently have none

Quote:

Originally Posted by dodgestang

Those tires need to be at 15-17 PSI for best results in my experience. Based on that 60' you were above 20 psi.

You added the gearing which increases your acceleration potential and attempted to compensate with a stickier tire, but if you are not managing your air pressure properly you will not see a gain in your 60' and therefor your overall time. Compare the 60' on your new time slip with that of your old timeslip and tell us what they are.

I was actually at 17 psi should i try something like 15 or 13

Quote:

Originally Posted by BKid

The heat can really slow these cars down. Did you run your last run when the air was cold that would do it. Let you car cool before you run it. These motors do not run well heat soaked. If you ran your car last time out and it was 30 degrees or so , and now go and run at 100 degrees that would do it. The cold air makes the car run easier and faster. Not sure that is the case here, you need Mickey Thompson drag radials which hook. Slippage can cost you a lot of time. Think about it ,you slip for say a second ,and then you finally move.

Well when i got to the track i let the car cool down for about an hour and a half before the first run and after that i would let the car cool about 45-60 min between runs

BKid · 06-05-2009

Bingo your elevation is killing you. I also race at a high elevation so that is exactly what it is. You need to make sure your not getting any slippage, that will hurt your times also. Yea if you raced at sea level your times would be like almost a full second less.

BKid · 06-05-2009

Did you run with more gas in your tank

PLstang · 06-05-2009

Your shocking the tires harder out of the hole.

You're most likely blowing them off and if you're not then your dead hooking and dragging the motor out of the hole.

I'm gonna bet, like Reggie, you blew the tires off.

You need to work on your suspension. Just making more power is only part of the equation. Doesn't matter if you put 10,000hp to the ground if you can't hook it up.

The reason why the times are not what you expect, most likely, is the car is more aggressive out of the hole and not hooking up. When you had less power out of the hole it probably hooked up better. The only reason you didn't so worse is that you made it up on the big end. The problem is that you have to make twice the power on the big end to make up time as you need on the short end of the track for the same time increment.

In short, that's why we always tell you "work on that 60'"!!

dodgestang · 06-05-2009

13 PSI is too low.

Based on the information you have provide so far I would:

1. Keep them at 17s
2. Lower my launch RPM by 1000 and check the 60s

418wstroker · 06-05-2009

Something doesn't seem right...am I the only one who is noticing the trap speed as being a bit off for even a stock 4.6?

BKid · 06-05-2009

It is the elevation you guys come up here, and race ,and watch your times go up. At least a second if not more, and with the heat forgetaboutit. I have seen you launch and you need suspension work, you are getting slippage. I would suggest some Lower control arms for starters.