Drag Racing Tech - My trap speed is low. What are H/C A4's trapping?

I ran my car a couple weeks ago, and I was pretty disappointed with the results.


I ran a 12.95 @ 107.6 with a 2.0 60 foot in October. My mods at the time were Pacesetters, ORY, and a Magnaflow catback. The temperature at the time was 50-55 degrees.


Since then I've added quite a few mods, but the ones that affect my trap speeds are:

MTI lid
LS6 intake
PRC 2.5 LS6 heads
Cam (228/230 .571/.573 112)
3600 stall
Moser 12 bolt w/3.73's
ZR1 wheels 17x9.5 and 17x11

So I go to the track a couple weeks ago and the temp is 85 degrees. I ran a best of 12.1 @ 111.9 ...WTF? :barf:

My ET could be better after some suspension, but that's not what this thread is about.

I realize that the stall, the 12 bolt, and the heavy wheels, and the temp change explain some of the change in trap. But I only gained 4mph!

Is it time to start looking for problems?

I would have your tune checked. I ran a 12.01@113 with full weight, bolt-ons (stock H/C) and 3500 converter. You should definitely be able to get more than that w/ your setup.

I agree.I ran high 11s@114mph just before our track closed.everything the same minus the 9in. with a 3000 yank converter.you should be around 113-114mph.

If your shift points (1-2, 2-3, 3-4) aren't at least 6500, you're no where near your potential.

AND .. make sure she doesn't shift into OD in the 1/4!! ..lol Been there!! That will cause a lot lower trap speed for sure.

That's what I was afraid of. :(

My car shifts at 6000 - shift points weren't raised.

If you're still on stock settings then I think they're around 5600 .. not good for drag racing! The good news is ... it's fixable ;)

shifting@6500rpm also removed torque management completely.

what brand converter? converter plays a huge roll

126 mph here, What kind of stall is it, That has a big effect on mph.

126 mph for me as well. TC does make a difference but if your shifting at 5600 then thats probably most of your problem. Fix that and your ET will drop amd mph will jump up.

My car is shifting at 6000 RPM. I had headers/tune on the car about a week after getting it, so I guess I never noticed that it shifts at 5600 stock. You guys think I should have the shift points raised?

My tranny is a Performabuilt Level 2 4L60E with a performabuilt 3600 stall. I'm starting to wonder if I should get a Vig 3200 or 3600.

There's also a noise in my engine bay that sounds like a vac leak, but my shop can't find any evidence of one. So after checking it out they finally said that cars will develop quirks as they are modded, and that a vac leak would cause a poor idle, but it wouldn't explain low dyno numbers. (360whp unlocked on a mustang dyno).

I really appreciate your help guys, and any more is welcomed. :usa:

Where did you make peak power at? I'm pretty sure 6k rpm is to low, I was shifting my 224 cam back in the day at 6700 rpm, worked nicely with my TC and shift extension, TRex liked 7200 rpm so it just depends on the combo.

I don't know where I put the dyno sheet, but I'm pretty sure it peaked when my tuner let off at 6000.

i think it both
1 you need to bring that car to 6500
2 You get what you pay for when you buy a converter

My car is shifting at 6000 RPM.... low dyno numbers. (360whp unlocked on a mustang dyno).


Trapping 122 with a GTO. I trapped 119 last weekend at 90*+
I think raising you shift points will help but I don't think that's your only problem. Shouldn't your rwhp be 400+ with that set up?

Trapping 122 with a GTO. I trapped 119 last weekend at 90*+
I think raising you shift points will help but I don't think that's your only problem. Shouldn't your rwhp be 400+ with that set up?


(360whp unlocked on a mustang dyno).

Not too bad considering...

Start by rasing your shift points and go from there.

Hmm ok. Thanks for the advice guys. Looks like a Vig 3600 and 6500 rpm shifts are in my future.

or a yank Pt4000

+1 .. if you're staying NA, I'd seriously consider a 4K Yank.

pt 4400 here,127.5 mph , 3125-3150 lbs

Your 1st problem is that Performabuilt Converter :barf:

+1 .. if you're staying NA, I'd seriously consider a 4K Yank.


I plan on spraying in the future. :angel:

I'm in the same boat (N20 in the future) so, you're gonna' have to just live with the weak 60's (1.6's) until you get to hit the converter harder with the N20. Flash the hell out of it until then .. and get those shift points up there!!!!

Good luck!!! ;)

Junior

pt 4400 here,127.5 mph , 3125-3150 lbs

pt4000, 3520#, 121mph

I plan on spraying in the future. :angel:Dont get a PT series Yank if your gonna spray, go with the SS3200 or 3600.

Well, I went back to the track last friday and ran a 11.93 @ 113.5 with a 1.68 60 foot. Better, but still not where I think it should be.

I raised my shift points to 6300...you guys think 6500 will be too high?

I'm also going to get a FAST 92/92...stock TB and LS6 intake just aren't cutting it.

It sounds about right me.

6500 is not to high.

Nothing wrong with a LS6 and ported TB, but the 92 will pick you up a little and bet your MPH jumps a bit to.

121.76 here.

That's what I was afraid of. :(

My car shifts at 6000 - shift points weren't raised.

mine is at 6600ish wiith a 228/228 114 not to say i not having probs mine is worse lol 109mph spinning...

[QUOTE=SlayerMaro;9533908]
Since then I've added quite a few mods, but the ones that affect my trap speeds are:

MTI lid
LS6 intake
PRC 2.5 LS6 heads
Cam (228/230 .571/.573 112)
3600 stall
Moser 12 bolt w/3.73's
ZR1 wheels 17x9.5 and 17x11

So I go to the track a couple weeks ago and the temp is 85 degrees. I ran a best of 12.1 @ 111.9 ...WTF? :barf:

QUOTE]
If you want MPH get a Supra. Et wins races not MPH.
Here are my mods: LS6 intake, Lt/Ory, 3:73s 10bolt, UD, and Magna Flow exhaust. cam 230/232 and 853 casting head with port work and 2.02 intake and 1.8 exhaust. Post you dyno graph and lets see what it looks like. Also what is ur elavation? BTW we both have the same trans and vert.

11.76@117

http://i116.photobucket.com/albums/o8/spatton76/dyno.jpg

If you want MPH get a Supra. Et wins races not MPH.

But MPH will determine how much ET potential the car has. It'll also let you know if a car is running right for its mods.

Here are my mods: LS6 intake, Lt/Ory, 3:73s 10bolt, UD, and Magna Flow exhaust. cam 230/232 and 853 casting head with port work and 2.02 intake and 1.8 exhaust.

11.76@117

That looks about right. But what if you ran 12.2 @ 110? Would you still say ET wins races and MPH are for Supra's? Or would you say "Holy crap something is wrong and needs to be fixed!"

The first step in diagnosing a problem is realizing a problem exists. That is something the trap speed can tell us. I'm sure the OP didn't expect to break any records. He just wanted to be in a "normal" range for his mod list. As do we all.

Well, we need some more info 1st. I was alil of a smartass with the Supra thing.
But we need to know 60ft, weight of car, and altitude. Also a dyno graph. In MD he can run at MasionDixon (up in the Appalachian Mt. or down close to sea level at MIR)

BTW looking at ur mods and times we will have a great race

But MPH will determine how much ET potential the car has. It'll also let you know if a car is running right for its mods.



That looks about right. But what if you ran 12.2 @ 110? Would you still say ET wins races and MPH are for Supra's? Or would you say "Holy crap something is wrong and needs to be fixed!"

The first step in diagnosing a problem is realizing a problem exists. That is something the trap speed can tell us. I'm sure the OP didn't expect to break any records. He just wanted to be in a "normal" range for his mod list. As do we all.

Yep, this is how I think of it. I just want to be where my mods suggest I should be. I want those few more MPH so my car has the ability to run lower ETs.

My car is full weight minus the spare and jack, and plus SFC's and heavy ZR-1's 17x9.5 and 17x11. I think I'll just get a set of stock wheels for M/T's out back, and run the stock wheels/tires up front when I go to the track.

Anyway, my run at was a Crapitol Raceway.

60' : 1.681
330: 4.894
1/8: 7.594
MPH: 90.59
1000: 9.942
1/4: 11.937
MPH: 113.56

Shift it at 6400 if stock bottom end, you are shifting too low. Don't change anything anything else. Should go 114 at least.

I went 123 with a newer combo (115 old h/c combo), but this newer car had more converter, and was 300 lbs lighter I would guess.

Well, we need some more info 1st. I was alil of a smartass with the Supra thing.
But we need to know 60ft, weight of car, and altitude. Also a dyno graph. In MD he can run at MasionDixon (up in the Appalachian Mt. or down close to sea level at MIR)

BTW looking at ur mods and times we will have a great race

Looks like we would have an excellent race. I love the races where you win/lose by a fender. Really gets the heart pumping :D

Yep, this is how I think of it. I just want to be where my mods suggest I should be. I want those few more MPH so my car has the ability to run lower ETs.

My car is full weight minus the spare and jack, and plus SFC's and heavy ZR-1's 17x9.5 and 17x11. I think I'll just get a set of stock wheels for M/T's out back, and run the stock wheels/tires up front when I go to the track.

Anyway, my run at was a Crapitol Raceway.

60' : 1.681
330: 4.894
1/8: 7.594
MPH: 90.59
1000: 9.942
1/4: 11.937
MPH: 113.56


Hey who tuned your car?? I see you are in md and near me.

Thanks PSJ. I'll ask my tuner to bump up the shift points again.


A50 - I'm in College Park. Bret @ FBC tuned the car...seems like he does a good job.

Thanks for the tips so far...I think some intake work, shifting at 6400, and using lighter wheels at the track will help. I'd like to trap 115 N/A before I spray. :D

Raceweight?
Stock bottom end?

Honestly if it was me I'd shift at 6600, run a ported 90/92mm FAST intake + 90mm TB, and run a 4.10. Car should go 11.3-4@118mph. Spray 150 on top of that and you'll go 10.3.

I'm not sure of my race weight. But it should be around stock, or maybe a little heavier with the subframes and the heavy wheels.

My car is my daily driver, so as cool as 4.10's would be, I need to get at least decent gas mileage. I'm in college, what can I say. lol

I have the stock bottom end. I trust your opinion, so if you think that is a good RPM I will do it. Though it seems a little high to me. As for the intake, that sounds like a good setup. I'll be buying it soon. :)

I'm looking to spray 125-150...my goal is not too tough, I just want to run a 10.7 or better with spray.

Thanks, PSJ.

Yea, Bret at FBC did my car as well and i am more then happy with it. He has tuned about 12 cars for me in the past. I am sure he will get it right for you.

Bret prides himself on making his tunes right for everybody. i've had my car tuned by a couple other shops before going to FBC (Bret) and i can tell you that he is the only guy that will be tuning my car if i can help it:chug:

Yep, he does a great job. I really doubt it has anything to do with his tuning. ;)