TIMMEH

Guys, I ran my car at the track this past weekend and I must say I was disappointed with the results. I believe the problem is one of several things. 1, my tune sucks *** (which could be a distinct possibility since I haven't mastered the art yet) 2, I'm losing compression in a cylinder. 3, bad driver mod which could also be a possibility since I haven't ever run a car with this big of a stall in it. 4, the stall isn't a true 4000.

The humidity was ****, over 90% and the temp was in the 80s, but all I could muster out of my car was 1.74 60's on ET Streets, 7.80 1/8th mile times, and 12.21's in the 1/4 at 111 mph. Now, I only had 2 runs, but with the mods I have, I should be running at least 11.9's in that kind of climate. (F1 cam, Hooker LTs, etc)

My questions are, what's the best RPM to stall it up to in order to get the best launch? I was launching at around 3K before the car wanted to inch forward. I was told earlier, that I should be able to stall it up closer to the 4K mark, otherwise it isn't a true PT4000. Is that accurate? I did buy a used TC, but it only has 1500 miles on it. It feels like it's pulling harder, but something's not right.

I was expecting the timeslips with a 4000 stall to be a lot different than with my old 3000 stall. Maybe it's bad driver and I haven't learned my car yet. *shrugs* I mean it is a new stall / tranny combo...

Ragtop 99

iTrader: (7)

I stalled my YTP 4200 to about 2500 rpm. That gave the most consistent launch for me. I know others go a bit higher, but I would start to overpower my brakes or my tires if I went higher.

You can not brake stall a converter to its rated stall; the brakes will not hold the torque. Foot braking to 3000 is about right for a low 4000s stall converter.

With your 60', I suspect you are spinning a bit. What pressure did you run the ET streets at? You should experiment with 60' time starting from about 2000 rpm and going up in 250 rpm increments. If your 60' is better at 2000 rpm than at 2500 or 2750, then you have some spin.

TIMMEH

That's just it, my tires aren't spinning at all. They hook like a **** at 22-24 lbs. But you're right, I do need to experiment, just wanted to know where to start and what to look for.

Ragtop 99

iTrader: (7)

I can tell you that it can be hard to feel the slight spin between a 1.74 and 1.66 60'. I've seen the variation on my car.

Just for grins, next time out try 18lbs well heated, and a 2700 rpm launch and see how you do.

Jorday

I agree that it can be hard to tell a slight spin. People watching my car launch tell me they can see the tires spinning off the launch when I can't really feel it.

TIMMEH

okay, I'll give it a shot. I guess I just need to play with the launches then.

JNorris

iTrader: (4)

What were your times (60’ and ET) and trap speed before the 4000 converter?

What gears are you running?

What are your RPMs when you leave a traffic light and you are keeping up with the traffic?

Does this converter seem loose compared to your 3000 stall?

John

F1_SS

I have the same setup as you (F1 and PT4000), when i get my car back ill try to foot stall it and let you know the results.

Colonel

"I was told earlier, that I should be able to stall it up closer to the 4K mark, otherwise it isn't a true PT4000. Is that accurate?"

That's wrong. If you could footstall it to 4000 then it would more likely be a 5000 stall.

IMO, you either have a power problem off the line or you are spinning. That converter should have no problem pulling 1.5 60fts with a DEAD hook.

TIMMEH

With the 3000 stall I would cut 1.70 60's, and run 7.6's, 7.7's in the 1/8th on stock internals. With the F1 cam added, I cut low 1.7 60's, high 7.7's in the 1/8th.

3.23's

RPMs up in the 2500-3500 range until the converter locks.

Yes, it's looser.

F1_SS, I look forward to your results...

F1_SS

maybe your just not transfering weight very well. Humidity also has a big factor, as well as DA. Check your plugs, see if your throwing any codes. Try checking everything.

F1_SS

what are you dyno numbers by the way? I would like to know what my car will do with the F1 and full bolt ons but i may not get that chance since ill be adding a new cam (MS3 or F/A4, or T-Rex).

TIMMEH

I haven't dyno'd since the new TC went in. Weight transfer is fine, and the DA isn't taken into consideration due to I was comparing my car's performance, with a car that has stock internals and a 3800 stall...he was running 12.1s...he should have been hitting 11's too, however I should have been faster than him.

JNorris

iTrader: (4)

On WOT shifts what RPM does your engine drop down to on each shift?

98Raptor

Just to let you know I have the SS3800 and I only stall it up to about 2200-2400. You want to get it up in the power band but you also want to hit the stall hard and not already be there.

I have also done some playing on the dyno to test this. By gunning it at diffirant rpms I would get differant results on my torque. When I started I was gunning it at about 3500 and put down 350rwtq. After sveral times of playing with it I got the best results at about 2700 rpm with 390rwtq. And thats on a 305rwhp car. Every time the car still peaked at 3800 (the stall) but the lower I could get it without it down shifting the better torque numbers. Dynos don't mean anything but they are a good tuning tool.

Now with 350rwhp I am puting down 415rwtq.

I would try lanching at about 2700 and see what happens. What tires are you running? If you are running slicks I would drop the psi down to about 12 also. If DR than down to about 14-16.

TIMMEH

thanks guys, I'm going to be trying different launching patterns pretty soon. I'll let you know.