djm_e22

iTrader: (2)

Hey LT1 guys help me understand something. I am tired of argueing with my buddy. But his tranmission guy says that a lower stall is better for drag racing because you don't want a loose stall because you are losing horsepower. My buddy's engine makes 500lbs of torque at 2500rpms and 600lbs of torque at 4400rpms at the flywheel. The tranmission guy says he needs a 2500 stall. Why would he say this for drag racing? Wouldn't he want close to a 4000 stall. Am I right or is the transmission guy right?

Joshiedoom

iTrader: (4)

Why dont you stick with stock then if a lower stall is so much better? Misinformation is a crime IMO

djm_e22

iTrader: (2)

That is exactly what I told him. Now I have heard that the higher the stall the more slip. For example a 2000 stall slips maybe at 5% at the 2000rpms and higher and the 4000 stall may slip at 7% at 4000 and higher. But I don't think that would be enough to lose the race.

97Z28SS

iTrader: (5)

It really depends on how much tq the engine makes and where (rpm), what gears are in the car, what size and type of tire and how much the car weighs. A big block makes so much more tq than a sm block so it can use less converter and leave just as hard. You want the converter to stall near peak engine tq for an all out drag car but on a dual purpose car with stock type suspension too much converter and the car will be lazy during daily driving.

djm_e22

iTrader: (2)

Exactly. He makes peak torque at 4400 but the guy is telling him a 2500 stall would make him faster at the track.

1961ba427

iTrader: (26)

X2, but I think 2500 is too low a stall unless he is trying to make his passes on street tires....which would make NO sense with a 600 ft lb big block. Also, keep in mind that a convertor rated at 2500 is going to stall up more behind a high tq motor like his. Maybe that is what the trans guy is trying to say?? Either way, I don't see a typical 2500 conv stalling up anywhere near his 4000 rpm peak.

FASTFATBOY

iTrader: (23)

And he is correct, but the right stall will make the car QUICKER.

djm_e22

iTrader: (2)

I don't think that is correct. If you get a 2500 stall converter made to the specs of your car, it should stall at 2500rpms(at least if its a good company making it). Now maybe your talking about taking a 2500 stall out of a small block then sticking it onto a big block, then yes it will stall higher because that stall converter was set up for the small block not the big block. Right?

1961ba427

iTrader: (26)

Quicker vs. Faster

I didn't catch that. LOL Funny thing is I spent 30 min trying to explain the difference to my kids the other day. I told them my SS is FASTER than my 61, but the 61 would blow it's doors off in a drag race. They still don't get it.

djm_e22

iTrader: (2)

Sorry a little confused. haha. Who is correct?

FASTFATBOY

iTrader: (23)

Tight converter(2500) will make the car have more MPH in the 1/4 but hurt ET.

The RIGHT(looser) converter with make the car ET better(quicker) and have less MPH.

Wicked94Z

iTrader: (26)

im not sure id agree with that... the motor would probably fall back on the higher stall converter during the shifts, higher stall is probably alot smaller and lighter, etc. you dont really see a 2500 stall for racing use, unless we're talking about a cummins or duramax. this transmission guy... i wouldnt spend my money with him

Puck

iTrader: (17)

Smallblock rules don't always apply to big blocks, and even then every build is different.

Usually, you want around 500rpm stall rating below peak tq for drag racing, and a 4k may on paper seem like the best bet when bench racing...but who here thinks they can hook 600ft lbs of tq flashing off the line??? Without a crazy drag setup, that's not gonna happen.

He may have a BBC, but it could be a street rod, and could very well end up quicker in the 1/4 with a 2500 stall.

Like stated, it depends on his gears, weight, cam, etc. If someone told me MY build would be quicker with a 2500 stall, then I wouldn't let them even wash my car, let alone work on it .

djm_e22

iTrader: (2)

I told him the only reason he would be quicker with a 2500 is if he can't hook with a higher stall. But if he can, which their are plenty of people with that power that can, he would no doubt be faster with a higher stall. By the way that is 600lbs at the flywheel, before he attaches the th400 and 9" rear end. And yes the same rules do apply as a small block. If he can get traction with the big block, the torque converter with the stall nearest his peak torque wins.

Johnny-LT1-runner

iTrader: (15)

You keep saying he won't hook, but is that assuming DS or street tires?

djm_e22

iTrader: (2)

I don't know why they are saying that because first off that my buddy's engine is 600lbs of torque at the flywheel. By the time it goes through his th400 and 9" it will be in the mid 400 most likely. He will be using slicks. Also the transmission guy never said about him not getting traction. Matter of fact the tranmission guy assumed he would get traction because he said the higher stall will just get you a better start but you will lose at the end of the track. So can anyone now explain why he would say this or is he just simply wrong?

nighthawk15

He's right and wrong at the same time. Like explained earlier , the higher stall will get him off the line faster, IF he can hook, and really the launch is probably the biggest factor in getting a good e/t outside of brute power. The car will trap at a lower speed, but the e/t should most likely end up faster. This is exactly why you can see a stock WRX and a stock LT1 Z run eachother and despite the canyon sized gap in trap speeds, the e/t won't be all that far apart (with a good launch the Z will be quicker still, but not by as much as the power/speed difference would suggest). Its for a different reason, yet with a similar result, but amplified. So GENERALLY SPEAKING, remembering that there is no hard fast rules here since no two builds are exactly the same...

higher stall = faster launch, slower acceleration

lower stall = slower launch, faster acceleration

Wicked94Z

iTrader: (26)

quoted so you can't delete it... that makes absolutely no sense.

nighthawk15

It doesn't make sense that a looser converter that slips more, but lets you launch closer to the peak of the power band would result in a lower e/t, but also lower trap? That lower trap wouldn't just magically happen, so would the car not have to accelerate slower AFTER leaving the line?

suicidal racing

iTrader: (14)

higher stall is what he wants..

you really want to put a end to this have him call up ptc and give them his full specs of car,trans,gear,tires,motor info and they will spec him out the right converter for his combo..