Torque Converter v Gears

[cyclone03]

Several years ago one of the car mags did a test comparing different torque converter stalls over different gear ratios.They tested both small block and big block Chevys.
Of course I can't remember the results.

So my question is..........
Would a higher stall converter that still retained the full lock up of the stocker out perform in the 1/4mile a car with only a 4.10:1 gear?

My thinking is freeway performance (RPM) would be unchanged so drive train noise and vibes would not be an issue.Fuel mileage on the highway would be unchanged.

Am I over simplifing this or am I on the right track?

[mensrea]

Your hypothetical is interesting, I would love to see a head to head with a 4.10 and a converter, since I have both I can't tell you.

ALl I know is that the converter added poines, increased gas mileage and looks really cool. IT aint cheap though, although I think Dennis may be able to get a group rate.

[SergntMac]

IMHO, regardless of other mods, you're not going to see a decent launch without 4:10 gears.

You pose an interesting question, just how much HP/TQ does a custom torque converter add to the program? I've not found any hard facts on it myself, yet, and I'd like to know too. However, if it's power to the wheels you want in the long run, why not both?

[mensrea]

I saw thirty some horses to the rear wheels on my car, I don't know what it will do with a stock one, gotta be close to that. Obviously, the converter doesn't increase power, it just transfers it that much more efficiently. I wouldn't be surprised to see gains in the area of 2/10 in the 60 foot and 3/4 in the full quarter mile. The torque multiplication on the 9 1/2-inch series is 2.53 to 1 compared to stock at 1.93 to 1. The torque multiplication of the converter will deliver an increase of up to 50 horsepower to the rear wheels (I saw around 30ish)

[RancorKeeper]

I'm gonna go with SergntMac on this one. A converter won't do much for the stock motor, considering the power band hasn't changed. But steeper gears will always multiply the available torque at the wheels, and the effect is more pronounced in a heavier car. I'd imagine a decrease in 60' time of at least 3/10s with a swap from 3.55 to 4.10.

[mensrea]

Well all I can tell you is my experience, and the experience of others, the PI converter DOES benefit a stock motor, more ponies and reduction in 1/4 time are hard to beat.

Some of the SS guys here suggested az converter from the start, and they love it as well. Do a search for converter on here and you can see the results.

Again, the change to a new converter is a definite help, better gas mileage, better horses, etc.

If you had to pick one, pick the 4.10s cause they're cheaper, if you've got the cash to do it, swap the converter. I promise you will notice a difference. I have it in mine, and love it.

[cyclone03]

What I was looking for was the same or better 1/4mile performance as the gear change WITHOUT the highway mileage loss the gear change would give.

I contacted PI asking about the the lock up function and they say there clutch is more durable than the stocker.

OH to have the money to test for myself.

[mensrea]

Well I don't have 1/4 mile times, but I have the dyno that shows increased HP.

I would be curious to see if anyone did a before and after with the 4/10s in the 1/4.

If you have the money do it, you won't be disappointed.

Here's a link to a thread discussing the converter - converter thread

[RancorKeeper]

Originally posted by mensrea
Well all I can tell you is my experience, and the experience of others, the PI converter DOES benefit a stock motor, more ponies and reduction in 1/4 time are hard to beat.

Well, my experience is quite different, so here's my two cents on the subject. I've been in literally dozens of 5.0s with the old FRPP 3,200 stall converter and can't say there was any noticeable difference off-the-line unless the motor had an upgrade to the E-303 cam (or something similar, like an intake or head swap). Also, when I was on the fence about whether to put the S-10 converter in my Caprice or buy a 3.73 ring & pinion, I drove several club member's Impalas that had a high stall converter & none of them felt any quicker out of the hole, but every car that had steeper gears put me back in the seat. I just don't see how upgrading to a higher stall is going be a better performance mod when the engine's torque curve hasn't changed - not that the factory stall is perfectly suited for the Marauder - but a few hundred rpm difference won't make do much for better 1/4 times, IMO. At least, not as much as a gear swap. Obviously, taller gears will affect gas mileage, where a torque converter probably won't, unless you go so high with the stall that it is actually higher than the rpm the engine starts it's power climb. Interesting discussion though, and I'll look at your dyno plots, but they don't tell the whole story without before & after results from the track, as you know.

[mensrea]

This is getting annyoing...

I did not say you should do the converter instead of the 4.10s, I said if you had the money do both.

What we need is someone to buy and install the converter, take it to the track, then take the converter out, put in 4.10s and then go to the track, etc.

My dad always said there is an ass for every seat so I take what I hear from other people with a grain of salt. There is no requirement that anyone on this board or any board know what the heck they are talking about, so let me say it again... the converter improved my gas mileage, made a noticeble difference not only in off the line, but passing as well, and the dyno numbers sure helped.

If you don't want a converter, don't buy one.

[tetsu]

Originally posted by SergntMac
IMHO, regardless of other mods, you're not going to see a decent launch without 4:10 gears.

I disagree strongly with this statement. You realize that a high stall t/c (I'd go with around a 3500) would eliminate the bogging on launch. Straight to the band and bust them wheels loose.

Plus our ****zitty t/c is giving away power for no good reason 95% of the time besides having too low a stall.

However, gears are alot cheaper.

I say for best go-go do what Mensrea did (if you have them deep pockets) do it all.

If I was in Mensrea's enviable position, I'd go right off for a bullet-proof tranny with some rethinking on the gears (rather than waiting for the stocker to puke during a pull.)

Johnny (who can't wait for Spring so we can have a meet at da Grove and see Mensrea's wheels freak out!) (Maybe we can pool our milkmoney and chip in for some drag radials for him!)

Party on!
Johnny

[cyclone03]

Mensrea,
I hope its not me being annoying.

To keep this going..........
I'm not looking at "bang for the buck".
For those who have done gears,does anybody have before and after 1/4 times?I know most go with a chip to correct the speedo and improve performance.

I emailed PI and there converter has a 2.5:1 torque multiplying factor over the stock 1.97:1 of the stock converter.I didn't ask about stall speed.

[mensrea]

Cyclone,
Not you being annoying, just all the people with opinions and thoughts... I know from experience that the tc will help you out, how much who can say.

[Billatpro]

mensrea is giving you good advice, you have to take the advice of a guy who is using it and getting results. Do the gears first, it's cheapest and then do the converter when you can afford it, unless you afford both now. As for myself, I'm going with Reinhart triple, 4:10's and the converter this spring and then I'll start thinking about "Blower"

[SergntMac]

Johnny, you disagree with everything I say, and I kind of enjoy that. But I still disagree with your strong disagreement, because it's just not logical from where I sit in slower Illinois.

Let's not "what if" this stuff, it's simple engineering and doesn't need to get complicated with opinions. A rear gear reproduces what it's fed, and as the ratio numbers grow, so does the reproduction. 4:10 spin faster than 3:55, all the time, from creep to top end, period.

A high performance TQ reduces drive-line power loss, it does not produce more power on it's own. Our customary 20-25% drive line loss from flywheel to tiires, is reduced to maybe 15-20%, (who knows what the numbers really are?). Point is, all it will do, is push more engine power to the rear gear, period.

Improving the efficiency of a TQ as it is discussed here, is surely a worth while mod. However, it comes with a price tag, and I doubt any of us would get the full "bang for the buck" payback if we retain the stock 3:55 gearing. It will show improvement, yes, but not all it could with 4:10 gears. You don't need a 1/4 mile time slip to figure this out, it's simple engineering, and a touch of math.

I'm sold...new TQ for me by spring, let the dyno tell the truth.