BowTieBlood

Kind of a heated discussion on another site about torque converter vs. gears on an LT1 car. Started with a guy saying that torque converters out weigh gears for "biggest bang for the buck" because you can "pick up .5 in the 1/4 with a 3500 stall converter." What's the scoop in how the two compare over all, not just one guy's tests, but Corvettes/F-bodies/Whatever as a whole, which is the most beneficial over all for the money and/or not for the money? For example, to get things started, lets say a 3000 stall converter cost the same as 3.73s for my car, which one is going to benefit me most 1/4 mile wise and why? Let's pretend bone stock cars here, which type of mod will benefit them the most. Automatics obviously.

TreyZ28

Well, if you get a high stall- youd be hard pressed to launch well without steeper gears. Its like "heads vs cam" in a way. You can do each one with the other component stock but they really flourish when together are correctly.

a 3400 stall and 2.73s are going to cause some problems :)

LT4BUD

It is just my feeling that doing nothing but putting in a 3500 TC will not get 0.5 seconds gain UNLESS you have racing slicks to hookup!

Having said that it seems that TC helps mostly at getting of the line, but once you get to lockup speed (say 3500 rpm) then the overall gear ratio will determine performance.

Need to do both, plus tires to maximize capability of engine, BUT if I had to choose only one for a stock LT1 on street tires, I think you would benefit most from gears.

No data to back up above, just my gut feeling..

TreyZ28

well, thats the reasonging behind stall + gears. You aren't going to hook worth a damn with tall gears and high stall :no:

vader86

TCs only help at launching. Gears allow you to get to high rpm quicker.

Either one can knockoff .3-.5 provided you can drive.

TreyZ28

the biggest reason to use gears and TC is that you can actually launch at a higher RPM without spinning-
gears alone just mean less resistance/more mechanical advantage

I am willing to bet that gain from TC + gears is greater thn gears alone + TC alone.

And time gains depend on powerband. you wont gain as much in lower reving motor as opposed to a high revving motor


[Modified by TreyZ28, 8:50 AM 12/5/2003]

vader86

I'm talking about his car, either will knockoff .3-.5 for a 95.
Not even close for the L98, it cant handle the gear and too much stall will make it spin like crazy.

The gains add together for the LT1, gears and TC can put it in 12s.

TreyZ28

:cheers:
i didn't mean to get all knit pickey on you, I just made a general statement. :cool:

this ones on me V
:cheers:

hippy

You guys are saying that a car with 3.73 will spin less than a car with 3.07? Are you serious? A torque conv by itself with 3.07 will produce a hell of a lot less tire spin than the same conv with 3.73 gears. I bet a quality Vigilante tc with stock gears, street tires and a good driver will get you damn close to .4-.5 by itself.

65Z01

The gears vs TC issue is like apples vs oranges...it all depends on what you want.

As stated, a bump in TC stall speed gives a harder launch and thereafter has no effect on performance, assuming that the after-shift RPM is above the stall RPM.

Gears will produce more torque at the rear wheels in each gear and are good for use with an engine that's not as "torquey". Gears should be chosen so that you are at the top of a particular A4 gear going through the traps.

My preference is the better launch from a little more TC with stock gears.

CFI-EFI

I'll put my money on the converter. Although it's no LT1, my stock Crossfire picked up about .3 in the 60' and .6 in the 1/4 with a 2600 Vigilanti. I regulary compete against a 2000 Z28 LS1. With his stock 2.73 gears he couldn't catch me until around the 1000' mark. One day, with a little help from a hole shot, he DIDN'T catch me. Going against my advice for a converter, he swapped gears. He went from 2.73 to 3.73s. His 60's dropped .05-.10. and his ETs by .2-.3. He STILL doesn't catch me until the 1/8th. I am talking about time trials, here. Heads up racing. I honestly feel a good 3000 rpm stall would have him 60 footing right along beside me. Instead, he is playing catch to me for half the track with a car that now runs a half second quicker than mine. That's how *I* see it. Good luck, and...

RACE ON!!!

BowTieBlood

Good info guys, keep it coming, it's all making more sense it what I originally thought. :cheers:

TreyZ28

With a low gear and high stall, you are trying to go zero to a higher speed instantiously than with steep gears and the same stall.

think about it;
at 3400 rpms, whos MPH is higher? the guy with 3.07s or 3.90s :)
It puts a lot less stress on everythig to have shorter gears as well

SBNova

First of all, a high stall converter only allows you to leave the line at a higher RPM, which usually happens to equate to a higher horsepower and torque level. Its like using a clutch in a manual car- leaving the line at 1500 is nothing like leaving at 3000. The downside that nobody has mentioned is the heat buildup of the high stall. If your cruise speed is lower than your rated stall speed (provided the TC is non-lockup) you will overheat your tranny and shorten its life considerably. Thats why even though that 3500 stall will certainly help you off the line with your 2.59 gears- its not recommended that you do it.
The gears will multiply the engines leverage on the wheels and also place the engine higher into its powerband.

For an L98 I would say gears first. Probably no deeper than low 3's. Avoid 3.73's and probably 3:54's too unless your TPI is modified. The converter wil help here too, but stay on the mild side like a 26-2800 stall. You dont want to waste some of that lower RPM grunt that these engines make.

I has a 3600 stall in my daily driver Nova. While some claim its streetable I often think its too much. Its a lockup so it doesnt heat up too much with my 3.50 gears, but it gets kinda old reving the motor just to creep forward at a traffic light. My car will absolutely sit still in drive at an 850rpm idle on level ground. It MUST be revved to 1000-1100 to start moving- with my foot off the brakes.

Hope this helps....

The Money Pit

With only one mod or the other on an otherwise stock engine,I'd put my money in the gear change.The converter advantage will only apply on the launch and the gear change is applied thoughout the run in every gear.Your mph may even be higher due to the change.I've seen cars that couldn't even reach max rpms at the trap due to under gearing.

The real question is who only changes one thing when they mod a car? :skep:


[Modified by The Money Pit, 7:45 PM 12/5/2003]

Lord Odin

:eek: Whoa, good thing I got a trans cooler when I did!

CFI-EFI

AND reconnected your TCC.

RACE ON!!!

BlackC6LS3

so i guess 3.54's and a 2600 vigilante sound like a good combo for a stock 93 lt1

Beach Bum

Torque Converter will provide much better et gains with a TPI motor than gears..... in fact, I recommend you don't bother with gears with a TPI motor, no real et gain by my experience.

However, I think LT-1's love both due to their flatter torque curve and more rev happy manifold.... but I still believe a torque converter will provide better gains than gears.... yes, they will build up a little bit more of heat, but just run a $ 40 B&M tranny cooler.... takes 10 minutes to hook em up. My 700R4 has now lasted literally 1000 1/4 mile passes with a Vig 9.5" 3000 rpm converter.... and for over a year it was my daily driver on the stop and go freeways of socal. In addition, your lock-up torque converter will have no effect on your highway gas mileage.

good luck
Beach Bum

hippy

Here is some good advice, Beach knows his crap.

A lock up tc isn't going to hurt tranny life or mpg. Going to a higher stall is not only fun but gives a good low end boost. For best et pickup I am still in the camp that a tc will give you the best gains. Everyone wants to stick 3.73's in their cars and can't figure out why they don't et faster. Put a tc in and get a car that's in it's powerband NOW before you even leave the line.



[Modified by hippy, 4:24 AM 12/6/2003]