mpe488

What would be the difference in trap speeds between a 3.42 A4 LS1 to a well-driven 3.42 M6 LS1 with equal mods? I'm just wondering exactly how much of the M6's advantage in trap speeds comes from their gears.

s346k

iTrader: (4)

i would guess 1.5-2 mph.

a stick car doesn't have the advantage because of the gear difference, it has the advantage because an automatic eats more hp. stick cars have a mechanical connection, whereas the autos rely on fluid being pumped to actuate the ****. and pumping that fluid is what eats hp.

Roarin_8

iTrader: (5)

Yup, but a stall changes all of that.

mpe488

I relaize that, thats why I wanted to know how much of the difference should be accounted to the transmission and how much to the gears.

s346k

iTrader: (4)

...a stall just changes the first 330'...but sometimes you get lucky and get some trap out of it, too.

s346k

iTrader: (4)

gears won't show a great deal of variance until you start talking cars that trap over 110 mph. there is a gray area between stock and 110 that gears really don't do much except lower your 60.

Roarin_8

iTrader: (5)

I got real lucky with a gain of 6mph

redsscamaroboy

iTrader: (7)

mine gained a little too. 104 to 110 mph. The stall is good for more than 330 ft. shift extension is everything.

But to add something to this threads question.

I ran my auto with stock 3:23 gears for 5 years,and resently switched to 3:42 gears and found nothing at all for a gain.

Hope that sheds some light for ya. Too small a change to really matter.

Dave

Roarin_8

iTrader: (5)

I bet you gained rpms in highway cruising though

s346k

iTrader: (4)

with the addition of a stall and NOTHING else you gained 6 mph?

going from 104 to 110 is like gaining 20 rwhp.

i haven't noticed any gain from 50-110. ..but i was using my gf's 6 spd car as a reference. maybe the track will tell otherwise.

Wesmanw02

iTrader: (4)

Thats pretty much how I would have explained it. Like you said, the gear ratios help more with the ET than the trap speed, but both will be lower for the automatic due to it being less efficient than a manual. A fluid coupling (torque converter) will never be as efficient as a direct mechanical connection, no matter what you do.

No, it really doesn't. A stall can help with ET and trap speed due to being able to keep the engine in the higher RPM's, but its actually less efficient than a stock torque converter in terms of parasitic loss. Anytime you have more slippage you lose more energy, simple as that.

glennhl

Actually gaining 6 mph is like gaining 55 to 60 hp

Roarin_8

iTrader: (5)

He was asking about mod for mod with a manual, I stated that a stall changes that because a manual can't add a stall for obvious reasons. This stall less efficient than my stock one? I gained a full second and gained 6 mph, how is that less efficient? Maybe when you talk about regular street driving, there I'd agree. It's less efficient in saving gas but saving gas is the least concern in a horsepower junkie's mind.

Roarin_8

iTrader: (5)

Unless you want to count the SSRA but I can't say anything about that since it doesn't show on the dyno.

s346k

iTrader: (4)

no tuning?

Wesmanw02

iTrader: (4)

Thats pretty much what i was refferring to. Its definitely faster, but less efficient in the fact that it wastes more energy than a stock TC. So with the stall converter, you will generally put down less WHP than a stock unit would, and fuel economy will be worse. Of course, thats irrelevent for drag cars, being that you will be going faster down the track either way.

Roarin_8

iTrader: (5)

I dynoed 313rwhp and 331rwtq, I don't think that I lost much HP with this stall and those numbers are locked numbers.

The only tuning I had done was to the transmission: shift points, torque management.

Oh and my raceweight was/is 3505 with me in it 1/2 tank of gas. The only thing I removed was the spare and jack.

REDWS6ROCKET

iTrader: (4)

my buddy stangkilr's m6 car ran 11.98 at 121 and my stalled car ran 11.91 at 116. he has 4.10's i have 3.73's.

BlackHawk T/A

iTrader: (3)

So basically he caught you right at the end for the tie, but would have kept going and passed you with his 5mph advantage. That's a pretty big difference but I bet your 60' is different than his and he is making a little more power too.

redsscamaroboy

iTrader: (7)

Funny thing is that my MPG went up 1 from 22 to 23 after swapping out rear ends and reprogramming for the new gears.
Only made a few 100 rpm diff.

In the same weekend drove it to work Friday and in town Friday night, then raced all day saturday,took my son to a Pistons game in Detroit Sunday and found no E/T or mph inmprovment at the track,but the gas mileage is a nice little bonus though.

I need to get my car tuned,only has a Predator tune. Not a downloaded 1 either.

3650 race weight(big heavy full option car )

Dave