yardpro

here is the undeniable example of why Mark is wrong....

put your 5 speed in 4th gear and time the 0-60 acceleration

now do it again in second gear...

which gets to 60 faster???

second, of course, because there is more mechanical advantage, not that the car makes any more hp in second...

you are doing the same thing with a rear end gear change, you are changing the final drive ratio, therefore the mechanical advantage..


ok, you can close this thread now, because my logic in undeniable and infallible....

928er

I think we should have a tech session and remove kibort's transmission. fab up a direct drive......

blown 87

928er

well, it should function exactly the same according to Mark..... right?

blown 87

Correct, according to Mark, it should make zero difference.

yardpro

since gearing makes no difference, let's get with Bill and let him know that he should stop sweating his transmission problems and just throw away this trans. He should just put his efforts in a direct drive from motor to rear end.

think of all the money the auto manufacturers have con'd us out of over the years....

we should all rise up and revolt

Landseer

Nah, its been beat to death for the last X years.

Serenity now.

tv

I'm with Yardpro.

And I have the 2.54 in my 85 Euro and that combo is da bomb. (but I wouldn't mind 3 more gears and paddle shifts thrown in)

yardpro

i would LOVE to get the 2.54 or better rear end in my car...

So to anyone that has one lying around, i am in the market.....and since it doesn't make any acceleration difference, you can now sell it to me really cheap...

IcemanG17

"Church of Kibort".....damn thats funny

Okay in an effort to (fuel the fire) clarify things I made some calculations......I think Jeff's car dyno'd around 290ftlbs peak...so I will use that as a #

GEAR Trans Peak Wheel torque (acceleration)
1st 2.20 2345ftlbs
1st 2.54 2850ftlbs (+17%)
2nd 2.20 1538ftlbs
2nd 2.54 1657ftlbs (+7%)
3rd 2.20 916ftlbs
3rd 2.54 1060ftlbs (+13%)
4th 2.20 638ftlbs
4th 2.54 736ftlbs (+13%)

So the peak acceleration of the 2.54 trans is somewhere between 7-17% better than the 2.20 rogerbox....I actually thought 3rd gear was the biggest difference....at least thats where my "butt-O-meter" feels it the most.....

Yes I am jealous of Jeff's new tranny :>)

Mike LaBranche

Hell, I'm jealous of Jeff's S4 all the way around... different beast than the one he pulled up in a year ago. Poor thing didn't want to idle and everything made noise. Now... it's a solid, quick and fast, animal. I'm sure the 2.54 gears make a ton of difference, the 2.7's in the 5 speeds are a real hoot.

Rocketman928

Just look at a motor bike. If you want to accelerate faster use a bigger rear sprocket (or a smaller front).
If you want to go faster, do the opposite.

Think of a mountain bike. 9 speeds at the back - 3 at the front - same leg horse power.
Think of the front 3 sprockets as 3 different diffs.
Try to climb a steep hill with the big front sprocket!
Its all simple physics.

dr bob

At the same road speed, the engine makes more horsepower in second than it does in fourth. Key is "at the same road speed". MK has the right idea from zero to top speed, ASSuming that you can get to max horsepower at top speed, the differences in performance will be negligible IF the torque "curve" is a straight level line. But it isn't, so it isn't. With torque increasing with RPM, horsepower increases faster than RPM. As MK says, it's all about the horsepower.

Now, back to your regularly scheduled argument.

blown 87

Well that depends if the car is in a steady state cruise, then the HP will be equal in any gear, or if it is decelerating then it will be less, or say accelerating in a higher gear, then it will be more, same for a lower gear.

So what you say is confusing, and that is something you rarely are.

The bottom line is still the same, with a 2:73 rear gear in ANY gear the same 928 will accelerate faster than if it had a 2:20, and you know it.
And in my 87 it will also have a higher top speed according to most here. (again, I do not know for sure on that one)

I guess what I am asking is are you trying to agree with MK on his gearing makes no difference BS?

Sorry, I really could not tell from what you wrote.

killav

I had an old hot rod pick-up that I would take to the drag strip from time to time back in my 20's. It had a stout 383 in it with a turbo 350 trans and positrac rear end with 3.08 gears. I swapped the 3.08 rear end gears with 3.73's with no other changes and dropped almost a half second off my quarter mile times.

It did suck on the highway after that, with no overdrive, 295-50-15 drag radials, it would spin the motor pretty high just going 60 mph. But it sure was fun 1/4 mile at a time. Changing the gearing made it "pull harder" at the drag strip but it would "run out of gear" on the highway........