OK, I've read quite a bit in here about people seeing mid 12's at 106 mph. 12.7 @ 106 is the most common. My old corvette was a 1992 ZF6. For awhile best time NA was a 12.600 @ 111.11.

I launched it at 6,000 RPM's on ET streets. Dropping the clutch, the tires would dead hook. ZERO wheelspin. Then I would speedshift the rest of the way through the 1/4. I don't see how I could of possibly wrung any more ET of it. I was all but power shifting it, and I was launching it like it freaking owed me money.

How the hell do you guys go almost the same ET as I did, but with 5 less MPH?

 

Your running a stick which will always MPH anywhere from 4-6MPH faster than an auto with the same power.

Not only that but a good coverter will accelerate the vehicle harder/quicker through the 60' with its multiplication ability vs a manual which will bring down the ET, so the ETs match in the end.

Obviously there is some generalizations here, but in the nutshell that is why your MPHs are higher than an auto with the same basic ET.

 

As a good general rule, the mph is a power indicator. The ET is a measure of how well that horsepower is applied through the entire 1/4 mile, with the emphasis on the launch and the early part of the 1/4. The last car I had that ran numbers like those, had a best of 12.21 @ 111 mph. It had power similar to yours but it was better off the line. It WAS built to be a torque motor, and it DID just barely lift the front tires.

RACE ON!!!

 

You also have to remember that Et is more torque related and mph is a measure of horsepower. I've seen head/cam cars with similar HP numbers as mine run the same mile per hour but be 0.5 slower in ET because mine was a stroker and had alot more umph off the line with the torque.

 

neat, what were your short times on that Vette and what was the gearing??

With an A4 the TC can make up for gearing to a great extent. For example Vic'89 is running 3.07s with (I believe) a 2,400rpm TC; I believe he is getting the lowest ET for his current HP (i.e. MPH).

 

first off,I think most of those cars are L98"s,or some really geared/highstall, LT1 automatics.As far as the L98 cars,they have alot of torque,and will 60 and 1/8 mile better than your car,than start to fall off,where your LT1 makes ground at higher speed.

 

Josh, what mods did you have to get those numbers on your 92 (1992 Corvette - ZF6 - 475 RWHP/620 RWTQ) ?

 

The stick makes the difference. Hell my friend's car with a nearly identical engine runs 12.2 @ 112 with his auto, but I'm only pulling a 12.9 @ 109.99 last time out with my stick.

 

I'm friggin lost on this... HP is relative to torque at any given RPM so how can more torque get you a better 60ft??? wouldn't a higher RPM capable car be able to do the same with traction and a higher launch? And my relatively stock LT4 ran 111 in the trap but I had a pathetic 2.6 60ft and a 14.0 ET. So how does that translate since my tires went up in smoke on that run??? My best ET is 13.4@106

 

The auto torque converter mulitplies the torque to the tires by 2-3+ times (I think) so this energy will pull the car up to speed faster over 60 feet. The reason you trap 111 is because you were accelerating for a longer time. If you have .6sec longer to accelerate, you have the extra mph (weather was probably better too). You would think the 60' would accelerate you to a faster mph, but it isn't necessarily so. This is why most "bests" (mph&et) aren't on the same run.
I'm sure someone here can explain it better...

 

The main reason is very simple.

Manuals have a near 100% (obviously there are losses, but...) transfer of power

whereas with an auto your coupling the power through a torque converter with fluid coupling.

I just spent the last 3 hours on the phone with Rosslertrans and TCI trying to make this coupling better.

Right now my car is seeing as much as 11% slippage through the converter! I go through the traps at 6500rpm, where my MPH with zero slippage says I should be around 5800rpm.

What that means is I am basically throwing 11% of my power out of the window in the form of heat, through the converter.

When you buy a converter, the manufacturer does his best to get the fin angle right ect to best compliment your setup, but this is VERY difficult to do the first time. And why most reputable manufacturers wil offer a 1 time upgrade for free. You pay the shipping.

Anyways after talking with them, I we think that tightening up the converter ~800-1000 RPM will gain me back as much as 8% of my power. On a 600hp motor that is almost 50hp!

But to bring you back to the conversation at hand, you see I only said gain me back 8% and not the full 11% I am seeing. That is because without a lockup converter, you will never see 100% coupling in the sense you do with a manual trans. Therefore a manual will typically MPH much better than an Auto.

But this is where people get lost...the auto will usually accelerate quicker than the manual in the begining of the track, where more ET is gained, hence the two setup will ET the same, but have much different MPHs.

Hope that example clears it up.

 

You need more gear to get ET with a manual campared to an auto. A softer engaging clutch can also help since it won't pull bog the motor as much.
If everything is optimized a manual trans will be quicker and faster because it eats less power. Optimizing usually isn't very driveable in a lot of cases. Just check out stocker class racers at a national event. A friend of mine's 89 305 TPI firebird runs 12.00 @ 108 with a stock(er) motor.

 

DAMN! What kinda 60' is that?!? Freakin 1.4?! That's MAKING USE OF THE POWER! On the Nitrous, I can only HOPE to run 12.0 @ 115