2.56 Gear, Stock Converter, 4100 Pounds, NA 11s?

[skinny z]

The owners 496 made 580 HP and 600 TQ, ran 11.84 @ 119.46.

That would be an interesting time slip.

[vortecpro]

Here you go......best ET, worst MPH.

[BradH]

It's got a better 60 than I'd have guessed. Best MPH seen? Is it coming close to 121?

[Old School]

Here you go......best ET, worst MPH.

Yes, it did run those numbers in negative air. In the summer and fall it was a 12.3-12.5 car. The owner is to be commended for the engine build and the attention to detail. Very nice car.

[vortecpro]

Although he did see negative air early on in the day, theres still the fact the baro was under 29.2, just remember 0 DA in a 29.2 baro IS NOT the same as a 0 DA in a 30.30 baro.

[vortecpro]

Here you go......best ET, worst MPH.

Yes, it did run those numbers in negative air. In the summer and fall it was a 12.3-12.5 car. The owner is to be commended for the engine build and the attention to detail. Very nice car.

With his kid in the car, first time out.

[Dragginwagon406]

Does the 2.56 gear have limited slip? Seems like it must be to run that quick.

I can answer that question…

Yukon Spartan locker.

Honestly, even with the 467 is was tough cracking into the 13s with the open differential…but the car was lowered back then, and still had a 2.25” Flowmaster exhaust.

14.1 @ 105+ mph open, car was miserable on the street and on the track
12.92 @ 108.96 with the locker (3” Torque Tech, 70 Series Flowmaster), car was good on the street and dead hook at the track

[Dragginwagon406]

I somehow suspect this isn't going to be as difficult as it seems.
Once I read ported heads....

Wallace says:


Screenshot_20211122-112042.png


I'll go out on a limb and say 470 HP is a walk in the park. (Even if it is an average across the rev range...)
More than one of my racing friends have 11 second cars.
12 seconds in the first eighth.
10 seconds in the other eighth.

It’s harder than you think. The combination of poo gear and converter add about 0.8-0.9s to your ET.

Somehow, most of your horsepower shows up though.

I ported the heads according to Mark’s videos.

Your analogy about the 12s in the first 1/8 and 10s in the last 1/8 is pretty close

[Dragginwagon406]

Here you go......best ET, worst MPH.

Yes, it did run those numbers in negative air. In the summer and fall it was a 12.3-12.5 car. The owner is to be commended for the engine build and the attention to detail. Very nice car.

To be fair, I wasn’t hammering down first time out…the car was still lowered, not transferring weight properly, and had a serious tendency to axle hop.

I didn’t think a 12.29 @ 116.45 at 4275 lbs in 2300’ air was too bad. No doubt, the good air at Martin helped, but so did a well-prepped track (and a better prepped car).

Hot Rod Power Tour saw more than a few 10-Second cars not get out of the 12s. At least I had realistic expectations…after the first pass. That’s why I was giving rides down the track.

[1980RS]

This thread delivers when you know the answers. I have always believed when you make a lot more power you need less gearing, Dragonwagon proved it.

[steve cowan]

I am impressed,
My opinion is to run a genuine 120mph in a true streeter is not as simple as people think.
600ft/lbs does not hurt either

[vortecpro]

The beauty this build is the pure street ability, GM engineered converter, 2.56 gear, Cooper street radial tires, just a super fun car you can drive any where with the factory type drive line, no OD trans which I like a lot. Of course I told Mike this could be done, many thought I was crazy, but Mike made it happen with this survivor Monte, nice work! I can't wait to build my version: A 1970 ElCamino with a 2.56 gear, factory converter, and 650 HP with a lighter tire rim combination and a street drag radial, should be very interesting.

[econo racer]

Wonder what it would run with a 308 gear? Nice combo

[Monza355]

The beauty this build is the pure street ability, GM engineered converter, 2.56 gear, Cooper street radial tires, just a super fun car you can drive any where with the factory type drive line, no OD trans which I like a lot. Of course I told Mike this could be done, many thought I was crazy, but Mike made it happen with this survivor Monte, nice work! I can't wait to build my version: A 1970 ElCamino with a 2.56 gear, factory converter, and 650 HP with a lighter tire rim combination and a street drag radial, should be very interesting.

What’s the approximate stall speed of this converter and is it a 12” or 13” unit ?

[Dragginwagon406]

Wonder what it would run with a 308 gear? Nice combo

Thank you!

3.08 isn't a horrible gear for a compromise of track and street, but my guess is, the combination would not work. The 2.56 gear has two purposes, help calm down the launch for 225/70-15 street tires and two, act like a 3.90 out the back door. Once the car is rolling, the 2.56 keeps the engine in the peak power for a long time, albeit missing torque multiplication from the gears.

I do have a second 12-bolt with 2.73 gears, it is tempting to give them a try if I've got an engine and valve train that can handle the added rpm. I'm just not sure it's worth the added wear and tear and if the deeper gear would upset the current balance on the hit. On my last pass, the good air was going away, I was able to flat foot the launch - a first with this combination. My best pass was a slightly more cautious launch, but the air was better - both passes ran the same mph 119.27. The car went 119.47 with a very conservative 1.93s launch in the best air I saw - I so wish I would've flat footed the first launch.