Ok, so, i've gotta get around to assembling one of my transmissions soon, and trying to decide which to use, i've got two, one from a corvette MM6, the other a GTO box with the MN12 gearing, tire size will be a 255/40-17 ultimately for daily use rear, as for the rear gear ratios, i've currently got the early Q45 center section in, with its 3.54 gearing, but of course it would be pretty easy to grab a J30 R&P and install in another Q45 housing, giving me the 3.91 J30 ratio, and I have also been looking to pickup a newer Q45 3.69 center also.

Gearing for the MM6 box:

1st 2.66
2nd 1.78
3rd 1.30
4th 1.00
5th .74
6th .50

The MN12

1st 2.97
2nd 2.07
3rd 1.43
4th 1.00
5th .84
6th .56

Here is a dyno graph of a LS2 GTO with the same cam i'll be running, which should help a little, this should be about the same as what i'll put down. The blue lines

 

So I did a few calcs. They're really similar. The MN12 has very consistent ratio changes, where it drops 70% up through 4th. The MM6 has a bigger 1-2 drop, but tighter ratios elsewhere. I like the MN12 personally. The ratios are overall greater. I'd put a 3.54 behind it, or a 3.69 with DR's. Those both make for a pretty agressive 1st gear with 375tq and run out way over 50mph (i think). I don't have my calcs with me, but 6th will probably run out over 250mph, which isn't really relevant except that it implies a nice low cruising rshared_pm in 6th.

 

Found my spreadsheet....

So with the data you gave me, the MN12, a 3.538, and assuming a 2700 lb car:
Your peak accel in 1st is about 45ft/s^2 or 1.4G, which you'll probably never get without a slick and drag suspension, which means you'll always blow away 1st even though it'll run out to 50mph on your 255. Just for reference, I'd blow away 2nd in my S13 on street R's with 34ft/s^2 accel.

So 1st goes to 50, 2nd to 72, 3rd to 104, 4th to 149, 5th to 177, and 6th to 266mph.
RPMs drop to 5.0k shifting at 7100 in 1-4, with 5th dropping to 6k.
In 6th at 2k you'll be doing 75mph.

In the race sim part, it's still slower than my old 425whp S13, but not by much. That dyno chart has a ton of area under the curve, even though it's about 40whp light.

 

Was there anything else done to that gto besides A CAM.

 

Cam*

 

Oh no a S, i meant CAM

 

It was sarcasm, calm down killer.

 

Probably has shorty headers or similar construction stockers.

 

My bet is probably typical bolton setup, longtube headers, catback exhaust, air intake setup. Maybe a slightly bigger throttle body, probably not.

That is a fairly tame cam though, I was looking to go a little bigger, but really dont want a rough idle, a good bit more power can be made with stock heads and a bigger cam, but at the expense of the idle for the most part, honestly with that kind of power curve it should be awesome on the street, probably run mid-high 11's at the drag strip, and with a 150 shot put me into the 10's with very little trouble, all while maintaining great driveability and fuel mileage.

 

The post where I found it was 2006 though, and no other info was given, generally a lot of setups now are making a bit better power with similar cam specs, 224-228 or so duration usually putting down something like 410-420 RWHP with full exhaust, air intake and an underdrive pulley.