lt4 fd

Man you'd better make some videos of this... thing... after your finished with it. I was actually planning on an LT1 3rd gen swap, if you couldnt tell from the name, but decided it was too much of a hassle so I bought an F-body, oh well. Good luck....

Soma07

Well I guess that depends on what you consider "useable". With the 93 T56 and its .62 6th gear 3.23's are very usable IMO. With that combo my car would pull in 6th gear as low as 50mph. Granted you werent going to win any races that way it had enough grunt such that downshifting wasn't nessecary. With lots more torque and considerably less weight to carry around I dont think Jim will have any problems making use of 6th gear.

Jim: If think you're on the right track with something like a 3.23 or 3.42 gear ratio. I run 3.42's now on my 93 T56 and I wouldnt want anything higher. Partly beacuse I'm lazy and I dont want to shift any more often than I need to, and partly beacuse it would push my crusing RPM @70mph higher than I would like.

My $.02

jimlab

Thanks Jason. Looks like I'll be going with 3.42s, since although I'd like just a little less gear, I can get my gears more cheaply if I can interest other people in going in on a group purchase.

SStrokerAce

Honestly I want to see the actual dyno printout scanned in.

12.5:1? Why do that on pump gas in a car? You better run high octane (100) or run it really cold.

Please post the flow numbers at all lifts too, not just 3xxcfm numbers. BTW who did these heads? and how are they still 215cc's?

Bret

jimlab

I only have the numbers that Mark Montalvo sent me, he apparently has pictures of the dyno monitor during the dyno session(s) and video, but I haven't seen either. He simply sent me a quick write up of what happened, and you can see that here...

http://home.earthlink.net/~jimlab/images/dyno1.jpg

It might actually be closer to 12.2:1. Mark had custom pistons made and we sold the ones that I sent him, so I'm not sure where it ended up, but it is in the 12.2-12.5:1 range, static. With a 26x/26x @ 0.050" solid roller cam, obviously dynamic compression is lower. It is a pump gas engine, and the car is not intended to be a daily driver.

B&B Performance did the heads under Mark's guidance. They were custom cast AFR 215cc raised runner heads with reverse cooling revision. 2.10"/1.65" valves. I was specifically asked not to publish the flow figures, however.

http://www.c-zone.net/markm/JimLaBre...e/DCP_0373.jpg
http://www.c-zone.net/markm/JimLaBre...e/DCP_0379.JPG
http://www.c-zone.net/markm/JimLaBre...e/DCP_0383.JPG
http://www.c-zone.net/markm/JimLaBre...d/P1020025.JPG
http://www.c-zone.net/markm/JimLaBre...d/P1020031.JPG
http://www.c-zone.net/markm/JimLaBre...d/P1020032.JPG
http://www.c-zone.net/markm/JimLaBre...d/P1190035.JPG
http://www.c-zone.net/markm/JimLaBre...o/P1010114.JPG
http://www.c-zone.net/markm/JimLaBre...o/P4260021.JPG

Bret, if you are at all in doubt of the power my engine made, you're more than welcome to contact Mark directly and ask him about it.

jimlab

We're going forward with having 3.42 gear sets made, thanks to everyone for all of your help!

Highlander

Sorry to resurrect such an old topic... If you have compared the z06 to a camaro you see how well the z06 mm12 was chosen... the 5th gear falls to around 5000+ after running a hard 4th which makes the car INCREDIBLY FAST! for the HP up top till 150...

One of the reasons I chose the 4.11 was because I wanted that 5th gear... 2 options: have the pinions and replace them (expensive and a lot of work) would still keep the 3.42 (just as you mentioned before) or put a 3.90 wich would make it very comparable...

The 4.11 made my car very nasty till 150 which is where I finish all my runs...

with a 26.1" tire like the firestone is a CRAPY combination for the track because I have to end at 118 in 4th and then run 5th... but I gained .4s launching on second gear which is what I do.. I dont run on slicks, but If I did I would go with 28" slicks which is better for traction and will equate to a 130mph 4th gear speed... (I think)

I would love that GM had a tranny with such a combo as I would change mine in a heartbeat...

OldSStroker

Heare's a calculator which I find useful:

http://murray.faithweb.com/formulas.htm#find_rear

Your speed should change with the ratio of the tire diameters:

28/26.1 x 118 = 126+ @ 6250

jimlab

BTW, I ended up going with an M29 T56; 2.97, 2.07, 1.43, 1.00, 0.80, 0.62. Same 1st through 4th as the Z06, but with better 5th and 6th gear ratios. In the back, I went with a custom fabricated mount for an '03 Cobra 8.8" IRS with 3.55s. I'll also be using RaceLogic's traction control system to help out.

Highlander

Somebody did a bracket for the camaro for the corvette IRS! the gig costed 750..

Where did you get the transmision???

I like the 5th and 6th of the corvette z06....
why didn't you go with the 3.73? 150.6mph in 5th? that is a good number

89ProchargedROC

just letting you know i didn't read through this thread and dont plan too, my opinion:

get the damn car together and get a BASELINE LOL

it isn't too hard/expensive to change gears

jimlab

Sallee Chevrolet, $1,700 + shipping.

Too much gear in 1st and 2nd for a street tire, and I'm not building a drag car.

Not to mention the fact that I'll be able to hit 150+ mph in 4th... 25.7" tall tires, 3.55s, and an arbitrary 7,500 rpm redline.

1st - 2.97:1 (10.54:1 final) - 54 mph, gear limited
2nd - 2.07:1 (7.35:1) - 78 mph
3rd - 1.43:1 (5.08:1) - 113 mph
4th - 1.00:1 (3.55:1) - 162 mph
5th - 0.80:1 (2.84:1) - 202 mph
6th - 0.62:1 (2.20:1) - 220+ mph, drag limited

You have to start somewhere, and when you're building from scratch, you might as well make the effort to come up with the right combination the first time.

89ProchargedROC

not to be the one here with the bad point of me view but in my experience, the right combination is usually not the first one

*shrug*

Highlander

but why 150 mph in 4th?????? Unless you plan on hitting 200mph I think its not worth it... You should have 135 in 4th and 150-155 in 5th.. that is just my opinion... good price on the trans

jimlab

Why? I think the top speeds in each gear are throwing you off a little.

The gearing I chose is comparable to a standard T56 (2.66:1 1st) with 4.10s with the exception of 4th gear, so the gearing is fairly short as it is for a street car. The only reason I will be able to attain such high speeds in each gear is the ~7,500 rpm redline and tire size, and that's sort of a side effect, not a deliberate act.

My goal was to smooth the solid roller out as much as possible at low speeds with the relatively short gearing (10.54:1 final in first), while still maintaining a reasonable freeway cruising rpm. ~2,000 rpm @ 70 mph in 6th is pretty good. Simulation also showed that my trap speeds would likely be highest with the 3.55s, since I wouldn't be shifting right at the end of the quarter, not that I'll be drag racing much.

Just because the car has 200+ mph capability doesn't mean that I've compromised the other gears. This is a ~2,700 lb. car with the equivalent of 4.10s and an ultralight rotating assembly in a 650+ horsepower stroker that we're talking about... not a car that I put 2.73s in to try to claim high speeds in each gear.

BTW, like my speedo?
http://home.earthlink.net/~jimlab/pi...es_new_lit.jpg