Well, I've decided to hold off on putting some gears in my TA due to the cost for a new 3 series carrier/gears/tune etc. I'll wait until I can afford a S60.

So, heres the question. Anybody put some good heads and a stout cam in a 2.73 geared car? I know some gears would help with the big cam but is this thing gonna be a complete turd? I'm looking into some ported LS6 heads and a good streetable cam that will make around 415 RWHP with some long tubes and a tune. A convertor and S60 will come down the road but for now.....I want power!

 

You can do what I did - install a complete low mileage 3.42 rear from a M6 car.

 

Hmmmm.....I wonder what LS1 3.42 geared rears are going for.

I mainly street drive the car although it's not my DD. It's pretty sluggish off the bottom now with the 2.73's and I'm afraid I'll hate it with a bigger cam. I guess there's always a 100 shot though........decisions decisions.

 

this was my situation. with 420rwhp and 2.73's, the car bogged off the line but when the cam woke up, it was like i was spraying. only managed a 13.1@112.

went to 3.73's and ran a 11.87(best) 12.00 (average) @118.

everything was with h/c in sig, dr's, stock tc. i know you want the power now, maybe go with n20 then. the stock h/c are good enought to get you moving and then spray, otherwise be forewarned you may have the same results until you get the gears done too.

 

Thanks myslowcamaro, that's exactly what I thought was going to happen. BTW, what were you're 60's like with the 2.73s and the H/C?

I actually like the idea of buying a 3.42 geared complete 10 bolt. I could have my 2.73 10 bolt laying around for if/when the 3.42 breaks. I was dreading the 3.73 gear install anyway.

Guess I'll start with a new rear end, long tubes, and tune. I can get the cam later. So what do you suggest, LS1 edit or HP tuners for a novice tuner that's going to continue to constantly add parts to his car.

 

they sucked. 2.2-2.4 60', felt like i could punch the gas, go get a coffee and have plenty of time before the car got to the 60' mark. even now with the 3.73's im only turning 2.0 60's, but i dont preload or any of that. and again, a better stall will help me.

ls1 edit is fine, although many people are happy with mad-z tuning. i dont know if he would do mail order tune, but bill henn (foff667) from this board is really good with ls1's and reasonably priced.

 

I went with EFI Live and have been 95% satisfied with it. It's been a little over a year since I've purchased and learned enough to tune my friends' torquer cams (232/234 .595/.598 112LSA). Granted, we're still working out a few bugs. But considering I've learned everything from the forums, I'd say that's not too shabby.

 

Larger cams not only make more power, but they generally move to power/toque bands up in the RPM range. Thus the good dyno # but slow ET effect that Myslow described. A stall will not fix this problem. It'll flash to a nice RPM then bog because the gears are starting off in a lower RPM. Decide which cam you want, then gear and stall to maximize and utilize it's power range. Set up is everything.

IMO, I'd hate to have a 420 hp car that couldn't break into the 12's. So my vote is gears and converter 1st.

I've seen used 3.42's and 3.73's go for $250 installed

 

Not if the stall speed and shift extensoin is right. It'll get you up in teh rpm band and keep you there.

 

But every time you shift you'll still drop too many RPM and be out of your power band.

 

Yeah, I am fully aware of the effects of a cam on the powerband, hence the question. I was just curious if anyone had done this on a 2.73 geared car before. myslowcamaro's results were pretty much what I expected, and are exactly what I don't want to happen.

I've seen some 3.42 geared complete rears going for $250-350 but most of them are from pre-99 cars that have the auburn diff in em........I've been around the auburn diff before and get sick of rebuilding them all the time. I'd rather stick with a torsen diff.

If I could find one within 250 miles of central georgia I'd buy it in a heartbeat and come pick it up. Anybody?

 

That's not how it works. The rear gearing doesn't change the steps between your trans gears. Once your up and going with a good converter it won't fall enough to hurt the performence after the shifts.

 

The trans is geared the same as it would be with a 3.23. After it shifts it'll fall into lower RPM than it would with higher gears. It will be below the power range of a decent sized cam after it shifts. Whereas if you are properly geared you'll stay in your optimum RPM range.

I raced an TH350 equipped 70 SS w/a 10" converter and 4.11 gears for over a decade. I do know a little about gearing and autos. W/the 10" converter and the 4.11 gears it would drop to ~3500 (IIRC), but when I went to more street friendly 3.08 gears and the 10" converter it would drop below 3000 RPM (2800 RPM IIRC)when it shifted. Not to mention because of the lower gearing it wouldn't acclerate as fast thus taking more time to climb in the RPM range it'll spend more time out of the optimum range. Now, if you have a cam that makes power from 3500-6500 like most LS1 cams, which gear is going to keep you in your power range? Basically the car went from throwing you back and moving quick to being a dog.

 

I just went from 3.42s to 4.10 and best to best only gained .02 in ET. You can not compare an old school motor that only revs to ~5500 with any motor that revs to 6500+. If a 5500 motor drops to 2800 after a shift then a 6500 rpm motor will only drop to 3800 with that same converter. And as I said with a GOOD modern converter it will NOT drop out of the powerband.
You trying to compare apples to oranges.

 

Thats fine, run a big cam with 2.73 gears, but when it gets beat by bolt on only cars don't say I didn't warn you.