turbojeff

iTrader: (30)

I guess it depends on the HP level and application.

I drove wingsfan LS1 FD and I didn't think the gears were that bad. A little short but I'd guess that the auto FD ratios would fit in pretty well. That 6th gear is pretty tall so cruising doesn't feel busy.

I think a stock LS1 (vette, carmello, or firechicken) has too tall of a first gear, I think those cars can go 58mph or so in 1st. That seems to tall. Again I think it depends on HP level. If you've got 600hp that is an entirely different game than a 320 rwhp car.

jimlab

Yep.

There's a big difference between a small block that makes 400 lb-ft. at peak and one that makes more than that from 2,000 to 7,600 rpm.

The Viper uses the same ratios with a 3.07:1 differential. You can turn your power into wheel speed if you've got enough low-end torque to get away with the taller gearing. Engines without much low-end torque need a lot more gear to get them quickly into (and keep them in) their power bands.

Final drive, first gear:
McLaren F1 - 7.66:1
Saleen S7 - 7.92:1
Viper - 8.17:1
Camaro/Firebird/C5 - 9.10:1
Z06 - 10.16:1
FD - 14.28:1

LT1RX7

Also I am hitting overdrive before the 1/4 with the 4.1's and a 26" Slick. It is hurting my ET and I am only trapping 125mph.

LT1RX7

I already am running an auto. I have a built 200-4r from a grand national with a transbrake.

LT1RX7

Yes.
The best I have run is a 11.1 @125. The track is slippery so it has more in it I would guess high 10's but I got booted for no cage.

I am putting in a monster cam right now too that should get me into the tens off the bottle then spraying I should be in the low 10's high nines if I can get it to hook.

kwiktsi

I know with (I THINK) 255/50/16 may have been 245's, don't remember now- I have had so many cars. Anyway, I was trapping right around my shift point with @ 3:42 gear and running similar times- 11.1@126 with my stroked 94 Z. I would think in a car as light as an FD with a 26" tire a 3:27- 3:42 would be plenty of gear with an LS1. Especially if you are bottling it- make the motor work a bit more and pull the car. NOS and forced induction love to pull with taller gears .
Joe

kwiktsi

Did that fit the LS1 or did you need an adaptor plate? I thought the GN was the BOP pattern and the LS1 was a standard chevy? Nice trans though, a lot of people knock it but it is light and can be quite tough if bult right and it should last quite a while in such a light car.

Also- LT1- do you have a link to pics of your setup or any other LS1 FD's? I would like to see that!!!
Joe

jimlab

Good deal. I wasn't aware of that.

SPOautos

What all was done to your LT1? Just the bottle? what size shot?

wingsfan

Ouch Man, why do you have to say such hurtful things about my car?

jimlab

Well, there is.

LT1RX7

Not an LT1 I have an LS1 just had the screen name from when I was thinking about doing it YEARS ago when Granny's was the place to be way before Hinson.

The motor is currently stock I have a 3.5" exhaust, a custom intake and ported TB right now. I have run an 11.8@117 off the bottle. I am spraying a 120 shot from a NXL kit right now but I am not getting the performance I should from it (there are many others that are experiencing the same thing).

I am putting a 242/248 (TREX) cam in it right now which will raise my rev limit to around 7200ish which will help but it will put me over 400rwhp too off of the bottle so I still need more gear. The stock 3.55 from teh Cobra rear I have should be just about perfect.

LT1RX7

As far as the 200-4r bolting to the LS1.

It bolts right up, the bellhousing I have is BOP and chevy. The only thing is instead of 6 bolts holding it only 5 holes line up correctly but there is no stress there anyway so it is fine.

wingsfan

True enough.

kwiktsi

Gotcha. I would love to see pics of the car- is there a link anywhere? How do you like the LS1 in it overall? Are you using solid mounts or rubber? I would think the FD with all the plastic inside would be one hell of a rattle trap with a v8 and stiff mounts, no? As said, I wouldn't mind one with an LS1 6 speed setup!! Please post a link if you have it . Thanks.
Joe

jimlab

From what I've heard/seen (video of NoMercy picking up his car), people picking up their Z07 Corvettes at MTI either kill the engine 20 times trying to get it rolling, or they blow the tires off. It takes a bit of getting used to, I'm told.

kwiktsi

One other thing- did you ever get a weight difference between the LS1 and 13b TT? I would assume it wouldn't be "too" much heavier if any due to the aluminum block and all. Did you keep and luxuries like AC or anything?
Joe

wingsfan

Try here. We weighed my car, and turbojeff's R1 on some scales. Pix of the cars on the scales there too. Added about 60 total pounds.

https://www.rx7club.com/v-8-powered-rx-7s-299/weighed-my-ls1-fd-today-50-50-myth-debunked-274368/

Here are some impressions from the first time Jeff and I autocrossed it under v8 power

https://www.rx7club.com/race-car-tech-103/autocrossed-my-ls1fd-today-1st-impressions-280030/

jimlab

~10 of which is due to the transmission alone. You do have a T56, right?

I weighed my Mazda 5-speed dry and my T56 dry, and they were 112 lbs. and 122 lbs. respectively, IIRC. I've got a list of weights of new and old parts that I've been keeping up to date during the build-up.

wingsfan

Yup, T56. And 17x9.5" wheels with 275/40/17s on each corner, which are likely heavier than the stock wheels.

I haven't made any efforts to lighten the car at all. I will when the turbo goes in, since I'll be adding about 100# of piping, intercooler,etc. I'm assuming that the turbo and the ac compressor are going to be about the same weight (my turbo weighs a spritely 37#) give or take a few.