GregP

Since the car has never run before and there is no reference for a baseline, how do I get a good first guess?

Wt ~ 2800# (actually hoping for lower but don't know what I'll be able to get to)
Gear = 4.86:1
Tires = 29.5 x 15.50
HP ~ 550 @ 6000
TQ ~ 560 @ 4500

Thanks - Greg




[Modified by GregP, 12:43 PM 1/3/2003]

gkull

Are you going to try and use all four gears in the 1/4? For an all out race machine you want your stall to be just under max TQ and above the stall speed durring gear changes. Like if your going for 7000 rpm shifts and your 1-2 shift puts you in second at 4000 rpm you wouldn't want a 4500 stall. You want stall to get you moving. then you wish that you had a lockup TC. The heat created is fantastic when you get into really high stalls. Heat is lost power

GregP

"If" the drag strip simulation I have is correct it would go through the lights about mid RPM in 4th (5000), or overspeed a bit (about 7300) in third. Not ideal, but I wanted a lower highway RPM than I'd get gearing it for max RPM in 4th through the lights. I'm "planning" on shifts at 6500 RPM, which would make the drop after the shifts be 4000 RPM plus or minus a bit.

I am planning to use a lock-up converter, and with the EFI should be able to program the lock points, although I don't know for sure if I can set a different one for each gear or what. I'll have to look into that some more.

The car will in all reality see more street use than drag runs, so I don't know if I want to go to real high stall for performance or pick something more mid-line. The drag stip simulation says I should have a 5000 RPM stall, but I think that's much too high. I was guessing (and I do mean guessing) something more like 3000 to 3500??

Thanks - Greg

gkull

The highest lockup converter I ever had in my 79 was 3800 stall. Right now I have a 3500. Which is plenty. Around town it really gets the tranny hot.

I tried auto & manually shift while in lockup and it just blew out the lockup clutches. It was fun while they lasted.

NoWorries

Hey Greg, I'm chasing you around the board. ;) I'm trying to learn this stuff too.

I didn't realize it was going to be a street car more than a drag car. That would make sense with the 200R4 setup then. John Mackey(to be found in the Drag Racing section) is running a 4400 stall with a 4L60E. He uses that car as a street car, and says that the 4400 isn't that bad. Does the 200R4 have a lock-up converter? If you go high stall, and streetable, you're going to need a lock-up converter. If its race only, a non-lock up converter is lighter.

:seeya

Jason Staley

Some other things you need to remember is that the rated stall speeds for a lot of convertors are based off of a 350ci application making ~300hp. Your higher torque & hp will increase the stall in any convertor, but your low wait will lower it so its kind of hard to know where the stall speed will be out of a off the shelf convertor. Also, not all convertors will take that much Hp so be careful to which one you buy. You might want to give B&M, Coan, etc. a call and see what their recommendation are. I know B&M's cateloge is pretty good and was helpful to me.

FYI. I have a 455 Olds (~500 ft-lbs & 420 Hp) in a Pro Street Oldsmobile Cutlass with a TH350, 4.11 gears, and 30" tall tires, that I run a 3200-3600 stall in. It does just fine on the street even without a lockup, but I tend to stay off the Highway. It can do it, but I don't like running above 3200 rpm for long periods of time.

:cheers:

8T1-7T9 BIONIC VETTE

I'm running a Super Yank 3500....I provided the info to Yank Company and this is the converter they recommended for my car.....It's best you talk to the guys building your converter.....They'll ask you questions about your cam....rear gears, tire height, trans, etc, and most important what you plan to use the car for.....Art Carr also builds custom converters to your end use.....Every car is different so talk to the guys who are building your converter..... :seeya Cappy

Jvette73

I always picked stall speed based on the camshaft powerband. IE: if yur cams band is 2500 to 5500rpm then 2500 stall would be a good choice. 3500 to 6500 then 3500 stall. And so on. The idea is to have the trans begin to deliver power off the line right when the cam is at the bottom of its powerband.

GregP

Thanks everyone. I plan to discuss the converter with the trans people, but like to have as much background as I can going in to ask the right questions (and dodge any BS that happens along).

-Greg

Ganey

Greg

Besides the TQ curve, another thing to consider on the street is traction, even w/ slicks, time for a burnout, etc..


:cool:

Jvette73

Greg, so whats the power band spread on yur camshaft? You dont want less stall speed then the bottom of the cam powerband. Its ok to go slightly above though. But too far above and you will be wasting the lower end of your cam powerband. So if yur cam were to be rated from 3000 to 7000 and you chose a 4000 stall, you would be bypasing the first 1000rpm. But in that same case a 3500 stall would not be wasting so much.

Also I see you chose the 2004R. i got that trans in my vette and love it. Comming up on 2 years of spirited driving on it and no problems so far. where are you getting yur 2004R from? I do know this, heavy duty high stall convertors for the 2004R are quite expensive.

GregP

Based on the dyno software predictions (all I have so far) the peak torque should be about 4500, with 400+ ft-lb from 2500 RPM on up.

I'm seriously looking at the Art-Carr trans (currently on sale for almost $900 off normal), but if it doesn't check out I'll go with the PTS trans. Either would use a 9" lock-up converter. "List" price on either trans is right around $2k, and another $800-900 for the converter. At list price I think the PTS has enough of a track record to make it the winner easily, but that $900 off on the Art-Carr sure has me interested.

-Greg