CadVetteStang

Of the two ’91 project cars I found, one is set up for automatic and the other for manual. As is, my planned install motor is rated at 550lbs.torque @3200 and 400 HP @4400 RPM . However, when tuned, it will have 575 – 600 lbs. torque @ 3500 RPM (depending on cam selection) and 450 – 500 HP @ 4500 – 4800 RPMs….

1. Will the clutch hold in the 6 speed?
2. Is a BOP Bell housing available for the 6 speed or would I have to use a similar adapter as required for the 700?

I do not plan on using slicks and it won’t see too many drag strip runs; it’s going to be a daily driver/ autoX racer ....... and it may see some stoplight action on summer max performance street tires.

73n95

For info on the M6 check out ZF Doc's web. I believe there are some specs regarding the manual trans and talk about torque handling. I'm pretty sure the standard ZF6 will handle it but they are expensive and hard to come by. Ican't help on the auto but it seems to me that there is more development on the automatics than the manuals. I'm a "3 pedal" guy so I'm biased.

Kevova

Its a matter of preference. You will need the D44 from the 6 speed car either way. The ZF should handle the engine if its in good condition. I doubt a 700r4 it survive long with the planned engine. If you are going to run auto I would look at a 4L80e or THM400 either would require some fab work.

vader86

My combo has 550 Tq at the crank or so, I use a Pro-built 700r4 and still have the D36 for now. The stock 700 cannot handle the torque very long. This built one can handle the power but in my opinion, if I had it to do all over again, I would convert to the 6 speed with a D44.

So I'd go with the M6 if I were you.

aklim

What do YOU, not what the other boys say, think you need for what you are doing? I don't autocross much so I wouldn't get a stick besides the wife cannot drive stick so it would have to be my car only. If I did more autocrossing, I would. With all due respect to Vader, I have about 420 RWHP and broke the D36 with a decently built 700R4. Disclaimer is that I do flog it at any ramp I think there are no cops around but it doesn't start from a perfect stop.

aklim

Wouldn't a 4L80E need a computer to control it? Is it going to be that much better than a built 700R4?

I also remember someone mentioning a very low first gear that they have with the 700R4 lately?

hcbph

50+ years ago (when I was young and stupid) I thought I was going to be the next Don Garletts, Ronnie Sox or Connie Kalita. I ran manual trannys and blew up my share of engines, transmissions, clutches and related parts. As I watched some of the big names in drag racing switch to automatics I didn't understand why as it was fun to shift, till I had a chance to try my first manual valve body. I started getting more consistent times, broke less parts and had better trap speeds at the tracks.

As someone far more knowledgeable than I explained, automatics by their very nature would absorb some of the shocks passed along with manuals and if set up correctly will shift better and faster than almost every driver on the track at that time.

I still am driving manuals after over 50 years of having a license and I drove a number of years before that (farming community) and it's still fun but I have to say I also have 3 automatics that do better in some areas than the manual does. All I'm saying is which way you go, there will be tradeoffs and only you can make those choices.

Kevova

700r4 3.06 first gear. There is a stand alone module for both 4L60e and 4L80e's along with some outfits that have modified them for more gear ratios. I myself would be doing the ZF.

gerardvg

I have a blower and have gone through at least 5 T700 R4 transmissions, that includes 3x very expensive heavy duty builds.

For track use go for the manual gearbox.

Don't forget the half shafts they twist like licorice with high torque, I got some steel ones made up.

cv67

The ZF6 wont break, some here throwing down more power than that and have never been cracked open.
Youll want a very sticky tire like an M/T or ?? similar even for st driving so you dont go backwards at 60. The typical nitto hp st tire isnt going to get it unless you can modulate your right foot but whats the fun in that

pologreen1

A 700r can be built just fine to handle your power. Even 1k hp. Right now if a racer skidwnit has an awesome deal on his built 400trans to put in a c4.

A zf can handle that power if it's a black tag but it's not meant for it. If you want stick and plan to make power and beat it you'll want a t56magnum.

cv67

Google TRC trans in Chatsworth Ca talk to Ron
He builds an unbreakable 700r been using him for over 20 yrs
He races sprint cars himself so he knows what power is. honest straightforward pull no punches guy. Did a great job upgrading my T56

If you got enough gear theres always doing a stout T400. even stock dont have to worry about much . Add a nice converter manual valve body..oh yeah! BUT autos are boring

QCVette

I've heard that the ZF can handle more than it is rated for, but the ratings are:

Black tag = 610 Nm (450 ft lbs)
Blue tag = 540 Nm (400 ft lbs)

In practice, I know they can take a lot of abuse and survive. I suspect they would work with your set up, but that is a guess since it is far above the transmission's torque ratings.

Good luck.

pologreen1

True, but expensive to repair.

If people think 700r4 is expensive...Call for quotes on a zf!! I did, guess what? I'm still auto, and actually the built auto is awesome and handles power fine, shifts good, and drivability with a 4k stall. Better streetable than many out there. Good tuner though.

CadVetteStang

Thank you all for the great input. You have helped me decide that it really doesn’t matter which tranny I go with for my purposes. That is, IF there is no difference in strength when using a BOP bell housing adapter for a non-Chevy engine. If there’s a BOP bell housing for the 6 speed, I would prefer that over the adapted automatic – but if both require the adaptor, then I guess it doesn’t matter.

Kevova

As you mentioned B-O-P bell house what kind of engine are you planning? Trans Adapt makes a plate to mount chevy bell housing to BOPK engines. Because the ZF was only in C4 I think it's unlikely there is a BOP bell housing with ZF bolt pattern.

CadVetteStang

Before judging, remember that the LT5 was not a Chevy motor either. And, I've been wanting to do this swap since the first underpowered C4 was unveiled. This engine is almost the same weight as the LT5 and has physical dimensions similar to the BBC. It's perfectly streetable at 450 HP, and with injection can get 22-26 MPG. You could call it a poor man's ZR1 if you are nice, or a rednpeck cheater if you are not so nice.... Enjoy the videos.






Stock power numbers - 1970
http://automotivemileposts.com/prod1970eldo.html

Build power numbers - aftermarket
http://www.crankshaftcoalition.com/w...e_500_Cadillac

Kevova

Sounds interesting, are using factory EFI manifold or something custom? You will need the Eldo rear sump oil pick up and pan.

CadVetteStang

Starting out (due to budget) I may have to go with a carb. This will at least get the car on the road faster. However, if I can, I will start out with the ‘76 factory manifold (even though the iron intake would make it 50 lbs. heavier than the LT5). But that would give me a chance to work out the bugs in the injection system. The factory injectors were overkill and will feed 500 HP on a sequential injection system. Eventually, I would get the MTS single plane intake and have the factory injectors and rail plumbed in.
(I just missed one at half price ($300) at a car show/swap meet and a F.A.S.T. injection system (used) for $300.

I have several rear sump and mid-sump pans. Since the Caddy mounts are a couple of inches forward of the SBC, and the distributer is up front, my goal is to set the engine back 2-3” to the firewall so that I don’t have to notch the cross member for front pulley clearance. In that case, I should be able to use the mid-sump pan. In that case, the Deville headers would be a bolt-on with no clearance issues.