C-4 vs. C-6

[TonyMadrid]

Hi all, I am building an A&C Cobra Kit and I will be using a 351W engine. I am not planning on racing it so I will not be stroking it or punching it out. I am planning to go with an Auto tranny and need some opinions on what tranny to use.

What is the basic difference between the C-4 and the C-6? What are the pros and cons of each? Also, what flex plate will I need, and what should I be looking for as far as the converter? Also what size tranny cooler is recommended for each tranny?

Any comments will be greatly appreciated.

[750hp]

Tony - for what you need, I'd definitely go for the C4 before the C6. The weight and size difference is amazing. you probably wouldn't even fit the C6 in your trans tunnel without some hammering and cutting.....

The C4 will cope with all the power that you can throw at it.

You need a 164 tooth, 28oz flexplate
Fit the biggest trans cooler you can fit / afford. You can never go too big with these.
Without knowing your engine specs, I'd hazard a guess at a 10", 2000 - 2500rpm convertor. Much less and the car will lurch into gear, due to the light weight of the Cobras. Much more and it just won't feel right. Yeah, it'll probably accelerate a little better with a 3000rpm convertor, but you'll keep wondering if you're in 2nd or top gear when cruising through the suburbs, and it'll sound like a ski-boat when you get on it....

[Ron61]

Tony,

All but one of the guy's around here used the C-4 because of the lighter weight. The drag races use them and have them beefed up inside. One friend used the C-6 and has wished ever since that he had gone with the C-4. I think that weight is the big difference and you can have the C-4 beefed up inside to take a lot of abuse. As for the flex plate I leave that to the guys that know more than I do about this.

Ron

[blubyu2]

I have a new tci c4 with about 200 miles on it if your interested


http://www.upstatecobras.com/phpBB/viewtopic.php?t=34



Greg

[dkjos]

Tony,
The C-4 is definitely the choice for a non-OD automatic. It soaks up a lot less HP than the C-6. If you have any interest in an OD type, check out both Baumann Engineering and Lentech. Their web sites have tons of good info on the AOD and AOD-E transmissions.

[Tom Wells]

Hi Tony,

I'll make those C4 recommendations unanimous.

I have a C6, but it's behind a 521.

The C4 will be lighter, have lower power losses, and easily withstand a modest performance engine - or even a fairly hot one

I also second the notion of an AOD type overdrive trans - it'll do wonders for your gas mileage and eardrums

Tom

[wingnut13]

Tony, I also say the C-4 is the way to go. It will soak up half the power of a C-6 and it's really light! I run a C-4 in my mustang, 3600 stall reverse manual valve body and a trans brake with 3.73 gears in the rear. On the not highway it's not too bad.... but not for a daily driver, too much stall. Also it WILL sound like a motorboat if you go with to high a stall. Since you have the 351W you will need a 28oz. flexplate and the tooth count will depend on the bellhousing, big or small.

[Mr.Fixit]

C-6 very well might not fit.

[TonyMadrid]

Its Decided! I'm going with the C-4 and I already have a TCI C-4 lined up.

Thanks Guys,

Tony

[Jack21]

There's a shop in Gaithersburg, MD called Performance Automatics that does just this with C4's. They have a pickup/van low gear they can put in these. They also have a Street Rod valve body for strong motors in lightweight cars so the tires don't chirp everytime it shifts. I talked to them when considering the C4 option.

That being said, having the car on the street, I would definately use an EOD trans, not a C4 in the car from Lentech or one of the other EOD trans vendors. Anything over about 40 MPH with the T5, and I'm in 5th.