how much HP/torque will a C4 take?

[lovehamr]

These must be some quite modified c4's because with a couple of early mustangs I got to where I could swap one in an hour just because I did it so often.  This was behind only slightly warmed over small blocks.

[manofmerc]

The best info I have seen on the internet about high hp c4s is on the 429 460 forum .A lot of street racers drag racers have their comments and buildups on there.And some of them are running 545s not 445 cu.in. . Most drag racers use a c4 for quicker et.s and that is always the case .Going from a c6 which is heavy to begin with to a much lighter c4 is a huge benefit .And then you have the lighter internals and probably less friction as well  .Unless you plan to drag race your truck I would go with a c6 .Less expense and less maintenance and it will hold up to a lot of abuse .A good valve body 5 clutchs in the high gear drum and thats about all you need .But for some real world info go to the 429460 forum click onto driveline lots of c4 stories there .I am just partial to c6s .I have three in my cyclones that I built myself and I am just familar with them .Nothing wrong with a good c4 Doug

[machoneman]

I like the C-6 as well but most over on the 460 Forum use the C-4 for one big reason: one gains about 30 hp due to less internal parasitic drag than a C-6

http://www.460ford.com/forum/archive/index.php/t-118570.html

[jayb]

I like the C-6 as well but most over on the 460 Forum use the C-4 for one big reason: one gains about 30 hp due to less internal parasitic drag than a C-6

http://www.460ford.com/forum/archive/index.php/t-118570.html

That's a fact, and you can really feel the difference.  When I swapped the C-6 out of my Mach 1 for the C-4 back in 2005, with no other changes it felt like somebody had released a dragging emergency brake on the car.  Night and day difference.

[turbohunter]

Is there a way to have a C6 gone through to help that sitch out? Or is the large parasitic loss inherent in the design and unfixable?

[Qikbbstang]

 NMRA forbids Powerglides in numerous classes.  The say the c4 will handle 1300HP and seriously  detail all the guts/mods to do it

[machoneman]

In a word, no.

I'll try and find a direct answer to that from a racing tranny shop (Art Francis? TCI?) I had contacted concerning the CC article via the other Forum long ago. The owner IIRC stated that the mere weight of all a C-6's internals (flywheel effect) versus a C-4's, or a "Glide for that matter, is what primarily causes the hp loss. Valve body operation, fluid routing and a few other things also contribute to the larger hp loss, none of which IIRC compare closely to the weight or the internal components.  Kelly's site has some C-4/C-6 details:   http://raceabilene.com/kelly/hotrod/trans.html

On edit: just remembered that the tranny expert also stated that the 'Glide has the absolute lowest weight of all rotating components (re: stock parts, all were tested w/o convertors) of all the trannys mentioned in the CC test. Not surprising then that it has the lowest parasitic drag.