Hey guys, I'm usually in the performance engine forum, and in fact I got so good at it (or lucky) that I now have a 302 that makes 378 ft*lbs and 330 HP, with 365 ft*lbs on tap at only 2000 RPM. I tuned it by ear, tweaking the timing until it got just right. Now I am barely feeling any acceleration improvement due to tranny slippage. My stock C4 was never built to take this, but it got along great with my stock motor, but the Windsor Jr. Heads, and Comp Xtreme Energy 250 cam, as well as every other go-fast part I could find just proved too much for it.
Here's the question: Jeg's has TCI Streetfighter tranny's priced at $729 for a C4, $759 for a C6, both will fit a SB, and come with a bellhousing, in any tailshat length. Is the C6 a better, more reliable unit? is it geared the same? Also, I am looking at a TCI towing converter for it, I want it locked up at low RPM, I don't need any slippage, I have hoards of low-end grunt.
Which brings me to my next question:
I am the proud owner of the superior 9" rear, problem is, 2.75 gears. Oh yeah. Hey, I get 15 MPG on the highway in that beast, 72 MPH @ 2500 RPM, in possibly the most unaerodynamic vehicle ever. I really want to swap into some 3.55's with an Auburn Gear Diffy. Are Richmond street gears worth the extra $, or will I get what I need from Jeg's house brand.
Last question:
If I do these transplants (3.55's w/diffy, TCI Tranny w/towing converter), or any combination thereof, how badly will my highway performance suffer? I'd hate to have to cruise on the highway at 3000 RPM, but It really comes out of the hole like a tired elephant to be powered by the stud-Windsor that lurks underhood. BTW, I have 29" tires.
Thanks for your help,
Rock On.
John F. Daly III
The TorqueKing

 

the c6 is a lot stronger than the c4... a lot stronger. they put it behind everything from a 302-460 and deisels too(i think). i might be sellin my c6 soon cause im gettin a 360/c6/np203 off a truck so i wont need any of my drive train anymore and i cant use my c6 cause the bolt pattern is different so im just going to sell it. the tranny just got rebuilt in late march, early april. it works just fine. but like i said i MIGHT be sellin it, depends if i buy that truck with all that other stuff or not.

 

The C6 would be a much better option. It was used behind many big blocks that twist a little harder than what yours does. Your C4 can be built to handle your 302 though. Jegs house brand gears will be fine for your app. Your 302 has a lot of torque for its size but I don't think you will be chunking any gears. Your 8.8 axles are probably where you want to put your money into.

 

if i was you i would keep the c4. it is a fine tranny. i dont have much experiance with gears sets, but i wouldnt think it would be to big of a deal to go with summits in house brand.


-nathan

 

Ok, so I like the C6, and I'll pair it up with the towing converter TCI makes, they say it locks up pretty hard, and real low RPM. Now, the million dollar question, if I switch to the 3.55's, how much difference is this going to make in my highway driving, and in my local, in town trips. I welcome any comments and opinions, and I'm very interested in those of you who have done this swap, I'm trying to get a quantitative analasis of the effects of these gears that everybody is telling me to get.

Thanks for the quick response on my other questions, you guys rock.

The TorqueKing

 

[updated:LAST EDITED ON 25-Apr-02 AT 01:36 AM (EST)]3.55 gears will be a night and day difference from what you have now but yet won't make the engine rev like crazy on the highway or drastically reduce fuel economy. Your engine is not built for extremely low RPM cruising. If you turned a few more RPM's going down the road you might even get better mileage. 3.55's will also be better for you transmission becasue it won't have to work so hard to get things going. Also you say you run 72MPH at 2500 rpms now. That would equal a 26.6" tire. Is that what size tires you have or is your converter slipping a lot?

 

Yeah, I have a good deal of converter slippage, at least it seems. I have 29" tires, so it must be slipping a bunch. So I'm thinking that this towing converter will definately help out my highway performance. Experience? Comments?

Thanks again for the speedy response

The TorqueKing

 

Ok, check it out, here's my engine. I don't hae updated pics on my site, I definately know better than to use Accel wires.

Windsor Jr. Heads,
Comp Xtreme Energy 250 (hyd. flat tappet) cam,
Edelbrock 600 carb,
Weiand dual plane intake,
Crane Energizer Rockers,
ARP studs, everywhere
MSD 6A Ignition/Blaster II Coil
Flowtech headers/Dynomax twin converters
2.5" pipes, unhushed
9.7:1 static compression
Fel-Pro gaskets
Comp Hi-Energy Pushrods
Cal-Customs Finned Aluminum vintage valve covers 1960's
14x2.75" K&N dish
Dyno 2000 reports: 378 Ft*Lbs @ 3000 RPM, 329 HP @ 5500 RPM

All of this is currently being funneled into that sorry tranny that I had rebuilt 20,000 miles ago. When I sent it away to be rebuilt, I got back an older core, it's all messed up, came with the wrong dipstick, so I kept overfilling it until I almost ruined it, all the pan bolts are stripped, silicone is keeping this thing together, it is such an unworthy unit that it makes me sick, I almost enjoy beating it to shreds and watching my prodigy engine make it smoke and cry. I thought about a trans cooler, but I don't really want this thing to live any longer. It's the kind of thing us gearheads bragg about, until we realize, "oh yeah, now I have to buy a new one." I think you'll agree, it's a pretty stout motor, not as tuff as a Powerstroke, but it has it's place in the kingdom. What you're telling me about the gears makes me wonder why I havn't done this before. I'm just real excited now about what it's going to feel like to actually be able to use that power.

Thanks again, all morsels of knowledge appreciated.

The TorqueKing

 

According to the chart I have a 29" tall tire with a 3.55 gear will give you about 2,600 RPM at 65 MPH...that's with NO slip in the converter. You may run 200-300 RPM above that unless you have a "lock-up" converter

 

 

the other thing that no one else has mentioned is parasitic loss of the trans. the C-6 is an absolute beast, and built right there is little chance that your engine will ever break it. The only downside is that your gas mileage will likely go down due to the C-6 dragging more on the engine. It takes more power to turn the pump, and i think the gears and synchros are heavier and harder to spin as well. It all adds up to less RWHP. If the built C4 will handle the power you'll loose less with it as well. Might be worth your time.

 

Do you realize you are responding to a six (6) year old thread?

The OP last posted in July '07.