Transmission Information.
If you look at chart it says the c-6 tranny robs 55 to 60 hp. Is this true and how much gas is this tranny costing me, just curious.

 

I say HOOOEY, ever seen one of those info commercials on tv saying this bolt on will add 20 horse power??

I have always heard the C6 was a bit to turn but what other choice do you have for the FE?

 

Actually I was wondering about other choices. Might be worth looking into a manual tran. down the road. I knew auto using more power and gas but that 55 to 60 hp, wow.

 

all automatics do. even the newer ones which are electronically controlled and have lockup torque converters. the design hasnt changed. its called parasitic loss, and it comes at a price 20% of your horsepower torque and mpg.

manual is 10-15%

 

I'm surprised they list the TH400 as low as they do, it is a huge power hog due to it's internal design, all sprag and disc clutches. I always heard it was 50-60hp.

 

So how much extra gas you think the c6 burns? Do not know exact milage on my 70 360 is but it's not great.

 

ALL OF THAT INFO IS GARBAGE FOR ANY ONE IN THE REAL WORLD !
it might be of some use to some engineer if they decide to build one from scratch !
I have run C6 , 400 , 350 , 727 , and manual trannies 465 , 435 , 19 , 18 , 98 with big blocks and small blocks and all have gotten around the same mileage , 8-12 MPG !

MPG mainly depends on how you drive and the condition of the engine !

 

I used to get 16 highway with a 390 four barrel in a 77 F150 and 3.25 gear with C6.

 

Agreed. All auto transmission dyno lower numbers than manuals. I just did a auto trans swap in my gto and i went from 429 rwhp(manual) to 397rwhp(automatic). Thats with a full built 4L60E transmission with a 3500rpm lockup stall converter and transgo shift kit.

 

This is why you have a throttle, gears and a differential. How often do you drive at maximum hp?

 

I'd say if you are worried about how much mileage your tranny costs you in your bump, you're barking up the wrong tree. Your truck's never going to be a mileage master, besides, amortize out the cost of changing out the tranny to a manual and then figure out the offset in the fuel cost for the next 10 years... just fill it up, pay the bill, and drive it with a smile on your face!

 

Well this isnt quite the same as his truck. in 1977, the lock-up torque converter was introduced which used a clutch in the torque converter to lock the turbine to the converter case, thus eliminating the 10-15% loss through the fluid and increased fuel consumption in direct drive gear (3rd). but 16 highway is pretty good, i wish my truck got anywhere close lol. then again, my truck has a 390,non-lockup c6, and 3.73 gears

 

I know it will be never be a mileage master just trying to get what I can out of it. Recently put pertronix and msd coil on it, in the process of putting headers and new muffles on right now. I was just thing this year might be a good idea to look for deals on a manual tranny. I was just kind of shock a c6 robs the much power. If I decide to go manual what should I look for, thanks.

 

OleGreen1971, I have never seen a C6 with a lock-up converter, AOD, AODE, 4R70W and E4OD have variations on lock-up converters. I had a 390 with 4 barrel which makes a huge difference and I had 3.25 gears. I also had a custom dual exhaust on the truck.

 

a manual wont make any difference for your gas mileage as there there is NO EASY ( CHEAP WAY ) to put a overdrive tranny in your truck !
and with ANY manual tranny your driving habits will play a big role in mileage in as in how long you keep it in a gear before shifting !