Blown 502 with TCI Super Street Fighter 700r4. Fuel mileage????

[badream]

I am pondering a purchase of a 502 with a B&M 420 Mega Blower, and would have a built 700r4 behind it. 3.73 rear end gears and 27 in tall tires, but i need to know if anyone can tell me what to expect for fuel mileage... Now i know you dont typically run a setup like this and concern yourself with what kind of mileage you get, but i wanna know how bad it is hahaha.... could a person stretch out 15 mpg outta this setup at 70 mph????? or is that a dream?? Thanks a bunch!

[badream]

Anyone have any idea?

[DeltaT]

Carb or EFI?

Jim

[Hambone!]

Sounds like it will be a killer fun ride, but I'd sure stay away from a 700. I've been through a baker's dozen of transmissions behind my N/A 502. I've used 400's and 700's. I've had local shops build them for me, as well as 2 TCI 700's that flared terribly going into 3rd. I sent them back, they returned them to me the same way. Real nice quality control over there. But anyway, even if someone could make a 700 hold up to that kind of power, the 3.06 1st gear is way too steep for anything but an effortless burnout. Depending on the effort and expense you want to put into this, I'd recommend either a 400 with a Gear Vendors unit, or similar, or else go big and throw a 4L80E in there. Yes, its more complicated, but its much more durable than a 700. Maybe some trans companies can chime in.

[DeltaT]

I also agree with springing for a nice 4L80E. IMO it's a better option than the TH400/GV OD because of the programmability of the 80E setup. After adding a 100 shot of nitrous to my old ZZ4, I lost the 2-3 shift on my 4L60 (700R4). After that I swore I would never underbuild on the tranny again and sprung for a built 80E. The added 75 pounds over a TH400 is easily made up for by the .70 overdrive ratio. I get close to 20mpg if I keep it below 70 on the highway, and when I get on it, I have it set up to change personalities over 50% throttle and it rips.

Jim

[SShep71]

Im looking into a similiar situation. Im doing a 462 pontiac with a 6-71 blower and EFI. I was told i should expect about 17mpg cruising. I was thinking of a 700r4 from TCI they promised it would handle the 650 HP Im looking at putting to it. I never thaught about a 4l80. How hard is it to run it in place of a 700r4?

[badream]

I am considering the 4l80 as well, i'll just need a different driveshaft.... I am worried that the 700 wont hold up, thats the only draw back.

[Hambone!]

The 700's have proven to be time bombs for me. Will never trust one again. Have been towed home from lots of places around MD, even drove it home in reverse once. Goddam things.

[opnwide]

Back when I was a kid, I raced a GTO in my '72 vette 350 with 700r4. As soon as I hit the button in 2nd gear, the clutches FRIED! I replaced the clutches (again) and actually traded the tranny even for a 4spd muncie setup which never gave me a problem with the juice.

[MrForce]

Im looking into a similiar situation. Im doing a 462 pontiac with a 6-71 blower and EFI. I was told i should expect about 17mpg cruising. I was thinking of a 700r4 from TCI they promised it would handle the 650 HP Im looking at putting to it. I never thaught about a 4l80. How hard is it to run it in place of a 700r4?

If you are looking at a 4L80E, it is computer controlled. Many of the current EFI management systems can control the transmission as well as the engine. The 4L80 without the E is, of course, non electronic. Being Turbo 400 based, they are stronger than the 700.

Rob

[Hambone!]

If you are looking at a 4L80E, it is computer controlled. Many of the current EFI management systems can control the transmission as well as the engine. The 4L80 without the E is, of course, non electronic. Being Turbo 400 based, they are stronger than the 700.

Rob

Is there a 4l80? How do you control it? Full manual valve body? Normally all the up / downshifts / line pressure, etc is all computer controlled. If this is something new, I'd like to know more.

[MonzaRacer]

700R4/4l60 is a trans that needs a lot of help and takes a real tranny guy to make live,, kind of like the 200 R4 was till Art Carr got the upgrades going then lots of people started building them to hold HUGE amounts of power.
Bill Taylor (BTE) formerly of TCI fame and PATC have built them to live with power. Big thing is quality in the guy who builds it because friend had 2 PATC Raptor trans one guy cant build crap there, the other guy did his second cars trans and that car has a 700R4 with 1400hp+ former Leonard motor in front of it with some hair dryers from Comp Turbo squeazin it!
For simplicity go 4l80e and one of the controllers or even twistmachines paddle shifter!