I'm curious, what kind of MPG would a TBI 406 get in my 91 Camaro? It has a 5 speed manual and 3.08 gears. The motor would have around 350hp and 420ft lbs of torque.

 

crappy because a tbi setup isnt gonna work nicely with a 406. your better off tuning a carb big time

 

Why wouldn't a throttle body work?

 

Why so little torque?

A 454 TB would work fine.

Won't make 350 HP in all likelihood.

 

A 400 was never know for gas mileage even with a carb.

http://tbichips.com/?page_id=48

 

itd require alt of tuning be restricted to many extents with what a 400 would like, your better off with a carb or different EFI system, or just run a 350 or something. the 400 tbi thing has been tried before it worked but it wasnt fuel efficient when it had power and it was an entire dog when it was built for mpgs.

 

It's tough to get the torque out of a 350 that 400 puts out... This car is my daily driver. I was hoping to get at least get 13 mpg.

 

I tuned a TBI 406 in a brick body style suburban. Had 3.42s and a 700r4 and 33" tall tires. It was built for torque with the 350 swirl ports on it. Ran an edelbrock 3704 TBI performer intake bored to 2" with a marine TBI on it. Ran great when it was finished and got better MPG than the 350 that was in the truck before the 400. Last I heard it had 35s on it and had 4.10s.

 

Probably get 2x that in the real world with a properly tuned TBI setup. I would not use the old 882 heads that came on the 400. Use a set of 193s or 810s off a TBI 350. Keep the cam very mild as well.

 

I want to use the stock TBI. I'm on a budget.

 

stock tbi aint gonna cut it, maybe if you bore it out shave it and so forth, if your looking for just bolt it on and go it wont happen, not easily.

i tried a tbi 406 it hated life, cam was too big and it wanted to much air, wasnt suppose to be a driver at the least wasnt coservative enough.

 

I also have a 350 lying around. It's a stock LO5 roller motor. Would it be better just to run that with a different cam and vortec heads?

 

Run TBI heads, the stock TBI will starve the vortec heads for air.

 

you can mod the tbi unit in itself pretty extensively for tbi heads. people do it all the time, theres good sites for the truck stuff gmt400.com and so on. i kept my old 383 tbi and it took some work but it ran great after i debugged it. vortec heads on a tbi is a very popular swap

 

Should I just spend the money for an aftermarket throttle body?

 

454 throttle body with 68 injectors bumped up, ultimate tbi mods should work, just by the adapter for the iac sensor i think it is.

 

Sounds like a lot of trouble for TBI... I really to keep it fuel injected, but it sounds like a lot just to keep it efi. Should I just go with a carb? I really don't want to as a daily driver.

 

staying tbi isnt gonna be cheap, youll need alot of tuning, and probably alot of mods to make it breathe and be fueled correctly. if your looking for an easy bolt on and go and make good power then youll be mistaken. most people dont know how to effectively tune a carb for good mileage, so maybe learn? or put your tbi 350 in there and pull the chip out of a early 90s truck if you have a 700r4

 

Haha no worries of not knowing how. My dad has been a mechanic for over 30 years and raced for many years too. I just ask for other opinions on here. Neither me or him want to go with a carb. I just don't want to deal with the cons of a carb....

 

And my cousin has a dyno