2015 5.7 TBI Upgrade

I have a customer wanting to put a larger TBI unit on his truck stating he will get better gas mileage out of it. Question; what size is the stock TBI unit (76mm?), is his reasoning correct, what size should he upgrade to, where do I get one from, other upgrades needed with a larger TBI???

 

Unsure of any reason to upgrade that unless he is running a SC. I have not heard of any benefits on a stock motor and don't know of anyone running one on a stock truck. I think there are 90mm TB available. No help on what it may take to make that work, other changes or upgrades needed.

 

If it helped MPG, Toyota would have put it on the engine.

 

This. Toyota really did everything they could to push MPG as far as it could go, that’s why our oil filter housing is plastic.

 

All a larger intake will do for N/A is cause it to run lean for a millisecond before the computer uses fuel trims to add fuel back in.

It may throw a dash light if it consistently sees high positive trims and it's irrelevant to mpg because it's going to always shoot for 14.7 to 1 anyway.

If he were to correct the MAF table to match the new intake then everything would be the same as stock (fuel trim-wise, fueling wise) with just a slightly better throttle response. Again, no notable change to mileage.

 

Damn Toyota and their engine management systems!

That said, I agree 100%. No appreciable advantage other than the mileage gained by reducing weight from a wallet….

 

Lol. The ol wallet weight reduction. I'm a pro at that one! Haha.

If it makes you feel any better, GM and Ford and the others would all work pretty much the same way.

A clean, easy flowing filter and an easy flowing exhaust would be the best bet.

I guess in that respect a larger intake would technically be less restrictive and theoretically "help"but I think it's not anywhere close to a noticeable improvement. Even a good air filter is minimal and that's probably a much much better help than an intake.

Once you start talking top end performance the larger intake would matter. That's the real purpose to this kind of upgrade in my opinion.

 

These people pretty much nailed it.

 

Add some LT headers on NA and your client will smile at his 1-2mpg gains...

 

These two nailed it. i played around with this a few years ago. There was a similar discussion a while back about this, here.

First attempt was porting and polishing the tb, then looked at the larger one by Prospeed, which requires an adapter.
Even if you could run a tune/remap for the MAF sensor, the problem is still the intake itself…between the design of the inlet tube and the internal runners. Without a s/c application, a larger tb would be a potential waste, if not a problem for n/a application.

if you want ‘cooler’ air, consider the tb bypass mod (search the forum for it).
As mentioned, for n/a applications, one of the best go-to (proven) hp gains is LT headers and @dirtydeeds dual race exhaust.