Im currently thinking about swapping out the factory exhaust manifold on my 20R for a header from LCE. For those of you that have done the swap before - how much of a difference in performance and economy did it make?

Im not too concerned with added performance, but would love to maximize fuel economy and efficiency as much as possible. Current setup is as follows:

Fully rebuilt 20R
Holley Sniper 2300
Ported intake manifold
LCE Mild Street Performer Camshaft (440/446" @ 206/208* LSA 110*)

 

On my 1979 Celica, with no intake mods, I saw a 15% increase in gas mileage (20mpg > 23mpg). But that also included removing the cat con and 2" exhaust.

 

Out of curiosity on the efficiency standpoint, would the Tri-y/4-2-1 style of OEM/Thorley be better than the 4-1 style of LCE and other brands? People say the 4-1 is better for higher RPMs and the tri-y is better for low-end torque, because of the scavenging effect. I'd imagine Toyota used 4-2-1 for a reason -- efficiency?

I can't compare stock to what I have. My truck was already setup by PO with Webber carb, Hedman 4-1 header, no CAT, 2.25" pipe, I put on a Dynomax muffler. No idea what my fuel economy is, I don't put enough mileage on it

 

Curious, what size exhaust you went with after removing the 2"..

 

With that cam, you should see about the same results as @MrDinkleman.. that cam, even tho not ass aggressive, is pushing more volume of air, so freeing up restricted air flow in the exhaust just amplifies the current mods. That Holley carb you have is self adjusting?

 

Oops, sorry. Poor syntax on my part. I meant I removed the cat con and put IN a 2" exhaust. Oh, it had the requisite (for the day, 1980s) turbo muffler at the end, as well.

Oh, and to complete the answer to op's question, I don't know what if any improvement in performance I got since I didn't have access to a dyno...

 

Thanks! That's what I thought too. Its not a carb- I have a Holley Sniper 2300 EFI system on it. So yeah, it auto-tunes based upon driving conditions and as it learns the fuel map.

 

Fancy!! Haha