Best exhaust diameter for a 4efe engine

[Jim.c]

What is the best exhaust diameter for a 4efe for performance

[aarzlp]

Our lass has a 3.5 tip going to a 1.75 and thats what most people use I thinke this is some help

[Jim.c]

Yeah that helps cheers. Was it just a universal back box on a coustom pipe or just the standard pipe

[richardc9052]

If you're talking about from the manifold back then 2" is bang on. Mid section being straight through to a back box.

Any smaller and you lose top end, and bigger and you lose bottom end. Also adding any extra silencers or a cat takes away from overall power.

This is info I gained from the road dyno in a det3 (power curve data based on acceleration in a set gear) not overly accurate but noticeable changes where made and I could feel the difference with buy butt dyno lol

Tested 1.75, 2.0, 2.0 with mid box, 2.5, 2.5 with mid box. All stainless from a 4-2-1 20v 4age Mani customised to fit a 4efe.

ECU was modified to allow rpm increase (6800-6900 before valve float) as I was not running the det3 in FIT mode at the time

[Jim.c]

Thanks Richard that is very helpful. I have got a early Corolla 4-2-1 manifold to put on. Did you make the exhaust yourself or have it made. Think I will go for 2 inch in that case then thanks

[richardc9052]

I made them myself and sold the other 2 when I found the one I wanted to keep lol

Bear in mind now the 2" straight through is loud when you use the throttle. I would advise a throttle type silencer if you have neighbours that already hate you or police that don't like loud cars lol. I didn't bother but I live in the country side

[wickedep]

2" is best....