7m-ge Intake runner dimensions

[amichie]

have found a couple of different sources that suggest the intake runners on my 7m-ge engine should be about 36mm to have a peak torque in a useable rev range.

The book "Four stroke performance tuning" which seems to be very good reference fo NA stuff suggests that the intake runners should be about 1.1 to 1.2 times the intake valve diameter for a sports non race set up in a four valve engine.

It also suggests that intake runners should be up to 1.3 times for a race application.

Given that a stock 7m has 32 mm intake valves this gives a target intake runner diameter of approx 35 to 38mm.

For the race application I would need approx 41mm intake runners.

So why did toyota make the over 43mm in diameter at their smallest point, is it to moderate the torque to make it more granny friendly??

This online calculator suggest my torque will peak at approx 6500rpm which is way too high to be useful.

http://www.wallaceracing.com/runnertorquecalc.php

The intake runners seem to be a little short also.\

Has anyone tried reducing the intake runner size on Toyota engines? I think it is common on old V8 engines

Anyway, I am considering making up some venturi style inserts for the intake manifold to see what effect it has.

 

[Nick M]

Toyota went with variable length manifold, through its air intake control system, later called acoustic controlled intake system, or ACIS.

They wanted more volume delivered to the cylinders.

The rules of thumb are often good, but just that, a rule of thumb. Each engine will be a little different. Consider the increased volume of the turbo engine, and need for larger runners.