I was sitting here going through some old intake threads and I was wondering. Has anyone here gone beyond the 50mm boring of an Eddy TBI manifold? i know to most it wouldn't be very cost effective and there are better intakes out there but for the few of us that have the facilities to do this cheaply I wonder if it would work. Any thoughts?

 

I think 2" is about as much as you can go. I will mic mine but I think I went 2.00 and change and called it quits. You get pretty thin around the EGR ports and water jackets at that point.

 

I have personally taken a stock GM TBI manifold to 1-15/16". I have heard, but cannot confirm, that it can go out to 2" no problemo.

I know a fellow who has a Holley TBI and it comes out of the box at 2", so it is reasonable to assume it can go bigger.

 

i just bored out my edelbrock to 2.005'' and it seems like that was as far as i could go the egr port opened up a bit more than expected though doubled in size on the bore closest to the egr valve.

 

The newer 3704 intakes can go about 50-51mm max. The older 3704 (older than 7 years ago) the casting would not allow you to open them up to 50mm without breaching other ports.

Slightly increasing the size of the EGR valve ports inside the bores isn't an issue especially if you use and EGR valve block-off plate.

My 3704 is right at 50.25mm. Most stock intakes with casting # 14102182 OR 10166133 can be opened to 50mm without issue. I have tried other casting numbers and they were not sucessful.

I have done many intakes and once you get passed 50.25mm then the walls get paper thin.