OMC 3 Cyl expansion Chambers

[johnsonracer]

I am currently in the proccess of building a 3cyl 920cc omc to run pipes.

Has anyone done this? I have had the side of the block milled and welded up to fit flanges. Obviously plugged where the exhaust used to exit so the cooling water doesnt escape down there.

What is everyones comments on expansion chambers over pure megaphones?

I will build a set of megaphones purely to run it at night and get some footage of her thrown flames out!

Everything else has been done to it. 19s fron half. Finger ported, head work etc etc. The never ending quest for more speed has brought me to exhaust work.

[Detroit Whitey]

You need to talk to Tim Kurcz

[johnsonracer]

Ill try get in touch with him, cheers.

[Mark75H]

Steve Benson built some with expansion chambers too. Years ago his were among the fastest.

Both guys are members here on BRF and have posted recently.

Expansion chambers will make 30 to 50% power increase, megaphones 15-18% max.

[Mike Schmidt]

E mail me at teammsr@comcast.net or call me at 860-349-9310 and we can talk.

Michael D-1

[BRIAN HENDRICK]

This is a 497 set up as a FEH with very nicely engineered triple expansion chambers. It ran quite well in Reg-2 about ten years ago. However with the advent of the Runne 'pulse' tuned system, it was no longer (as?) competitive. I suspect that as the motor was designed to be 'pulse' tuned, that simply bolting on a set of pipes will not be effective, unless you were to re-engineer the porting. But nothing ventured, nothing gained.