Exhaust Ideas

[Arnold Cunningham]

I've got my 557 CI Tall Deck Big Block Chevrolet on the "bench" now. It's running well, but it's loud as fkk and sounds basically like a top fuel dragster.

It's a marine motor that will be running straight through exhausts out on the water, but at home (and in a marina), I need a little more silencing.
I've put a pair of 36" long mufflers on it - and they might quieten it down a little, but not so much that I can expect the neighbours to love me.

Most successful was running the mufflers then into a 85L incinerator bin that I packed with glass wool for loft insulation - but it's destroying the glass wool instantly, I can see there are glass fibres about a foot back up the exhaust already.

I can't run a water cooled exhaust - the overlap on the cam will make the reversion unacceptable, it'll fill itself up with water......

Has anyone got any better ideas for silencing while I set it up @ home?

[Arnold Cunningham]

Just tickover so I can set up the baseline fuel & timing such that it starts and idles well at home, along with checking and integrating all the other systems too.

Ultimately, I'll need to work out a way to silence it a bit more under power as well, but one thing at a time....

I've ordered some proper exhaust wadding - but with the dustbin setup , I'm still asking the glass to to disipate the exhaust gas, so imagine it still not lasting long..

Edited by Arnold Cunningham on Sunday 12th November 18:17

[Arnold Cunningham]

Thanks - yeah, that's along the lines of the way I'm thinking. I'll mock it up with the mig once installed and if it works, get a proper version made.

I'm actually thinking of a butterfly that redirects exhaust out and back through a 4" perforated section (our through the walls and then back in again) for idle use, along with a balance pipe upstream as well. And then under load, the butterfly opens giving it full beans. I'd neeed to be mindful that it'll only be maybe an 8" length (else it'll look like a donkey's dick sticking out the back), and also water jacketed too.

For idling on the drive, I think I can make the incerator bin work if I just finesse it a bit - first run didn't have perforated tube, it just vented straight into the wool. I think if I put a perforated tube in for it to vent through, wrapped in stainless wool and then with the glass wool around that, that'll probably be a bit more robust. I don't care so much that the glass wool disintegrates I'd be packing is only to be used when needed - just that I don't want it sucking the wool back up the exhaust, and it needs to be as quiet as possible.