Question about exhaust system
 

I'm swapping the exhaust on my 311 SR1 Formula. Got a set of EMI Thunder aluminum manifolds and risers. I needed to have some 3 inch riser spacers. Eddie Marine discontinued the spacers so I had to have some made up. Took one of the risers to the machine shop so they could use it as a pattern. So now the risers, spacers, and gaskets all have water jackets on all four sides. We went to bolt the spacers up today and we see that the manifolds DO NOT have any water jackets in them, just the four threaded bolt holes. So we don't know what to do. The manifolds and risers have a plug for a hose, but that would leave the spacer a "dead zone". We don't know if that's an issue or not. We don't know if we got the wrong manifolds. We don't know if we're just being stupid or not. Basically we don't know squat. Anybody got any ideas? Thanks.

Re: Question about exhaust system
 

ive got 28 sonic with emi thunder.your right there are no holes on the machined surface that is so there wont be any leaks of water dripping back down into the exhaust chamber.and yes there are holes in the riser they are there only for when you take them a part to clean or replace gaskets they will be able to have a good flush.the spacer wont be a problem as long its alu or stainless.the only problem you might have is the hose from the manifold to the riser being short.other whys you have a great system.

Re: Question about exhaust system
 

there ya go ...now finisher that Focker up !

Re: Question about exhaust system
 

Eddie marine makes their risers with a 3 inch "lift" option.

Re: Question about exhaust system
 

They told me that option was on the Stainless Risers only, not on the aluminum ones which I have.

Thanks guys for the info. I don't mind feeling stupid for being careful, I do mind feeling stupid for being stupid.

Re: Question about exhaust system
 

I've got a set of EMI 3" spacers collecting dust. Make me an offer.

Re: Question about exhaust system
 

I actually needed two sets (4) for both motors. Where were you when I needed ya???:D
I put a thread out and a wanted ad in the wanted section over a month ago. Wish I'd known. Do your EMI spacers have water jackets in them? Would like to at least know that. Thanks for trying....Appreciate it. Russ

Re: Question about exhaust system
 

Id be scared to run a 3" aluminum spacer that wasnt water jacketed. The exhaust stream is very hot right there. Im making some 1"ones for my Gils just to add O2 sensors and Im am serious thinking about going SS instead of Aluminum for the same reason.

Re: Question about exhaust system
 

And Im not talking about water jackets that transfer water through the flange. Thats the Merc design and it sucks. But I wonder if the spacer shouldnt be jacketed with a hose in and hose out to cool it. Unfortunatly, this make it a whole lot tougher to build.

Re: Question about exhaust system
 

Well the spacers have already been milled out of solid aluminum billet. And they machined the water jackets in all four sides using the riser as a pattern. They did a great job.

Yesterday Scott and I were talking about how to cool the spacer and it would take an "inlet" cut in on all four sides, which would be virtually impossible to do, particularly the side against the engine. It seems reasonable that water will get into those jackets by law of "water runs downhill" by the water running down from the risers above, and that water would transfer heat. Now if the water gets hot enough to steam, as the steam escapes, water from above should replace it.

Responses have been that's how they are running them. I'm going to call Eddie Marine tomorrow just to run this entire scenario by them and see what they think, just as a caution. Thanks for the input.

Re: Question about exhaust system
 

As long as the water outlet from the riser is smaller in area than the water inlet area, the system will become pressurized and threreby filled completely.

BT

Re: Question about exhaust system
 

OHhh Ok, so the spacer wil be getting some water from the riser? The riser has open water jackets at the flange like the merc does? I wonder why they did that?

I suppose as long as it is getting water then it should be OK.

Re: Question about exhaust system
 

Yes, the the spacer will definitely be getting water from the riser above, so it's not like it's a "dry hot zone". Also like Blue Thunder said, the outlet is smaller than the hose inlet and the four water jackets combined, so the system will have to be pressurized. I didn't think of that but it makes perfect sense. I'm reasonably mechanically inclined and I really don't think it's going to be an issue, especially considering that other people are running the same system with no problems.

I actually kind of like the idea of no water jackets in the manifolds, as stated above, it further secures the inability of water to leak back down into the cylinders.

I'm stiill going to call Eddie Marine but I think it's going to be okay. As far as hose length goes, I'll just get the threaded couplings I need, then go buy the hose and double hose clamp it in place. Should work fine.

Re: Question about exhaust system
 

Pic of EMI 3" spacer.
http://www.offshoreonly.com/forums/a...d=113237&stc=1

Re: Question about exhaust system
 

Looks exactly what Roehr's machined for me, except the corners are rounded. Thanks for posting that picture.

Re: Question about exhaust system
 

I've got a closed cooling system and 3" risers on my 454 engines. There is a solid stainless steel plate between he gaskets that seperate the spacers from the manifold and the riser. It seems like the spacer then isn't getting any cooling water because the coolant circulates in the manifold and the raw water exits thru the riser--that's totally isolated from either water source.

For whatever the reason the spacer never seems unreasonbly warmer than the manifold or the riser...

Check out the plumbing and parts on BAM's website to verify the solid gasket plate.

Poorsche

Re: Question about exhaust system
 

Poorsche, thanks for the info. Any chance you have BAM's website address handy?

Re: Question about exhaust system
 

www.mercruiserparts.com is site--here is link that shows a solid blockoff plate for different manifold riser--but same principal---http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=817442%2090&ivar=images/CRUISER/817442.90/25A.png&inbr=1608&bnbr=13&bdesc=EXHAUST+MANIFOLD%2 FELBOW -- another pic at http://www.engines1.com/images/barr/pg63.jpg

Def talk to Mark Berman at mercruiserparts.com--great guy and absolute straight shooter on this stuff

Poorsche