Ok so I have a set of emi exhaust with stainless steel short risers with the silent choice system.
The problem: I am going with a bigger cam (not sure of the specs yet I am working with bob m on that) but we both agreed that the exhaust will need to be modified to prevent reversion. I want to keep the emi's so I called Eddie marine and they gave me 3 options.

#1.....go with a full dry pipe, I don't want to go that route.

#2.... They could extend my riser and dump all of the water out the end of the pipe near the exhaust tip connection. The pipe would be extended about 16" from where it ends now. So it's basically taking the place of the silent choice diverter.


#3....they could extend the pipe the same amount and install a fitting to dump some water overboard while still having a few holes at the end of the pipe to cool the exit point. I guess this would be called semi dry or semi wet however you want to look at it.

Option #2 will this be enough to prevent reversion???

Option #3 in another post someone said they went this route and it melted a hole in the rubber coupling connecting the riser to the exhaust tip. I am not sure if it's a common problem or if it was on that one install. Perhaps there wasn't enough water flow at the end of the riser.

I understand that I would be losing the silent choice with all of the above options but that's ok with me. I guess if I wanted to I could run mufflers.

Any thoughts as to what option would be best?
Thanks
Derek.

Hope you can find your answer from someone other than EMI. I would contact IMCO for the answer if someone doen't supply a good option.

Get the long risers and get rid of the silent choice system. Sell in on the swap shop, craigslist or ebay. Bob will set you up with a great cam.

Option #2 should be fine as long as the cam is not too radical. That is how probably 80% of aftermarket exhaust is.

#2. A cheaper alternative than EMI long risers to replace your short ones would be to have a local shop tig weld some stainless extensions onto the exhaust portion of your current risers. Bring the extensions as close as you can to your transom to prevent reversion. This will accomplish the same thing as the long EMI risers without the bling.

I too was thinking that option#2 would be best if it prevented reversion.
When I called EMI to get my options they told me $200/$250 to cut my short risers back and re-weld a longer piece on. I didn't think the price they gave me was to bad. When I get around to selling the Corsa system that should cover the cost of the exhaust modifications and new gaskets.

Nobody has any info on option #3 ??

Thanks again,
Derek.

I have used both IMCO and EMI. Chris at Eddie Marine is great to work with prices are good for the amount of work.
Bob Mandra has done all my cams the last decade.
The exhaust will determine what cam profile you can run.
Bob will point you in the right direction, and he has told me he has never suggested a cam that had reversion. I once thought I had it, it was a leak in exhaust riser gasket caused a vaccum bringing the water back into the exhaust. I would have never thought about that until Bob drilled me with questions. Priceless advise. You must want to run a big ass cam to run dry pipes.

http://www.offshoreonly.com/forums/d...e-exhaust.html

they will be fine,,mine's I @.050 is *226 & E @ .050 id * 236 o a *112 lsa.. with the emi alunimum risers..no reversion ever..

Option #3 will be extremely loud and should not be necessary.