cdaniel525

iTrader: (1)

I just installed my new motor and am having some reversion issues with the EMI Thunder Manfolds the HP S/S Risers...
Noticed some water under the valve covers, so pulled manifolds off and found water in some of the ports of both manifolds. I then eliminated the water to the risers, but still cooled the manifolds... idled it that way for a few minutes, and pulled manifolds off again and they were bone dry. Also pressures checked the risers with no problems, and also pressure checked the block and heads, and everything was good.
So that said, Im 99% sure its reversion and I really dont want to pull the motor and install a new cam. Its dyno tuned and makes great power...

So Im looking for some help on how to convert my risers to be dry!?

I know I pretty much need to cut off the end of the current riser to where both pipes will be exposed... maybe the outer pipe a bit more to be able to weld the inner more easily.
Then extend the inner pipe that is the exhaust, all the way out the transom...
And then extend the out pipe out the transom as well...

- Where I get confused is what to do at the end of the 2 pipes?? Do you make them even in length, or extend one longer than the other??
- Also,how do you setup up the water outlets?? Just weld some spacers in between the inner and outer pipes to keep them even and let the water free flow right out the back?? Or at the absolute end, weld the 2 pipes together, and then inside the boat weld in a bung and install a water dump through the transom?? Or what??? Lol
FWIW, theres an excellent exhaust shop near me (Mufflex) that specializes in stainless steel and high performance work... Including large turbo tubing, so im sure they can get this done. I just need to know what to do! LoL

Also the alignment is off by just a hair... I maybe need to drill out the transom to 4.5" and use transom flange gaskets... no biggie, but HOW do you drill out those holes larger!?

Thanks a lot guys... Im dying trying to get this boat on the water after dumping all this money into the motor and having these issues now... I really dont want to send them back to EMI with who knows how long to ship there, complete the conversion, and ship back!

Really appreciate anyone's help/comments/suggestions!!

Ryan00TJ

iTrader: (8)

Just have stainless extensions welded on to your current exhaust portion of your risers. Tack weld extensions with the riser mounted in place to the current angle of your tips. Then pull the riser and fully weld. If done right the extension should not touch your exhaust hose. Bring the extensions to about 1 inch off of your current tips. Nothing else in your setup will have to change. I've done this with great success combating reversion. My latest 496HO risers with 12.5" extensions...

cdaniel525

iTrader: (1)

Thanks for the reply Ryan...
So you don't cool the extensions at all?
Where does the water dump? Sounds like it's still mixing in the same location inside the stick riser if I'm just welding the extension directly the current riser.
FWIW, my risers are already currently fairly long and mix right at the end... see pic below. And there's maybe a foot to the inside of the transom.

Sorry for the confusion...

[ATTACH=CONFIG]541765[/ATTACH]

Cole2534

iTrader: (1)

1) The extensions are still cooled by the water,. They're simply welded to the inner tube with a complete circumferential weld to effectively extend the pipe's runner length. Water will be flowing between the hose and the inner runner.
2) Water 'dumps' in the same spot, but it doesn't mix with the exhaust gases until much further down from elbow.

3) I'd just call EMI and inquire about custom tails. Stainless Marine built mine, so I bet EMI would also, and I had them spec'd as long as possible, with anti-reversion rings and O2 bungs on each riser.

Not cheap, but they're shiny!

cdaniel525

iTrader: (1)

I did talk to EMI but my concern was with how long they will take to complete it and the shipping time since we're on opposite coasts....

Thanks for the info tho Cole! Makes a lot more sense now and is very simple... I thought you sealed the ends of the pipes, and there was a bung inside the boat that you plumped to a water dump... I know I've seen those dumps... Are they for a completely true dry exhaust?

Can anyone tell me how to open up the exhaust holes thru the transom a lil bit?

murfman

as to opening up the holes buy a good holesaw in the size you want, bolt a piece of plywood to the inner transom using the thru bolt holes from the exhaust flange, figure out the center (if you want to offset, raise, or lower the outlets a little) and cut it out. This is the easiest way to get a true round hole.

SB

iTrader: (1)

As far as I remember, there is no water reversion dam or etc with the Eddie's. Problem I have with these and Gills is they have a smooth transition between the inner and outer pipes at the end of the tails. Very easy for water to works it's way back up.

They'd be better if the inner pipe did not tranisition to the outer at all. In fact, even better if the inner was slash cut a little. Longer on top of inner than bottom of inner.

I would bet this would help[:
Imagine a 1" tall piece of stainless sheet formed into a wave. The breaking part of the wave points towards the transom. Put this in the tailpipe just before the water enters the exhaust stream. At the bottom of the pipe of course.

There, I said it...one of my 'should work fixes' that I've never shared. LOL.

SB

iTrader: (1)

Look at the 'reversion dam' in this manifold.

cdaniel525

iTrader: (1)

Damn.... killer info SB! Who makes that manifold?
I'll see if my shop can make something like that at the end of my system... or maybe at the current riser end.

I almost wonder if just adding that alone would stop my issues, but probably not worth risking!?

cdaniel525

iTrader: (1)

Murfman... thanks for the info as well. Found one at Lowes! ��