EMI Thunder?
 

How good is the EMI thunder exhaust and how much HP is to much?

They are build pretty well. They can run a moderate amount of larger power thru them. I wouldnt use them for a some applications, or applications with huge power. It really depends on what you are looking to run thru them & what kind of cam set up you will run...

If you need a price or have other questions on them, feel free to give me a call during the week.. :)

Jamie / Lakeside Restorations 570-639-2628

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Fixx
 

i have run some 540's with excess of 680hp,no problems! :) work well, and i hav sold lots of sets as well with no issues..EMI rate's them to 700 hp with the ss rised's..

Did you really ask how much HP is to much?

Not in the way your taking it . I built my motor to 675 hp with a 100 hp shot of nos this winter . Now are those exhaust going to work. NEVER TO MUCH HP NEVER HAVE ENOUGH MONEY!!!!!

I think with any over 550 HP you would see gains from header exhaust. I do know I have seen those on some pretty big engines though however that doesn't mean there not sacrificing HP either. Raylar has done extensive testing with exhaust on the dyno. Maybe he'll see this and help out.

i have a set of emi i ran them for about 5 hours on my supercharge application about 950 hp and no problem I got a set of CMI and did not notice any difference only like 2 MPH faster.

This is EXACTLY what I have done...ran the EMI's for close to a year on a 700+HP 540 with no issues, short risers and no reversion. Spent almost $6000.00 on a custom set of CMI's and got a 2 mph (gps) increase in speed...sure as Hell not worth the 3K per mile an hour...and something that I will never do again. Put a Blower Shop supercharger on the motor and saw a massive increase...way more than my boat was capable of handling, but I did not run the EMI's with the supercharger to compare, so I cant help you there. You can get the EMI's straight from them and save alot of money by not going thru the middle guy. Also look on E-Bay as there are always advertisers there selling them for a very reasonable price.

Do you think they make any more HP than stock gill.

Fixx
 

glm will make more hp then gill:lolhit:

No...I dont think the EMI's will make more HP that Gill's...Stainless Marine...Rex Marine or any of the others. The numbers that all these guys fabricate...key word here is fabricate...is nothing more than pure BS to me. All the manufactures "claim" more HP than their competition. If they really do add 25 more HP, or 50 HP more than the other guy, then why do we all need to change cams, intakes, carbs or distributors. Point is they can all do their dyno testing and come up with the numbers that they want...real or not. Hell...I can take your Briggs & Straton lawn more motor and put it on a dyno and show that it is making 600+ HP by doing exactly what all the manufactures do...as well as some high performance marine motorbuilder shops. Its more of a feel-good thing on the exhaust manifolds...one person might like brand A, and another likes brand B. They are all roughfully the same and they will all give you about the same. It just depends on whether or not you want to pay double for brand A over brand B or vice-versa.

That pretty much confirms with what Gellner had told me then. About 25 hp gain. Depending how efficient the hull is you pick up about 1 mph per 13 to 15 hp gain.

you serious?

There you go, but I wont believe anything the manufactures tell me anymore. I was told by CMI that I would be noticing something like 100 HP when I got the headers...then I pulled my head out of my @$$ and figured out that I had been had. I really wouldnt believe 25 HP either...more like 10 HP at the most in REAL life. As for how much HP to increase your speed...I have heard some doozies...10 HP to 25 HP per mile per hour. I will agree that it depends on your boat (hull) as some are more atuned to speed than others. I do not own a Fountain, but I would bet that it takes less HP to get a Fountain to run faster than it would a Baja or a Checkmate...but with some hulls, you could put the motor out of John Force's funny car in a boat and you will still have a sled.

I had gils and changed over to CMI because I got a great buy on them as well as the little extra HP. To me 2 MPH is huge and respectable with what I have for engines. There has been moments where I would have paid a boat load of cash to have that (2mph) just for a moment. I'll be on the dyno in the next two weeks and see just what it is. If the difference between the gils is anywhere from 20 to 25 HP I will be happy. If not I'm not to concerned about it. The guy that told you a 100 HP was on crack. That was very misleading if it's true. I can see why your not all about CMI however you should never have fallen for that either. We all learn the hard way unfortunately it sometimes hurts where it counts most.

I am running EMI thunders with long risers on a 693HP 540. When my boat had the stock 502 mag 415hp engine there was NO speed difference from the stock mercruiser iron exhaust. The only difference in EMI Thunder from most other manifolds is that they have individual runners like a header. Most other manifolds have just a large open area in them. In my opinion I would spend the extra money and get Keith Eckert manifolds next time. Jeff Wurl

Fixx
 

I have no idea,,just a sarcastic comment.. sounded funny to me :)