Exhaust manifolds for 502
 

Looking to update the exhaust manifold in my Formula 242 with a 502/bravo drive. Nothing too radical like the CMI headers or anything, just a good setup between $1500 & $2100 is what Im looking for.
I have a longer duration cam so I want to eliminate possible reversion. (Duration @ .050":224 degree Intake, 234 degree Exhaust)
Been looking at EMI, REX Marine, IMCO, Revolution marine so far.
Good contact, would be great also.

Thanks!!

You can get the "radical" CMI's in that price range.

I have Lighting Headers and zero problems in three years. Perfect fit custom made for my boat.

I have nothing bad to say about my Stainless marines. The clamp configuration of the riser to the manifold is a great design. No direct water passage from the manifold to the riser, uses a by pass.

5 year warranty, best in the business. CP performance 1600-1800 per set.

If you're looking for longevity, I would go with Stainless Marine. As mentioned previously, the manifold to riser connection is of a great design. Simple and effective.
If you want to go tubular, I would look at the CMI Uni-Top.

I have had great luck with Gils' Wet Offshore manifolds and risers.

So I have a lot of options.
What makes one better than the other?
What is the benifit of having water injected in bye each seperate cylinder?

I would imagine, could be wrong, that the cast sets would be more durable. do you have header leaks with tube style, like on a car. What kind of maintenance is required with either cast or tube styles.

JRZ, Who has a good price on the CMI headers?
The lightning seem very reasonably priced for sure. How are they for longevity?
Todd, do you (RM) offer stainless risers?

Thanks for the help

Revolution marine all of the way. It is tough to find performance items at a good price that perform well but, Revolution has done just that. Good price and Perform excellent. Give them a try I dont think you will be disapointed. :D
Mark

Especially for the price....I got them on ebay for less than $900 new. For personal pride I had to throw a few coats of duplicolor engine enamel on them and wet sand them with 400 wet paper between coats to get some of the marks off them from the manufacturer grinding off the casting flash....but they look GREAT now and sure sound better than stock. I only picked up about 100 rpm....but I'm set up more for lower end torque anyhow. In a nutshell....I'm happy with them for the price as compared to the prices on the competitions.....

I vote for Stainless Marine also. I read somewhere that they have NEVER had an engine puke due to a leak in their manifolds.

just finishing up installing two pairs of revolutons on a non step 35 fountainw/502s. they are great for the price, and if you have any problems they are probily the best at techical help, if i had it to do all over again i
would use revolution marine.

Correct again....Todd at Revolution Marine was very helpful on a minor problem I had with their power steering bracket not fitting right (1986 factory hardware on Gen V blocks)....I had to modify their bracket a little bit by elongating one of the mounting bolts...he was very concerned about it and got back to me promptly...I give him an A+ on customer service....Glenn

Communcating with Revolution Marine now,

Thanks for all the input.

Check out www.arizonahotboats.com/exhaustdyno.xls

Question: Are the Revolution exhausts the same as Eddie Marines EMI's with that aluminum riser?
Gary

The difference between exhaust manifolds is the grouping of the exhaust ports.

When cylinders #5 and #7 fire in succession, on the port side of the engine, the exhaust gas from #7 may enter into the #5 exhaust port. Firing order 1-8-4-3-6-(5-7)-2. These exhaust gases in the #5 cylinder will keep it from making maximum power. The same holds true for the starboard side when cylinders #8 and #4 fire in succession. The exhaust gases from #4 may enter into the #8 cylinder 1-(8-4)-3-6-5-7-2.

Individual tube headers work well (for one reason) because they separate the exhaust pulses between #5 and #7 (port side) and #4 and #8 (starboard side).

Any well designed exhaust manifold will keep the #5 and #7 exhaust ports separated on the port side and the #4 and #8 exhaust ports separated on the starboard side.

Some high performance exhaust manifolds actually group the #5 and #7 exhaust ports together.

When you purchase an exhaust manifold, check the cylinder grouping. If #5 and #7 are grouped together it is a poor design. The Gil manifolds (and some others) have a divider between the #5 + #7 and #4 + #8 cylinders.

Dennis Moore

You said you want to lower the chances of reversion. With that you probably are going to have to move to a dry exhaust or increase the rise, which is going to narrow down the field. In your price range I see your options as Stainless and Lightning, Eickert and CMI will probably be a little more than $2100 but will be in the range.
Are you running in Salt or Fresh water?
Here in Atlanta I know of several people who have run Lightning headers for more than 8 years without problems, and bang for the buck nothing can touch them. They are a true header like the CMI, come with a 2 yr warranty and you can pick a set up for around $1500.
Hot Boat mag did a test on headers with a 502mpi a few years back and CMI and Eickert caused the engine to go lean enough where the ECM needed to be reprogramed to add more fuel. Not sure if any other headers also did this, but I'm pretty sure none of the cast units such as IMCO, Eddie Marine flowed enough to warrant a reprogram.
Stainless has a great warranty, CMI its name. It seems as the Eickert is the best flowing exhaust as backed by Hot Boat and the earlier dyno post...also its in Dennis's book.
Innovation is selling them for $2000 a pair. You will need to have tail pipes made for them, but if you want max performance above all else...buy them.

Will never be in salt water.
You guys are all great!
Thanks for getting me up to speed on this subject.

Stainless marine has the best customer support on the planet.

Chase910
Who is Innovation?
"Innovation is selling them for $2000 a pair."

Dana
 

Has anybody tried DANA marine?

Innovation Marine out of Florida.
They built all of Volvo's HP engines, the 500,525 and 600. They are also I believe the only ones allowed to touch Mercury's HP500 engines running in the factory class boats. They also build engines for the gov't.

Anyhow, they bought alot of the manifolds a while back. I can't remember if it was before Eickert sold the molds to some guy in California or after but they have them and quoted me $2000 per pair. You still have to have the tailpipes made, but they can hook you up.

Their number is 941-355-7852.

Re: Exhaust manifolds for 502
 

I have a set used manifold new tailpipes Merc HP(Gils)