Exhaust manifolds for 502
10-01-2003, 09:11 PM
#12
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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.
would use revolution marine.
10-01-2003, 09:32 PM
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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
10-02-2003, 02:26 PM
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10-02-2003, 06:24 PM
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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
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
10-03-2003, 08:48 AM
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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.
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.
