Revolution Marine SB manifold

[MOP]

This is the Small Block manifold RM will be releasing in June, I guess I will run my iron till then. I will be breaking in engine anyway, any pros or cons on pairing ports?

[Dennis Moore]

I find it hard to understand the theory behind connecting the #5 and #7 exhaust ports together. These two exhaust ports discharge in sequence and are responsible for the exhaust system being overwhelmed with exhaust gases. Even stock automotive exhaust manifolds (not designed for performance) separate the exhaust pulses between the #5 and #7 cylinders (the main exhaust outlet almost always is placed between the #5 and #7 cylinders on the drivers side of an automotive engine).
The basic theory behind designing an efficient V8 exhaust system is to separate the two cylinders that fire in sequence on each bank. This is the #4 and #8 cylinders on the starboard side and the #5 and #7 cylinders on the port side. If we had 180 degrees of crankshaft rotation separating the exhaust pulses between each cylinder we wouldn't have a problem but 4+8 and 5+7 fire within 90 degrees of each other. Cylinder #5 has the exhaust valve still hanging open when the #7 cylinder starts blowing out exhaust gas at maximum velocity. Some of the #7 exhaust gases will enter the #5 exhaust port before the valve has a chance to close and pollute the incoming fresh air/fuel mixture.
Dennis Moore

[MOP]

Thanks Dennis, I remembered from years back dealing with Cook headers they paired in a crossed Y's not side by side Y's! They it was to have one charge help the other. On to Plan B or C want full tubes but in cast!

[Walt. H.]

Hello Dennis,

You have a message e-mail from me waiting here.

Thanks,

Walt, H. :wavey: