Any advantage to having the exhaust manifolds opened up a bit? Just curious
Let me correct all of you its a cummins designed manifold to work in that application as is the one for a school bus or whatever. Just sayen No back to the debate .The Dodge manifold is not really a log manifold. The 7.3 Power Stroke and 6.6 Dmax are excellent examples of bad log manifolds.
The Dodge exhaust manifold provides a good deal of direction and organization. It does cause some confusion when the charges enter the stream with the other exhaust charges, but at least they are pointed in the same direction.
Remember that air (intake or exhaust) does not like to turn a corner. When it has to, it looses velocity and in the case of exhaust it will loose temp also.
Now, just to confuse everyone, you can preserve some velocity in air flow by enlarging the area in a turn.
JayBuller, if you got that sort of EGT reduction, you must have done something right.
The really hard part of porting is to make sure that you balance the air flow evenly amongst the cylinders.
Believe it or not, the headers on my truck are 1 1/2 inch tubing on the outside. I am also planning on reducing the size of the up-tube from almost 2 inches to 1 3/4. With the headers on the truck at the 1/8 mile track I got .35 tenths of a second reduction in ET. It was still slow, but then this one is still stock. I cruise down the road with about 50 degrees less EGT and from all appearance, it looks like a 5% increase in fuel mileage. The jury is still out on the fuel use.
My bad man !Well I guess I am really messed up then. Ford = International, GM/Chev = Izusu and the wonderful old Dodge = Cummins. We all know what we are referring to, however I am so so sorry for the lack of proper credits.
But then I am old and don't give a .