I was told an X pipe is only beneficial to engines sizes over a 302. So unless your running a 351 or larger, go with the H pipe.

 

If you can get the resonance part right, displacement shouldn't matter.

It's more like 302's and under being somewhat more likely to have exhaust system sizing that's a little too big for the displacement than 351's and up that may have led to that "rule of thumb".

I'd first be interested in muffler flow numbers . . .


Norm

 

Norm can I get your thoughts on this. I appologize if I am hijacking the thread.

I was looking over the firing order of a 5.0 HO as well as cylinder configuration and this is what I resulted:

5.0 HO
Firing Order: 1-3-7-2-6-5-4-8
Cylinder configuration:
Front
5 1
6 2
7 3
8 4

Pairing cylinders that fire 180 degrees apart:
#1 with #6
#3 with #5
#7 with #4
#2 with #8

So from I'm understanding and what I have read not only here but from other sources (did a little bit of research) this is what I came up with:

Left collector (Driver)
8 3
2 5

Right Collector (Pass)
1 4
6 7

My reasoning with the specific arrangement is so that no collector experiences any pulses with less than 180 degrees from the previous pulse. Of course that is from my understanding so I could be off. 2 complete turns of the crankshaft is one cycle of the firing order. 2 turns of the crank=720 degrees. Each cylinder fires 90 degrees apart.

My other reason for the specific arrangement is so that it leaves the option of using 4:2:1 mergers/collectors such as the one pictured and really pair the 180 degree cylinders together before they collect into the final pipe. So using these collectors:

Driver
8 and 2 would be paired
3 and 5 would be paired
then the resulting two pipes would be paired

Pass
1 and 6 would be paired
2 and 8 would be paired
then the resulting two pipes would be paired

This would involve bringing #2 and #3 over from the right side to the left side and bringing #6 and #7 from the left to the right.

Also, would there be any benefit or harm in using an x-pipe with this set-up?

Thoughts?

 

Makes sense to me since each cylinder fired will alternate which collect it dumps into, but will the benefit of appropriately paired cylinders be outweighed by increased restriction from tubing and bends?

 

Very good point. I will say yes and no. The gains if any would be minimal but more than anything I'm going for the tone. :flamesuiton:

 

Dilemma,

This seems to be the accepted idea by many on the net, that if I were to take the first 4 cylinders in the firing order and place them on top of the next 4 cylinders, those would be my pairs. Which would result in pairs:
#1 w/ #6
#3 w/ #5
#7 w/ #4
#2 w/ #8

I was thinking that a complete cycle of the firing order would be 2 turns of the crankshaft: 720 degrees. Each cylinder would then fire 90 degrees apart:

Again:
1-3-7-2-6-5-4-8 with 90 degrees in between each cylinder. So I would say the 180 degree pairs then would be:
#1 w/ #7
#3 w/ #2
#6 w/ #4
#5 w/ #8

Which of these 180 degree pairs would seem correct to you?