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HP exhaust manifold verses Header comparison

Very nice Bill.

My simple, non-FAST exhaust manifold motor in your car could go 10.90s at 125-126 with your 60 ft, at Atco in the fall.
 
Kind of funny

That same video is on the FIRST PAGE of this thread
 
You can design a cam to make exhaust manifolds better than they are with today's tech with roller cams and such. But I would ask the gurus here how they do it.
 
Turboomni said:
You can design a cam to make exhaust manifolds better than they are with today's tech with roller cams and such. But I would ask the gurus here how they do it.
Click to expand...

There's no magic. The same technology that has helped all hotrodders has also helped hot rodders using manifolds. Faster rate cams, better flowing heads, more cubic inches.

Honestly, nothing is new or changed, except until recently as some people have actually tried to make more power with manifolds. Since the beginning of time, the first thing hot rodders did was to put headers on the motor. Why? Because they make more power on everything.

The only thing that makes power is the intake. A good exhaust system (headers) helps the intake. A bad exhaust (manifolds) can hurt the intake. The only time the intake and exhaust are actually working together is when both valves are open at the same time. Not unlike any other motor, you need to find the sweet spot for when the intake and exhaust opening and closing events are. The cam event sweet spot for a manifold motor is just different than for a motor with headers. So you simply find ways to help the intake with little or no help from the exhaust. Obviously you will bump up against diminishing returns sooner without the exhaust helping the intake..

In 1969, Super Stock magazine, and I think Ronnie Sox at the wheel, drove a A12 car to 12.90s at 111 mph with crap tires. Everyone knows that the car was a bit of a ringer and speculated that it was at least super tuned on a chassis dyno. Maybe a valve grind, maybe a head mill. I don't know, I'm just speculating. But the point is it went 12.90s @111 mph in 1969 with exhaust manifolds and a very crappy factory exhaust system.

Because some folks make a living in the hi performance world, including specing custom cam grinds, I don't normally share freely their intellectual property. But I'll say this, the factory cam went 12.90s @111 in 1969. Trust me, there is no rocket science here. The factory pretty much figured it out 50 years ago.

From my perspective, Bill getting that cast iron intake to go 11s @115mph with that compression ratio is magic.
 
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I thought the ability of a roller cam design could help exhaust manifolds because they open fully so quickly and stay fully open much longer than a tappet cam is able to. It was my thought there would be more time for flow. Maybe I am totally missguided.
 
All motors benefit from opening the valves faster and further.
 
The context was for a given duration. And of course, moving the valve faster is quicker lobe rates.
 
I watched that episode and was quite sure that is what he would find out. HP exhaust did a better job than the headers. He got more HP out of the motor. Not much but a better result. So That is why I stuck with my exhaust manifold's. Plus they keep the heat away form the motor. Just my two cent's.
 
blue69runner said:
I watched that episode and was quite sure that is what he would find out. HP exhaust did a better job than the headers. He got more HP out of the motor. Not much but a better result. So That is why I stuck with my exhaust manifold's. Plus they keep the heat away form the motor. Just my two cent's.
Click to expand...


I don't think you watched the above episode as it came out today. If you watched it you would see the HP manifolds did very poorly compared to the Max Wedge manifolds and headers in this test.
 
and the 426 Hemi came with headers but big tube quality headers woiuld be more efficiant. 2 1/4 tubes for a 426 Hemi
 
My understanding is that if they are cast iron, they are considered "Manifolds". If they are tube steel, they are headers.
 
Put on headers and loss the weight. An engine dino is not the tell all and never will be. To many people put to much into what dino readings contain. It maybe a great source of information for the matching of other components. But to me that is about where it stops.
Just looks at the steps some have gone to to loss a few pounds of car weight.
 
I agree 10oo percent 3 B. Its an art to put a ride on a diet and you can't even notice. The dino will NEVER replace the 1/4 mile. If I have an engine shop, I program the dino to be 20 percent higher and everyone is happy
 
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