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Discussion Starter #1
Two 900hp Pontiacs with different head/ intake set ups. Both 535's on pump gas. What would cause the torque difference? 100ft lbs is a quite a bit

One is a tested combo with the other having little dyno time so im sure it will pick up but 100ft lbs??
 

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At what RPM did each make 900 HP?

Stan
 

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Discussion Starter #3
Stan not sure on the one with more torque but the other is 7200. Just guessing but id bet the other is close to the same
 

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I would not think so for the same RPM. Remember if both engines make the same HP at the same RPM that means that they are making the same torque at that RPM. There is a DCI RAV build floating around now. Is that one of these 2?

Stan
 

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Discussion Starter #5
Yes Stan it is. Just didn't want to start a pissing match on PY.

I really like the V head layout just trying to figure out why the torque number is so different.
Could that be related to velocity? Port too big? Plenum too big?
I'm just trying to understand before I start dishing out any cash

Kevin
 

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Kevin,
I would need some more information about the second engine. This is what the DCI RAV build looks like if I rough it into PipeMax.

Stan
pipemax_pontiac_535.gif
 

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Kevin,
I would need some more information about the second engine. This is what the DCI RAV build looks like if I rough it into PipeMax.

Stan View attachment 90298
About 30 tears ago we had a 509 chevy on the dyno.Customer brought some new 4-2-1 collectors to try.Engine made same HP around 810 but lost 100 # torque over std collectors.
 

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Discussion Starter #8
Bill C thanks. It appears to have the same set up from what Slowbird said.

To clarify are you talking about a tri-y set of headers or just the merge style collectors?
 

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Stick a reducer on the end of the collector and see how it effects the curve, if the collector is 4", slip a 4" x 3 1/2" reducer on it and see what it does, around 12" long (there is no magic number).

Also give Stan your spec. and have him run the numbers in pipemax for header sizing and see how close you are with the dyno headers.
 

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Bill C thanks. It appears to have the same set up from what Slowbird said.

To clarify are you talking about a tri-y set of headers or just the merge style collectors?
Just a collector change ,.
 

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Discussion Starter #12
Stick a reducer on the end of the collector and see how it effects the curve, if the collector is 4", slip a 4" x 3 1/2" reducer on it and see what it does, around 12" long (there is no magic number).

Also give Stan your spec. and have him run the numbers in pipemax for header sizing and see how close you are with the dyno headers.
 

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Discussion Starter #13 (Edited)
BBF612
The motor that is down on torque is using a set of heads that I really like. Pontiacs version of the Ford tunnel port.
I was just trying to understand why it was down. I don't want to knock the build in anyway as it has only been run several times on a dyno and sounds like it is also a new dyno and possibly operator.
If it's something as simple as a collector change that doesn't bother me at all. If it was from let's say too long of a runner that would be a major problem since I have a tall deck block and would have to add length to the runner via an intake spacer.
 
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