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Discussion Starter · #1 ·
So I came upoun a PRC manifold for a decent price and decided to pick it up. Since I would have both manifolds off the car, I decided to try to find out how much bigger is the PRC.

Starting witht he PRB I covered the flange and all the holes that would allow water to escape, then I filled the manifold all the way to the t/b flange with water. I measured all the water that came out of the PRB and came up with a total volume of 3qu 8oz.



Next I followed the same steps with the PRC and came up with a total volume of 3qu 16oz.






Taking in consideration that plenum volume would be the same in both manifolds, the difference between the two is 8oz. Dividing that by 4(runners) the PRC's each runner is 2oz bigger than its sisters PRB's runners.

So 2oz is not that much when you think of liquid, but if you take that and transform it into cubic in. you come up with about 3.6 cubic inches or about 6% in each runner that the PRC is bigger than the PRB.

Just something that you guys might find interesting. :cool:
 

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That's all well and good, but the real comparison is in the flow rate. The amount of volume in the manifold doesn't really mean much if it just sits there, since it doesn't really affect the potential of power from the manifold.
 

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Discussion Starter · #11 ·
That's all well and good, but the real comparison is in the flow rate. The amount of volume in the manifold doesn't really mean much if it just sits there, since it doesn't really affect the potential of power from the manifold.
well the flow and volume works hand in hand up to a certain ammount. so we allready know that the manifold makes more power and it flows well enough, but did you know how much bigger the runner were comparing to a PRB???
 

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well the flow and volume works hand in hand up to a certain ammount. so we allready know that the manifold makes more power and it flows well enough, but did you know how much bigger the runner were comparing to a PRB???
No and we still don't since this was a volume test of the manifold as a whole, not just the runners. The flow and volume, what? The flow rate is measured in the volume of air. You mean the reserve capacity and the flow rate. Yeah, it does matter if you're talking about a large volume difference, but we're talking just 8 oz. that's not a lot. Though it's still good to know, since you now know how little difference the volume is between the two and you can see how much flow rate affects the power.
 

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Discussion Starter · #15 ·
Like I said, taking in consideration that the plenums on both manifold are the same, and that 8 oz difference is in the runner themselfs. Wich comes down to 2 oz per runner.

So you look at the 2oz that are liquid, and if you convert that to volume of air you end up to 3.6 cubic inches per runner.

You say that we still don't know?

We may not know for sure that that ammount is 100% correct, untill you take a manifold, cut in half, measure the runners or do a volume test on each runner.

But I did not have a spare PRC manifold to cut it and do all the measuring, so this will have to be second best IMHO.

So you can take it as you like, but im sure that there's lots of peeps that can call this test "close enough" for what we are doing.
 

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Like I said, taking in consideration that the plenums on both manifold are the same, and that 8 oz difference is in the runner themselfs. Wich comes down to 2 oz per runner.

So you look at the 2oz that are liquid, and if you convert that to volume of air you end up to 3.6 cubic inches per runner.

You say that we still don't know?

We may not know for sure that that ammount is 100% correct, untill you take a manifold, cut in half, measure the runners or do a volume test on each runner.

But I did not have a spare PRC manifold to cut it and do all the measuring, so this will have to be second best IMHO.

So you can take it as you like, but im sure that there's lots of peeps that can call this test "close enough" for what we are doing.
I'm not saying it's not good to give someone an idea of what the volume difference is, but coming from an engineering stand point you still have to many variables involved to get a accurate conclusion as to the experiment being conclusive.
IE: the picture of PRC

That shows the vacuum port for the booster that could hold extra water and it's not truly part of the plenum and since it sits at an angle the water doesn't fully fill the throttle body area.

I'm not trying to discredit your work, just showing you were there are flaws.

Either way it's still good to know information.
 

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Discussion Starter · #18 ·
You have good points, but if both of the manifolds are done with the same set up then it should not matter.

I could see a proble if one manifold was done with a t/b and one with out, but both of them had the booster port pluged.

Also I was measuring volume difference between the two manifolds, not the total volume of one manifold.

So while your ports are valid if you are trying to verrify that the manifold has a certain volume, they are NOT valid when you are only measuring the difference between the two.
 
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