Would need to know a lot more about those numbers and how they were obtained. Also, did the runners get opened up and shortened? If all you care about is airflow, just put a big open plenum with large radius's and no intake runner at all. That will outflow ANY manifold by a LARGE volume, but it will make horrible power. I would be VERY surprised if even the stock dart single plane did not outflow the HP500 manifold by a significant margin but that wouldn't tell us much about what it would do on an engine.

The flow of a manifold runner is only signifcant when you're comparing runners of equal length and size. If not, you're comparing apples to oranges. The tunning effect of the runners can be significant, and since we already know the dart manifold tunes WAYY too high for these engines, any increase in flow might easily be undermined by the lack of tunning.

Also, because the single plane plenun volume is compromised for fuel distribution with a carb, and the flow bench is only flowing one runner at a time, the larger plenum volume of the HP500 manifold, although still not as large as it should be, will make a real difference in actual "on engine" airflow, since the dart runners will end up stealing airflow from each other.

Then we have other factors such as unequal airflow between cylinders from the horribly non-symetric runners on the single plane manifold, and all the extra fuel you need to throw at the engine to make up for that, and that doesn't even start to take into account the idle and torque characteristics of the longer runner manifold which will be significantly better than the single plane carb manifold.

You start to see that the flow bench is not always the best place to compare intakes, unless you are only looking for one factor.

I did data aquisition in one of the top airflow facilities in the world for over a decade, and although the flow bench ruled for developing cylinder heads, and also for refining an existing manifold design, it was not used to decide which manifold was better.

Whewww, meant to write a sentence or two. Weird what comes pouring out of a human brain, even after 6 years away from the stuff.

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And my reply was just an informed opinion as well, but I guess that's what I get for offering such on this forum. Seems too many boating people don't want any of "that there science stuff". You could of at least bothered to read the entire post where I pointed out how critical flow work was for cylinder heads, but again, I guess my fault for writing beyond your attention span.

To be honest, if I really wanted to show your ignorance, I would have pointed out just how silly you sounded offering "flow numbers" for a manifold without any sort of conditions behind the numbers: with or without the head, what type of heads, pressure drop (which is NOT standard for manifold testing), but then again, my fault for trying to provide some real info around here instead of just jumping in with rude insults!

For anyone that clicked on the link ,it's NOT CORRECT. I called cp today and asked to verify the price for the part # shown and sure enough,it was 529 for short deck,519 for long deck version. I would take 10 each at that price!!! The salesman started gathering my info and the truth came out,that price is just for a throttle body,NOT A MANIFOLD,THROTTLE BODY AND RAILS! When they did the description,the layout and the pricing with the part number there must have been a mix-up,the actual kit pictured has a different part number and cost 895$,still not too bad of a deal though,Smitty

Smitty, I was wondering about that price!! Was going to order a few for myself. That and MSII and harness would have been under $1K. I am glad you did the leg work, saved me some time.. Thanks!! :) :)

Dick

I didn't post it for the price, even $895 would be reasonable. I was looking at the power they claim on an N/A motor.

The price was incredible though,too bad it wasn't correct. I just paid 509$ for a FAST throttle body so when I saw a whole bbc kit for 519$ I figured if they actually would sell it for that I would buy some up,I know several people that want more power out of there mpi systems,that would allow you to upgrade and still use most the stuff you already had,Smitty

GPM, I read that and saw what you mean. Then I got to thinking they didnt actually identify the Holley equipment. I wonder if it was apples to apples comparison.

But you are correct. 989hp is a lot. I dont know if you could make a manifold and gain a heck of a lot doing it. At that level, bolting one on.. and making that power is simple enough.

Either one would be an improvement over the Mercruiser or Arizona stuff. You could use any ECM, harness and injectors. I'm sure you would lose less HP to back pressure when using a centrifical supercharger.