Thread:

boost question

I had my fuel system flowed for 15lbs of boost, I talked to mooneyham, gave them cubic inch, blower size and rpm, they said to overdrive the blower at 35% to make the 15lbs, then I looked at the BDS book and it shows 20% over for 15lbs and then I looked at The Blower Shop book and it says 35% also. So my question is who is closer to being right? I know there are variables and its not exact but I want to be close when it goes on the dyno. what are you guys runnin your blowers at and how much boost?

Originally Posted by hydroman916

I had my fuel system flowed for 15lbs of boost, I talked to mooneyham, gave them cubic inch, blower size and rpm, they said to overdrive the blower at 35% to make the 15lbs, then I looked at the BDS book and it shows 20% over for 15lbs and then I looked at The Blower Shop book and it says 35% also. So my question is who is closer to being right? I know there are variables and its not exact but I want to be close when it goes on the dyno. what are you guys runnin your blowers at and how much boost?

And some one here is suppose to know what you need without an engine size or a blower size how?? What fuel. Is the blower stripped? 18 strips, or 6 strips.(tips and sides or just tips)
There may be some good info here, but not a one has ever shown me they were worth a shit as a pyschic.

555 chevy, 10:71 stripped mooneyham, 9.5 compression, alcohol

Originally Posted by hydroman916

555 chevy, 10:71 stripped mooneyham, 9.5 compression, alcohol

BDS is being a little optimistic. I'd go with TBS and Mooneyham. With an open exhaust and a good set of heads, along with a long camshaft your boost will be lower than BDS is showing.

Remember, boost is the RESTICTION to flow. Its the pressure that builds up in the manifold. The better the engine breaths, the more air that it will pass. BDS's numbers are based more on "street" and average marine builds. Short cams and lousy heads, and a restrictive exhaust will show more boost at the same blower on something that can breath.

Originally Posted by BOYWONDER

Corey Corey Corey.

11-1 at 18% overdrive on blower =
You know that. Hope all is well can't wait to see her run.

Ya but 9.5-1 at 35%=
I can't wait to hear and drive her

Originally Posted by BOYWONDER

Corey Corey Corey.

11-1 at 18% overdrive on blower =
You know that. Hope all is well can't wait to see her run.

Well thats going to be a far cry from 15psi, I don't care who made the blower

maybe if the cam is out of a Suburban?

Originally Posted by gn7

Remember, boost is the RESTRICTION to flow. Its the pressure that builds up in the manifold. The better the engine breaths, the more air that it will pass. .

That line never made any sense to me.

A BAE hemi looked like the best flowing head design I've ever seen.

They put 50# into this one,

Mark I thought you had accepted that as fact.

It makes perfect sense. Boost is a measure of the air pressure produced by the power adder in excess of what the engine can flow.

Originally Posted by Unchained

That line never made any sense to me.

A BAE hemi looked like the best flowing head design I've ever seen.

They put 50# into this one,

I'm thinkin the restriction is the valve not the port size ?

If you imagine a single port size, small valve dia, then just change the valve dia, isn't there less boost ?

STEEL where the hell are you ??????????

I see it as just volume of air being push in, not a restriction. It is how much air you are putting in to a defined space, closing the valve and then compressing it. That is why all the factors matter. Blower size, striping, pulleys, and RPM define how much are is being pushed in to the manifold. Intake runners, valves and cam events say how the air transfers to the cylinders. Then the bore and stroke define where it is all stored until the intake valve closes and the final compression takes place.

Just how I wrap my brain around it.

You could open that small valve farther and for a longer duration also.

Originally Posted by wizbang

I'm thinkin the restriction is the valve not the port size ?

If you imagine a single port size, small valve dia, then just change the valve dia, isn't there less boost ?

STEEL where the hell are you ??????????

Originally Posted by Unchained

That line never made any sense to me.

A BAE hemi looked like the best flowing head design I've ever seen.

They put 50# into this one,

Take that induction, blower, and blower pulley set-up and stick it on an average 454 and you'd probably be seeing 70#. LOL.

Edit in: (Sorry had few phone calls, had to exit out for a few.)
Which will see more power ? Even at a far lower boost ? Answer: BAE Hemi
Which is consuming more air + burning more fuel (assuming same fuel) ? Answer BAE Hemi
Which engine is more of a restriction ? Answer: The average 454 But it has higher boost right ?

Originally Posted by cfm

Take that induction, blower, and blower pulley set-up and stick it on an average 454 and you'd probably be seeing 70#. LOL.

Edit in: (Sorry had few phone calls, had to exit out for a few.)
Which will see more power ? Even at a far lower boost ? Answer: BAE Hemi
Which is consuming more air + burning more fuel (assuming same fuel) ? Answer BAE Hemi
Which engine is more of a restriction ? Answer: The average 454 But it has higher boost right ?

Isn't the BAE as effficient as a AJ ??????

Do you think the BAE is better than the AJ ?

Just curious ?