540 to 572 How much Boost?
 

The 540 was making 12psi of boost at 6000rpm, now I'm going to a 572 with all the same components. (The compression is staying the same at 8.25) The only difference is the bore and stroke 4.560 x 4 3/8

Heads are AFR 357
Intercooled Whipple 2.3 quad rotor EFI
Stellings exhaust

How much would you expect the boost to drop at similar rpm?

Re: 540 to 572 How much Boost?
 

Maybe way to simplistic but arithmetically you are increasing your volume roughly 6% so maybe it would decrease your boost 6%.

Re: 540 to 572 How much Boost?
 

more like 6% less than previous pressure on an absolute scale. Atmospheric is around 14psi. Boost was 12 psi. Total absolute was 26psi. 6% of that is 1.56

New boost using this method of estimation is 12-1.56= 10.44 psi.

Nothing ever works out that close to theoretical since each aspect of the airflow thru the motor makes a difference, but this is a close place to start from an estimating standpoint.

Re: 540 to 572 How much Boost?
 

I was also figuring about 1-2 pounds lower, but it looks like its going to be about 3+PSI lower.

We are still chasing some ingition issues, so I don't have a good HP pull to compare, but rpms are rpms.

If it makes the same power at 3PSi lower thats great. I just don't see how that could be possible. I'm not that lucky. :eek:

Re: 540 to 572 How much Boost?
 

When I did the same thing your doing but from a 502 to 540 I lost 2 pounds of boost,3 seems a little high but there are definately other dynamics that come into play,Smitty