zt260

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?

zahndok

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

mcollinstn

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.

zt260

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.

articfriends

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