496 with cast iron heads or 454 with with aluminum heads ?
#11
Member
MASTER JOURNEYMAN
Join Date: Apr 2003
Location: Fenton MI
Posts: 38
First off, Ed, I would like to see those flow numbers if you don't mind posting them.
Second, I have been warned about the uneven distribution with plate systems and have decided to buy the following system when the time comes. Does any one know about this or have any experience?
http://www.wilsonmanifolds.com/shop/...d=39027.472847
Adam
Second, I have been warned about the uneven distribution with plate systems and have decided to buy the following system when the time comes. Does any one know about this or have any experience?
http://www.wilsonmanifolds.com/shop/...d=39027.472847
Adam
#14
Senior Member
SENIOR BUILDER
Join Date: Oct 2004
Location: Woodbridge, VA
Posts: 101
I'll chime in but from a cylinder head standpoint it looks like
Ed has covered it very well.
It's true that port volume is a problem on engine that use
large doses of NOS, .. CFE went back to rectangle ports, . .
I have NOS heads like that and also have very large oval
ports for NOS , .. but those are all big chief style heads
This being said, I don't think true oval port designs belong on
conventional style BBC heads, .. and the current oval port
heads are really closer to rectangle ports with a bigger corner radius, .
and not true ovals.
A port that is that close to the deck and has to make the turns it does doesn't
really lend it's self to the true oval port shape, . it's easier to get the air "happy"
and turn the air & fuel in a rectangle port.
Big blocks need a nice wide floor, .. .
I'll agree, the 049 is a little easier to build / port then the 990, .. the important thing
is the actual size or cross sectional area of the port. That engine with
a peak power rpm of 6500 will want around 3.1" of cross section.
That's actually fairly large for an oval port, .. and if you're adding the NOS
it's not going to be close to large enough.
I think Ed has made a good suggestion, . . save up a few dollars and
get an after-market aluminum head with a large enough port.
Curtis
Ed has covered it very well.
It's true that port volume is a problem on engine that use
large doses of NOS, .. CFE went back to rectangle ports, . .
I have NOS heads like that and also have very large oval
ports for NOS , .. but those are all big chief style heads
This being said, I don't think true oval port designs belong on
conventional style BBC heads, .. and the current oval port
heads are really closer to rectangle ports with a bigger corner radius, .
and not true ovals.
A port that is that close to the deck and has to make the turns it does doesn't
really lend it's self to the true oval port shape, . it's easier to get the air "happy"
and turn the air & fuel in a rectangle port.
Big blocks need a nice wide floor, .. .
I'll agree, the 049 is a little easier to build / port then the 990, .. the important thing
is the actual size or cross sectional area of the port. That engine with
a peak power rpm of 6500 will want around 3.1" of cross section.
That's actually fairly large for an oval port, .. and if you're adding the NOS
it's not going to be close to large enough.
I think Ed has made a good suggestion, . . save up a few dollars and
get an after-market aluminum head with a large enough port.
Curtis