496 with cast iron heads or 454 with with aluminum heads ?

[keb1]

Need your opinion ?
My 454 2 bolt is at the machine shop right now.
Should I...........
Have the 454 machined & assembled with 4 bolt mains & 496 rotating assembly.
or.......................
Just add Dart Pro1 aluminum oval port heads & matching oval port intake.
-
Either option is going to cost approx $ 3,000.00. (all my slush fund)
What is the best way to go ?
What will give me the best bang for the buck ?

[edvancedengines]

Are you going to be running nitrous?

Oval port Intakes are not great on nitrous engines. Before I get corrected let me explain. One of the top nitrous head suppliers to the industry is CFI Carl Foltz. CFI last year went back to the rectangular ports with radiused corners for their nitrous heads only.

If this were a street engine I would go for the 496.

If this is an index or bracket engine I would say go for the 496.

You did not tell us the cylinder head options if you go with the 496.

Ed

[keb1]

Sorry..I should have added more info.
Present engine before I modify it is............
454 BBC - never cut 2- bolt main with cast iron crank / steel rods
heads: GM 990 retangular port open chamber - 2.19 int / 1.86 ex
presnt compression: 12 1/2 to one
intake: Holley strip dominator / Quik fuel 950 cfm / magana flow pump
cam - Comp - solid roller - 244 duration with .631 lift
Crane roller rockers
MSD - crank trigger / 7AL3 box
-
No I don't plan on running nirtous
50 % street and 50 % strip
glide trans with 4.88 gear with 9 inch ford / spool rear end

[edvancedengines]

Seems like you have a pretty good combination for what you are wanting to use it for. My suggestion is to get a good set of aluminum heads that are not too big for what you have but are just a tad bit more than what you need. That way later you can step it up some more. You can get some really wonderful heads for what you're doing for less than the 3,000 you mentioned.

Do not under estimate what the 2 bolt 454 Factory block will handle. IT is strong. I suggeest to get a good steel crank of some sort and good rods unless you already have good ones.

For an application like you have, I like the Canfield heads, Competition Products is a good source for them. Talk with Butch Patterson. He is an engine builder too.

Ed

[cepx111]

My god man you must have deep pockets to drive a ride with that big of a motor which I'm sure your using race fuel on the street, I cringe every time I have to put 25 dollars in my suburan's 40 gallon tank and get 7.5 gallons just to get to the local track and back, then buy 5 gallons of race fuel for 35 bucks for the car, oh dont you just love racing? Worth every penny to me.

[henny]

Hello
Sorry to ask a different question on your topic, but how much is a safe shot of nitrous on oval heads?
I had intended on using a 150 -175 shot on my 427 with ported ovals
take care
Tom

[billhendren]

We have run that much many times without problems.the biggest problems we see if its a plate system is distribution due to different manifold designs. with the manifold off the engine install the N20 plate and trigger the N20 and gas,look how much is going down each port,if its not equal send the plate and manifold to your N20 supplier so they can custom build a spray bar to fix the problem.Bill

[henny]

Hello Bill
Thanks very much for the info. I will do that
take care
Tom

[badrad]

Go for the 496, those heads aren't far off some aftermarket castings for flow.

[edvancedengines]

I will go on record and say the 990 Chevrolet casting s are not near as good as I used to always think they were, and that many people even now think they are. The lowly 049 Oval Port can easily be made to out perform them without much money invested. Almost all decent aftermarket Aluminum heads will be better, not becuase they are aluminum, but becuase of the port shape and flow charastics.

I had suggested the Canfield, but just look around and see there are others that are pretty good including the factory GM small aluminum heads.

I suggest to get a crank and rods if you can afford them that is not cast iron or cast steel. Get Eagle, Scat, BRC, Cat, or anything you can afford that will be better than the cast stuff.

I am ok with the cast factory crank up to the 600 hp levels. That is it. I am ok with factory steel crank up to 1,400 hp levels. It is stronger than most think. I am ok with good factory block up to that same 1,400 level when block has been studded and prepped.

If you wiat and look you can likley find good used aluminum heads reasonable where guys are stepping up and getting rid of their smaller stuff. As far as I am concerned the intake you already have and everything on top would be fine with either size engine.

If Curtis comes on here and disagrees with my thinking about the 990 follow his advice. I can post flow chart results of both the 990 and the 049 oval with same size valves and same minor port work and you can see them side by side.

Ed

[firestone]

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/index.html?lang=en-us&target=d24.html&lmd=39027.472847

Adam

[mytmouz]

I have one of those plates, but I haven't tried it yet. Really a quality looking piece.

[Racefab57]

I also like the look of this system. love the burst panels.

[cboggs]

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