Reply With Quote500 hp from a BBC is a piece of cake on pump gas. There is no way you will need or be able to use a 1050 carb. 850 at the most.
So right now I have a 454 w/~375-400. It spins an "A" to ~4900 -whatever that comes out to be on the calculators. With the not-so-off season around I've been trying to get suggestions for what it would take to get a reliable ~500hp. I'd like to stick w/my existing heads -they are only a year old, use pump gas (91 here in SoCal), and no NOS (although it would be fun.) The boat is a cruiser, so I'm not looking for huge speeds -just a solid pick up in power with reliability.
It's a '96 454, 990 rect port heads, 9:1 compression. The carb is a Q-Jet -that will be changed out. The recommendations so far have been change cam & carb for a solid & safe 500-500hp (0.636 lift 256 duration @ 0.50 on a 108), with a 1050 carb. Any other suggestions? Ideas or recommendations? What will the parts list consist of and $?
If this combo is good for a reliable 500+hp... I'll be one happy camper!
Thanks!
LC
500 hp from a BBC is a piece of cake on pump gas. There is no way you will need or be able to use a 1050 carb. 850 at the most.
You would make well over 500 hp if you bought some new heads. I understand you wanting to keep them, they cost a pretty penny. I dont know anything about that casting of head but a port & polish job would probably let them breathe a whole lot better. A new cam and carb will make a difference but what intake are you running and are you running headers?
Holley 850
Airgap high rise Dual Plane
Bowl Blend on the 990's and gasket match intake and heads
Matched cam to CID/rpm/Head flow in a hyd roller profile.
The motor that we have in my moms hydro makes 550-600HP. It has merlins that are out of the box, with 10.1 comp and a 630 lift roller. The carb is an 830. You will never need a 1050 for 550hp way to big of a carb. I have tried a duel plane and an open plane and did not see any differance. For a lake boat I would go with the duel plane. Just my 2 cents.
you didn't say how much you would spend?. how about a procharger?. 3LBS boost would do it plus be easy on the motor. 1050 way to big.
IMO the rectangle port heads are a bad match for a 5,000 to 5,500 RPM 454. A set of '049 large oval ports (the older '781's are scarce, and virtually identical) with a stage 1 porting job and the large stock valves (2.19/1.88) would be a much better fit. Porting as noted by cstraub may help.
Are you running headers? If you have log manifolds, IMO, you are screwed much over 400HP.
cstraub would be a good cam source. He's a fine grinder that knows his stuff.
Also, his advice for intake is my intake, and would be great.
My 454 is only running arround 8.3:1, with stock '049 heads (2.06/1.76 valves), Performer RPM Air Gap 2.0 manifold for oval ports, .565" x 232* (@.050") custom hydraulic, and Lightning headers thru-transom.
5,000RPM solid, Berkley "A", 400 HP, under a 700 CFM Holley.
The heads are right now at a local racing shop with lots of boat engine (including jets) experience, Stage 1, increase valve sizes, port match intake, reduced valve stem size. $1500
They say they can and will outdo the Aluminum Edelbrocks. :idea:
Thanks for the replies.... I know this board has tons of bbc gurus! Here's a little more info to chew on
The heads are:
12562920 Cast Iron Gen V & VI Cylinder Head Assembly Gen V and VI cast iron head with 118cc open chambers, rectangular intake ports, and 3/8-inch rocker stud holes. 2.18-inch intake valves, 1.88- inch exhaust valves.
No logs, just the stock merc manifolds. It's a closed engine bay -so it would have to be water jacketed $$$$$! The intake is an takeoff (so I was told) of the RPM Performer.
A blower sounds good, but the belt would require moving the rear bench forward... not really the best option. For now I'd like to go with a engine combination to achieve this -on paper it seems resonable.
Cstraub, what do you think would be fit for this combination? An 850dp & cam? What else is needed to make this happen.
...still learning!
I don't think the manifolds will help you, but I don't think they are as bad as the old log manifolds are.
Jacketed Lightnings like mine will set you back aprox. $1900, plus 4" tips if you don't have already. (another $200)
Trying to find some info on the heads. So far, all is just specs on the heads as you posted.
No way arround needing adjustable valve train parts to replace the stock Gen 5/6 fixed stuff, unless they are already set up adjustable as you have them.
I claim no guru status, I'm just trying very hard to maximize my 454, with minimum outlay of cash (sometimes a hard comodity to find). That includes reliability as well. It has given me a good feel for what works well. I have little doubt I will see 500HP or better come spring (that 700 CFM carb has to go away tho finally). Should get just under 6-grand on the nitrous and that is too much for the 700 to keep up with.
Holley 850
Airgap high rise Dual Plane
Bowl Blend on the 990's and gasket match intake and heads
Matched cam to CID/rpm/Head flow in a hyd roller profile.
Perfect advice!! Just add headers and a good ignition.
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