440/512 Build for boat

[snoc653]

I'm rebuilding the 440 in my jet boat.  I have a 72  440 block and heads (casting number 3462346).  There is no hood to clear so I'll be running a Weiand tunnel ram with either two 4's or an Enderle Birdcatcher  injection system.   I'm not really a Mopar guy, more like a what ever flavor at what ever time type person.  They all can be made to run strong and I like being a little different.  The goal is to be  between 650 and 750 hp.  The initial plan is to use the stock heads having them ported and larger valves added.  I am thinking I want fuel I can buy at a local station so either 93 octain or E85 (this is where I'm hoping the experience and knowlege from this board will help).  Keeping the stock steal heads cool is not a problem, more likely getting the engine up to temp will be a bigger problem.  So, what should I keep my C/R at to use these fuels (i'm thinking less than 11:1)?  Also we run water through the exhaust manifolds to keep the river cops from giving noise tickets, so lobe seperation on the cam can't be too large as this tends to cause reversion (sucking water back into the cylinder).  I'd like this motor to make peak HP between 6500 and 7300 RPM if that is doable.  If not where should I expect it to max at.  In a boat application we don't run water pumps or radiators (unless you count the jet pump and lake).  If the boat handles well at the speeds it should run with this build, it will probably get an additional 250 shot of NOS.  Other variables I've not finalized yet are MSD vs Mag, girdle or not, and solid vs hyd roller lifters.  Thanks in advance for the suggestions and help.

Glenn

[Long Island RT]

I'm far from an expert, but I'm building my own 512 stroker and after reading the info on this site - your stock heads will choke your engine - especially since your talking about 7000 rpm's.  There are so many affordable aluminum head options out available that with the $$$ your spending, it'll be worth it.  Somebody correct me if I'm wrong but an aluminum head will also allow you to squeak out a few more compression tenths without detonation (probably because they run cooler?).

On another note - My current 440 came out of a '69 Tahiti with a Berkeley jet drive.  I still have the custom water pump housing with a stainless radiator capped tank on top.  I also have water injected aluminum exhaust manifolds for the 440 where the water fills an outer chamber of the manifold and then enters the exhaust flow after a short elbow, well past any issues of backflow into the exhaust ports.  I have a bunch of other stuff too.

Let me know if your interested - the price will be cheap - I'd just be glad somebody else could use the stuff.

[Challenger340]

B Impellor ?

650-750 will be hard these days, read EXPENSIVE, with the Iron heads, and you'd most certainly require alot of Compression, and probably straight Methanol to get there.

As stated above, Some aftermarket Aluminium Heads, would be far more adviseable for the 650-750 level.
Especially with Compression Ratios close to the 11:1 mark on the lower type fuels, 93 or E85.

[Long Island RT]

I think it's an A impeller.  That old Tahati weighed at least a ton and the motor was mild, probably around 400-450 hp.  She'd push 65 MPH on a slight chop.  I still have the Jet drive w/jetovator if anyone is interested.  I wish I still had the hull now - My 512 would probably push that old anchor to at least 80!

[firefighter3931]

A 500 inch motor will not make 650 peak hp power at 6500+ rpm with a stock standard port sized head.  You might be able to make that number at a lower engine speed with a max ported iron head but it won't be at pump gas compression levels.

To hit that mark comfortably will take a max wedge intake port aluminum head like the Indy EZ-1 and a well sorted out combo. 



Ron

[snoc653]

the heads were going to be template ported plus a little more port work.  In a boat application the alluminum heads don't do as much to fight detonation as it more of a problem bringing your engine up to temp as opposed to keeping the heads cool.   I am reconsidering the indy heads as compression for the motor is now looking to be in the 13:1 range on racing fuel.  The class I am now going to run the boat in doesn't allow E85.  This year FI was legal and there is talk that next year it won't be, so back to a pair of 660s or 750s on my tunnel.  Generally speaking we use engine oil temp to tell us when the motor is too cool while running.   Island RT if you still have jet stuff send me a pm and I'll see if any of it will work.  Always need spare parts for these things when racing.   Trying to talk the garage owner into selling me the 71 charger he has sitting there apart.  Nothing but dust growing on it.  Shame to let a good car just sit.  At least it is inside.

[firefighter3931]

 I am reconsidering the indy heads as compression for the motor is now looking to be in the 13:1 range on racing fuel. 

That will be your easiest path to the 650hp target. A max ported iron head will have difficulty making that power number....even on a big cube motor. Peak power is a product of cylinder head flow as well as port cross section....small heads on a big motor will just bring the peak power in at a lower engine speed. With 500 cubes you need a big cylinder head like the Indy EZ 1 or one of the CNC versions of that head....with a max-wedge intake port window. 


Another option would be a set of CNC ported Edelbrock RPM's which use a standard port window but the peak power will come in lower than 6500 rpm....probably closer to 6k or so. The CNC'd RPM heads can support that power with big compression. 



Ron

[daytonalo]

Sounds like a ton of money to only go 80 MPH ! I was always told life begins @ 100 in a boat

[70daytonaclone]

whats in your boat Daytonalo? I used to work on light outboards in Miami 30 years ago.