zimm17

I have a 1996 454 magnum with only 25 hours on it (reman block from prior owner). I had the heads off and pressure checked over the summer- they're fine. Put on an Edelbrock performer rpm air-gap intake. Has Dana marine exhaust. Thunderbolt V ignition.

Boat runs great, 71.4mph @ 4900rpm with a 25p 3 blade.

I'm wondering if I'll see any worthwhile improvements if I pull the engine, throw on some AFR CNC 305cc heads, and the full Crane roller setup (731 cam, lifters, roller rockers, pushrods). It already has the stock 750cfm carter AFB type carb. I might go with a 850 cfm double pumper. It's about $5k in parts- I'll do the work myself. Wonder if I'll actually get 100 more HP and maybe 5 more mph.

I also don't get anymore than 28psi oil pressure, so I can add a new high pressure oil pump while the engine is out.

The other option is to look for a take out 500EFI blue motor- but then it's a crap shoot to the condition of it- great deal if it holds together, but not a good deal if it needs a rebuild right away.

Stingray69

If guage and sender are working correctly, 28 psi signals ALL NEW BEARINGS.
First.

zimm17

Uhhh oh. I better get a new sender on there and test her out. It's been acting up because sometimes it'll go to zero or 5psi, but the low oil press light doesn't come on and then it'll go right back to 28 again. I'm pretty sure it's the sender- I've actually been waiting for something to blow up for an excuse to get a 540, but one step at a time. At least with new heads, I can reuse them in a new shortblock down the road.

Stingray69

Get it working right, then shop for more cubes, keeping the 454 as back up/put back, when needed/selling. A 500hp, freshened, will get you way faster, way easier, than surgery to the 454.

Put 5K into the 454, and you'll STILL be wanting to put those add-ons on a 502.

Kidnova

Have you checked oil pressure with a mechanical gauge ?

zimm17

The mechanical gauge is my next step- my dad has one. I'll get that checked out this week. Hopefully just a gauge problem.

I'll keep my eyes pealed for a 500EFI or 525EFI takeout over the winter.

KAAMA

iTrader: (1)

How fast was the boat BEFORE you did the mods to the 454?

AFR heads are great, but I would try and get into the 500 cubic inch range (like at least 502cid) before spending big money on a new set of AFR heads----that is unless you're really bent on having the AFR's. And by the sounds of it you're already talking about a 540cid engine even.

As difficult as it may be, try and make up your mind of what size cid engine you want end up with and hanging onto for a while otherwise, you're going to be spending a lot of money for parts that will only work well on a particular sized engine---especially HEADS!

If you like upgrading with mods then, I would at least try and buy a carbed version of a 502 first and then go from there with expensive head mods if you want. There's usually less headaches with carbs vs EFI. Also, there's reliability in cubic inches and an 800cfm Holley carb would be fine for a 502cid engine and have even heard of them working well on a 540cid. Have fun with your project.

zimm17

Well the oil pressure is just fine. 42psi at idle with the mechanical gauge. Just bought new senders, waiting to install.

I'll just have to figure out if it's worth the trouble of pulling the motor and putting on the $5k in parts for that extra power (75HP?). I'd hate to build a new motor when this one is basically new. Unless it blows up, then I'd build up a 540. Guess I'll just leave it alone for now.

Donzi502

I just spent a whole bunch of money on a 454. Probally got the same gain as i would have got with a 4.250 crank and i still have a 454. Next winter a 4.250 crank will be going in to make the most of all the recent mods. 454s where great 10 years ago. 500 or bust i say.
Jas

PatriYacht

A small supercharger would give you a larger boost in power for less money.