Hello-
I just got a 454 and was wondering what the estimated horsepower and torque would be.
454 bored .30 over SRP pistons(212135) slightly under 10.1 compression with
Merlin rectangular iron heads 320cc intake runner (2.30 intake valves)
Comp marine .575 hydraulic flat tappet cam w/crane roller rockers
Holley single plan high-rise intake w/ 850 dp
Cmi fusion tube headers.
Stock Merc Ignition.

Thankyou

id say 450 hp and 500 torque.

450hp

They are nice pistons, I have hit 4 valves with them and still no holes. lol
That flat tappet cam is leaving a lot on the table. I'll guess around 462.3HP

Thankyou for the quick replys. Any good gains by converting to Hydraulic roller? if so around what lift
Thanks Tom

I use to run solid roller cams 252°/264° 0.669"In 0.623"Ex, with fully ported and wedged Merlin heads with those pistons. I dyno'd 590HP/564TQ. They were pretty high strung and would not recommend that.
I would put something comparable to Comp lobe 3122/3113 on a 114. The engine builder I share a shop with builds a lot of Comp cams off this page.
Also, note by no means am I an expert on cam shafts. There are more people qualified on here for that. This would be my opinion and gut feeling with your setup that I am familiar with. It would probably put you over the 500HP and increase TQ.

Others please correct me if I'm giving misleading information.

How do we guess hp when all we are given cam wise is lift ? Or am I missing something.

10:1 CR seems a little on the ragged edge for an iron-headed marine engine. I would be careful with camshaft selection - you may raise your dynamic compression ratio if you go with a cam that has less overlap than the current one. Sometimes bleeding off some cylinder pressure can be a life-saver.

I'm running a similar set-up as the op and per the prev owner they are right at 500HP@5K rpm.. Top speed confirms that HP to be close.
93 octane only!!!

I'm no expert but with his compression and cubic inch I'd tighten the lobes a little.