[66sprint6]

We're trying to sell our Round Port engine that we bought a while ago. Of course, the first question that prospective buyers are asking is how much HP. We don't know what cam is in it, but here are the other specs:

SRP pistions, 4.155 with a 7cc valve notch
Eagle crank, 4.25 sroke
Edelbrock 72cc heads
Assuming nominal .004 deck height and a .039 compressed gasket thickness

I went on Butler's site, used their CR calculator and found the engine to have an astounding 11.67:1 CR with this combo. Any guess on what kind of horsepower/tq this thing makes? We're trying to figure out what to do with it. The CR numbers are scaring some people away.

[steve25]

Without knowing what Cam is in it makes things a crap shoot!

I will say that if the motor will idle nice when fully warmed up at no more then like 700 rpm in gear, then it's likely that it will be making no more then 450 hp.

[Butcher]

Do you at least know if the cam is solid roller, hydraulic roller, hydraulic flat tappet, or solid flat tappet

[66sprint6]

Hydraulic roller.

[65madgoat]

Head work? Or stock e-heads? Could be anywhere from 425hp to 535hp I'd say and torque 50+ over those numbers respectively

[66sprint6]

I believe stock E-heads. But not confirmed. Thanks for the replies, we're just trying to figure out what to do with this thing.

I have to give a shout out to a member on here who lives nearby. He sold me a great Quadrajet at a good price and has been helping me along. His handle is GTO Firehawk John. The cars and engines that he has blew my mind. I posted on here for a bit to give him a break from my constant questions. He's spent a lot of time helping me out, I really owe him one.

[Stan Weiss]

Have you ever done a cranking compression test on this engine? If so what were the numbers.

Stan

[77 TRASHCAN]

I got same comp ratio.
The general rule of thumb is that a person can accidently get 500 horse power out of a 455.
I would promote that number, if needed.
Just a thought.

[b-man]

Just tell them you estimate 500 horsepower. It’s easy to find examples like Ken Crocie who dyno tested a 455 with Edelbrock heads that easily made that number.

Then tell them everything you know about the components used and get on with the sale.

[Gach]

Two things, a 461 ci motor, with a Crower hyd cam, 520 lift with 72 cc..E-heads made 500 hp. On pump gas. I think compression work out to 10.75. Not 100 % sure on that. Number were back up at drag strip.

So I’m guessing with hyd roller and that compression, it’s probably around 525-550 hp.

.2 no problem with that compression running pump gas. I’m at 11.5 with my 505 and a 739 lift solid roller. No issues what so ever. You can actually run 2 points more compression with aluminum head. And still be safe for pump gas.

Most hyd roller cams never see more then 650 lift. That motor to replace or build today from scratch is around $12,000.00 complete.

PS: the E-Heads had no port work, just a clean up and valve job checked.

[steve25]

You just can’t get around that basic fact that especially for a non purpose built flat out race motor, no less a street strip motor that for every 100 Hp you plan on making your going to need to run .100” of lift.

[77 TRASHCAN]

Originally Posted by Stan Weiss

Have you ever done a cranking compression test on this engine? If so what were the numbers.

Stan

Getting a cranking compression test isn't a tall all deal BUT helps give you an idea on potential octane requirements.

A degree wheel and dial indicator setup is not an impossible thing to do, to get cam information...

[slowbird]

Originally Posted by steve25

You just can’t get around that basic fact that especially for a non purpose built flat out race motor, no less a street strip motor that for every 100 Hp you plan on making your going to need to run .100” of lift.

Where did you read these? Not sure I agree at all.
.750 lift made 900hp on pump gas. I don't think that's a rule at all, just coincidence it might work on some combos

[steve25]

Your talking a race motor making a high level of VE, I am not just as a clearly stated, or I thought I clearly stated.

[PAUL K]

Originally Posted by steve25

You just can’t get around that basic fact that especially for a non purpose built flat out race motor, no less a street strip motor that for every 100 Hp you plan on making your going to need to run .100” of lift.

Originally Posted by steve25

Your talking a race motor making a high level of VE, I am not just as a clearly stated, or I thought I clearly stated.

So you're saying all you have to do is throw a pair of SM heads on a nice 400 CID shortblock and you'll make 600 HP using a .600 lift cam? Or 700 HP with a .700 lift cam?? I assume that'd be with pump gas since this is the street section and you clearly stated you are not referring to a "race" engine.

Could the OP measure his current valve lift and come up with an answer to his question?

[slowbird]

Originally Posted by steve25

Your talking a race motor making a high level of VE, I am not just as a clearly stated, or I thought I clearly stated.

It was 10.8:1 compression, not much of a race engine.
I think your rule is based on coincidence, most street cams have .500 to .600 lift, most engines make 500 to 600 hp. That's just coincidence. Anyway, sorry to sidetrack the thread.

[Stan Weiss]

I calculate the min valve lift using ci, rpm, VE%, and valve size. You could say in someways I am looking for a needed curtain area.

Stan

[steve25]

Gez guys, I am just saying it’s a pretty good rule of thumb.
If your running .500” lift and your making 580 Hp out of a mild street motor then I am happy to be wrong to that side of equation .

[slowbird]

Originally Posted by steve25

Gez guys, I am just saying it’s a pretty good rule of thumb.
If your running .500” lift and your making 580 Hp out of a mild street motor then I am happy to be wrong to that side of equation .

Serious question can you provide lobe specs that has duration at .050 between 235 to 245 (the most common duration used for 500-600 hp engines) that doesn't automatically produce .500 to .600 lift when combined with the most common rocker ratio of 1.5 to 1.65? Your rule is just a coincidence. And when give examples that don't fit your rule you write it off as a race engine.

[Gach]

Not saying you should put this price on it, its up to you. But one with just about same spec’s sold for $9500.00 on Facebook deal.