10 :1 vs 12:1 c/r ???

[76miller]

How much of a hp increase will you actually see w/ 2pts. of compression ? If the motor is done making power @ 6400 rpm how big of a role will the added compression play. Torque will not be a problem because it will be a stroker, but the big question is, is the gained hp of 12:1 c/r worth the cost of fuel ?

[IMPATIENT 1]

could be as little as 40hp gain, could add alot more. worth it imo, just run a less aggresive timing curve when you need to run pump gas

[wannabe]

Depends what you are doing with the boat. I have ran high octane in another boat and an old Bronco and I am F'ing done with that $hit. For me up in Washington it was a complete pain, I even have a station within a few miles of my house. I carried extra barrells and always ran out. Let's say you want to stay a few extra days when your out boating...sorry no fuel for you, not to mention the crazy costs!!
If you don't already have it throw a shot of N2O on it, you will be happier with that than the pain of FINDING high octane when you need it...oh and by the way don't plan on using octane boost.
Also be careful trying to back timing down, it may bnot work with the combo that you have or if you do it will run like crap!!! Been there

[Sleeper CP]

How much of a hp increase will you actually see w/ 2pts. of compression ? If the motor is done making power @ 6400 rpm how big of a role will the added compression play. Torque will not be a problem because it will be a stroker, but the big question is, is the gained hp of 12:1 c/r worth the cost of fuel ?
All else being equal assume an 8% increase(that's 4% per point)
Example: if the engine is making 600Hp w/10:1 it will add approx 48 HP with the compression bump.
Keep in mind you may be able to gain an equal amount with a very good set of heads (that's flow,port shape and combustion chamber) without having to go the 12:1 route. If you can stay under 11:1 and with the right cam and timing you can make good (very good) power with 92 octane and not detonate. The Ford combustion chamber and flat top or dished piston you will run to get to 11:1 is a big advantage that you will have to keep the detonation down. ( just my .02)
Oh, could run the "old" 565 (855 hp engine) w/10.8:1 on pump gas at 32* timing with out a problem. We didn't do it much but a couple of times to get back to camp.
Sleeper CP
Big Inch Ford Lover

[cfm]

All else being equal assume an 8% increase(that's 4% per point)
Example: if the engine is making 600Hp w/10:1 it will add approx 48 HP with the compression bump.
Sleeper CP
Big Inch Ford Lover
If motor is already optimized for 10:1, 12:1 will need a cam swap and add another say 40-60hp on top of that 40hp from compression alone.
So, yeh, many motors going from 10:1 to 12:1 and making appropriate other changes, big power is realistic.

[Sleeper CP]

CFM,
Exactly, as far as optimizing the engine that won't happen unless he makes a cam change. That's why I stated "all else being equal" If I re-call correctly I don't think 76 Miller ( Wayne) runs a roller cam in that engine.
If he is going to build a stroker and put 12:1 compression in it with the correct cam he can make some big power. But he may not want a high maintenance engine.
Sleeper CP
Big Inch Ford Lover

[cfm]

Yup.
I quoted you to add to what you said, not differ.
10:1 big cube engines can really make decent power. Most definately.
Also, if you don't change anything else adding more compression will usually reduce max hp rpms. IE: lower the powerband's rpms.
==========================
Is there a detailed list of the engine as it sits now ? Or planned build up ?

[76miller]

All else being equal assume an 8% increase(that's 4% per point)
Example: if the engine is making 600Hp w/10:1 it will add approx 48 HP with the compression bump.
Keep in mind you may be able to gain an equal amount with a very good set of heads (that's flow,port shape and combustion chamber) without having to go the 12:1 route. If you can stay under 11:1 and with the right cam and timing you can make good (very good) power with 92 octane and not detonate. The Ford combustion chamber and flat top or dished piston you will run to get to 11:1 is a big advantage that you will have to keep the detonation down. ( just my .02)
Oh, could run the "old" 565 (855 hp engine) w/10.8:1 on pump gas at 32* timing with out a problem. We didn't do it much but a couple of times to get back to camp.
Sleeper CP
Big Inch Ford Lover
Sleeper-
I would rather go pump gas, but I'm just not sure. If 12:1 is going to have the hp # to reach my goal than so be it ! I don't mind checking springs, and valve lash, but the cost of race fuel doesn't seem to inviting w/ a tunnel ram deal. Check your pm's:idea:

[76miller]

Yup.
I quoted you to add to what you said, not differ.
10:1 big cube engines can really make decent power. Most definately.
Also, if you don't change anything else adding more compression will usually reduce max hp rpms. IE: lower the powerband's rpms.
==========================
Is there a detailed list of the engine as it sits now ? Or planned build up ?
CFM
I'm not bumping c/r on a current motor. I did run a motor on 10.5:1, but now I'm doing a new build and just don't know what c/r to run.

[BrendellaJet]

CFM
I'm not bumping c/r on a current motor. I did run a motor on 10.5:1, but now I'm doing a new build and just don't know what c/r to run.
Wayne, ask your builder this question. Better yet, tell him you want NA, X amount of horsepower, on pump gas. He knows the drill. Also, youd be surprised to see just how close to 12:1 he is with pump gas.:idea:
if you want to see what one of his motors can do let me know and Ill take you for a ride. My boat is a 21 footer and it gets up and moves pretty well. When I had it in my 18 is was just sickening how hard it pulled.