how much hp to turn impeller?

[LVjetboy]

Well if comparing corrected hp/cuin...
Dyno tested: 1.33@6200
9.8:1
N/A carbureted
89 Octane
Hyd. roller
Mufflers
The 1.33 maybe a tad low because I'm running better flowing mufflers than the dyno test above.
jer

[Infomaniac]

Originally posted by DogHouse
Well I hate to be argumentative, ok not really, but here are the hp/ci numbers we made, also posted in another thread:
With n/a EFI, 91 oct, we made 1.22 @5000, 1.32 @5500, 1.34 at 6000, 1.36 @6500, corrected of course because that's the only way to provide meaningful comparisons of engines tested on different days under different conditions. Yes, in the boat on a normal blazing hot day they will be lower. My boat regularly sees over 6k rpm. This motor also idles between 800-900 rpm and carries over 700 ft-lbs torque from 3100-6000 rpm. No exotic parts here, just a solid roller, coatings, 10.8:1, 36 deg timing, coolant temp while on the dyno in the 150-160 range, no detonation, EFI with knock sensor just in case. Tested on Larry Peto's "fudge factory" dyno. Anyone who doubts the validity of Larry's work or his dyno, just go to Havasu for a poker run and see who everyone is chasing at 165 mph. Ok, this last poker run not withstanding (blown freeze plug, oops, everyone has a bad day now and then). I think that the 1.2 number is a good target for a mellow low maintenance motor (i.e. hydraulic roller valve trane) that can also be tolerant of lessor grade fuels, but it is not the cutting edge of pump gas any more.

Let me make one thing perfectly clear: I HAVE NEVER SAID ANYTHING NEGATIVE ABOUT Larry Peto OR HIS DYNO. Any other engine builder either.
And I believe your engine falls out of the criteria that I related to. Some people focus on the 1.2 thing quoted and fail to see anything else stated.
One more time for the record. N/A ,CARB, STOCK MERCRUISER RANGE RPM's
Maybe not the best forum to use this example in. Jets typically turn more RPM's. I generally keep this info in the gear heads forum. And it is directed primarily for sterndrive engines.
Also no EFI computer adjusting the fuel and ignition curves to allow more compression. Compression and RPM's will make a lot more power.

[DogHouse]

Originally posted by Infomaniac
Let me make one thing perfectly clear: I HAVE NEVER SAID ANYTHING NEGATIVE ABOUT Larry Peto OR HIS DYNO. Any other engine builder either.
Agreed, you have never come right out and stated that any particular builder is full of sh!t and has a jacked up dyno, but repeated comments about "fudge factories" and "fudge masters" can easily lead one to believe that you would discredit anyone that makes more than the golden 1.2 ratio, including several people who have posted on these boards. Then when you say that a person can get a motor claiming a higher ratio and not make the boat go any faster, that pretty much shows me that you don't believe their power claims. That is fine, certainly your right to believe or not believe whatever you want, but it is also our right to argue the point! And by the way, you are not always clear about the stipulations surrounding that number. That's one of the problems with arguing numbers on the boards, not easy to make sure we're comparing apples to apples.
As far as my motor is concerned, I don't think that it's all that great, but it does exceed what some people have said to be the limit for pump gas, hence the argument! It's definitely not the most optimized example here; others have done better. After looking at my dyno sheets I see that I have too much cam for the rpm that I like to run and could probably make a little more torque and better power at my target rpm with less duration. We also did not have enough dyno time to finish fine tuning the efi at the very top end and it's slightly fat. Probably never notice the difference in the boat though.

[Infomaniac]

Your right man. Everyone is intitled to their opinion and also to debate someone's opinion.
I like to make sure the debate is friendly professional and actually appropriate if I am involved.
Most of the time if I question someone's numbers, I do not have a clue who built it. And I never questioned yours.
The only time I really feel that dyno correction factors have been fudged is when an astronomical number is produced that exceeds very reputable engine builder's numbers by far.
I ran dyno's for many years and have first hand knowledge of the process.
********OH YEA *********
Sometimes the debate leads me to acknowledge that I was full of shit and sadly mistaken.

[DogHouse]

Originally posted by Infomaniac
********OH YEA *********
Sometimes the debate leads me to acknowledge that I was full of shit and sadly mistaken.
Welcome to the club, LMAO!

[Moomawnster]

Originally posted by LVjetboy
Aggressor B @ 4000 = 200 hp
That's actual power not rated. Now if you did build that 355 to put out a true 400 hp at the lake...then 80's are possible with your jet.
jer
Thanks JB 240 hp was the factory rating in 1986, I figured 17 yrs has taken some Hp out of it , Is 400 hp a reasonable # for a 355 ? I want to start this thing soon , spring is coming !

[LVjetboy]

Moo...a corrected 400 possible with good flowing heads and cam. Even 450 with trick heads and right combo check this:
383 Cubic inches
Hot Rod/Summit 383, from Hot Rod March 1992
350 block, .030 over
3.75" stock 400 crank
5.7" production rods
Keith Black Hypereutectic Pistons, Compression 9.5:1
Crane Cams hydraulic cam; 236/246 @ .050, .510/.512" lift, 112deg lobe sep
AFR 190cc aluminum heads, 80cc chambers, 2.02/1.60" valves
Crane Cams aluminum roller rocker arms; 1.6 intake, 1.5 exhaust
Edelbrock Victor Jr. intake mainfold, Holley 750 double pumper carb
1-3/4" headers
450@5750
This engine is the same exact engine that Summit sells as its 450hp 383 engine. It is streetable and even with stock parts, it should last since it is only meant to rev to 6000 rpm. This one is available from Summit, I believe the engine minus accessories is about $3800.
That'd get you 375-400 actual at the lake, depending on where you boat of course. That with a small block weight savings and you're cookin!
But guys like Info are more qualified to answer your engine questions than me.
jer

[Moomawnster]

LV .... Thanks for the tip , my builder doesn't like strokers or blowers because of longevity concerns but I wasn't sure I could do this on pump gas at all . Very encouraging ! 400hp will now be my goal .........
All aluminum is my dream motor ! $$$$$$$$$$$

[DEL51]

Is this a normal post. TEST

[Infomaniac]

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