mike tkach

iTrader: (3)

im not getting involved in another cam thread but i will tell about a similar build i did for a buddy about 10 years ago,it had edelbrock marine heads,509 cu in,8.5 compression ratio and a crane 741 cam.the exhaust is imco power flow with silent choice that only gets run in quiet mode when in a marina.to my suprise it has no reversion issue but it idle,s at 900 rpm.dustin did the tune and it peaked at 740 with dyno headers.it sees about 25 hours a year and had had no problems and other than oil changes it has had no work done to it,still has the origional ngk plugs.ADD IN,it has had several water pump impellor replacements. i don, t have the dyno sheet,s because i gave them to the owner so i don,t remember what peak rpm was but i think it was just under 6000 rpm.

Eliminated572

There were a few of us that had some talks about dyno simulations (N/A form) on 502ci engines (Stock headed, single plane, 850carb) with various cams. Results were actually fairly close. Mike, the 741 did very well. Obviously with boost or higher flowing heads in the equation would vary greatly.

HP500 cam. 222/230, 110LSA, 536hp/606tq 68* Overlap (Peak HP at 5k)

525 EFI cam. 236/244 114 LSA . 566hp/586TQ and avg 466/470tq overlap 70* (Peak 5400)

Erson 230/236 112 LSA . 570HP/598TQ and avg 464HP/471TQ overlap 71* (Same peak but notice the power/torque increase vs the larger duration 525 cam. Says LSA alone can trump duration)

Custom Comp Single Pattern 245/245 114 LSA. 651/651 lift. 573HP/582TQ and avg is 474/475 overlap 78*.

Crane 741 236/244 112LSA 580HP/590TQ and avg 482HP/485TQ overlap 78*

Lunati 242/252 114 LSA 582HP/584TQ and avg 487hp/486tq Overlap 78*

Lunati 240/245 112 LSA 577HP/591TQ and avg 477HP/480TQ overlap 77.5*

crower 236/244 114 LSA 565hp/597TQ avg 455/465. overlap 64*.

Custom Comp 243/251 112 LSA. .627/.632 . 585HP/593TQ average was 486hp/497tq, overlap 77*.

Crane 651 244/256 114LSA .632/632 594hp/561tq. average is 493/488tq. overlap 84*. (Peak HP over 6k/ peak torque over 5k and larger overlap - Bit big for 502 with standard induction)

Eliminated572

Still trying to understand your logic here. Out of steam at 5000 RPM? If I was to look at this sheet, I would say prop for 5600... She's still building at a decent rate from 5k-5600... What you are saying is confusing at best IMO.. Looks at 525efi curves, and where they are propped for max speed.... Anyway, here is the sheet in graph form:
[ATTACH=CONFIG]563709[/ATTACH]

ICDEDPPL

iTrader: (1)

Why would you prop for peak torque unless you want to go slower and break drive parts regularly? If that theory was true then according to this graph you would prop for 3600 RPM.

Eliminated572

I agree... if the power is there, it's there. The old rule of thumb is to put them at just before power flattens out.. could mean right before peak or a few hundred earlier (as seen above).

14 apache

iTrader: (1)

If you are looking for max speed prop it to max HP.. If your racing throw that out the window..

Eliminated572

I agree with that. Torque needed for acceleration would be of great benfit. But for pleasure boat, I don't see how this engine shouldn't be propped around 5600ish... plenty of "steam" above 5k

sutphen 30

have you run this engine?if so what prop and what rpm?

Eliminated572

So far it's been over propped. 95GPS 5000-5100rpm 31 p5x 1.36 gear 3 3/8 upper pulleys 8.75 lower pulleys making 5psi. I think it needs 29 p5x props and 3.125 uppers. Should bring boost up to 6 to 6.5psi. Rpm likely would land in the 5600 range

midwest272

Maybe try some 1.50 ratio drives ?