Brad Perry

Hey Marc,

Would you mind extrapolating a little on the cooling and oiling, if it isn't a trade secret??

KAAMA

Bobby, I was wondering if you could help me out here a little. I do NOT have blowers, rather my engines are naturally aspirated 540's (short decks) with Dart aluminum 310cc PRO-1 fully ported heads, Dart single plane intakes, stock Holley mech secondary 950HP carbs w/4-corner idling, Stellings tubular headers, MSD crank trigger system, Crane marine grade iginition boxes, Crower hydraulic roller cams 236*/244* on 114* lobes degreed in at 108*, 9.7 comp ratio, 32* of timing/full advance.

The engines were dyno'd.

I usually cruise at @3500rpm. The fuel burn rate per hour is 148lbs and BSFC is only 0.41 with EGT's @1350*

At 5500rpm the fuel burn rate per hour is 146lbs and BSFC is 0.39 and yet EGT's are roughly about 1350*

The BSFC numbers seem quite low and yet the EGT's say that I'm okay---I don't get it! The carbs came stock with #78 size jets on all four corners and that's what we used during the dyno tests and we didn't change them. And yet, when I put the engines in the boat and ran it on Lake Michigan in 45* air temps, 160* theromostats. And yet I still get BLACK TRANSOM which indicates a RICH condition. My question is: WHAT THE HECK IS GOING ON HERE? Do I still need to drop the jet sizes? Am I missing something? I just don't get it!

Thanks in advance
Mark/KAAMA

KAAMA

BTW Bobby, that's using 93 octane fuel from Amaco.

razor1115

Kaama,

We have the same engine, other than the heads. Same cam but 112 ls on mine. I run 4" EMI Thunder w/ ss risers. I believe these are severely hurting performance for this size cu. in. Did you dyno yours and what were the results?
What results do you get in the boat and RPMs

My set up
540 cu in (w/ 6.135 Forged rod)
9.5:1 CR
236/244 cam 112 ls 108center
GM iron rect heads (ported polished bowl blend gasket matched 2.25 intakes 1.88 exhuasts, intakes unshrouded)
Dart single plane (polished, ported, gasket matched)
950HP Holley
EMI 4" exhaust

Not running how I believe it should

KAAMA

Razor1115,

My 540's make about 682hp @5500rpm. Heads have 2.30" intakes valves and 1.88" exhausts.

Depending on what boat you have, the results are going to vary. My boat is 32' Active Thunder. I am turning the engines up to 5700rpm with 30" Bravo One props. I do have a set of labbed 32's to bring the rpms down.

You didn't say whether your cams are hydraulic rollers or not. Rough guessing, I would say you should be right around the 590-620hp level. A friend of mine is running about the same set up as you with the cast iron World Products heads with some pocket porting, Crane hydraulic roller 236*/244* on 112* lobes, 9.0 comp ratio and his was dyno'd at 595hp each. He runs his in a 35' Cig with Stainless Marine exhaust manifolds with dry 4" pipes going all the way out/through the transom and it runs something like 70-71 on the GPS. Hope that has helped a little.

razor1115

That helps a lot. I'm in a 24 Outlaw running 75mph. Cam is roller hydraulic. You're right on the number: Makes 585-600 hp on dyno at 5500. Problem is, can't get over 5200 in the boat. Thinking I may actually try a SMALLER prop??? Running same prop as 460 hp motor that came out, though.....Also used Dyno headers, my EMI's are probably pretty restrictive

Thanks,
Zack

bobby daniels

HI KAAMA! HOPE THIS HELPS. FIRST, HAVE YOU DONE A PLUG CHECK? WE DO ONE WITH NEW CHAMPION PLUGS BECAUSE THEY ARE EASIER FOR ME TO READ. RECOMMEND ONE CHECK AFTER A FEW MINUITS CRUISE WITH A NEW PLUG. TRY ANOTHER AFTER A FULL RUN-NO IDLING!
YOU CAN HAVE MANY PROBLEMS WITH THE CARBS, POSSIBLY AIR BLEEDS NOT SIZED CORRECTLY, INTERNAL LEAKS, ETC. THAT COULD CAUSE THESE PROBLEMS.
THE TEMPS YOU QUOTED ARE HIGHER THAN WE LIKE TO SEE IN A BOAT THEREFORE I WOULD NOT TRY ANYTHING LEANER-YOU COULD HAVE A DISASTER!!!
IF YOU ARE LEAN, AS I SUSPECT, TRY 3 SIZES BIGGER JET. THE WORST IT WILL DO IS SLOW DOWN FOR ONE PASS, IF YOU LEAN IT ANY MORE AND IT IS ALREADY LEAN, YOUV'E GOT A SERIOUS PROBLEM.
ALSO CHECK THE IGNITION SYSTEM. (((CRANES ARE KNOWN FOR WEAK SPARK AT TIMES))) TIMING NOT REALLY CORRECT, MISSFIRE FOR ANY REASON FROM PLUGS, WIRES, CAP, ROTOR, BOX, COIL OR ANY OTHER PART CAN CAUSE BLACKENED TRANSOMS AND WEIRD THINGS TO HAPPEN. A WEAK COIL WILL CAUSE ALL THESE. ALSO, HOW DID YOU GET BSFC IN THE BOAT????
ALSO AND E-TYPE COIL WORKS GREAT WITH YOUR SET UP WHICH BY THE WAY LOOKS `LIKE ONE MEAN BULLET

KAAMA

Bobby, if I said that I got a BSFC in the boat then that is not correct. We got it off the dyno. The coils are Crane PS92 coils and the carbs are new----everything is pretty much new although I know that doesn't always mean much. We'll be doing a plug check in the spring. I just got the boat running about a month ago and it's cold here now. There is still raw fuel on the transom. I guess the plug check is our next step. Thanks Bobby

Mbam

Mark, what kind of fuel pressure are you running? I have found anything over 5 lbs will dump fuel when you come off a wave. Brad, I am too poor a typist to go into it here. I have no plans to be in the engine bussiness, so I will think about putting some of it up on my site.

KAAMA

Marc, I'm using Edlebrock mechanical fuel pumps with Holley fuel pressure regulators. The Edlebrock pumps have 6 valves internally and I went with them because the Holley mech fuel pumps weren't keeping up with the fuel demand real well---the Holley's have only 4 valves internally. I have mechanical fuel pressure gauges at the helm so we're running at about 7psi at idle and about 6.5psi or so at WOT. Since I have gotten my boat running again, I have only been testing it in CALM water so I'm doubting it is dumping fuel, but it's still something to watch for. Sounds like pehaps I should adjust them down a little eh?---or at least be more aware of. Thanks for the tip Marc!