710 cam alleged a copy of the Ilmor 710hp Viper based Boat motor cam

[MrCreosote]

In another thread (closed) someone remarked something to the effect why anyone would use a boat cam in a car.

Comp Cams did just that with their Muscle Car cams. They offered OE duplicates and also improved versions.

All engines were boring ho-hum with just a few degrees here and there and marginal changes in lift.

All except for one: The Square Port BBC 425/427.


"...offer a step up from original equipment cam designs. These cams are stronger than stock and are tailored to the high compression engines of the sixties and seventies, through the design techniques of today."

Here is the cam to replace the 425/427 242/242 .520/.520 114CL OE cam:

11-551-5: 242/250 .575.604 110CL

Which is a "Solid-Jet boat with A or B impeller. Skiing, pleasure, performance."

The boat buys need low-mid range torque to get the hull out of the water. They inject cold water into the exhaust heaters to "shrink the pipe diameters" to get higher low-rpm torque.

Sounds like would be a beast of a street engine...

I had a 425/427 in a C20 and almost tried this cam. A BBC nitrous street racer I met said the high lift cams really "woke up" the square ports.

[v10viperbox]

Boat cams are just setup like car cams but for a more civilized idle as boats need the low RPM to move around in docks and it needs to be a more consistent power delivery. "Yes they have better cooling available so they can go a little more aggressive on the top end as well. I see no reason to ever use a boat cam in a street car except when you want the cleaner idle down low which most hot rodders do not want. They want choppy exhaust noise to show that they have a cam in the car.

[SilverACR]

Water goes into the exhaust to keep the temps down in the engine bays. There is little air flow under the hatch and it would get dangerously hot under there. My BBC in my boat has cast exhaust with rubber pipes out the back of the hull. Cold water ain’t doing nothing for performance.

Also I disagree with the smoother idle. Boats tend to cruise on plane at 4000+ RPM so the cams are more for that range. My boat and my friends boats sound like drag cars. No need to care about vacuum in a boat.

[MrCreosote]

Exhaust water injection is like "anti-header wrap." While wrap keeps gases hotter with higher velocity and higher tuned resonance, spray cools the gasses, reduces velocity and lowers resonance (hence my "shrinks pipe diameter" comment.)

When you hit the spray, you can feel the torque come up.

[SilverACR]

Good article from west marine. https://www.westmarine.com/WestAdvisor/Exhaust-System-Basics

[RedTanRT/10]

Anyone looking for a Comp Coupe Cam? I just changed the heads and cam and have a nice used one avaliable

Here's the specs;

Part Number :P4510171

Recommended for use with Race Engine Controller and 3" Race Exhaust. Cam lift = 0.320" I/0.320"E. Duration at 0.050" = 220.00 I/230.5 E. Cam Center-line = 117° after top dead center.

Reach out via PM

thanks,

Mike

[TooBlue]

Nothing negative intended toward OP but who cares if Ilmor uses the same cam in a boat that makes 710 HP.
Horsepower doesn't know if its on water or land? 710hp is 710hp. Of course the engine cooling in a boat is radically different. Things like a clogged sea strainer can smoke a motor in a minute.

I agree that power band in low, middle or top end of the RPM range is very important. That depends on what the car is used for.

( I have a 708 cam and it not only sounds good, it performs. I do want to add it is in a tuned engine with headers, CAI and other bolt ons)

[OK Falls GTS]

Have two 6.2 [ 377cu ] engines in my boat. Crane cams used in the past for automobiles. Mercruiser found them perfectly suitable for marine applications. Their risers have anti reversion bumps cast in.
Blue Scorpion engine is around 375HP that has bit more aggressive cam.
My Black Scorpion engines have 350HP, have these cams. I found them it's been used long time ago in Chevs.
From Merc Racing Service Manual 7:
Engine 377 CID (6.2L)
Lifter Type Roller Hydraulics
Rocker Arm Ratio 1.50 to 1
Valve Lift
Intake 0.510 (12.95)
Exhaust 0.530 (13.46)

Lobe lift +- 0.002 (0.051) I= 0.340 (8.636) E=0.3534 (8.9763)
Dur @ 0.050 I=222 E=230
Ilmor never did change out cams in the Viper marinized engine. They had to design their water cooled exhaust manifolds to make sure reversion wouldn't be a problem. Friend and I installed a ZZ572 crate engine in his home built boat, we had Eddie Marine to fabricate a tall S/s riser for it because of the cam's overlap. That was back in 2006, engine is still in the boat.

http://www3.telus.net/spectrasonly/Craig's%20Eddie%20Marine%20exhaust

[Whiskey]

Are you saying the Roe 710R cam is a copy of a boat motor cam?

What are the full specs of that boat motor cam. What I will say is that my Roe 710R cam is not a low RPM TQ cam.

[pokeyl]

Are you saying the Roe 710R cam is a copy of a boat motor cam?

What are the full specs of that boat motor cam. What I will say is that my Roe 710R cam is not a low RPM TQ cam.

Is your car cruse smooth below 2200 RPM?

[Whiskey]

Is your car cruse smooth below 2200 RPM?


Yes, it drives almost like stock. It idles at 800-ish rpm (about 50rpm higher than stock). Other than being lumpy it idles great, never stalls I can even take off without touching the throttle still. It is a little buck-ish in part throttle (0-10% throttle) in parking lots. I just get rolling the push in the clutch. Other than that coupled with my Paxton it pulls harder and harder as RPM climbs all the way to 6300rpm.