The case for tuned 4 cylinder 4 strokes

[loop]

probably a dumb question but are any of the 4 strokes pushrod motors and if not,why?

[blacktruck]

probably a dumb question but are any of the 4 strokes pushrod motors and if not,why?

All the 4 cylinder ones mentioned are double overhead cam, except the merc is single overhead.

[blacktruck]

Hope no one actually wants a 150 hp ProXS, I have had one on order through a local dealer since late February. Has anyone actually taken delivery of one of these engines?

So it's backlogged as well? I thought since it was just a tuned 150, it would be available right away?? Unless it's just sold out. But I haven't seen any real reports on it yet so maybe it's delayed for some reason.

[loop]

All the 4 cylinder ones mentioned are double overhead cam, except the merc is single overhead.

Thats what I thought andl to the best of my knowledge all the 6cy motors are too. Just wondering why they wouldnt try a simpler, lighter weight, lower maintenance and more compact push rod motor.

[David]

Is the 150XS a 4 valve engine?

its easier to do a crossflow canted valve head with overhead cams then pushrods, and easier to do a 4 valve head. I suspect the cam ramps can be steeper. But GM is still working magic with pushrods.

[powerabout]

Thats what I thought andl to the best of my knowledge all the 6cy motors are too. Just wondering why they wouldnt try a simpler, lighter weight, lower maintenance and more compact push rod motor.

ls3 standing on its end....

[blacktruck]

Thats what I thought andl to the best of my knowledge all the 6cy motors are too. Just wondering why they wouldnt try a simpler, lighter weight, lower maintenance and more compact push rod motor.

I think the advantage of the OHC is the efficiency and longevity, plus they aren't necessarily heavier. The SOHC design from Merc is smart for simplicity, SOHC can provide plenty of torque. The DOHC, can are really efficient and rev really high.

[loop]

ls3 standing on its end....

exactly
even half of one would make a strong light durable motor

[blacktruck]

Is the 150XS a 4 valve engine?

its easier to do a crossflow canted valve head with overhead cams then pushrods, and easier to do a 4 valve head. I suspect the cam ramps can be steeper. But GM is still working magic with pushrods.

No, it's a 2 valve. It won't ever rev like the Yamaha, or Honda, but can make decent power. The 3.0 150 4S Merc is pretty bulletproof.

[FMP]

Had a 115proxs out for a spin, Lund 18. I just kept waiting for something to happen. Smooth yes but not anywhere near what I expected for performance. Stupid four blade prop, set up by dealer, wouldn't turn 5201. Maybe 29hrs on it, needs to back for diagnostic check, no snot in it at all. Etec 115ho would eat it.

[powerabout]

Had a 115proxs out for a spin, Lund 18. I just kept waiting for something to happen. Smooth yes but not anywhere near what I expected for performance. Stupid four blade prop, set up by dealer, wouldn't turn 5201. Maybe 29hrs on it, needs to back for diagnostic check, no snot in it at all. Etec 115ho would eat it.

thats why we buy 2 strokes

[FMP]

Was looking for a comparison video etc for the 115proxs vs 115ho Etec , can't find anything?

[wtsjr66]

Don't know what the problem is, but like I said been waiting over six months with no firm delivery date in sight!!

[blacktruck]

Don't know what the problem is, but like I said been waiting over six months with no firm delivery date in sight!!

That's crazy. You'd think there would be an update. I haven't even seen OE pics of one in the wild yet, or performance tests.

[powerabout]

I wonder if half a ls3 would have a better torque curve than a Merc 150 4?
How about a 3.0ltr 140MCM engine in aluminum with a better head??