PCM torque curves...

[core-rider]

Well to add my $0.02... Looking at the dyno curves from above, I'm not as concerned about the peak numbers as the touque curve itself. Look at the two curves... The 6.0 starts at just above 300 ft. lbs. where the 5.7 starts around 340-350. Granted there are about 5 RPM difference between the two graphs, but I take that as the 5.7 gives you better touque numbers where you need it... down low. It takes torque to get you moving, horsepower keeps you there.

Again, I'm just gonna repeat what has already been said. If your looking for boats and that's the only thing you have questions about... test drive both and make an informed decision. Nearly everyone of us on here will have a different way a weighting our boats and different uses for them. Find out for yourself!

Personally I wouldn't spend that much extra for the little benefit. I'd just re-prop it. I'd rather spend that money on something like upgrading the stereo, extra ballast, paying the note!

[TRBenj]

I take that as the 5.7 gives you better touque numbers where you need it... down low. It takes torque to get you moving, horsepower keeps you there.

Im not sure I agree with that. Im not sure what the bigger boats have for holeshot, but I get well over 3k RPM when going WOT out of the hole. IMO, midrange power is the name of the game in ski boats, not low end torque. The ZR6 should be a solid all-around improvement over the Excal.

The LY6 hp/torque chart was actually squished on GM's site. Stretching the scale to match the 350 makes the curves look like this:



*note: the hp of the Excal should be greater than the ZR6 below ~2300 RPM (where the torque curves cross) since they are both on the same RPM scale. I double checked and I didnt make an error when combining the graphs- there is some problem with the GM charts.

[ski36short]

FYI - the PCM 6.0L is an LQ4, not an LY6; I think the ZR6 has been a PCM engine longer than the LY6 has been in the GM lineup. Torque curves are different as the LQ4 has a fixed cam position and not VVT. And somehow Indmar claims 400hp on their LY6?

[TRBenj]

FYI - the PCM 6.0L is an LQ4, not an LY6; I think the ZR6 has been a PCM engine longer than the LY6 has been in the GM lineup. Torque curves are different as the LQ4 has a fixed cam position and not VVT. And somehow Indmar claims 400hp on their LY6?

Good info. As far as I can tell, the main difference between the LQ4 and LY6 is the VVT. Theyre both from the same block family, and both sport iron blocks mated to aluminum heads. I dont see the LQ4 on GM's marine page, so perhaps the ZR6 will get the LY6 at some point. It appears the LQ4 debuted in '99, while the LY6 is new for '07.