Engine options - G23

[ironj32]

Ironj32, how are you coming along with the prop test and review.

Still waiting for the props to arrive from Acme...should be any day now.

[TRBenj]

It seems a few folks are providing guidance on powerplants for a 5900lb boat using experience gained from driving a 2600lb boat?

Surely there is something to be gained by knowing how some the engines in question compare in an apples to apples fashion. Yes, the application here is different- bigger hull, more weight, different driveline components with different ratios- transmissions, v-drives, props... but the engines and their powerbands remain unchanged.

Taking a quick look at the published (peak) horsepower figures for the engines being compared is a lousy way to determine what will work best on any given application. If the boats in question are generally propped such that they turn 4500rpm coming out of the hole, then THAT is a good reason to choose a 6.0L over the Excal. But no one has said that (does anyone know?). If the larger boats are only pulling 3000rpm out of the hole, then thats a different story... in which case, the Excal would be just fine (at least in terms of holeshot).

What will be trickier to determine is whether or not to choose the 450 over the 409. I have not seen any published hp/tq curves come out from PCM that would allow you to make a good comparison, at least from behind a keyboard. From what Ive been able to gather anecdotally, the 450 has more hp across the entire RPM band than the 409. If thats the case, then that is impressive, as usually it takes a tradeoff in low end power to make more hp up top (and usually at a higher RPM), especially when holding the displacement constant.

[OKWAKEBDR]

If the boats in question are generally propped such that they turn 4500rpm coming out of the hole, then THAT is a good reason to choose a 6.0L over the Excal. But no one has said that (does anyone know?). If the larger boats are only pulling 3000rpm out of the hole, then thats a different story... in which case, the Excal would be just fine (at least in terms of holeshot).

I can't get my 210 (with a 5.7) out of the hole in under 3000 rpm.

[pSchwade]

Surely there is something to be gained by knowing how some the engines in question compare in an apples to apples fashion. Yes, the application here is different- bigger hull, more weight, different driveline components with different ratios- transmissions, v-drives, props... but the engines and their powerbands remain unchanged.

Taking a quick look at the published (peak) horsepower figures for the engines being compared is a lousy way to determine what will work best on any given application. If the boats in question are generally propped such that they turn 4500rpm coming out of the hole, then THAT is a good reason to choose a 6.0L over the Excal. But no one has said that (does anyone know?). If the larger boats are only pulling 3000rpm out of the hole, then thats a different story... in which case, the Excal would be just fine (at least in terms of holeshot).

What will be trickier to determine is whether or not to choose the 450 over the 409. I have not seen any published hp/tq curves come out from PCM that would allow you to make a good comparison, at least from behind a keyboard. From what Ive been able to gather anecdotally, the 450 has more hp across the entire RPM band than the 409. If thats the case, then that is impressive, as usually it takes a tradeoff in low end power to make more hp up top (and usually at a higher RPM), especially when holding the displacement constant.

From a purely mechanical prospective - the larger the boat, the more thrust you will need to get the boat up to speed. Not only do you need to account for the increased inertia, but being a boat, there is also a larger wetted surface (more skin drag) and at low speeds the added weight (especially in the bow) will be fighting the hydrodynamic forces that want to bring the boat on plane (form drag).

If a 210 is running above 3k rpm with a 5.7 I dont see any way possible for the G to be less than that with the 343. Now the 409/450 on the other hand might be able to do it with the right prop because of their increased torque (gives a higher sustained power/thrust at a lower rpm) which makes an ironic point - if you could stay under 3k rpm @ take off there wouldnt be much of an advantage to upgrading to the bigger motor, but you have to have a bigger motor stay in the range where you dont really need it. It seems like each motor can be prop'd to be adequate - but adequate is a relative term. My 6.0 gas truck would get the job done towing the boat, but it couldnt do it faster than 70 up hills - so I got a duramax.

[sja]

I have driven/ridden the G23 with the 450 (loved the finish of the boat and that wake!!!) For my own purposes I was looking for something with a bit more power when driving the boat empty. I will be trying out the 550 and was wondering what to expect from the additional 100HP. I have been looking for all the info I can get on these 2 engines. I have found a lot of the above comments/analyses helpful. I was interested to find a California EPA web site that rates engines for emissions standards and offers max power in KW (which seems to be a simple conversion of 1KW = 1.34 HP).
From my reading of this it actually rates the 550 (6.2 L) a full 99 KW (133hp) more power than one 6.0L PCM and 109 KW stronger (146HP) than the other 6.0L engine. If this refers to the 407 and the 450 that would put the hp difference between them at only 13 hp.


Those of you who know a lot about engines please make sense of this for me. Are the tests invalid? Or are they talking about different engines than the 409 and the 450?


Here is the 2012 info from the website:


PLEASURECRAFT MARINE

Executive Order

Engine Family

Star Label

Engine Disp. (cc)

Max. Power (kW)

Application

HC+NOx Cert. Level (g/kW-hr)

HC+NOx Standard/FEL (g/kW-hr)

U-W-013-0030

CPCMM06.0CT1

4

6000

269

INBOARD

2.21

5.00

U-W-013-0031

CPCMM06.2SC1

3

6200

378

HIGH PERFORMANCE INBOARD

14.00

16.00

U-W-013-0032

CPCMM06.0HO1

4

6000

279

INBOARD

3.21

5.00

[ironj32]

Thought some of you might be interested in the RPMs of the 450 with the stock prop (Acme 2313).

Full Factory Ballast:
*Getting out of the hole: hit 4000 rpms
*Riding at 22 mph: runs right about 3700

Full Factory Ballast & about 2100 pounds extra ballast
*Getting out of hole: hits 4100
*Riding at 24 mph: between 4100-4200
*Riding at 25.3 mph: between 4100-4200

[TRBenj]

With those RPM's, it makes perfect sense as to why a 6.0L would be preferable. Finally, some data to base decisions off of. Thanks!

[robertsmcfarland]

good data to compare when you try the two props, thanks

[robertsmcfarland]

just wondering, on the speed vs the ballast load, were the different speeds just hypothetical or are you increasing speed in ratio to ballast load to perfect the wake,on the original question and answers on the g23 they said you could lower the speed to almost 20 and still have that perfect wake, whats your opinion or take ?

[tdc_worm]

Thought some of you might be interested in the RPMs of the 450 with the stock prop (Acme 2313).

Full Factory Ballast:
*Getting out of the hole: hit 4000 rpms
*Riding at 22 mph: runs right about 3700

Full Factory Ballast & about 2100 pounds extra ballast
*Getting out of hole: hits 4100
*Riding at 24 mph: between 4100-4200
*Riding at 25.3 mph: between 4100-4200

interesting fact: PCM recommends a max sustained cruising rpm of 4k rpm. i am curious to know what running these enormous boats with ridiculous weight will do the rebuild interval on these small block engines...time will tell i suppose...

[ironj32]

just wondering, on the speed vs the ballast load, were the different speeds just hypothetical or are you increasing speed in ratio to ballast load to perfect the wake,on the original question and answers on the g23 they said you could lower the speed to almost 20 and still have that perfect wake, whats your opinion or take ?

Yes, the increase in speed is due to increase in weight and rope length. My girlfriend can run full factory ballast at 21-22 mph. We drove it with no ballast last night, and were down at about 18mph...the wake actually looked pretty decent for beginners. It had a nice shape and looked to be bigger than anything else I've ever seen with no ballast.


The props finally arrived today, so I'll be testing them over the next few days and will post up the results.

[robertsmcfarland]

Good, I will be interested in the your results and opinions, thanks

[ironj32]

A little bit of an update.

I don't think I mentioned this in the previous post, but the max speed with an empty boat and the stock prop (2313) was 38 mph @ 5400/5500 rpm...obviously you would not want to run it at this for more than a few seconds. I typically like to keep it to no more than about 28 mph.

I put on the 2315 last night (same as stock prop, but less cup). Riding at 24-25 mph, the rpms were right around 4400-4500 (an increase of about 200-300 rpms over stock). We kept the ballast the same as usual.

The whole shot seemed to be a little bit better (not huge difference, but maybe it'll handle more weight), but where I noticed the biggest difference was in the tight turns. It almost seemed as if the boat down was down shifting with this prop. RPM's would jump to about 5000 and it would hold speed just fine (like a 230). Only one time of the entire night did the boat stay at lower rpms in a turn and act like the stock prop (rpms drop to about 3900 and then takes a few seconds to get back up to riding speed).

Unfortunately the big orange thing in the sky was covered up from storms moving in, so we were pretty rushed and I didn't focus too much on the performance and #'s of various speeds / weights. I'll try to get a little better info next time out. I'll probably give one more day to the 2315, and then switch it to the 5 blade to see how that does.

[vision]

Thanks Ironj32, this is quite helpful. I am hoping the 5 blade will maintain the whole shot but knock down the RPMs by 200 at 22mph.

This maybe my unfamiliarity with GPS based speed control, but the amount of engine RPM surging to maintain speed was much greater than I have experienced with my other boats. The speed control was excellent, varying less than 0.2 mph. But the engine surging was quite striking. Perhaps this will also change with the 5 blade prop.

[ironj32]

I'm glad it's helping!

As an FYI, I believe you can change the sensitivity on your cruise control, so that it doesn't surge so much. I'm guessing that this will let it get a little further away from the target speed, but might give you some more desirable performance.