XS 550 Opinions

[MileHiGuy]

I know this engine has not been out too long but what is the general opinion of this motor in the long term working as hard as they have to make the big G boat's go? Are there any 230 (or G23's) out there with some hours? I don't think the supercharged LSA has a very good reputation for reliability but thats not a PCM.

At our altitude, the 450 is not a great option. A high altitude dealer (6500') did some testing from 0 to 23.5 mph
A 450 with stock ballast, stock prop and 3 people was over a minute
They did some prop swaps and got it down to 24 seconds (sorry I don't have the size, pitch and cup info)
A 550 with ballast and similar people was around 11 seconds (4.7 empty). The boat topped out at 40.7 MPH at 5400 rpm.

Unfortunately the longer plane times does not work well with my shorter lake that I spend much of the summer on.

Think this motor is good for the long haul or will people not want to touch a 500 hrs boat with a 10' pole? I like to keep my boats a long time and I am nervous about this one with it costing SO much.

Opinions please!

[AllianceBJJ]

You are right, engine and PCM combo not a long lived history.....You are not going to find long term experience numbers on this engine option. Good luck on figuring out your few month long season at altitude with the other few people up there...you guys are just the minority that is not well servesd..

[MileHiGuy]

Our seasons are not that short but our air is thin it does not pay to be under powered. This may be a case where the Ilmor 7.4 has the advantage but the G is one sweet boat!

[AllianceBJJ]

Have you tested the 7.4? Not sure you are going to find it as an advantage or as much as you may think. I wasn't that terribly impressed with it vs. the 550.......

[MileHiGuy]

I have no doubt that the XS550 runs awesome. I just hope it doesn't need frequent rebuilds...

[AllianceBJJ]

I have no doubt that the XS550 runs awesome. I just hope it doesn't need frequent rebuilds...

So have you tested it? What advantages are you expecting to be there in the 7.4?

Is the 7.4 a proven marine engine that won't require "frequent rebuilds"? What is your definition of "frequent"?

[Miljack]

The 7.4 is a LS based engine, as is the 550hp/supercharged version of the PCM and Indmar engine. Because the 550 is supercharged, the boosted engine at your altitude will not be affected as badly as a normally aspirated engine, no matter the displacement.
Given the modest boost levels of this setup, the engine should be reliable. You would probably be best served to run good fuel in these engines...

[MileHiGuy]

So have you tested it? What advantages are you expecting to be there in the 7.4?

Is the 7.4 a proven marine engine that won't require "frequent rebuilds"? What is your definition of "frequent"?

Good point... The 7.4 is un-tested as well... Can you tell that the local MC dealer is getting in my head?

I think Miljack is right that as long as fuel quality stays good, the forced induction should not create a problem.

Under a 1000 hours would be frequent in my book.

[Miljack]

The LS engine platform is a very robust engine and can make ALOT of power with the stock bottom end and handle it no problem. Even though the 7.4 is in the competition, ILMOR is a premier engine builder with a ton of racing experience to help them manage the demands thrown at a marine application. They marinized a Viper engine for use in off shore boats with very good results. They also engineered and built an outdrive for the same application.
What altitude will you be running the boat? The supercharged 550 will be less affected than the 7.4 at your Denver altitude and higher.

[MileHiGuy]

Miljack, we run 80% of the time at 5500'. Once a year we venture up to a mountain lake at 7700'. In the past, I could not use my ballast with a lot of people but for just one trip, it was not too big of a deal.

It sounds like the XS runs stellar and have zero concerns that the power is adequate. I was hoping to get some feedback on motor for service intervals, fuel usage, technology advances that will make this motor last as long as the boat.

As an example, in our group we have a supercharged Sea Doo that come to find out later needs to have seals and bearings replaced on the supercharger every 200 hours or we run the risk of a catastrophic failure. That and the thing uses fuel two fold to what we are used to.

Sorry to compare a Bombardier to a PCM, but you never know what to expect. Does anybody know if this motor is a closed loop with O2 sensor? I know they recommend Premium but fearful that i may not get quality fuel when we venture down to Lake Powell and am stuck with using toy tank fuel from the 600 gallon toy-tank fuel. I am wondering how well this motor responds to lesser quality fuel? My wife's Ecoboost Ford will run better with premium but will be safe with regular through knock sensors, O2 sensors and programming. How does PCM compare?

[Miljack]

Well, digging around a bit, one can find some complaints about the CTSV's "rattle" from the blower drive, which apparently GM was aware of, but have now addressed with a solid coupler inside the snout of the blower drive. The early versions used a torsion spring to help quiet the blower feedback noise from the drive.

Given the CR specs of 9.1:1, this engine NEEDS premium fuel! I did notice on the pics from PCM's site that the port side exhaust header has an 02 sensor (or what looks exactly like one, where it should be) in the collector area. With that CR, and 9psi of boost, this engine will require good fuel and spark management to keep detonation at bay...
I'm sure this beast engine, in that G23 will use some FUEL! Do a search on Iron32 (I think that's his user name) and he documented how much fuel his G with stock+ ballast uses for a run...(and that's from his 450hp version)

[perry386]

Miljack, we run 80% of the time at 5500'. Once a year we venture up to a mountain lake at 7700'. In the past, I could not use my ballast with a lot of people but for just one trip, it was not too big of a deal.

It sounds like the XS runs stellar and have zero concerns that the power is adequate. I was hoping to get some feedback on motor for service intervals, fuel usage, technology advances that will make this motor last as long as the boat.

As an example, in our group we have a supercharged Sea Doo that come to find out later needs to have seals and bearings replaced on the supercharger every 200 hours or we run the risk of a catastrophic failure. That and the thing uses fuel two fold to what we are used to.

Sorry to compare a Bombardier to a PCM, but you never know what to expect. Does anybody know if this motor is a closed loop with O2 sensor? I know they recommend Premium but fearful that i may not get quality fuel when we venture down to Lake Powell and am stuck with using toy tank fuel from the 600 gallon toy-tank fuel. I am wondering how well this motor responds to lesser quality fuel? My wife's Ecoboost Ford will run better with premium but will be safe with regular through knock sensors, O2 sensors and programming. How does PCM compare?

The nautique site said that the XS550 requires premium fuel but all of their engines are made with a tolerance to 10% ethanol so you should be ok. However, the XS550 is actually a Cadillac engine and my wife's CTS got really messed up from regular fuel.

[MileHiGuy]

The nautique site said that the XS550 requires premium fuel but all of their engines are made with a tolerance to 10% ethanol so you should be ok. However, the XS550 is actually a Cadillac engine and my wife's CTS got really messed up from regular fuel.

Did detonation make its way past knock sensor safe guards?

[Zach@n3]

The 550 has two o2 sensors(as well as any pcm with CAT's). I would imagine running over 9.0 to 1 and 9 psi from a blower then being loaded up to the gills and WOT that even knock sensors might not be fast enough prevent failure if premium fuel isn't used. You can usually skimp all day long on N/A motors that require premium pump fuel but the added cylinder pressure and temperature from some type of FI takes that out the window. I would imagine PCM would just laugh at you if they had a warranty claim with 87 fuel in the tank. Oh fyi octane booster won't help your cause a bit. In the turbo car world they say if you hear detonation than it's to late. I wouldn't even skimp and run lesser fuel in a 450 just because of the greater load in a marine application as opposed to auto.

[migs]

does anyone else find it hilarious that someone with a G23 with the XS550 even thinks about using Reg vs Premium?