2018+ XStar prop thread.

[maniacmikes]

I thought I would check back in on this thread and try to give a little update with some data for anyone interested.

I have the 6000 GDI in my '18 Xstar. Stock prop is an 18x16. Surf RPM's were about 3,700-3,800. When I cruise, I like to keep RPM at 4,000 - so stock prop cruising speed was 24.5ish. Stock prop had zero issues pulling, heavily loaded, full ballast + 400 pounds lead for wakeboarding with single tab auto launch and it still ripped out of the hole without hesitation. with no ballast the thing accelerated like a Ferrari.

I didn't get great data with stock prop - as you know, fuel mileage is dependent on how you use the boat, so I like to get a mix of activities over time, but I really didn't. Stock prop was using between 7.5 and 9gph.

I switched to a new Acme 3289 prop. Found the best deal at Nettle props. It is an 18x17.5.
Surf RPM's went down to 3,300-3,400. Cruising speed went up to 29.5mph. Obviously it is much quieter at lower RPMs. Fuel usage went to between 5.2 and 7gph.

There is very noticeable difference in pull coming out of the hole. It's only an issue with stock ballast full +400 lead and 3+ people in the boat: it had trouble getting on plane with single tab auto launch. I don't ever use that much ballast for wakeboarding, so it is not an issue for me - but be aware.

With just stock ballast full except rear at 75%, 400# lead and triple tab auto launch it got on plane in a reasonable amount of time..but I felt like it was about max without a really long time to get on plane.

I am at 2100 ft elevation. Lead is 100# in bow, 100# under coffin seat, and 100# in each rear locker.

[Dan2060]

What is the regular altitude stock prop size and pitch?

[Dan2060]

Sorry posted on another thread because I couldn't find this one. I used a OJ 18x17 prop this weekend at 4000ft with a 7.4 engine, crew of 8. Came off the 18x16. Funny thing is side by side can't really tell a difference. In the water, the engine noise is more quiet, uses less gas, gets out of the hole with no issue. For instance, surfing went down to 3200-3300 RPM. Approx a 300 rpm difference. Wonder if i could go a little more. Engine did not seem to lug.

[FourFourty]

Probably 75% surf and 25% wake.

And wakeboarding EASILY burns more fuel. I don’t know who said surfing burns more, but I always burn more fuel wakeboarding.

[chieb]

My understanding from comments on TT is obvious that lower engine rpm = lower fuel usage but I am guessing increased pitch leads to less slippage too (of course diameter makes most difference) but pitch must help slippage. Correct me if I am wrong to think this.

[Dan2060]

So what I'm hearing is that you increase pitch ans therefore have to increase throttle, which increases firm consumption

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[Dan2060]

I’ve never had consumption go up when switching to a higher pitch prop. It has only gone down A LOT. Usually 30ish percent. But I never went excessive on the change either. I’m guessing if the engine was really lugging, it might not have gone down.

I didn’t have a ton of time on the Star with the stock prop, but I have it back on now for “special olympics” (long story) week, and needing to load up excessively for wakeboarding. I’ll probably switch back next week, but will let you know what my consumption is like. I was averaging about 7gph on the 18x17.5.

Is that 7gph more surfing or wakeboarding? My understanding is that surfing uses a lot more gas because you are pushing through water and never really planed out?

[FourFourty]

440, Sounds like we are counting on you! Bring us the real world data, not the fake news

I’ve never had consumption go up when switching to a higher pitch prop. It has only gone down A LOT. Usually 30ish percent. But I never went excessive on the change either. I’m guessing if the engine was really lugging, it might not have gone down.

I didn’t have a ton of time on the Star with the stock prop, but I have it back on now for “special olympics” (long story) week, and needing to load up excessively for wakeboarding. I’ll probably switch back next week, but will let you know what my consumption is like. I was averaging about 7gph on the 18x17.5.

[Dan2060]

440, Sounds like we are counting on you! Bring us the real world data, not the fake news

[chieb]

Me too, hard to know which one to order.

[lashburn1]

Guys,
Recall I'm considering going from a 18x16 to 18x17 prop. The theory was that lowering the RPM would decrease fuel consumption. However, I emailed an online prop retailer and they suggested that if I make this change my fuel consumption may actually go up while surfing. Thoughts? Engine having to "work harder"?

this is my theory too, based on the same investigation.

However , 440, has done a good bit of his of testing and Fuel tracking, hes had some decent results.
Makes me want to try another prop or change pitch a bit in my Spare if possible.

[Dan2060]

Guys,
Recall I'm considering going from a 18x16 to 18x17 prop. The theory was that lowering the RPM would decrease fuel consumption. However, I emailed an online prop retailer and they suggested that if I make this change my fuel consumption may actually go up while surfing. Thoughts? Engine having to "work harder"?

[FourFourty]

440 are you happy with the 18x17.5? Should I assume that is as aggressive as we could go on xStar with 6.2 I’d like to drop surf rpms a hair more then you are seeing if possible. Since the 3289 doesn’t show up on ACME website, I am wondering if there are others like 18x17.75 or 18x18 that i should try.

No lack of power for me, had a full 16 people on the boat on the weekend.

I welcome your thoughts. Thanks.

Umm........ I don't know. If you only surf, you'd probably be fine. I definitely wouldn't want to go with more pitch on my boat. Wakeboarding with my extra bags under my coffin seats has proved to be a little bit of a struggle with more than 2 people in the boat. It gets there..... but its slow.

Because of the added bags in the middle, and the gen2 bags, I probably need more bow weight..... But its just got such a great lip on it right now!

Probably going to throw 200 lead in the bow, when we wake tomorrow AM. Maybe I can tell you what I think after that.

I guess if you were only going to wakeboard with low ballast, youd be all good.....

I'm looking at the same thing. I have the 7000 and am at 4000 feet. Considering going from oj 18x16 to the 18x17. Hate to spend that kind of money for 200 or 300 rpm and it doesn't save on fuel. The new star with this big engine sure gets thirsty.



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Not sure how it would work out at 4k feet, but that 7000 is an animal. I wouldn't be surprised if Eric let you try out that 18x17 and return it/swap it, if you didn't like it.

One thing is for sure, he will make sure you are happy with the prop you end up with.....

[Dan2060]

Figured I'd start a thread for those interested in changing from the stock prop size on the XStar.

I didn't spend as much time, as I should have, collecting data on my swap. I have a few data points though, and I am happy with the switch.

Stock prop with the 6.2 was an 18x16 OJ. I switched to a 18x17.5 (#3289) ACME prop. This is what I observed-

- Top speed was 35 on the stock prop, it is 41 on the #3289.
- Surf rpm was 3350 on the stock prop at 11.0. Its 3100rpm on the #3289
- No problem getting to wakeboard speed with stock ballast full plus 1100 bag on center floor. I'd say (educated guess), that it would handle stock+ 2-3k of ballast and people, before you'd need to drop back down in prop pitch. Who knows though, autolaunch is a wonderful feature, and I was only using single tab....
- I didn't get any GPH data, but I can tell you that a couple hundred rpm drop at surf speeds will typically reduce consumption dramatically. I did a long term measurement on my G, on a similar prop change. The new prop dropped surf rpm from 3300 down to 3000, and that dropped fuel consumption from 9gph down to 6.5gph (both measured over an entire season and 150ish hours each).

In past experience, I had seen cleaner surf waves on several different boats with an ACME prop (no idea why). I saw no change on this boat at all. I also surfed both sides before and after the switch. No change, except that the boat is a little quieter on the ACME because of the increased pitch, and lower RPM.

I'd have no issue with trying an equivalent prop from OJ on this boat...... And Eric is awesome to work with, if any of you want to try a different prop, and haven't worked with him in the past.

I should have GPH data on this new prop before too long. This time of year is a good time to get an accurate reading. The boat only goes out to tow this time of year.

I'm looking at the same thing. I have the 7000 and am at 4000 feet. Considering going from oj 18x16 to the 18x17. Hate to spend that kind of money for 200 or 300 rpm and it doesn't save on fuel. The new star with this big engine sure gets thirsty.



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[chieb]

440 are you happy with the 18x17.5? Should I assume that is as aggressive as we could go on xStar with 6.2 I’d like to drop surf rpms a hair more then you are seeing if possible. Since the 3289 doesn’t show up on ACME website, I am wondering if there are others like 18x17.75 or 18x18 that i should try.

No lack of power for me, had a full 16 people on the boat on the weekend.

I welcome your thoughts. Thanks.