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Old    Jay (ironj32)      Join Date: Jan 2007       09-09-2010, 4:39 AM Reply   
Just wondering how horrible the gas consumption of the 8.1L is? Maybe some CIE guys can help me out?

The MCX (with a big wake prop) just doesn't seem to be enough for how much weight I would like to run.
Old    Tony (Tloud)      Join Date: Aug 2010       09-09-2010, 9:08 AM Reply   
Hey Jay check out the Parks Bonifay X-Star thread... gas consumption is mentioned a little

Quote:
Chattwake (chattwake) Join Date: Jan 2010 Today, 6:01 AM Reply Quick Reply
I heard about a guy demoing a new LSV with that same motor in this summer. Supposedly, they went through 70 gallons of gas in one day just driving around and pulling about 10 sets
http://www.wakeworld.com/forum/showthread.php?t=783426
Old    Brett Yates (polarbill)      Join Date: Jun 2003       09-09-2010, 10:09 AM Reply   
If you are weighting it super heavy I would think the 8.1 would be ideal and wouldn't be any worse than a propped down MCX. With the torque that 8.1 delivers it should be able to spin a bigger prop and run at a much lower RPM than the MCX with similar weight. I seem to remember older posts that had people saying they were getting better fuel economy with the big block.
Old    Jay (ironj32)      Join Date: Jan 2007       09-09-2010, 10:34 AM Reply   
Quote:
Originally Posted by polarbill View Post
If you are weighting it super heavy I would think the 8.1 would be ideal and wouldn't be any worse than a propped down MCX. With the torque that 8.1 delivers it should be able to spin a bigger prop and run at a much lower RPM than the MCX with similar weight. I seem to remember older posts that had people saying they were getting better fuel economy with the big block.

That's what I was thinking. The MCX seems to work very hard when running 5000+ lbs. I would imagine that an 8.1L running 5000-6000 lbs would be fairly close in regards to fuel consumption, just for the simple fact that it isn't working nearly as hard.
Old    M-Dizzle (liquidmx)      Join Date: Jun 2005       09-09-2010, 12:34 PM Reply   
For some reason I want to say MC was having issues with either oiling or cooling the 8.1 setup. Not 100% positive...maybe someone else will chime in.
Old    Brett Yates (polarbill)      Join Date: Jun 2003       09-09-2010, 12:37 PM Reply   
Quote:
Originally Posted by liquidmx View Post
For some reason I want to say MC was having issues with either oiling or cooling the 8.1 setup. Not 100% positive...maybe someone else will chime in.
I know that the 8.1's have been known to burn oil so you have to stay on top of checking the oil and adding oil.
Old    Dan (hco)      Join Date: Jun 2006       09-09-2010, 12:55 PM Reply   
M-dizzle- the 8.1's are known to overheat moreso than other engines.
Old    MD (monroeyd)      Join Date: Jun 2006       09-09-2010, 8:18 PM Reply   
I have the 8.1 in a Supra 24, it's gets about 8 gph pulling riders. That's with about 3k in sacs plus crew. Heat stays pretty consistent. Doesn't really burn oil either, but the engine only has 170 hrs. A buddy of mine has the same motor in in a Malibu LSV and it runs pretty similar with 400+ hrs.
Old    MD (monroeyd)      Join Date: Jun 2006       09-09-2010, 8:20 PM Reply   
He uses the wedge too.
Old    mojo            09-09-2010, 9:59 PM Reply   
get it if you can, but there's no need for an 8.1L engine with the right prop and proper weight distribution. that is insanely too big to have in a boat for these purposes. think it over. just ain't right.
Old    Tallredrider (talltigeguy)      Join Date: Sep 2003       09-09-2010, 10:13 PM Reply   
I have never heard of overheating being much of an issue. I have heard the oil burning rumor a few times. Mine uses a bit of oil, but never enough to have to add oil before I get to 50 hours.

The torque is incredible. I have an X45 with the 8.1 and run about 2,000 pounds plus people, so I don't go near as heavy as you do, but it jumps up the same as if it were empty. The RPM's are a little higher, but the engine doesn't seem to notice the extra weight.
Old    Jay (ironj32)      Join Date: Jan 2007       09-10-2010, 4:27 AM Reply   
Thanks for all the info guys.

Mojo - I've been thinking it over for a long while now, and that's why I'm asking people about the 8.1L (also looking at the LY6). With the maximum ballast setup of what an MCX will push (with the ACME 1235), the wake is just is not what I prefer if I'm going to be spending $50-$70k on it. With the full PWT ballast, plus another 800 (give or take a few) in the bow, it just struggles dearly to get up, so we end up draining some out of the rear tanks. Don't get me wrong the wake is still VERY GOOD, and I definitely will ride it any day of the week. But again, if I'm spending that much $$$ on a boat, I want a bit more.
Old    Joe Sellhausen (joesell)      Join Date: Apr 2001       09-10-2010, 6:33 AM Reply   
I have the 8.1 in my Epic. It does use more gas when it's unweighted, but it doesn't even notice when it's fully weighted. I had 5200#(give or take), and 5 people in there a few weeks ago, and it jumped right up like it was empty. I don't think I'll ever go back to a smaller engine. It's just so nice to not have to worry about it.

I also heard the oil rumor. I don't think it's true, at least not that I've seen.
Old    Adam R (wakecumberland)      Join Date: Oct 2007       09-10-2010, 7:54 AM Reply   
I have the 8.1 in my truck and they do burn some oil in that application but mainly because GM runs a 195* thermosat. I'm running Mobil 1 and a 180* stat and no more burning oil. Im sure the stat on the marinized 8.1 is 160* or so. I doubt it burns oil.
Old    Brett Yates (polarbill)      Join Date: Jun 2003       09-10-2010, 8:30 AM Reply   
Quote:
Originally Posted by ironj32 View Post
Thanks for all the info guys.

Mojo - I've been thinking it over for a long while now, and that's why I'm asking people about the 8.1L (also looking at the LY6). With the maximum ballast setup of what an MCX will push (with the ACME 1235), the wake is just is not what I prefer if I'm going to be spending $50-$70k on it. With the full PWT ballast, plus another 800 (give or take a few) in the bow, it just struggles dearly to get up, so we end up draining some out of the rear tanks. Don't get me wrong the wake is still VERY GOOD, and I definitely will ride it any day of the week. But again, if I'm spending that much $$$ on a boat, I want a bit more.
ironj, I don't think Mojo understands that you want to run 4-5k in your boat and that the MCX(even propped down) isn't going to cut it. A normal 22 foot boat doesn't need more than 350hp. A 22' boat that weighs 4k dry and has another 5k plus added to it does. 9-10k is probably the weight of most 28 foot cruisers. Not to mention it is probably burning more fuel and putting added stress on the motor which is only going to shorten it's life. Would spinning everything at a higher RPM also shorten the life of the transmission?

Generally speaking I wouldn't waste my money on the bigger engine if it didn't need it because you won't get hardly any of the extra price in resale. In your situation though I say get a bigger engine.

The CIE crew should be able to tell you the difference between the LY6 and the big block as they have had both in an Xstar that they weight heavily.

Your other option is pull the MCX out, sell it and drop in a cummins or Yanmar diesel. Then you would have no problem pushing that much weight and your economy would be a lot better. You could probably even buy farmer's gas that doesn't have the highway/street tax.

Last edited by polarbill; 09-10-2010 at 8:37 AM.
Old    Matt Anderson (xaggie)      Join Date: Nov 2002       09-10-2010, 9:15 AM Reply   
These links should keep you busy well into 2011. Having owned the 8.1 in my last 3 MasterCraft's this is my 2c.

Over two years of pulling the Southern Region Collegiate Qualifier at a private lake (SETX) I can give first hand experience about fuel consumption between the L18 and the LY6 in a pure "tournament setting". Over the course of roughly 15 hours (qualifiers and finals) with stock ballast + 3000 lbs and 5-8 people in the boat the LY6 (170gal) used 35 more gallons of gas than the L18 (135gal) did over the weekend. Combined with the fact the L18 was able to use common 87 octane stored in barrels on site while I had to pull the LY6 boat out after qualifiers to get premium in town.

Is this your typical boating experience? No. What it does illustrate in vivid clarity is with a more powerful engine you spend a much shorter time at or near WOT to achieve the same desired wake performance. Am I saying an 8.1L engine is going to be more fuel efficient than a somewhat more modern 6L? Of course not, but it was not designed to be.

I spend 80% of my recreational time on the water with 6 or more people in the boat. I want to know with all their assorted lady things, 300lbs of stereo gear, and whatever else may be in the boat I can fill the ballast and pull a big guy out of the water then turn around and run 40+ mph home if I so desired. As I said before the only reason NOT to have it in your boat is the initial cost, any other engine in the X-Star or above is a compromise.

http://www.mastercraft.com/teamtalk/...ad.php?t=36146
http://www.mastercraft.com/teamtalk/...ad.php?t=19553
http://www.mastercraft.com/teamtalk/...ad.php?t=20371
http://www.mastercraft.com/teamtalk/...ad.php?t=29892
Old    Jay (ironj32)      Join Date: Jan 2007       09-10-2010, 9:50 AM Reply   
Thanks Matt! Very helpful insight!
Old    Tallredrider (talltigeguy)      Join Date: Sep 2003       09-10-2010, 9:58 AM Reply   
Matt,

Do you know what prop you had on there? I have a 14.75 X 17.5 and my RPM's are a bit high, and the engine does not seem to groan at all getting up on plane, so I think I can use more pitch, but was curious to hear what others are running.

Wakeboarding in the X45 at 24+ MPH with 2K total ballast the RPM's are around 4100.
Old    Matt Anderson (xaggie)      Join Date: Nov 2002       09-10-2010, 11:45 AM Reply   
I'm currently running a 14.5 X 21 Stainless OJ. It's the best all around setup I have found. It's not as sharp out of the hole as the prop you mentioned, but is much better all around I feel. I pulled the above mentioned tournament with that prop and it worked fine. I'll get exact RPM's at wake speed this weekend, but it runs 52 on GPS @ 5,100-5200 RPM's. Thus I'm running out of power before prop on the top end.
Old    Tallredrider (talltigeguy)      Join Date: Sep 2003       09-10-2010, 12:21 PM Reply   
And I guess I should mention my top speed unballasted is 42MPH and I run into the rev limiter at 5400 RPM. So it could go faster, but the prop is spinning as fast as the engine will let it. I am at 2700 feet above sea level. I could care less about top end, but I do see that as a symptom of too low pitch. I got this size and pitch prop at the recommendation of both the OJ and Acme guys, so I am a little reluctant to do something different...but my RPM's are a bit too high from what I understand.
Old    C.I.E..... Evan (guido)      Join Date: Jul 2002       09-10-2010, 1:21 PM Reply   
Hmmmm... Matt, very interesting. We've never done any actual consumption measurements.

Jay, what's up man... You'll love having a X-star. I'm so spoiled by that boat. I'm not sure I could ever go back to a smaller boat.

I wont really get into what type of ballast we run. The boat is basically maxed out. Between 4 batteries, huge stereo, lead, water, etc.... the wake is always really awesome. I joke that wakeboarding is a different sport behind that boat.

LY6 is the minimum motor. They're bomb proof and will haul a nice load around. I mean, we've done everything we could to blow one up and I'm pretty sure it's impossible. Their only weakness is that they blow at high altitude. Anything over sea level and we have to start dropping weight. The other downer is that with the ACME prop we're running now we turn 4,200 rpm's at ride speed. 30 MPH is about the top speed of the boat.

The L18 was the big dog. You could load the boat till it basically sank and still get it on plane. Downside?? Well, I'm not sure about the other guys running them, but we went through 5 motors in 3 years. I think the best we did was 200 hrs. They seem to really like it if you break them in really gingerly. It's a big block that runs at 3,800 rpm's all day. That just can't be good. We tried bigger props, but it didn't have quite the punch it needed to turn lower rpm's. I think it's a tuning thing. That motor should be tuned for torque, but it's kind of high strung for a big block. And yes, they do burn oil. About a quart a week when you run them hard. Not that big of a deal because the motor held like 9 or 10 qts. Just make sure it's topped up once a week.

Before anyone comments, please keep in mind we run our boat maxed out, heavy. It's our choice. I'm sure you could unload and get much better fuel economy and longevity.

That said.... Economy. Umm, or lack of. My closest estimate would be 12 to 15-ish gallons per hour. Assume that every time someone touches the water it'll be 5 gallons. That's been pretty standard between our 8.1 and the 6.0. Because of the lame economy just driving around we stay away from cruising. We try to ride from the time the boat hits the water. I'm sure it'd be much better if you unloaded, but we leave a few thousand pounds of lead in the boat and generally leave the rear sacks (fly high) filled. No, we don't have to trailer.... We're only 200 yards from where we store it to the water.

Let me know if you have more specific questions. Like I said, I LOVE that boat. It's big, comfortable, and the wake is mackin'.
Old    C.I.E..... Evan (guido)      Join Date: Jul 2002       09-10-2010, 1:25 PM Reply   
Oh, pretty sure we're running a X45 prop right now. Same as Talltigeguy. I think it's a 14.75X17.5
Old    Bruizza (bruizza)      Join Date: May 2009       09-10-2010, 1:39 PM Reply   
Damn it sounds like you CIE boys are running major major weight!!!
Old    C.I.E..... Evan (guido)      Join Date: Jul 2002       09-10-2010, 2:59 PM Reply   
I've heard of people running more in their LSV's and 24' Supra's, but the X-star has a tendency to like a ton of rear weight, so it really drags a$$. I'm sure if you balanced the weight out it would be more economical, but we've tried running more front weight and the wake starts to go away in a hurry. We run a lot of lead weight, too so our estimates are less speculation based on what someone claims goes in a water bag and more backed up by a scale.
Old    Jay (ironj32)      Join Date: Jan 2007       09-10-2010, 4:43 PM Reply   
Thanks for the reply Evan,
It sounds like you guys use your XStar the exact same way that I do (right now I have a 2000 XStar). I do ride an '06 with the MCX quite-a-bit, but as I said, I think that the wake can get much bigger....sounds like the LY6 will accomplish what I need.
Thanks again for all the info everyone!
Old    Ron (ronskal)      Join Date: Jul 2006       09-10-2010, 5:10 PM Reply   
I would think the big block is preferred for all that ballast. I do remember posts from Travis Moye where he pulled the PWT with the MCX.
Old    C.I.E..... Evan (guido)      Join Date: Jul 2002       09-11-2010, 8:09 AM Reply   
Travis pulled this past year with a LY6 boat that had it's mufflers removed. I was suprised it got on plane in Reno, but even at elevation it got the job done.

Jay, I figured as much. You'll be happy with a LY6.
Old    Jeremy (wake77)      Join Date: Jan 2009       09-11-2010, 10:57 AM Reply   
^^I second that (that's what's in our Star {LY6}). Except for a faulty fuel pump, there have been zero issues.

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