PLEASE FOR THE LOVE OF GOD USE HIGH OCTANE IN YOUR NEW BOAT

[DW]

Per my previous comment, fuel type does hinge on who did the calibration. As for premium fuel requirements, only the 6.2 L87 has it as a requirement from GM, as it has an 11.5:1 compression ratio and the others are 11.0 or lower. The perception that 'new technology' needs premium, it is actually the opposite. The new technology allows better fuel targeting, more accurate timing, better combustion chamber burn hence actually lowering the octane requirement (per the same compression ratio). Hence, the 5.3 DI and others at 11.0:1 compression ratio can run on regular where 10:1 used to be a break point. Again, to my previous comment, the marine calibrations are actually very conservative as is the fuel octane recommendation for many good reasons. When it comes to slalom use, as Eric noted, the engines are not running anywhere near WOT, it is all about the impact on the transient characteristics of the fuel calibration.

 

With this, perhaps it is time to introduce the next 'innovation' to slalom, an octane setting in ZO so now we can choose between 87, 89, 91, A, B, C, 1, 2, 3... :D

[skierjp]

In my 6.2 supercharged Corvette ZO6 I run nothing less then 93. But in my 2021 6.2 Ski Nautique it doesn’t seem to matter. I do run 93 before and during tournaments but I’ll bet there is no way tournament sites are buying 93 for gas during the event.

[lpskier]

@AdamCord That just about sums it up.

[The_MS]

I’m leaning towards what @Jody_Seal says due to his vast experience and from my experience using my 200 with 6.2. The rest is all hearsay

[AdamCord]

@DW that’s actually a great idea. These DI engines may have enough power on 87, they just are not mapped with the ZO for it to work well.

[UWSkier]

@DW you forgot the + settings...

 

Actually, maybe you should just use + if you're running 87.

 

I know the idea is for ZO to be "simple" but PP with Zbox has settings to increase and decrease the responsiveness.

 

Down the rat-hole we go.

 

I love new tech as much as the next guy, but my PFI engine runs exactly the same on 87 as 93 and has all the power I could ever need. Exact same WOT RPM with both fuels. Same GPH burn while skiing. Same spark advance.

[6balls]

Minutia beyond my skill level. Far bigger power changes in my high horsepower boats and cars based on temperature/humidity and thus density altitude than octane.

[MarcusBrown]

[Drago]

C'mon CC, break the chains off that wallet of yours (with the barber too) ?

[AdamCord]

@MarcusBrown why even bother wasting money on that fancy ski boat, the flow can be found behind anything

 

 

[Bruce_Butterfield]

 

[MarcusBrown]

@AdamCord you are pretty much spot on!

 

Truth be told, 99.9% of competitive skiers (myself included, along with almost all of the skiers on BOS) have more fundamental issues than the octane of the fuel they put in their boats.

 

Near as I can tell, springing for more Octane at the pump is about the lowest ROI move most skiers could make when it comes to breaking PB’s.

[keithh2oskier]

@MarcusBrown I take a offense to shitting on Arco 87.

[AdamCord]

@MarcusBrown as I stayed previously in this thread, the LOUD title was meant to get the attention of tournament organizers, especially for high level tournaments. I couldn’t care less what someone does with their own boat on their own lake.

 

That being said…the DI engines in these boats were all tuned to run on 93, and they all ski better on 93. So if you’ve already gone as far as buying one of these boats, why not give it the gas it was designed for?

 

I gotta say, I certainly feel a lot closer to the flow point when I’m skiing wide and early with less effort than I do when I’m fighting to make it to buoy width with an underpowered boat.

[MarcusBrown]

@AdamCord I would agree with you about the FlowPoint....the passes that feel effortless, like you are in a perfect dance with the boat, are often a requirement for anyone actually coming close to entering the flow state.

 

I just don't agree with a call for "All Hands On Deck" centered around the supposition that octane is whats limiting skiers from reaching better scores...

[Horton]

@MarcusBrown Do ZO settings matter? Does the right Prop matter? Do 5 thousands of an inch matter on your fin?

 

With the DI motors Octane matters. With none DI motors does it matter? - NO.

[aupatking]

With older 5.7 motors, which is more important, non-ethanol or high octane? Around here, finding anything non-ethanol higher than 89 is rare, if non-existent. I go with non-ethanol in my own boat (5.7) over higher octane with ethanol. Maybe if I was still running a new boat I’d feel differently, but I’d also add a remote fuel-water separator to the setup

[dvskier]

@aupatking Have you tried using pure-gas.org to locate non ethanol fuel? It’s usually up to date.

[Jody_Seal]

This is some funny sheet!

AIT???

There's white ones . There's black ones...

Different map for each!!

Need x50 install to optimize the burn...

All tournament organizers need to know which AIT they are running.!!!?

How many of you have done cup consistency on a palate of ACME propellers??? I can tell all that prop A is not going to be consistent cup wise with prop B,C,D ect! Close but thousands of an inch different.

Bottom hook of the boat again not consistent from boat to boat. Rudder torque, bottom prerelease, hull weight, hull weight and CG all affect a boats performance and is inconsistent from same model boats coming out of three different molds

Wait! Fuel grade is going to cure all! LOL.

Your analing me!! Is that a word?

 

 

Going to ski today, had my BM and got a white AIT.... premium fuel , A2 on the ZO, sheet!° Even got that new fangled sure as sheet path!!! Going to be epic for sure!!

 

Dude!!!

[chrislandy]

@Jody_Seal looking forward to the PB report later then

[ReallyGottaSki]

Just take out the blue power band and put in the red power band, everyone knows red is faster

[Hockdog]

Yep, the red spring is the f’shizzle.....

[MarcusBrown]

@Horton you made my point exactly....

 

My answer would be not really: ZO settings matter, insofar as its important to keep them consistent through time. Has anyone ever done a double-blind test to see if a skier could actually decipher whether they were being pulled by their favorite B2 setting, or if the driver suddenly had switched it to A1? I would guess that most skiers wouldn't be able to pass that test. If 5 thousands of an inch really mattered, my opinion is that there are more fundamental issues in technique. Propping can matter. Octane, it probably could make a negligible improvement on overall performance through time, given a large enough sample size....but I just haven't seen the data one way or the other and my gut tells me its mostly smoke and mirrors.

[jjackkrash]

I use 93 because that's how I roll; I want to make sure every ounce of HP I paid for is on tap and I am not all that price sensitive on the gas. But Marcus is most likely correct about double-blind testing. It is a real bitch reliably picking up on small differences out of a blind.

[Adam Caldwell]

Wow.

[brettmainer]

To elaborate on @adamhcaldwell’s post…

I think the consensus is that DI engines need the 91 or 93 octane gas, just like the owner’s manual says. 5.7 and 6L engines run fine on 87 octane…wait for it… just like the owner’s manual says. And CC and Marcus (to those of us who knew him as a teenager) need new barbers.

 

Since most tournaments have at least one if not all DI engines, TOC’s should provide 91 octane or better gas. Other than the cc’s hair, this shouldn’t be a controversial post.

[skibug]

Glad we got the 6.0 in our new MC, we can continue to use the cheap stuff and still ski at max performance, and sometimes really bad.

[slow]

It would be interesting to see the results of a blind test to see if elite slalom skiers could pick 87 or 93 though out the day with an engine that allows both but recommends 93 at a typical site(low elevation).

[ski6jones]

First world problems.

[slvrbulit]

@MarcusBrown that was good. Also I totally agree with you

[bigtex2011]

Octane is the least of my problems. I dont think the 6.2 in my boat even knows anyone is back there. I'm not drag racing it. just running up and down the lake at 34.2

[eleeski]

Interesting reads on the power from different octane fuel.

 

https://nasaspeed.news/tech/engine/octane-vs-horsepower-separating-fact-from-myth-in-the-debate-over-which-fuel-makes-more-power/

Their conclusion on the energy in fuel: "We found that the more expensive, higher fuel grades did not add more power. On the contrary, the engine lost 2 to 3 horsepower versus the more affordable 87 octane."

 

https://www.caranddriver.com/features/a28565486/honda-cr-v-vs-bmw-m5-ford-f-150-dodge-charger/

Their conclusion for direct injection engines: "If you buy fuel with an octane rating above the manufacturer's requirement, you're likely to feel it in your wallet more than the seat of your pants."

 

Standard temperature and pressure where engine power ratings get figured is defined as 60 degrees F, 29.92 barometric pressure, and dry air (zero humidity).

 

Engines lose about 3% of their power for every 1000 feet of altitude as the air gets thinner. Colorado at over 5000 feet will have the engine power reduced by over 15%. A lot of skiing happens at high altitude. So boat designers will certainly factor that in and provide enough excess horsepower to operate properly at altitude - as evidenced by the good results from high altitude skiers and sites.

 

Altitude reduces the tendency for an engine to knock. Octane rates the resistance to knocking. At altitude you need less octane to keep the engine from knocking. Or your computer will need less derating to prevent knocking from lower octane fuel.

 

Density altitude measures how different environmental conditions affect air density reported as an altitude equivalent.

https://www.weather.gov/epz/wxcalc_densityaltitude

 

At 3% per thousand feet of altitude loss in engine power, a 90f humid day in Florida will have a density altitude of over 2000 feet or 6% loss in power. A boat's performance has adequate power for the average Florida summer day – nobody's complaining there. Excess power!

 

The max power numbers (calculated at standard temperature and pressure) are higher with premium gas by a small margin. Real world conditions vary this maximum power. Waterskiing is typically done at hotter and higher situations. While the power is reduced by those conditions, so is the need for higher octane. So you can't add the 4% 87 octane loss to the 6% Florida heat loss. In Colorado, the faster burn of the lower octane fuel might actually improve the engine's power output. The owner's manual will specify the fuel that gives the highest numbers. If I'm doing a drag race on a cold winter day at my lake below sea level, I'll run 93 per the manual recommendation. But the same drag race in Colorado on a hot day will favor the 87 (I've experienced the benefits of lower octane on altitude performance in my airplane). That's why 87 is also approved in the manual. And if the manual approves 87 octane, it assuredly will not hurt the engine.

 

Athletes do look for any advantage they can find. On paper, losing 4% of a boat's power looks bad. In real life, that optimally warm summer day sees the engine lose more from the heat than that – while the engine octane requirements are less. In real life, a slalom skier will only require a fraction of the engine's maximum output (that was specified to meet jump requirements). If you aren't using C3+ with its intense and immediate power call, there will be even more excess power. The new DI motors are bigger and more powerful than the engines they replaced in the same hulls – more excess power. Its a stretch to believe that small changes in maximum engine power could have any effect on a slalom skier.

 

@Horton 's boat goes to a lot of tournaments (thank you John!). Since he apparently has bought in to the premium gas myth, his boat will cost the tournaments more (tournaments do burn a lot of gas). Add the IWWF fee, the Safesport class fee, the judges clinic fee and who knows what other surcharges will be created and I wonder if tournaments are really worth it?

 

Maybe I'm too much of a cheapskate. The price of premium is diluted by the $1 per gallon price increase that has happened. And gas is a fraction of the cost of the skis, the boat and the lake (even the taxes on those items!). Add the physical therapy and yoga sessions to keep me moving well enough to ski – waterskiing is an expensive activity. Hopefully I can stay affluent enough to keep skiing.

 

If using premium makes you happy and you can afford it, by all means use it! But don't bring me a fiver of premium for my boat.

 

Eric

 

[jjackkrash]

@eleeski wrote:

 

"Their conclusion for direct injection engines: 'If you buy fuel with an octane rating above the manufacturer's requirement, you're likely to feel it in your wallet more than the seat of your pants.'"

 

That suggests to me you want to comply with the recommendation, and the recommendation is at least 91 but 93 preferable for the 6.2L di. I have not seen anybody suggest running more than the recommendation (and I would not do so).

 

Also, again, your take on the energy/power for fuel by octane rating is not really relevant if the computer is derating the engine by 20% (or whatever the figure is) if you run 87. All those calcs are great unless the computer is throwing a monkey in your wrench. Post up what the derate is for the 6.2L engine done by the computer; if it tracks your calcs then you make good points.

 

[escmanaze]

I can't imagine spending the money I spend to be a skier and then cheaping out on my gas when the manual clearly states / recommends otherwise. Wow!!!

 

I can understand putting in lesser gas, if the good stuff is hard to find or is a really significant detour to get to. Here in Utah (4,500 feet) 88 ethanol free is very easy to find. But 91 ethanol free is very difficult to find. I get really picky and insist on 91 for my brand new snowmobiles, but I'm willing to just roll with 88 ethanol free for my 25 year old boat.

 

What I really really can't understand is actually physically bringing a keg of gas to give to the boat owner as payment for the tow. I would personally just prefer to sponsor a buddy a tow and do him a solid than to throw his "mystery liquid" in my beloved baby.

 

Different strokes for different folks I guess. Crazy how different we can be and still (hopefully) get along.

[eleeski]

@jjackkrash The power loss from 87octane in the direct injection engines tested by Car and Diver in the above article was around 4%.

 

The power loss from using the boat on a hot day in Colorado (or Chapala Mexico where world championships have been held) might approach 20%. Knocking is unlikely on 87 octane at that altitude so the computer should not derate the engine due to fuel octane.

 

@escmanaze The manual might recommend 93 but 87 is approved for use by the manual. No engine damage will occur from using 87 octane.

 

If "cheaping out" only affects maximum power by 4%, are you really willing to pay a 20% extra cost for 4% of an engine's power that you will never use. Especially when environmental variations are commonly a bigger factor (which we as skiers are commonly exposed to and deal with).

 

Gas is hard to get at my lake. I do appreciate delivered gas. If I'm worried about the quality, I filter it through a water separating filter before it goes in the boat.

 

Eric

[elr]

It really doesn’t matter what the fuel related power loss between different grades is. If the computer derates hp by 10% the 400 hp boat you practice behind becomes a 360 hp boat in a tournament e.g different. If you’re paying $100+ for a tournament set you should get as close as possible to the 400 hp practice boat the conditions allow.

[6balls]

@elr then on a hot, humid day do you bag it at a tournament b/c even with 93 you are getting short-changed on HP? Do you think 360 hp(down from 400) can't dominate you? It can dominate me.

 

Please understand this is not a personal shot at you, just continuing to play the argument and agreeing with @eleeski

 

Shoot...my bubble butt has 310 hp on PP...I ran 2.5@39 on ZO with a 400 hp boat I have no idea the octane or the weather that day...I think I just had a good day. Pretty sure it was a hot day, but I ran it the first round when it was 65 degrees--far different temp than the 3rd round that day when it was hot--no idea the octane put in the boats.

 

The point being atmospheric conditions the day of the tourney will overwhelm any octane issues in terms of motor performance...and we don't control the atmosphere.

 

For the best of the best who have near perfect technique--maybe octane is a factor. Many of us have bigger fish to fry in terms of getting more buoys.

 

 

[Adam Caldwell]

 

[escmanaze]

@eleeski

"If "cheaping out" only affects maximum power by 4%, are you really willing to pay a 20% extra cost for 4% of an engine's power"

 

Yes. For sure yes. Absolutely.

 

Gas probably totals 10% of what I spend on my waterskiing addiction each year. So a 20% price increase in gas makes my overall cost of skiing go up a whopping 2%. I literally promise I won't notice - and it's not cause I'm filthy rich or anything like that either.

[MillerTime38]

I really enjoy this thread, makes me miss waterskiing a lot less while living over in Japan. Just when I thought the sport couldn’t get more elitist now people are crying about what octane others use in their boats ?

[ReallyGottaSki]

Also consider even the brute lt1/ 6.2 is only capable of around 250 HP at 3600 rpm when wot. Lesser engines much less. All these engines are part throttle when skiing except for jumping, and run at higher vacuum part throttle, really only using maybe 130ish HP or less steady state. The delta is the available responsiveness to pulls.

[Jody_Seal]

with a given boat and a given propeller and a given gear ratio it takes X amount of horse power to pull a skier at x mph. This formula is the same whether the engine has 500 hp or 280 hp.

Commonly it only takes around 180 hp to run a skier at 36 mph through the slalom course. That available 400 plus horse power never comes into play.

So now we are talking throttle response in relationship with zero off. Again only about 50% of

Throttle is needed to maintain 36 mph through out the slalom course..

 

Do some of you really think you are using or needing all 450 hp available in slalom??

 

 

[ScottScott]

I think we need to look at who this recommendation is really aimed at, and adjust your usage accordingly. Should a record tournament, certainly an open level tournament go cheap by using a lower octane fuel in a DI engine.....NO!!! And probably high level skiers that ski in those type tournaments with DI engines should consider the recommendation for their own training. I think thats the main point here. For the average user, or even class C tournaments, is it a big deal?.....probably not. Hell, I disconnected the blower fan in my prostar....IN FLORIDA. I don't think I am going to see much difference in octane for my use at 22/28 off at 32mph, or even some of the better skier/friends that may ski behind my boat that get into 32/35off (of course I have the 5.7, so....this doesn't really apply to me anyway.)

[eleeski]

This explains everything! Open skiers at record tournaments are in an alternate reality where the rules of science don't apply. I'm not sure how they channel this phantom excess irrelevant horsepower but it must be critical to them.

 

Make a rule to require the most expensive gas - not for any technically valid reason but "for the love of god"!

 

Eric

[elr]

@6balls - the tournament officials can’t control the heat and humidity they can control the gas that goes in the boat.

[Horton]

I think a lot of you have lost sight of what this thread is/was really about.

 

The original point is when you bring your $100,000 boat to a tournament skiers at the top of the field will ski better if you spend that extra 50 cents per gallon of gas.

 

Tiny things make a difference in the sport. The best skiers optimize everything. Many of you guys freak out if they don't have the right rope but will use any fuel?

 

[slow]

No sure that’s been verified.

[Horton]

@slow engineers at MasterCraft tell me it makes a difference. Elite skiers tell me it makes a difference.

[AdamCord]

So the whole goal of this thread was to bring attention to this issue with new DI boats at the higher end of the sport. I gotta say from that perspective it sounds like this has been a resounding success. Thanks to @eleeski, @MarcusBrown and many others for bringing the attention to this issue that was needed!

 

Thanks @Horton for confirming with the Mastercraft engineers what many of us trying to run very shortline have been feeling the last couple years. I honestly wish the fuel type didn’t matter. It would be cheaper to ski and it would be one less thing to worry about when headed to a tourney.

 

Lastly my offer still stands - anyone with deep pockets want to help me develop and electric boat drivetrain? Then we will never have to talk about octane ratings again :o

[keithh2oskier]

Delete.