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

[AdamCord]

All of the later model boats have high compression engines that were designed to run on 93 octane (US Octane) fuel. They all have the ability to run on 87 but that does NOT mean you are getting the best out of your boat. We are asking the boat to react very quickly to a skier who is doing everything they can slow that boat down. The Zero Off programming and the engine torque curves were optimized by the engine engineers using HIGH octane fuel!

 

When you use a lower octane the engine will retard the timing and reduce the power of the engine. You might think you can't tell a difference, but I promise you it is hurting your scores. All of the big three slalom boats ski MUCH better, especially as the rope gets very short, with high octane fuel. These boats are very expensive. The price difference you pay to use 93 vs 87 octane is minimal in comparison, so why not get the best out of your boat? Especially in a tournament every boat should be using 93 octane.

 

Each of the manufactures state this plainly in their manuals.

 

Mastercraft:

 

Malibu:

 

Nautique:

 

So please, for the love of god, stop using lawn mower fuel in your $90k+ ski boat

[Ed_Johnson]

I agree, just wish our current administration would quit approving Russian pipelines, and closing down ours to cause gas prices and transportation costs for all goods and groceries to sky rocket. The cost between regular and premium is now significant.

 

Does it make any sense that after we finally reached energy independence we would just, give that up...Please explain why we now want to pay more for everything !!!

 

 

[MISkier]

I don't even use 87 in my lawn mower or small engines. I have a gas station about 7 miles away that sells 90 ethanol free. I run that in the boat as well, though mine is not a new boat. It's a 2009 with the Indmar 5.7.

[AdamCord]

Someone who has measured gas used per set can chime in on this, but I’m guessing it’s between 1 and 2 gallons. If we round up and say it’s 2 gallons and look at average fuel prices in USA:

 

 

It’s about a $0.60/gallon difference between regular (87) and premium (93) fuel. So rounding up to 2 gallons per set that’s max $1.20 extra per set to ski behind a boat that’s running well and giving you a really good pull instead of a boat that is underpowered and making you consider quitting and taking up golf.

[dvskier]

I use 90 octane ethanol free gas in my 2004 SN 196. Run a can of Sea Foam through it annually. No problems ever. We get big time heat and humidity swings and I’m convinced the ethanol free fuel is the key to proper performance. It’s $0.50/gallon more but worth the expense to me.

[jjackkrash]

I use non-ethanol 93 in all but the rarest cases. I also don't like accepting gas for rides 'cause who the hell knows what's in the can. I just wish my own diet was a clean as my boat's diet maybe I'd run better.

[wawaskr]

Well, all I can say is those gas prices are not in CA, filled my truck yesterday with 87….$4.62/gallon

[jcamp]

I would love to hear the story that inspired this post!

 

[skiinxs]

@AdamCord Finally someone who agrees with me! I have taken a lot of heat carrying my own gas to tournaments for my boats to ensure they get a steady diet of top tier 93 octane. I really wish there was someplace to get 93 non-alcohol in my area.

[eleeski]

87 octane fuel is more energy dense than 90 octane. As long as there is no detonation, 87 octane will provide more power (and better fuel economy).

 

@AdamCord is correct that the computer will adjust to prevent detonation by retarding timing and retarding the timing will reduce the engine's power. It's not given that the change in settings to compensate for a faster burning fuel will always result in less net power.

 

Consider a high altitude lake. The lower O2 pressure lowers detonation sensitivity so the computer will not retard the timing as much (at all?) for a lower octane fuel. Don't ski high altitude sites? Really?

 

Consider my lake. I'm below sea level. But between today's thermal low pressure, a bit of humidity and the hot temperatures, my density altitude was over 4000 feet! Not unusual for a lot of summer tournaments. Low octane will work fine in these conditions.

 

As a pilot who has nearly 2000 hours flying (legally) with 87 octane fuel in my Cessna, I noticed that the plane burns less fuel, climbs better and cruises faster on 87 octane auto fuel than the 100 octane avgas. (Do not run avgas in your boat - the lead will ruin your sensors.) I also experienced less maintenance on the lower octane fuel (but I'm blaming the 100LL's lead, not the octane).

 

Blanket statements about the superiority of high octane are not consistent with the science and technology. For sure, your slalom scores are far more affected by other factors than the octane in the boat gas. Being able to afford a few more sets with cheaper gas should make a bigger difference.

 

87 octane is an approved fuel for most of our boats. Enough said.

 

Eric

[MillerTime38]

Just another excuse for skiers to use because they missed a pass. “I would have run that but the boat probably has 87 octane but I am used to 93” ??

[ALPJr]

We always ran 89 octane in our 92 Prostar. Added one small bottle of STP in spring, mid summer and fall winterizing. Ran like a champ and used ~3 gallons an hour, a little less than 1 gallon for 6 passes at 34mph.

[chrislandy]

@eleeski I'd have to disagree there, going from a standard EFI throw anything in it to a high comp engine, I had to run 97 (different in the UK - but I think similar to 93 in the US) to avoid predetonation. If I could only run standard unleaded I had to either add an octane booster or back the base timing off 2deg, even then you still felt it every so often.

 

No running on LPG so a bit different!

[ReallyGottaSki]

I also dissagree that higher energy density correlates to higher power.

The ECM will adjust the fuel mapping to keep everything stoichiometrically happy by feedback from the O2 sensor as you know, the limits are how much air into the engine and spark timing, not fuel delivery. I maintain the best that can happen is one may use slightly less fuel, as remarked, if timing is not pulled back too much.

Then the new direct injection engines are a different animal altogether and i would err on heeding the recommendations

 

[Than_Bogan]

Bah. Another reason not to buy a new boat.

 

2021 and we can't tow one measly human without special fuel?

[Jody_Seal]

I have to agree with Eric. Your daily bowl movement will have a bigger impact on your skiing then what grade fuel your running in your boat.

 

These LS engines are originally designed to run at far higher cylinder Temps then what is utilized in the marine application. One of the biggest overlooked service item i see is poor performing thermostats. Owners think it is fine that their ls engine is running at 150 degrees, when it should be running at 170-175. At 150 degrees the engine is in a cold enrichment phase and is running way to fat. At that point it does not matter what grade fuel in the tank the consumption rate is increased.

 

Here is an interesting article on fuel Vapor pressures, https://www.epa.gov/gasoline-standards/gasoline-reid-vapor-pressure.

 

"Direct injection is a form of fuel injection that is gaining popularity as auto manufacturers work to improve fuel economy. ... A common secondary benefit of direct injection is the ability to use regular-grade gasoline in engines that might otherwise require more-expensive premium fuel."

 

My advice to my customers is try and run a quality fuel in your boat. Stay away from the small mom and pop gas stations. Run e-free fuel if you can and if you can't make sure the fuel in the tank is e-free

and stabilized before winter layup.

Make sure the engine is running at correct Temps and religiously maintain correct service intervals.

 

Metamucil works well too!

 

 

[Horton]

I believe that with the DI engines like the PCM 6.2, Malibu 6.2 and the Ilmor 6.2 the high octane is critical.

 

With the Ilmor 6.0 MPI ( most ProStars ) premium fuel does not really matter [as much]. ( I am not a mechanic. This is what I have been told by smart guys. )

 

My trusted source informs me I have it wrong. All hail octane

[2Valve]

A year ago I was paying $2.01 for premium. Now it's close to $4. My older PCM mill runs fine on 87. I don't see much of a difference in my boat's performance to justify getting raped at the pump.

[JackQ]

The only benefit of Octane is knock reduction, it is better, it does not have more energy, it is not cleaner! If your engine has high enough compression to require, and run lower octane the ECU and sensors will reduce the timing accordingly, it may cost you 10-30hp that you are not using anyway unless you a a jumper i the 200s or at high altitude.

[lpskier]

I had a conversation with @adamhcaldwell on this very topic Sunday morning at breakfast. To say he is passionate about using high octane fuel is an understatement. Given his engineering background, skiing abilities and the fact that he works for Cummins, I, with my background in English and history, will defer to the expert.

[DW]

Fun topic to discuss, but an accurate answer would come from the calibrator as he/she knows what spark / fuel maps they set up. One can be quite confident none of the engines are really set up for peak or maximum performance as the key priority is to ensure reliable operation over a wide range of conditions including the ability to run on various octane / quality fuels. And correctly so, as the extra few Hp would be pretty worthless if you holed a piston on your third set of any given day.

[Bruce_Butterfield]

@AdamCord WHY ARE YOU SHOUTING?!?!?! Sure octane rating will have a tiny effect on an engine's response when its pushed to its PEAK power, but in the paraeto analysis of things that effect a skier's performance, fuel's octane rating won't make the top 100.

 

On paper, yeah there is a difference but I have a hard time believing ANY top level skier could notice the difference in a blind test.

[skierjp]

I can guarantee that when a boat gets filled at a tournament, sometimes 2 or 3 times it’s not 93 Octane. I’ve even heard them admit it.

[jhughes]

This is a good PSA. Generally it seems like most folks don't know that the 5.3 and 6.2 are DI motors. They have direct injection, very high compression ratios (11 and 11.5:1 for the 5.3 and 6.2 respectively). Aluminum blocks, variable valve timing, etc. They are a whole other generation of LS motor. Nautique/PCM started with these in 2016 though for a while they'd be offered alongside traditional 6.0 and 5.7 which are older technology motors.

 

So generally I agree with @AdamCord , people need to understand the DI motors need the good stuff.

 

THAT SAID, I'm assuming we are talking about a Malibu here. I do not think that Malibu has figured out the DI motors yet. This is just my opinion. Last year we had the 6.2 and it ate impellers like cookie monster though it generally felt OK to ski behind. This year we have Malibu's 5.3 and everyone I ski with is struggling. This is folks from 15 off to 35 off so nobody is skiing 41 but universally the boat is not fun to ski behind. This is in sharp contrast to my SN200 with a 5.3 which feels like a dream to ski behind in comparison. Literally the same motor in both boats but with different marinizations so I have a pretty controlled environment back to back.

[skiinxs]

I certainly agree it depends on the engine and if there is no detected detonation and the resultant ECM detune, higher octane fuel has no benefit. The 6 liter engines I ran in my '03 through '16 Nautiques ran fine on 87 octane and never experienced a fuel de-tune reduction in timing that I was aware of. The direct injected 6.2's I have run from '17 to present are a different animal. Although the direct injection should make them less prone to detonation, because the fuel isn't injected until each cylinder is under compression and ready to fire, apparently the higher compression causes a need for the higher octane at max timing advance. Although they run fine with 87 octane, they are running in an octane detune mode and have significant timing pulled, resulting in a loss of horsepower. I was under the impression that for slalom only, 87 octane would be fine at the reduced horsepower, since the engines are extremely strong, just a little less strong on lower octane. Adam made a good case why this isn't true. Jump is the reason I ensure I am always on 93 octane. I don't want my boats to be in low octane de-tune mode with a lot of 87 in the tank when a good jumper comes over. Simply running all of the 87 octane out and putting in 93 isn't an immediate fix, as the ecm has to relearn and it may take a couple tanks to get all of the horsepower back, unless the battery is disconnected forcing a quicker relearn.

 

Here is an example. At Regionals a few years ago, I showed up with my 6.2 Nautique full of 93 octane top tier gas and six 5-gal cans of 93. When checking in the boat I had a discussion and was told that the lake gas was 91 octane. I drove all over town and found that there was nothing above 91 octane available and decided to let them use lake gas on refills since I didn't have enough for the whole four days and I would use my 93 in my truck (same 6.2 engine). When it came time to pull the big 35 mph jumpers in the last event, bottom line, the boat was weak. Times were in, but not great. Power factor had to be cranked up to 7 instead of the usual 3 and MT speeds were down by approx 2 MPH. Immediately after the event I plugged in my Diacom and saw that it was running in a fuel de-rate mode with a LOT of timing pulled. (I believe the lake gas was way below 91 octane). When I got back to my lake I made a couple wide open passes to check top end with the same gas. The boat would barely run 43 mph in jump mode, gate all the way up. It usually would run 51.2 mph on the rev limiter. I topped off with 93 from my tank (It was about half full), put in a couple cans of Klotz octane boost, disconnected the battery for a couple minutes to force a re-learn, then pulled a couple slalom sets. I then went out and made another high speed pass. Ran over 51 mph. I then plugged Diacom back in and the de-rate was gone and no timing was being pulled. I believe that he boat was down at least 50 horsepower on the gas from regionals.

[AdamCord]

@lpskier are you telling me that the 11th ranked Open slalom skier in the world and also the 34mph record holder, who spends his days standing inside a test cell pushing marine engines to their limit, MIGHT know more than some armchair critics about how different fuels will effect the performance of a high compression boat engine as the rope gets short?

 

 

 

[kmenard]

I only use 92 or 93 and then just cut it with lake water to save on money.

[BraceMaker]

@AdamCord what's your opinion for when that begins to be important? If I never pull anyone shorter than 35 off 36mph would the derating of the engine be enough to matter?

 

Do you have enough background knowledge on the engine management of the E-Controls system to comment on if there is a way to live feed a gauge for engine octane/derating?

 

Thinking about how there are gauges for flex fuel engines that can give you an idea on the fly of how your fuel is mixed so if you were running a 1/4 tank of E85 and topped up with E10 and then ran it down a 1/3rd and added rec gas.

https://www.innovatemotorsports.com/products/ecf1.php

 

If its perhaps OK to run 87 pulling kids around the lake but you wanted for if that was actually causing a performance fault - would seem like this data could be helpful.

 

 

[AdamCord]

@Bracemaker this thread was mostly aimed at tournament organizers and promo boat owners. The difference in the boat’s performance becomes much more apparent the shorter the rope gets. That being said, anyone who is cutting rope will find it easier to get wide and early with the proper fuel in the boat.

 

If you use your boat for pulling kids, tubing, etc or you are not trying to cut rope and run your best scores then yes, 87 octane is fine.

 

If you are trying to ski your best or are putting on a tournament where you want people to run PBs then 93 octane is a MUST.

 

If it were up to me Regionals, Nationals, all Pro Events, and heck even all record events would be required to use it with all these new boats. These engines are not the carbureted 350s we grew up with.

 

As @skiinxs said you can use a Diacom to see the derate when using lower grade fuel. When GM developed these engines they actually made a case to try and make Premium the minimum available at the pumps!

 

https://www.google.com/amp/s/gmauthority.com/blog/2018/03/gm-once-again-calls-for-premium-gasoline-to-become-new-standard/amp/

[eleeski]

A good way to kill the sport is to raise the cost of skiing by 20%. Premium fuel is about 20% more. Hmmm.

 

I don't want to have higher entry fees to pander to the obsessive beliefs of a few. I hope social media does not fuel this irrationality.

 

Eric

 

Note: Oops. Using the official temperature from yesterday (108f) and the correct altimeter setting in the calculator, my below sea level site had the density altitude closer to 3000 feet, not 4000 feet as I stated (it felt hotter - but the official numbers are always less than we complain about). Still a pretty radical change in atmospheric density with an associated large reduction in engine power. Maybe my boat still needs an altitude prop?

[RichardDoane]

entry fees are going up for the events pulled with premium fuel, or pay $5 less per round for class C seems about right

[Horton]

@RichardDoane 6 passes is about 1.2 gallons. Cost increase per ride is not really much.

[matthewbrown]

We don’t have 93 in CA, only 91. We have E85 which would be awesome to run but the boats are not equipped with flex fuel capabilities.

[jjackkrash]

My layman's understanding is that the issue isn't just the usual knock issues associated with using lower octane fuel, its that the engine's computer will derate the engine more aggressively than one might otherwise expect when it detects lower octane fuel.

 

I also doubt the issue is as pronounced (if its an issue at all) using the old tech 6.0L boats. I absolutely love my 6.2L, but if up front and operational costs and durability were more of an overriding concern, I'd have checked the 6.0L box.

[Vernon Reeve]

There's a popular car guy who talks about this for cars, and the bottom line is to use the octane that your owners manual recommends.

[Drago]

What @Jody_Seal said, if the temps aren't up, you're dumping fuel/energy.

There should be a rule, *cough*, we need more rules, especially technical ones that require maybe testing machines at the site. @matthewbrown : looks like Cali can't have record tournaments anymore, sorry ;/

@adamhcaldwell It was probably the rope (seriously)

[kmenard]

@jjackkrash I love the 6.2 in my Yukon...but ya, that 6.0 was a beast and just didn't care what fuel you gave it

[The_MS]

Nothing but non-ethonal 87 for me. Most of the gas stations close to the boat launches on the coast have it. None of them like to carry the 93 non-E due to people wanting the 87

[GaryJanzig]

My boat calls for 89 octane or higher. 1994 Ski Nautique. I added marine Sta-Bil when I could not find ethanol free. I always pull the plug and open the engine cover when the boat is on the lift between sets to keep the bilge dry. I had no issues with regular gas. Two stations in the area started selling 90 and 91 octane ethanol free which I have switched to. Boat runs great with it. If your boat sits in the water all the time I would look for ethanol free.

[Dacon62]

I know there are differences but personal experience is that my 6.2 in my Truck would detonate on anything less than 93 octane. The lower the octane the worse it got. Computer could not adjust enough to eliminate it.

[RAWSki]

Interesting. What is being shown is very different than what PCM and Illmor published just a few years ago. The manuals for my '14 6L and '18 5.7 state the engines are designed to be run on 87-90 octane and I have been told by trusted mechanics that there is no benefit to running 93. However these are not HO - DI engines. @DW?

[eleeski]

Jump requirements drive the horsepower needs of a tournament boat. Slalom does not require as much power. Before speed control, a driver would often bury the throttle for a good jumper but I never saw that in slalom.

 

Larger slalom skiers do not seem to face a statistical disadvantage - something you would expect if there was really a shortage of power.

 

The altitude at Colorado (our Regionals site) lowers the available horsepower yet high level performances still occur there in jump (and slalom). The boats seem to have plenty of power - even with a large percentage of the sea level power missing.

 

Excess horsepower is excess horsepower. How much do we need to pay for extra excess horsepower?

 

We have fancy expensive luxury boats. Of course, a fuel labeled "premium" should be the fuel of choice. But 87 octane plebian fuel will still deliver the required excess horsepower - even if it offends our sophisticated tastes.

 

In half a century of skiing, I've never before heard that a tournament boat didn't have enough power for slalom. Modern boats have ridiculous amounts of power. How stressing over the power differences from fuel choices gained traction is beyond me.

 

It's the skier, not the octane!

 

Eric

[dbutcher]

My boat, a 2015, has a 5.7L engine with 9.4:1 compression ratio. My belief is that running higher than 87 octane gasoline would add no performance and would in fact be a waste of money that I could spend other ways. Am I wrong? As much as I use my boat, it could be about $500 or more per year.

[jjackkrash]

The engine that is the focus of discussion is the 6.2L with direct injection (and I suppose the 5.3L with direct injection could be part of the discussion). The 5.7L engines are based on decades old tech and don't need premium gas.

[klindy]

Tesla Plaid. Electric motor and no more octane issues. ?

[AdamCord]

@klindy yes absolutely! Anyone with a lot of money who wants to start a company making electric drivetrains for boats let me know. B)

[RAWSki]

The original post included a very generalized statement.

 

"All of the later model boats have high compression engines that were designed to run on 93 octane (US Octane) fuel"

 

I would agree @jjackkrash if this discussion is specific to 6.2L units.

[jjackkrash]

@RAWSki, that may be true about the generalized statements in the OP, but the second sentence in bold in the Ilmor manual, for example, singles out the 6.2L and states "It is highly recommended to use a minimum of 90 octane for 6.2L gdi/s engines." The GDI engines and specifically the 6.2L engine are different animals than the non GDI fuel injection systems used in the older 6.0L and 5.7L engines.

[brettmainer]

The 5.3 and 6.2 DI engines need the high octane. In my experience, 5.7L and 6.0L engines do fine on the lower octane. My 5.3L idled high and ran rough with 87 octane. No question it needs premium, since I’ve never had similar problems running premium.

[brettmainer]

I should amend the above post. We currently have two 6L club boats, but both are new this year and both have only been fed 91 octane. I don’t have personal experience with how 6Ls run on 87 octane, I was passing on info from others there. I do have thousands of hours experience with 5.7L boats with 87 octane.