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Roush 575 and Fuel Octane


Shodan01

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Ok - this is just to piggy back off my last thread, but I thought it would be broader if I just posted it outright.

I live on a fairly large lake, but it seems that the only fuel marina's in the water have 89 Ethanol Free fuel.

Before anybody shoots me over saying to pay over 130K on a boat and don't pay for gas please read further.


I am looking to order a 575 Roush Engine in my 24 MXZ upcoming (Unless I choose another but thats a different topic). The boat will stay on my lift annually except when the dealer pulls it in house for service as I am not purchasing a trailer, nor do I want the hassle of loading and unloading a boat every week or weekend I go up to the lake house.

What is the thoughts out there on running 89 Octane in these engines? If I were trailering, I am so anal I would have nothing but 93, but I am not, and I am concerned about it.

Anybody with true hours worth of experience in either this or the 555 from years past? I have heard (only through this forum) that the Raptor 6.2 is more forgiving with fuel but just checking.

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Ok - this is just to piggy back off my last thread, but I thought it would be broader if I just posted it outright.

I live on a fairly large lake, but it seems that the only fuel marina's in the water have 89 Ethanol Free fuel.

Before anybody shoots me over saying to pay over 130K on a boat and don't pay for gas please read further.

I am looking to order a 575 Roush Engine in my 24 MXZ upcoming (Unless I choose another but thats a different topic). The boat will stay on my lift annually except when the dealer pulls it in house for service as I am not purchasing a trailer, nor do I want the hassle of loading and unloading a boat every week or weekend I go up to the lake house.

What is the thoughts out there on running 89 Octane in these engines? If I were trailering, I am so anal I would have nothing but 93, but I am not, and I am concerned about it.

Anybody with true hours worth of experience in either this or the 555 from years past? I have heard (only through this forum) that the Raptor 6.2 is more forgiving with fuel but just checking.

Using 87 Octane on the LSA will drop 100hp. I would expect the same on the Ford.

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Ok - this is just to piggy back off my last thread, but I thought it would be broader if I just posted it outright.

I live on a fairly large lake, but it seems that the only fuel marina's in the water have 89 Ethanol Free fuel.

Before anybody shoots me over saying to pay over 130K on a boat and don't pay for gas please read further.

I am looking to order a 575 Roush Engine in my 24 MXZ upcoming (Unless I choose another but thats a different topic). The boat will stay on my lift annually except when the dealer pulls it in house for service as I am not purchasing a trailer, nor do I want the hassle of loading and unloading a boat every week or weekend I go up to the lake house.

What is the thoughts out there on running 89 Octane in these engines? If I were trailering, I am so anal I would have nothing but 93, but I am not, and I am concerned about it.

Anybody with true hours worth of experience in either this or the 555 from years past? I have heard (only through this forum) that the Raptor 6.2 is more forgiving with fuel but just checking.

I spoke with a dealer and a rep at a boat show for a fellow Crew member regarding the fuel on the M235, which also has the 575. The rep said you could easily use 91 octane with the 575, not sure if that will help you out since 89 is the only available.

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Tims- who told you it drops 100hp on an LSA? I'm sure it would back timing off a bit, but not close to 100hp I wouldn't think.

As for octane used on the RSC 575, I would be way more critical about it than I would with the LSA. The RSC is not built to be supercharged, and has a higher compression ratio because of that. It is at a much higher risk of preignition issues than the LSA is. I would definitely stick to 91+.

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If you break a piston ring land or beat the rod bearings out due to detonation from low octane gas will they still warranty the motor? Would be a question on my mind when putting 89 in the tank.

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Tims- who told you it drops 100hp on an LSA? I'm sure it would back timing off a bit, but not close to 100hp I wouldn't think.

As for octane used on the RSC 575, I would be way more critical about it than I would with the LSA. The RSC is not built to be supercharged, and has a higher compression ratio because of that. It is at a much higher risk of preignition issues than the LSA is. I would definitely stick to 91+.

It is amazing that when I called the one marina open today, he said they range typically between 89 and 91 (as if they really don't know)....which somewhat confuses me. I presume I could have gotten somebody who didn't know what was going on.

I hope to call all the others tomorrow.

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Tims- who told you it drops 100hp on an LSA? I'm sure it would back timing off a bit, but not close to 100hp I wouldn't think.

As for octane used on the RSC 575, I would be way more critical about it than I would with the LSA. The RSC is not built to be supercharged, and has a higher compression ratio because of that. It is at a much higher risk of preignition issues than the LSA is. I would definitely stick to 91+.

Testing done by Indmar. It's 3rd hand information, but I trust the source.

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It is amazing that when I called the one marina open today, he said they range typically between 89 and 91 (as if they really don't know)....which somewhat confuses me. I presume I could have gotten somebody who didn't know what was going on.

I hope to call all the others tomorrow.

I have an LS3 and it turned into a dog when running 87; to the point that I went out and picked up a gas caddy to fill it up on the lift. That would be my recommendation.

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I have an LS3 and it turned into a dog when running 87; to the point that I went out and picked up a gas caddy to fill it up on the lift. That would be my recommendation.

If you saw my lake lot you would not say that :lol: I typically go through a tank easily in a weekend, and since we spend 3 day weekends most summers it is not uncommon for me to top off twice a weekend or more...

As far as the tank, Duke Energy owns the lake, therefore we can't do that (although a wonderful idea).

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It doesn't sound like you have much of an option but as I stated in your other thread I would not do 89 octane at all. The lsa might have gotten away with it due to the fact that it called for 91 octane if I'm not mistaken so running 89 in it is the equivalent of running 91 in something that calls for 93. With the hot air coming into the intake, the higher compression motor, the supercharger (which will heat soak worse than a regular intake), and that low of octane I will almost promise you you're going to get some detonation in the motor. Read the info in this link as it doesn't sound like you believe me since I've typed the same thing three times now. https://www.tricktuners.com/detonation_explained.htm not trying to be rude I just don't want you to make the wrong decision and have to suffer any major consequences i.e. a blown motor that they don't warranty b/c your lack of good fuel

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If you saw my lake lot you would not say that :lol: I typically go through a tank easily in a weekend, and since we spend 3 day weekends most summers it is not uncommon for me to top off twice a weekend or more...

As far as the tank, Duke Energy owns the lake, therefore we can't do that (although a wonderful idea).

Here is a link to Sunoco regarding the mixing of octanes ratings. Maybe just get a couple gas cans of a higher octane from a gas station on your way to the lake and mix at the pump when filling up?

http://www.racegas.com/article/52

The formulas are really easy to plug in your numbers. 24 MXZ has a 70 gallon tank.

89 Octane (x) + 93 Octane (y) = 91... X and Y represent percentages of what goes in the tank.

Pretty simple math here. 50/50 mix gets you to 91 which is acceptable in the 575 per the reps, so that would be 35 gallons each, but I doubt you want to lug in 35 gallons of 93 octane for one fill up.

Now if you can find a higher octane than 93 at a gas station it may be worth just picking up a can. You could always get a fuel tank/pump for your tow rig and then transfer to a can when needed, but that is another expense and still a pain, especially since I don't know what your tow vehicle is or how far you would have to carry the can to your boat.

Hope this helps!

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The solution is to buy it with the 450 motor. Your power difference will not be all that great from the 575 after it pulls the timing. Save 10k you can put into other options and enjoy the boat. If you are near Lake Norman PM me and we can go for a ride with the 450. I need to exercise the boat!

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Any forced induction motor will be significantly more sensitive to octane rating I wouldn't go below what's recommended as your short sticking yourself on hp from timing being pulled. I know on my car (twin turbo but still forced induction) I am tuned for 94 octane and even then a difference in stations can cause the car to knock. If I put 91 in on the 94 tune it will knock almost immediately, especially under load.

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This is a huge problem for folks like me who live on the lake...i called 6 marinas, none of them have anything higher than 87 but they put octane booster in the fuel...the fuel is non ethanol.

Still trying to figure out what I am going to do to fill up my m235

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This is a huge problem for folks like me who live on the lake...i called 6 marinas, none of them have anything higher than 87 but they put octane booster in the fuel...the fuel is non ethanol.

Still trying to figure out what I am going to do to fill up my m235

Ironically, ethanol fuel would be a better option to use in that scenario. In fact, 89 octane with 10% ethanol would probably work as good as 91 octane without ethanol.

Besides that, all these new (most 2012+) boats have sealed evaporative emmisions systems. Ethanol fuel is perfectly good to use in them.

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Here is something I just thought of. It didn't come to mind because I can't get it here in VT, unless I buy race fuel with it mixed in already...... Can you get a tetra ethyl lead additive in your area? Some parts of the country can still sell it over the counter at parts stores and such........ If you can find that, you are all set. Dump the correct amount in when you fuel up, and away you go, without any detonation worries, and full performance.

or wait...... is the raptor engine catalyzed??? If so, you are still stuck. The LSA is not, so a lead supplement can be used in that.

Edited by TenTwentyOne
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Here is something I just thought of. It didn't come to mind because I can't get it here in VT, unless I buy race fuel with it mixed in already...... Can you get a tetra ethyl lead additive in your area? Some parts of the country can still sell it over the counter at parts stores and such........ If you can find that, you are all set. Dump the correct amount in when you fuel up, and away you go, without any detonation worries, and full performance.

or wait...... is the raptor engine catalyzed??? If so, you are still stuck. The LSA is not, so a lead supplement can be used in that.

OK you just piqued my interest. Please take a moment and educate the ignorant. What is tetra ethylene? What exactly does it do? Benefits?

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Hmmm, lead additive, exhaust in to water. Flint Michigan? A little lead goes a long way in nervous system toxicity - especially children. Don't think I would want my youngster spending any time behind that boat.

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OK you just piqued my interest. Please take a moment and educate the ignorant. What is tetra ethylene? What exactly does it do? Benefits?

Remember "regular" gas?? Its actually still available at gas stations in some states for off road fuel. The lead additive not only libricates and protects cylinder walls and Pistons, it also drastically reduces detonation. It's really good for an engine, but not so much for the environment.

Hmmm, lead additive, exhaust in to water. Flint Michigan? A little lead goes a long way in nervous system toxicity - especially children. Don't think I would want my youngster spending any time behind that boat.

That is a fair point, but I'm willing to bet that the average child comes into 100x the amount of lead that is in an every day sandbox, than they would behind a boat with treated fuel. Lead is naturally occurring at much higher levels in every day soil.

Not that I would suggest that it is perfectly healthy, as there is a fair argument to the negative impacts of lead "toxicity". But there is a difference between lead exposure and lead toxicity. I believe there is such a thing as lead deficiency, just like a lot of other potentially toxic metals that are also essential for life.

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Hmmm, lead additive, exhaust in to water. Flint Michigan? A little lead goes a long way in nervous system toxicity - especially children. Don't think I would want my youngster spending any time behind that boat.

Install FAE and you'll be fine (unless you're downstream)

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