Boat Gas????

[Ultra_Stealth]

I am just curious to know what grade of gas everyone uses. I have a 6.2 liter and use 92 grade fuel. I am wondering is 92 needed or can I get away with a lower grade of fuel for my motor? What does everyone else use?

[kimswang]

Depends on your compression. If is stock, 87 should do just fine...

[Ultra_Stealth]

Depends on your compression. If is stock, 87 should do just fine...

I am not a wrencher, so I would assume it is stock. No mods or anything.

[kimswang]

I am not a wrencher, so I would assume it is stock. No mods or anything.

A 6.2 is a stroked Chevy 350 engine. You might want to check the manual and see what they suggest. More important is that you add some additives to the fuel so you won't loose octane rating from the heat.

[Ultra_Stealth]

A 6.2 is a stroked Chevy 350 engine. You might want to check the manual and see what they suggest. More important is that you add some additives to the fuel so you won't loose octane rating from the heat.

Ok, thanks Kim. If I run 92, it won't hurt, right? What type/brand of additives should I add to it?

[RUNNIN A FEVER]

When I ran 91 in my stock 502 the transom would be fully covered in soot (unburned fuel). Reading up on the topic I found that the motor actually lost 1 hp using 91 in lieu of the recommended 87. I use 89 to be safe and the transom staining is gone.

[just another payment]

I always try to run 91 but on the occasions that I have run 89 everything seemed to be ok, now that is on a 454 carburated motor.

[kevnmcd]

Chad - I would assume that 91 is overkill for that 6.2L. Read the manual, but I would bet it would recommend 87. If so, your wasting your money putting 91 in there.

[Essex502]

With an HP525 the manual said regular 87 and that's what I've used from day one. No problems at all. Hot or cold. Go with what Mercury Marine recommends if you have a Merc motor. You can get their recommendation from their website.

[BADFISH II]

With an HP525 the manual said regular 87 and that's what I've used from day one. No problems at all. Hot or cold. Go with what Mercury Marine recommends if you have a Merc motor. You can get their recommendation from their website.

I heard the same with mine - 87 was fine. I ran it for a while until I thought that the smoke was caused by the octane (someone said the smoke was from running 87 and I should run 89, can't remember who though) but it wasn't obviously.

I'm going to go back to 87 only after I get it rebuilt because (correct me if I'm wrong) it should in theory run better (since the bottom end is shot, even the best cylinder AFTER the valve job is at a loss of 7% (leak down test) which I think is Merc's line for a rebuild) on 89? Meaning that I should get more power (even if not really noticeable) out of 89?

Since it's super slow getting on plane and I'm only getting 1mpg now that the ECM is adjusted right (1500 altitude instead of the 4K plus Absolute set it to) I need every ounce of juice I can get. should I even considering running 91 until I get it rebuilt? Maybe that would help a bit..

[Ultra_Stealth]

Thanks guys.

[kimswang]

Ok, thanks Kim. If I run 92, it won't hurt, right? What type/brand of additives should I add to it?

I always use stabilizer. Get it at Autozone or similar K-Mart shops for cheap. The normal one is fine, the marine ones take care of water in the fuel as well.

[Rude]

on the top of the intake on mine it states to run 87 octane. if i run a higher octane, the same as the other guys, my transom turns black.

[AnchorNPlay]

The only time you need to run 91 or above is if your engine is high compression. If its low compression, like I think most of these motors are, then 87 is perfect and that might even be a little overkill. Back east they actually have 85 at the marina's on the St. Johns river and some street gas stations. The elevation has something to do with it too, being higher you can use lower octane.

[PUMP 'HER']

Acording to The Mercury site (http://www.mercurymarine.com/engines/inboards/sterndrives/mpi6-2mx_specs.php) you can use 87. But what do they know?

[Ultra_Stealth]

Acording to The Mercury site (http://www.mercurymarine.com/engines/inboards/sterndrives/mpi6-2mx_specs.php) you can use 87. But what do they know?

Good man......Make sure you keep up with I am doing to this boat. It will be yours soon. :jump:

[vzw4u]

Should be fine with the 87. My 500 EFI's only need 87. I have tried the 91 and I get the black soot under the swimstep and I could not feel a difference in power.

[Red Horse]

I used to have to burn 100 octane in the jet boat until I retarted the timing. The guy I bought it from had the timing WAY off.

The last time gas started raising in price (good old 2 dollar gas) I started looking at it to save money.

[AnchorNPlay]

Good man......Make sure you keep up with I am doing to this boat. It will be yours soon. :jump:

Is that your boat I just saw on Craiglist? I new it looked familiar... I was "considering" looking into it,lol. Have to sell mine first if I did that.

[PUMP 'HER']

Good man......Make sure you keep up with I am doing to this boat. It will be yours soon. :jump:

Ready to trade when you are. By the way are you going to throw in one of the hot girls you keep talking about?

[SteveC]

I've had good luck with LL Av gas in the toon! Damn that blue gas is great. Sorry to trash this thread. Had a couple, no, more than a couple.

[PUMP 'HER']

Right you had a couple before you had a couple then you had a couple more right?

[kimswang]

I've had good luck with LL Av gas in the toon! Damn that blue gas is great. Sorry to trash this thread. Had a couple, no, more than a couple.

100LL is great and never goes bad, different from the cheapo auto gas... I used to get it for free when they worked on the airplanes... no more of that fringe..:headshake:

[Ultra_Stealth]

Is that your boat I just saw on Craiglist? I new it looked familiar... I was "considering" looking into it,lol. Have to sell mine first if I did that.

No, not mine. But it is for sale. :D

[Ultra_Stealth]

Ready to trade when you are. By the way are you going to throw in one of the hot girls you keep talking about?

I think you need two boats. I think I will keep it this summer. The chicks having been causing me problems lately. Trying to keep the one's together for the 4th trip is hard enough. Three of the girls that were gonna come, found out I hooked up with one of the other girls that is going, got pissed and now all three arent coming. I guess the one girl liked me but I didn't know it. :dunno: Oh, they were also supposed to be there for the regatta too. Try to round up some more eye candy. Anyone know any I have room on my boat......:D

[PUMP 'HER']

Geez dude, all the drama. Are you still in High School or what? :Laugh_at::D

[aquaholicbum]

AnchorNPlay The only time you need to run 91 or above is if your engine is high compression. If its low compression, like I think most of these motors are, then 87 is perfect and that might even be a little overkill. Back east they actually have 85 at the marina's on the St. Johns river and some street gas stations. The elevation has something to do with it too, being higher you can use lower octane.


you can use high octane with low compression if your running a blower motor,i run 110 oct @ 8:75:1 . gotta get a preloan from the bank tho -110 runs $6.86 a gallon

[AnchorNPlay]

AnchorNPlay The only time you need to run 91 or above is if your engine is high compression. If its low compression, like I think most of these motors are, then 87 is perfect and that might even be a little overkill. Back east they actually have 85 at the marina's on the St. Johns river and some street gas stations. The elevation has something to do with it too, being higher you can use lower octane.


you can use high octane with low compression if your running a blower motor,i run 110 oct @ 8:75:1 . gotta get a preloan from the bank tho -110 runs $6.86 a gallon


you're absolutely right, I was referring to natural aspiration only. I dont deal too much with boat engines, more familiar with cars, but the same thing guess. you dont "need" high octane for a low compression engine, but you do need it for high or you will get engine knock... but then again, that all depends on the tune....


My 350Z for example from the factory has to have 91 or you get knock with a high compression V6, yet a civic is REALLY low compression and you will be fine with85 and no knock....

again, depends on the tune....
Hope that made sense...

[AnchorNPlay]

AnchorNPlay The only time you need to run 91 or above is if your engine is high compression. If its low compression, like I think most of these motors are, then 87 is perfect and that might even be a little overkill. Back east they actually have 85 at the marina's on the St. Johns river and some street gas stations. The elevation has something to do with it too, being higher you can use lower octane.


you can use high octane with low compression if your running a blower motor,i run 110 oct @ 8:75:1 . gotta get a preloan from the bank tho -110 runs $6.86 a gallon


you're absolutely right, I was referring to natural aspiration only. I dont deal too much with boat engines, more familiar with cars, but the same thing guess. you dont "need" high octane for a low compression engine, but you do need it for high or you will get engine knock... but then again, that all depends on the tune....


My 350Z for example from the factory has to have 91 or you get knock with a high compression V6, yet a civic is REALLY low compression and you will be fine with85 and no knock....

again, depends on the tune....
Hope that made sense...

[liquidated damages]

The computer adjusts for the fuel. Mercruiser motors are built to use standard pump gas. I actually have never used anything other than 87 in my boat and we have a bit over 150 hrs on it. Now when we go to a 540 this might all change.