What octane does everyone run?

[TeamAllen]

Thanks anhaney! I still wonder if a higher octane would reduce that vaporing effect? Or reduce carbon build up on your valves and sludge build up in the intake runners?

[wannabewakeboarder]

89 on the water, This fuel has marine additives.

93 when trailer, Its cheaper

[anhaney]

Thanks anhaney! I still wonder if a higher octane would reduce that vaporing effect? Or reduce carbon build up on your valves and sludge build up in the intake runners?

No higher octane has nothing to do with it. It is temperature. If you look at cars that were in the 70's all the way thought he mid 90's they usually ran 180 or 190 T-state and those engines slugged up bad. todays cars start at 195 and some go to 205. I can never get my boat to run over 175. I now have 126 hrs on it. I did a decorbon on it and man the black smoke was sick. The mess on the drive way from the exhaust was huge and took for ever to clean up. The next thing I am going to do before I winterize it is the decarbon clean with MV4 again and run an injector and fuel rail flush. The boat idle smoother than it ever has for me after the decarbon. I never felt it brand new since I bought it with a few hours on it. But what a huge diffrence.

[TigeDuner]

87 in my MP 6.0. Runs great............

[Wake Havasu]

MX 6.2L 340HP Black Scorpion...runs just fine on 87.

Mike

Is black Scorpion a Merc product?

Do you run Perfect Pass with it?

Does that motor have fuel perculation issues?

[spharis]

have to run 91+.....

[dogbert]

No higher octane has nothing to do with it. It is temperature. If you look at cars that were in the 70's all the way thought he mid 90's they usually ran 180 or 190 T-state and those engines slugged up bad. todays cars start at 195 and some go to 205. I can never get my boat to run over 175. I now have 126 hrs on it. I did a decorbon on it and man the black smoke was sick. The mess on the drive way from the exhaust was huge and took for ever to clean up. The next thing I am going to do before I winterize it is the decarbon clean with MV4 again and run an injector and fuel rail flush. The boat idle smoother than it ever has for me after the decarbon. I never felt it brand new since I bought it with a few hours on it. But what a huge diffrence.

Good idea. I ran some gas treatment through mine and noticed more black gunk on my transom than normal. I didn't use MV4. Sounds like something to add to my next 100 hr. service.

[spharis]

Does the MV4 have to be used with the MotorVac pumps and such, or is it a true additive?

[dogbert]

BTW, I remember seeing a thread on this over on WSR. Here's a summary of what got posted:

FYI on octane requirements. Engine temperature, ignition timing, compression ratio and load are the key elements of octane need. Boats run a 140 degree thermostat and use an entire lake to keep them cool, they run very cool which reduces the need for higher octane. Ignition timing is not really advanced a lot on a typical ski boat and the compression ratio's are not that high. 87 octane should be just fine for almost all ski boats. In addition, the duty cycle is not that hard and it is mostly constant throttle. Higher octane fuels basically burn slower than lower octane. In addition, the flame starts later in the compression cycle. At the engine speeds used in ski boats, 2000 - 4000 rpm, 87 octane burns at the appropriate rate. Probably the bigger enemy of ski boat operation is RVP, or when the fuel evaporates and causes vapor lock. The top of the engine compartment is fairly warm, so the potential for fuel boil exists when the boat is stopped and skiers changing. Summer and winter fuels have different brews to accomodate the different requirements.

Hope this helps.

[anhaney]

Does the MV4 have to be used with the MotorVac pumps and such, or is it a true additive?

MV4 has to be sprayed in with a sprayer. I purchased a can that I dump the product into then put on the lid and use my air compressor to pressurize the can. The can comes with a little red hose and it reaches into the throttle body and intake. I generally use a old tooth brush to clean the throttle body then I take a rag and wipe out the throttle body. I leave the rest of the product in the intake. I then get the hose out hook up the fake lake, set up the throttle so it will run at about 1500 rpm and start it up. If you can it works even better if you warm the engine up before cleaning. This allows the cleaner to attack the carbon and dirt even better. CARQUEST sells the MotoVac MV4. It is under there Preventive Maintenance program. They have a product called MV3 that can be put in with the gas but I recommend not to . If you mix the ratio two strong it will take out fuel pumps. OTC makes a good injector cleaner system with chemical for that portion of the service. Next time I do it I will try to post some pictures of the black soot. We are supposed to do DOMSZ06 boat soon so I will take pictures. He has like 300 hrs on his so it should be a good one to do.

[dogbert]

Is this like a Fuel Injector Flush?

[anhaney]

Is this like a Fuel Injector Flush?

I will be in Austin next week. We can get together and I can show you how it is done. I was just informed that on the 12th I will be free. How far are you from Austin? I know you told me once somwhere else either in this thread or another but can't remember.

[dogbert]

I will be in Austin next week. We can get together and I can show you how it is done. I was just informed that on the 12th I will be free. How far are you from Austin? I know you told me once somwhere else either in this thread or another but can't remember.

I work in NW Austin. Sent PM.