Running 112 oct in mariner 200 efi.

[dentquip]

Think I got all my gremlins tossed in the river. 1995 mariner 200 efi. New stator, one switch box, c c m s four petal reeds, cleaned injectors, shaved heads to run pump gas, replaced all fuel lines, rebuilt all in fuel management system could get parts for & cleaned the rest, got rid of the three black boxes, removed the can and drilled the bottom of the mid section. Got in the water yesterday, idled a little rough and ran so so but smoked like a skeeter sprayin truck. Sure that was due to too much sea foam, merc quick clean and me adding too much oil (Penn synthetic) being paranoid about from where I put it all back together, but it did run more than it had in the past. Gonna drain that rich mix out and put in the right ratio. If I run 112 oct race fuel am I gonna screw this motor up or should I stick with 93 pump gas, or mix the 93 and 112. Thanks for everyone's help - could not have rebuilt this motor by myself without this "family"!!!

[JaySmithRacing]

Running 112 octane fuel in a pump gas compression motor is going to HURT power about 30 %.. Will it "hurt" the engine NO, nothing BUT the power and your wallet...

I don't run 112straight race gas in my race engines with 250 lbs compression...

Jay

[dentquip]

Thanks y'all, That's why I asked. I just assumed the higher the octane the more power but you know the assume thing. Ha ha. I,ll stick to 93 and good oil. Thanks again for taking the time to answer what may have been a stupid question to y'all.

[dentquip]

I did not do anything with the block so I,m sure it has the original "sleeve's" should I be running lower than 93 or how could I tell. I did not do anything with the rings or pistons either. Is there a way to tell which gas to run 93, 89, 87 or do I just need to try them. I really do not understand the whole octane thing - like I said earlier - I always thought the higher the number the faster you went - haha. Also, since I shouldn't run full synthetic can I mix the two gallons I got with two gallons of not synthetic to make a " blend" or do I need to not be running synthetic anything at all in this motor.r

[JaySmithRacing]

A 2 cycle engine has but an approx. 1.500" window to contain the total push that combustion creates. If the burn is not complete some of the push is lost because of its escape out the exhaust port. Equals loss of power. High octane fuels burn slower than pump gas and if the compression of the engine doesn't warrant the use of higher octane to prevent detonation the loss of power is apparent . The higher the octane above what is needed to prevent detonation the MORE power will escape as well as dollars from your pocket book....

Even at 225 lbs cranking compression at sea level I blend my race guys engines fuels and don't run "straight" 112-110...We have found through testing that one that has a handle on the weather conditions ( I use a Kestrell 4000 weather station to set fuel air raio for that particular day ) and fuel octane has an advantage from those that "guess"..

About oils I break-in on petrolium only and then on steel sleeved engines ( what you have ) use ONLY blends no 100% syn oils on steel, I've learned that lesson the hard way ..

Good luck,.

Jay