PDA

View Full Version : 87 pure gas or higher octane 10% ethanol?


skiknox
04-11-2013, 10:02 AM
LT-1 motor what would be better to use

east tx skier
04-11-2013, 10:08 AM
I'd go higher octane and treat it for the ethanol. Your LT1 is set up for a higher octane and you will sacrifice a bit of performance going lower. The only noticeable problem I have had with ethanol in my boat is that it tends to gum up the antisiphon valve if I don't run the boat regularly and don't treat the fuel during the season. My hoses and other components don't seem worse for the wear. Plastic gas tank on my boat. So no worries there.

j.mccreight@hotmail.com
04-11-2013, 10:46 PM
Your LT-1 owners manual states minimum 89 octane, my corvette buddies say at least 91 octane rating for moderate to hard driving (like how our boats are driven) and 89 octane in an emergency, regardless of ethanol content, never run 87 octane and drive it hard or it will detonate to death. Of course other MC LT-1 owners might chime in with their experiences...

JDJ_205
04-12-2013, 05:12 PM
Good Question.

I dont have an LT1 - just a regular 350 in my 95' 205. I've been using 87 octane the past few years.

East - what do you treat your fuel with during the season?

mikeg205
04-12-2013, 05:20 PM
Good Question.

I dont have an LT1 - just a regular 350 in my 95' 205. I've been using 87 octane the past few years.

East - what do you treat your fuel with during the season?

I have the same motor. I usually run premium because my can sit for weeks and fuel loses octane rating over time.

95 manual calls for minimum 89 octane - http://www.mastercraft.com/files/manuals/1995_OwnersManual-PS190-PS205-ProSport205.pdf

Seafoam and/or Marine Stabil.

thatsmrmastercraft
04-12-2013, 05:42 PM
Your LT-1 owners manual states minimum 89 octane, my corvette buddies say at least 91 octane rating for moderate to hard driving (like how our boats are driven) and 89 octane in an emergency, regardless of ethanol content, never run 87 octane and drive it hard or it will detonate to death. Of course other MC LT-1 owners might chime in with their experiences...

Not that I would recommend using low octane fuel, but doesn't the LT-1 have a knock sensor to retard the timing when experiencing detonation or pre-ignition to prevent damage? Of course the lack of performance with retarded timing wouldn't be any fun either. This coming from a Ford guy with a 1977 boat.

Rockman
04-12-2013, 06:02 PM
Not that I would recommend using low octane fuel, but doesn't the LT-1 have a knock sensor to retard the timing when experiencing detonation or pre-ignition to prevent damage? Of course the lack of performance with retarded timing wouldn't be any fun either. This coming from a Ford guy with a 1977 boat.

Yes, our 94 LT1 does have a knock sensor.

Not sure what gas the PO used (still about 1/4 of tank from PO last fall).

I am going to drain the tank and use for the lawn mower and fill up with 91 for the first tank and then switch to 89 going forward.

Only gas we use in our trucks (87 octane) or boats (89 octane) is Shell, BP and occassionally Speedway. Speedway, believe it or not does have good gas. We have never had any issues with them.

j.mccreight@hotmail.com
04-12-2013, 06:06 PM
Not that I would recommend using low octane fuel, but doesn't the LT-1 have a knock sensor to retard the timing when experiencing detonation or pre-ignition to prevent damage? Of course the lack of performance with retarded timing wouldn't be any fun either. This coming from a Ford guy with a 1977 boat.

The ecm is only able to retard the timing a couple of degrees, it will throw a mil beyond 5 degrees, continually using low octane with hard driving it will ping. Also fuel loses octane over time so add that to the equation.

Of course you already knew this;)

supreme112279
04-12-2013, 10:22 PM
The lt1 being a high performance engine, it like higher octain gas. IT would problally run just fine on 87 but 89/90 would be better and 93 would be best. ethanol is ok if you use your MC often but I hate it. I personally run 93 non ethanol. on the knock sensor, Im not convinced it really works. My camero doesent run any different with it unpluged.

JDJ_205
04-14-2013, 12:29 AM
I have the same motor. I usually run premium because my can sit for weeks and fuel loses octane rating over time.

95 manual calls for minimum 89 octane - http://www.mastercraft.com/files/manuals/1995_OwnersManual-PS190-PS205-ProSport205.pdf

Seafoam and/or Marine Stabil.

Thanks MikeG!

JimN
04-14-2013, 12:37 AM
Not that I would recommend using low octane fuel, but doesn't the LT-1 have a knock sensor to retard the timing when experiencing detonation or pre-ignition to prevent damage? Of course the lack of performance with retarded timing wouldn't be any fun either. This coming from a Ford guy with a 1977 boat.

All injected engines have a knock sensor but the LT-1 is higher compression, so it needs higher octane to prevent detonation. Lower octane fuel burns faster, so the combustion won't occur when it's supposed to, nor for the same duration.

JimN
04-14-2013, 12:40 AM
The lt1 being a high performance engine, it like higher octain gas. IT would problally run just fine on 87 but 89/90 would be better and 93 would be best. ethanol is ok if you use your MC often but I hate it. I personally run 93 non ethanol. on the knock sensor, Im not convinced it really works. My camero doesent run any different with it unpluged.

Re-connect the knock sensor, connect a timing light and start the engine, rev it up and hit a motor mount with a hammer if you want to see if it works. If nothing happens, check the knock sensor to see if it's bad. If you use the car in a hot, dry region, you can do a lot of damage to your engine in hte event that detonation (knock) occurs.

JimN
04-14-2013, 12:42 AM
The ecm is only able to retard the timing a couple of degrees, it will throw a mil beyond 5 degrees, continually using low octane with hard driving it will ping. Also fuel loses octane over time so add that to the equation.

Of course you already knew this;)

The ECM backs the timing off in 5 degree increments, until base timing is reached. When the engine is running at high RPM, it can need close to 35 degrees of spark advance in addition to the 10 degrees BTDC at idle for base timing. Big difference in performance between 45 degrees and 10 when it's running at WOT.

supreme112279
04-14-2013, 10:18 AM
Re-connect the knock sensor, connect a timing light and start the engine, rev it up and hit a motor mount with a hammer if you want to see if it works. If nothing happens, check the knock sensor to see if it's bad. If you use the car in a hot, dry region, you can do a lot of damage to your engine in hte event that detonation (knock) occurs.

Thats a good idea. I always leave it hooked up. That was a test a friend and I were messing around.

JimN
04-14-2013, 10:30 AM
Thats a good idea. I always leave it hooked up. That was a test a friend and I were messing around.

You won't see it do anything unless you or the engine cause the sounds the sensor is sensitive to- it's basically a narrow-band microphone and at idle, it's almost completely unlikely to pick up anything.