Summer is approaching and I am a little concerned about finishing my motor. I have a 468 BBC with a tunnel ram setup. The compression is somewhere around 11 or 13:1 just based on the compression tests I performed with a guage which was about at 220 lbs per can. I have never pulled the motor apart to verify exactly what I have inside. The previous owner said it had 4 bolt mains and a nice steel forged crank (gee, thanks for all the details mister).
My intentions:
I have an 8:71 blower and a pulley setup up underdrive it 30% for starters and then flip the pulleys after I have it dialed in.
At first it was my goal to measure my motor, find out what's inside, and buy new pistons and rings to get my compression to be at just around 7.5-8:1 so I can run on racing fuel or pump gas if need be.
Well, I KNOW that if I jet my carbs 96% larger, I can basically strap the blower on and be on my way with alcohol. Is this a good idea?
I am the type of person that does not like to rush things, by any means. But this will be two seasons I will be without a boat if I don't make my mind up and get this thing rolling.
Please give me your opinions on alcohol and if simply jetting your carbs to run a motor that was designed to be a high compression tunnel ram motor is basically suicide, even if it's just a temporary solution to get me running for the summer.......
Justin
IMHO...............
1. 13:1 with an 8:71 is suicide.
2. Alcohol is strictly for race boats (who want's to be carrying 55 gallon drums to the river)?
My advice........put your tunnel ram motor back together, enjoy the boat for the summer, in the mean time save some coin, next fall/winter build a blower motor.
Good Luck.
Do not put a blower on that engine unless you are running alcohol and have the block "O" ringed.
Alcohol works best blown with 11:1
More needs done to the carbs for alcohol than jets.
Infomaniac:
Do not put a blower on that engine unless you are running alcohol and have the block "O" ringed.
Alcohol works best blown with 11:1
More needs done to the carbs for alcohol than jets. Kind of what I thought. Time to buy some pistons. I don't want to have to get some fancy needles for my carbs to get it to idle either so I am going to tear my block apart and get it honed for some new pistons and rings.
I guess I really didn't want to deal with the corrsion prevention that you have to do every time you run on alcohol too.
Thanks for the opinions...
[ March 19, 2003, 11:34 AM: Message edited by: 78Eliminator ]
Alcohol is for drinking.
Seriously, set it up to run pump gas and you'll be happy you did. There is a reason you basically double the size of the jets in your carb. You're running through it twice as fast. You also brought up the corrosion factor. That's a biggie too. I wouldn't want to mess with it on anything I own. There were quite a few of my friends I go to the dunes with that started off with turbo rotary motors on methanol who after a season of dicking with it, detuned them to run on regular race gas. Not worth the headache unless you're strictly racing.
But on the flipside you could build your own still and make your own fuel.
Blown 472:
But on the flipside you could build your own still and make your own fuel.
http://www.mg-tri-jag.net/alcohol_fuel.htm
[ March 19, 2003, 11:48 AM: Message edited by: 78Eliminator ]
Stick with a pump gas motor
My 9.5:1 motor made 780H.P. On Amoco 93octane
And had a blast doing it "No headaches"
Running alcohol Reguires a lot of up keep and maintance Oil changes, Plugs, Ect, Ect,
You want more speed I told you to call me. argue
A friend of mine runs a BBC blown on alky w/ a 10.5:1 static compression, 8/71 @ 17% over and it hauls, 8.0's @ 142 in a hydro. Do not forget if you go to alky (which is not being affected by rising prices) that you also have to change fuel pumps due to the increased fuel flow and that alky does contaminate the oil very quickly, ie: change the oil often.........
Cranking compression and your camshaft play together to give you cranking compression. Don't try to guess compression ratio by cranking compression.
Alcohol will work on an 8 to 1 motor also. 11 to 1 is general but I have pushed 13.1.
Alcohol makes more H.P. Never put alochol in an unknown motor. For that matter, blown gas is risky not knowing what you have.
Special carbs or extreme reworking required for alcohol. Not just a simple jet change. Generally an expensive changeover. Bigger fuel system, bigger pumps, more frequent oil changes (till you get it right).
Lot's of guy's here run blown gas. I am sure they can help you with jetting and answers in general. But it would be a good idea to pull the motor apart and see just what you have.
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