Author Topic: Built Briggs V Twin Fuel Octane?  (Read 16965 times)

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Offline The Tank

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Built Briggs V Twin Fuel Octane?
« on: March 14, 2013, 09:32:04 am »
What fuel octane rating are you guys running in your built briggs engines. When I say built, I'm referring to being higher compression, cam, port work and all the other goodies. Before someone thinks I wanna run racing fuel, I'm not and simply don't have the compression but I think I may need a higher octane fuel. I'm currently running 87 octane fuel.My engine has a steady blue flame out the exhaust and it's not lean, it will make you tear at the eyes. If I lean it out any more than what it is now, the engine will stumble when revved. Timing is set at 30 degrees. Up in the air just debating on trying some 93 octane. I've always ran 87 with no problems and engine is running fine, I just don't like the steady blue flame. My header also started turning cherry red and CHT was at 358 degrees. Any suggestions?
Frank "The Tank" Woods

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Offline jd 111

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Re: Built Briggs V Twin Fuel Octane?
« Reply #1 on: March 14, 2013, 09:56:38 am »
if it is legal for you to run, you could jet it out and run alchohol, it burns much much cooler and is easier on parts, just like race fuel it allows for much higher compression with out predetonation. you would have to get an alky compatable fuelpump and new fuel lines because alchohol is very nasty to rubber and will eat it up. you would also need a billet oil pump gear and anything else in the engine due to deposits and traces in the oil. hope this helps, -Levi
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Offline The Tank

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Re: Built Briggs V Twin Fuel Octane?
« Reply #2 on: March 14, 2013, 10:08:24 am »
if it is legal for you to run, you could jet it out and run alchohol, it burns much much cooler and is easier on parts, just like race fuel it allows for much higher compression with out predetonation. you would have to get an alky compatable fuelpump and new fuel lines because alchohol is very nasty to rubber and will eat it up. you would also need a billet oil pump gear and anything else in the engine due to deposits and traces in the oil. hope this helps, -Levi
That would be legal in my class, but then comes down running the alky. I have no clue where to even buy it but I've got to do something, way too hot on the exhaust right now. Never had this problem until now. I did also forget to mention, the engine keeps a constant blue flame from a high idle all the way through wide open. I noticed the pipe glowing at an idle and it was idling at 1300 RPMs.
Frank "The Tank" Woods

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Offline willenglish

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Re: Built Briggs V Twin Fuel Octane?
« Reply #3 on: March 14, 2013, 10:23:50 am »
I agree that alcohol is what I would be running too if it was an option. There are numerous performance advantages....plus its a much safer fuel to run...as its not as vaperous as racing gasoline. Bought in bulk....its also much less expensive than racing gasoline. If you prefer to run gasoline...any racing fuel is better than convinience store gas. The ethanol blended into pump gas causes as lot of problems...and is very inconsistant. Myself...Im partial to Klotz racing fuel. Ive found it to be very consistant...and better starting. There are a number of differant formulations available.
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Re: Built Briggs V Twin Fuel Octane?
« Reply #4 on: March 14, 2013, 10:36:54 am »
EHT was at 358 degrees.
is that supposed to sac CHT or EGT?
Looks like a CHT?

I run race fuel when I can, but it is not high octane - I think only 89, not sure on that. You can buy low octane race fuel.
I buy it because it is pure, it has saved me alot of tuning headaches caused by the luck of the draw blends from the pump.
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Offline The Tank

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Re: Built Briggs V Twin Fuel Octane?
« Reply #5 on: March 14, 2013, 10:39:57 am »
is that supposed to sac CHT or EGT?
Looks like a CHT?

I run race fuel when I can, but it is not high octane - I think only 89, not sure on that. You can buy low octane race fuel.
I buy it because it is pure, it has saved me alot of tuning headaches caused by the luck of the draw blends from the pump.

Oops my bad, should have been CHT. Also, I'm running non ethanol fuel. We still have a couple gas stations here that sell it. Where can you get low octane race fuel? Our race track only has the high stuff.
Frank "The Tank" Woods

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Offline Johnson Mowersports

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Re: Built Briggs V Twin Fuel Octane?
« Reply #6 on: March 14, 2013, 11:12:48 am »
Is it at 350° at idle or during a race. If during a race that seems about normal if not way to hot. Try turning the timing back a couple degrees  and see if that helps
Also isn't that header really short on that mini? That can cause flames but wouldn't cause the heat issues
Josh

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Offline The Tank

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Re: Built Briggs V Twin Fuel Octane?
« Reply #7 on: March 14, 2013, 11:16:06 am »
Is it at 350° at idle or during a race. If during a race that seems about normal if not way to hot. Try turning the timing back a couple degrees  and see if that helps
Also isn't that header really short on that mini? That can cause flames but wouldn't cause the heat issues
Yep 350 idling at 1300 RPMs. The header is short but really no shorter than I've been running. Really the only difference is this one is more of a straight shot where my others had lots of bends in them.
Frank "The Tank" Woods

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Offline Johnson Mowersports

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Re: Built Briggs V Twin Fuel Octane?
« Reply #8 on: March 14, 2013, 11:20:24 am »
Drain the fuel you have in it now and go get a gallon of 110 octane try that it should run cooler. But it sounds like the intake isn't sealing right are u running plastic or aluminum
Josh

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Offline The Tank

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Re: Built Briggs V Twin Fuel Octane?
« Reply #9 on: March 14, 2013, 11:23:16 am »
Drain the fuel you have in it now and go get a gallon of 110 octane try that it should run cooler. But it sounds like the intake isn't sealing right are u running plastic or aluminum
Aluminum intake. I did have the carb off yesterday, low side jets were a little stopped up so I took it off to clean. Put the intake back on last night with new intake and carb gaskets. I checked it with carb cleaner and it made no difference.
Frank "The Tank" Woods

AKA "The Intek Outlaw"

Offline fomoco2266

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Re: Built Briggs V Twin Fuel Octane?
« Reply #10 on: March 14, 2013, 11:25:51 am »
would the length of the header cause running problems ? do briggs v twins really on back pressure to run ?  also is methanol an alternitave ? , sorry to be a bit vague , but , like i said , im new to this and keen to learn from you guys
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Offline Johnson Mowersports

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Re: Built Briggs V Twin Fuel Octane?
« Reply #11 on: March 14, 2013, 11:44:21 am »
Well try the 110 and turn the timing back a notch and see how it does
Josh

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Offline The Tank

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Re: Built Briggs V Twin Fuel Octane?
« Reply #12 on: March 14, 2013, 12:23:01 pm »
I'm gonna change fuel and play with timing tonight.
Frank "The Tank" Woods

AKA "The Intek Outlaw"

Offline Johnson Mowersports

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Re: Built Briggs V Twin Fuel Octane?
« Reply #13 on: March 14, 2013, 12:37:04 pm »
Make sure your key didn't shear
Josh

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Offline Rooster

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Re: Built Briggs V Twin Fuel Octane?
« Reply #14 on: March 14, 2013, 12:54:02 pm »
I get all my fuel out of the Jug Larry put in the trailer.....LOL???
Bert stole my cookies!!
 I think he used them to bribe Ed into something naughty?

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