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Optimum air / fuel ratio for marine engine

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Old 01-02-2007, 05:34 AM
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Default Re: Optimum air / fuel ratio for marine engine

EGT Temp. vary wildly depending on how far the prob is away from the exhaust valve.On a dyno the probes are usually 6 inches from the valve.This is hard to do on a marine water jacketed header. I had mine in the exhaust port next to the header flange,i saw temps in the 1700*range.The dyno showed 1300*with the probs 6 inches downstream !
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Old 01-02-2007, 08:40 AM
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Default Re: Optimum air / fuel ratio for marine engine

Originally Posted by MYSKATER32
EGT Temp. vary wildly depending on how far the prob is away from the exhaust valve.On a dyno the probes are usually 6 inches from the valve.This is hard to do on a marine water jacketed header. I had mine in the exhaust port next to the header flange,i saw temps in the 1700*range.The dyno showed 1300*with the probs 6 inches downstream !
To be blunt, given the variability of EGT measurements emntioned as a function of the distance from the combustion chamber, it would seem that all it is good for is cylinder to cylinder EGT balance check. Are there EGT numbers for that?
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Old 01-02-2007, 09:06 AM
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Default Re: Optimum air / fuel ratio for marine engine

Some helpful information regarding EGT and tuning parameters;
http://www.maxracesoftware.com/egt_probes.htm

Bob
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Old 01-02-2007, 01:42 PM
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Default Re: Optimum air / fuel ratio for marine engine

Originally Posted by rmbuilder
Some helpful information regarding EGT and tuning parameters;
http://www.maxracesoftware.com/egt_probes.htm

Bob
Incredible .. the stuff you come up with ....great info ...m
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Old 01-03-2007, 08:09 AM
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Default Re: Optimum air / fuel ratio for marine engine

Thank you gentlemen all!
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Old 01-03-2007, 08:46 AM
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Default Re: Optimum air / fuel ratio for marine engine

Originally Posted by 2112
On a closely related topic, does anyone know the formula to determine the amount of fuel needed for a specific horsepower? Trying to determine GPH of fuel pump. I have alway just gone overkill in the past.
I figure about .5lb/hp*hr. You can add 10-20% margin and that should work out fine. So for 100 hp do:

100*.5= 50 lb/hr

+ 20% = 60 lb/hr

You could just multiply that by hundreds and that should get you there. So, 700 hp = 420 lb/hr or about 60 gal/hr or 1 gal/min. Just be careful when sizing your fuel pump to know the operating pressure range for the pump. A pump curve is always best to know that your fuel delivery will be adequate at your operating pressure.

Rene

Last edited by oldandtired; 01-03-2007 at 08:49 AM.
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Old 01-03-2007, 10:18 AM
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Default Re: Optimum air / fuel ratio for marine engine

Im running a Revolution Marine aluminum exhaust manifolds. Is there any way to mount a EGT sensor in this type of exhaust?
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Old 01-03-2007, 11:17 AM
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Default Re: Optimum air / fuel ratio for marine engine

Originally Posted by hdtvned
Im running a Revolution Marine aluminum exhaust manifolds. Is there any way to mount a EGT sensor in this type of exhaust?
Yes,PM Nordic95 here on the board.He had a post on how he mounted an O2 sensor in his Revolution Manifolds.

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Old 01-03-2007, 11:58 AM
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Default Re: Optimum air / fuel ratio for marine engine

If the flange is thick enough where it mounts to the head you can drill there.Most EGT probes are 1/8 pipe thread,about 5/16". Be sure you don't get into the water jacket , or you're S______!
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Old 01-03-2007, 02:18 PM
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Default Re: Optimum air / fuel ratio for marine engine

Thanks Bob, Good Read!!

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