Anybody have any ideas on jetting as boost increases ?
Figure more air requires more fuel ?
Was very fat at 12% under , 5 lbs. boost ( 468, 871 (2) 825 Demons
Bumped to 5% under, 8lbs. boost plugs look very lean
Everything else stayed the same ( timing, fuel pressure, float levels, etc. )
Thanks for any ideas.:messedup:
I would think as more air is pulled in, more fuel would also be pulled in. The carburetor basically acts as a place for the fuel to be siphoned from. If the plugs are looking more lean, I would guess the reason would be due to increased heat caused by the increased blower pressure.
That would be my guess. I hope someone that really knows has an answer.
They compensate somewhat but there are just too many variables. I suggest you buy a pyrometer and combine that with plug reading. When in doubt..fatten it.
Thanks guys,
Guess i need to break down and get an A/F or EGT
Till then i suppose just fatten it up, and watch the plugs.
I disagree with adjusting A/F ratios to meet an EGT number.
The only accurate way to know about A/F ratios is with an O2 sensor.
Whatever the EGT number is after you've got the proper A/F ratios across the rpm ranges is not important.
I disagree with adjusting A/F ratios to meet an EGT number.
The only accurate way to know about A/F ratios is with an O2 sensor.
Whatever the EGT number is after you've got the proper A/F ratios across the rpm ranges is not important.
cool , i installed o2's on both headers
I disagree with adjusting A/F ratios to meet an EGT number.
The only accurate way to know about A/F ratios is with an O2 sensor.
Whatever the EGT number is after you've got the proper A/F ratios across the rpm ranges is not important.
All I can say is I have done it that way for many years and have never hurt anything. I just did it at Red Bluff and once again it worked for me. Your mileage may vary.
Remember I said in conjunction with a plug reading.
Here comes one out of left field.
How well do o2 sensors do with leaded race gas??
Here comes one out of left field.
How well do o2 sensors do with leaded race gas??
I get about one season out of each O2 sensor with leaded fuel, then they start to show fault codes. An over rich mixture kills them faster. A new sensor is about $ 55. I've decided to detune to 11# boost and run pump gas for this season while trying out this new boat setup.
EGT's are highest at Stoichiometric, you're using all of the oxygen available to burn all of the fuel available. From what I've seen most who tune by EGT's will try to richen it up to bring the EGT down. That would move you in the wrong direction.
Agreed,
when tuning with my lap top and trying the get the egt's down the a/f went so fat that performace went way down,
And also had to have the engine hatch re-covered since the soot was so heavy I couldnt clean it.
Racer
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