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Basic Engine Tuning

Old 08-28-2003, 10:52 PM
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What exactly is a wideband and what does it measure?

TDC is when the face of the rotor is closest to the spark plugs meaning parrallel or when the apex seal is on its approach to the plug and just past?

I assume that when the entire face is completely parallel. I just want to clarify so i don't try to learn off wrong assumptions.

And if both conditions (to retarded and/or to advanced) produce high egt's how does one tune the ignition off egt? You lost me on that one. Also when you say "playing" with fuel. How exactly do you mean?

Subtracting fuel at 4% intervals. If not 4% then at what percentage is the standard unit of deduction/addition?



Thanks for hangin in there Mike.



Anyone else care to help Mike explain all this to me?



Oh and great answer Bobby



D.
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Old 08-29-2003, 12:14 AM
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Originally Posted by Fd3BOOST' date='Aug 28 2003, 06:52 PM
What exactly is a wideband and what does it measure?

TDC is when the face of the rotor is closest to the spark plugs meaning parrallel or when the apex seal is on its approach to the plug and just past?

I assume that when the entire face is completely parallel. I just want to clarify so i don't try to learn off wrong assumptions.

And if both conditions (to retarded and/or to advanced) produce high egt's how does one tune the ignition off egt? You lost me on that one. Also when you say "playing" with fuel. How exactly do you mean?

Subtracting fuel at 4% intervals. If not 4% then at what percentage is the standard unit of deduction/addition?



Thanks for hangin in there Mike.



Anyone else care to help Mike explain all this to me?



Oh and great answer Bobby



D.
thats tdc





in regaurds to egt theres a range where they are low, and if you get too advanced or too retarded they go up. or to put it another way theres a happy spot



playing with fuel, ive heard 3%, but 4% is fine, theres no real standard, its just whatever you are most comfortable using. 1-2% is prolly too small to feel/see, and over 5-6 can be dangerous if you dont know what you are doing.



keep asking away, i'd like to learn something too



mike
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Old 08-29-2003, 09:23 AM
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That's a WONDRFUL photo of TDC



Tom
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Old 08-29-2003, 11:56 AM
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Originally Posted by tfhuth' date='Aug 29 2003, 05:23 AM
That's a WONDRFUL photo of TDC



Tom
yah, ive had to use it a few times



mike
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Old 08-29-2003, 12:34 PM
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A 14.7:1 air-to-fuel ratio is stoichiometric, or a situation where all fuel and all air are being burned in their entirety. Most high performance engines are tuned with a richer a/f ratio in mind to keep, at bay, any detonation that could possibly occur. Rotaries, of course, seem to like an even richer a/f ratio, as the extra fuel aids in cooling I believe. Plus, for the most part, the richer your a/f ratio, the more guarded against detonation you are even though a sacrifice may come in the form of not so optimal power outputs.



Interesting stuff this is.



Not sure if this has been clarified already or not: the higher the EGT temperatures are, the leaner the car is running. On a diesel this is the exact opposite, as higher EGT's dictate excessive fuel.



High EGT's on a gasoline motor = too much air and not enough fuel.



High EGT's on a diesel motor = too much fuel and not enough air.



Of course, timing is also a part of the mix which must be considered.
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Old 08-29-2003, 01:12 PM
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yeah bascially you're running a turbo rotary rich and using the extra fuel to keep the chambers cool(er)



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Old 08-29-2003, 01:50 PM
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Old 08-29-2003, 03:26 PM
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I now the bit about running lean and det, but the same person told me that if I was running to rich, I could also get det!



Is this correct or are they talking crap?



Dan
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