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A/F questions

Old Jun 28, 2004 | 07:09 AM
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shanedog
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From: Kansas City
Question A/F questions

I have a question I was thinking about, it may be stupid but here it is.

Is the A/f ratio being on the lean side the only way to damage your car with nitrous?

If you have all the A/f ratio's perfect throughout the entire power band, then couldn't you run say 150 shot safely several times a day?

On the wet kits (which I hope everyone with these cars is running) can't you just run a larger fuel jet and never have to worry about you A/F ratio and running lean?

Lastly, what is the safe range for our A/F ratio

Thanks
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Old Jun 28, 2004 | 11:58 AM
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Jime
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From: Arcadia, Florida
Default Re: A/F questions

Originally posted by shanedog
Is the A/f ratio being on the lean side the only way to damage your car with nitrous?

If you have all the A/f ratio's perfect throughout the entire power band, then couldn't you run say 150 shot safely several times a day?

On the wet kits (which I hope everyone with these cars is running) can't you just run a larger fuel jet and never have to worry about you A/F ratio and running lean?

Lastly, what is the safe range for our A/F ratio

Thanks
Good questions and I will give you my take on it.

You are putting much more stress on your engine running nitrous, especially a 150 shot. Even if the a/f is ok you could still damage or blow the engine. Imho detonation is your worst enemy and this can be controlled by timing and or race fuel. (I use 114 unleaded) I feel much safer but there is no guarantee because there are so many variables, ie nitrous pressure, fuel pressure, timing, octane etc etc.

I keep my a/f in the 11.5-12.0 range with a wideband and S-AFCII. However you also have to realize that the a/f is not the same at 90 deg as it is at 50 deg so its not just a set it and forget it deal.

From what I know about the 3.5, its a very robust engine and will take a lot of punishment, I have run a 200 shot on mine with no problems and guys have run higher but there ain't no guarantee.
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Old Jun 28, 2004 | 12:33 PM
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shanedog
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Default Re: Re: A/F questions

Originally posted by Jime
Good questions and I will give you my take on it.

You are putting much more stress on your engine running nitrous, especially a 150 shot. Even if the a/f is ok you could still damage or blow the engine. Imho detonation is your worst enemy and this can be controlled by timing and or race fuel. (I use 114 unleaded) I feel much safer but there is no guarantee because there are so many variables, ie nitrous pressure, fuel pressure, timing, octane etc etc.

I keep my a/f in the 11.5-12.0 range with a wideband and S-AFCII. However you also have to realize that the a/f is not the same at 90 deg as it is at 50 deg so its not just a set it and forget it deal.

From what I know about the 3.5, its a very robust engine and will take a lot of punishment, I have run a 200 shot on mine with no problems and guys have run higher but there ain't no guarantee.
Thanks for the reply!

I am considering an air fuel guage or something else to keep an eye on my air/fuel ratio. I am thinking about the wideband, can you please tell me about the S-AFCII and what that is/does and how much it is.....thanks!
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Old Jun 28, 2004 | 12:49 PM
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Default Re: Re: Re: A/F questions

Originally posted by shanedog
Thanks for the reply!

I am considering an air fuel guage or something else to keep an eye on my air/fuel ratio. I am thinking about the wideband, can you please tell me about the S-AFCII and what that is/does and how much it is.....thanks!
Most a/f gauges aren't very accurate, a wideband is the best.

The S-AFCII allows you to change the a/f at 12 different RPM levels in 200 rpm increments. It modifies the maf signal back to the ecu which in turn will increase or decrease the a/f ratio up to 50% each way which gives you a lot of leeway.

It has 2 data sets so I set one for N/A and one for spray. They are around $300.

This is the wideband I use. http://wbo2.com/default.htm

This is a site for info on the S-AFCII. http://www.apexi-usa.com/
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