6/6/03

Ed. Note:  Wady Hamam or Pro Mod Wad as he is known in the sport as drag racing's main nitrous Guru. He has been involved in nitrous oxide injection almost from its inception especially with the Pro Mod division.. He is originally from the Buffalo, New York area and has been involved in all types of racing from flat track motorcycles to fuel dragsters. In his wasted youth he even raced a fuel funny car powered by a blown and injected small block Ford! He and his brother campaigned a front motored Top Fuel dragster and lost a race against Don Garlits at the now closed Niagara Falls Dragway. His advice about nitrous problems is highly sought after but he is hard to get to. He has agreed to answer one question every couple of weeks for Drag Racing Online readers. Email your questions to: promodwad@racingnetsource.com, and he will answer the question he finds most intriguing. (Original caricature Pete Millar)

QUESTION

I have a 522 BB Chevy with a single carb and a plate system. I recently purchased an exhaust gas temperature gauge. What kind of temperature range should I be looking for the optimal mixture?

Secondly, can you shed some light on how to accurately read spark plugs? I have heard many stories and would like some clarification.

Thanks.

Cameron Stuart

ANSWER

Hi Cameron, The problem with exhaust gas temperatur gauges on a nitrous engine is more times than not the damage is done when you get the temp. reading. Generally, exhaust temps run between 1350 and 1500 degrees on a good nitrous tune up, so it is hard to say what is optimum.

As far as plug readings, the plugs will look new with a slight grayish or tan-ish tint on the porcelain when you have the right tune up. They should not have any specks or aluminum transfer on any part of the white. I would suggest that you go to www.koehlerinjection.com and bring up Nitrous Master. This site has great info on tuning nitrous systems and reading plugs, etc.

Thanks for the question.

Wady Hamam

Editor's Note:

As Wady suggested, Koehler Injection's Nitrous Master has some great information about designing, plumbing and using a nitrous system to best advantage. We have decided to expand our pool of tech experts and add Dave Koehler. Dave has been a racer, machinist, engine and car builder, and inventor for over 25 years. The past decade he has turned his attention to nitrous oxide injection and fuel systems. Next month he will have his own Q&A column. To ask Dave a question about fuel systems or related subjects, email fuelforthought@racingnetsource.com.

By way of introduction, we asked Dave to add his thoughts to the question above.

Cameron,

This is a common but fair question to which there is no cut and dry answer. You will not get two engines to feedback the same exhaust gas temperature number. We have seen "perfect" tune ups with 1100 degrees and we have seen them with 1500+ degrees. In other words, your buddies' numbers are useless to you.

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The problem lies with the placement of the egt probe in the header, the type of probe being used and the peculiarities of the engine itself. Oh, and let's not forget that an over-rich condition can lead to excess fuel burning in the pipes, giving you a high temperature reading.

So... What to do?

I would tap all the header tubes and move the probe around from tube to tube and find your leanest cylinder. Start with the lean cylinder and adjust your tune up by what your plugs are showing you.

The caveat here is that if you are too rich to begin with then your leanest (highest temp) cylinder may be showing you burning fuel in the pipes, so concentrate on the plugs first.

Assuming it is rich and you lean it out in baby steps, you will want to recheck all the cylinders from time to time to see if your original lean cylinder is still the leanest.

Once you find the happy spot for the plugs and the car is flying without needless damage, then you will have found what the "optimum" temperature is for your car on that particular cylinder.

As to plug reading, it is too big a subject to get into here. There is a whole chapter devoted to plug reading in the Nitrous Master software Tuning Files, with pictures that you will find helpful. You can access it at www.nitrousmaster.com.

Have a safe race.

Dave Koehler

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