Newbie with power..

How does detonation occur? In a simple sense the fuel simply explodes instead of burning in a controlled manner. How does it happen? If compression is excessively high, the fuel/air mixture will be compressed to the point it explodes (diesels). Since the piston might not be where its supposed to be (early in the cycle), the explosion provides a back force on the piston, attempting to run the engine backwards. This doesn't happen hormally (except a start backfire situation) because the flywheels momentum overcomes the detonation. What you hear (most often) is a "pinging" sound. What you feel is a hesitation in engine performance. If this process repeats it destroys the piston tops, eventually cutting through them and subsequently destroying the engine.

If you get pinging on acceleration but it goes away in cruise, up the octane gasoline you use. If this doesn't cure the problem, then see your tune up expert and explain the problem.

Normally speaking the engines computer adjusts the fuel/air mixture to accommodate engine performance that's satisfactory. This is why a computer controlled engine is superior to a carbureted engine (no computer). Whereas the carbonated engine may require 91 octane (or higher) to avoid pinging, the computer controlled engine can use 87 octane with equal or better performance.

Hope this helps.

Jeff

HogStang said:

Hey guys, within the week I will be blown.

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What's her name?

HogStang said:

Thanks a lot Jeff. Very informative.

So while I'm flooring it (street or track), what exactly should I watch and when should I (in the hopefuly rare occasion) should I back off?

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If you hear detonation pinging or hesitations then let off the throttle. Then find out why you can't go to full throttle w/o ping/hesitation. If properly tuned for the gas octane then this won't happen.

I wouldnt suggest going to the track without the chip. I just got head last week and was advised by everyone to wait for the dyno tune. I also have a automatic with a 2800 stall, 3:73 gears, and a shift kit. You are going to be hitting the rev limiter pretty fast and probably missing shifts at WOT.

Fonzarelli said:

I wouldnt suggest going to the track without the chip. I just got head last week and was advised by everyone to wait for the dyno tune. I also have a automatic with a 2800 stall, 3:73 gears, and a shift kit. You are going to be hitting the rev limiter pretty fast and probably missing shifts at WOT.

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Never run a blown car with out a tune.. The stock computer isnt setup to control that amount of fuel or air. As for detonation.. I recommend you drive your car around with out the radio for a while.. listen to the normal sounds of the car and if you hear any metallic rattling or pinging, let off the gas and don't get on it again until it's fixed. Air leaks after the MAF can cause this.. not running 93 Octane gas when tuned for it can as well. Too much timing will do it too. Lots of different variables will cause it is what I'm trying to say. Make sure your AIT sensor is mounted AFTER the blower as well.. mounting it prior to the blower will give incorrect temperature readings (air is cooler before being compressed by the blower). Get the thing on a dyno and have the Air to Fuel ratio checked ASAP.. the SCT chip may just be fine the way it is. You're far from the first blown auto GT, so I wouldnt be surprised if thier tune is pretty close to right for you. Good luck.. and as I said, be careful once the blowers on and be vigilant for detonation.. and get it on the Dyno ASAP to check the A/F. Watch for leaning out after 5500 RPM