Sorry I posted this in advanced tech... but I need a quick response, so Ill put it here...

So im having a debate with a local friend about nitrous oxide and he is trying to tell me that with too much spark advance (even on a stock LT1), the charge can detonate and cause the flame to travel BACK up the intake as an intake backfire.

I really dont wanna say he is wrong, because I have ALOT of respect for the guy and hell... he has a nitrous fed 396 LT1 running in the 9's, so I would assume he knows a thing or 2 about nitrous.

I just dont understand how a motor can backfire up the intake valve once it is already closed. On a stock cam, the intake closes at ~30* past BDC and the spark is advanced roughly 30-40* before TDC, which gives the crank NO LESS than 110* between the time the intake closes and the spark comes. Even if the intake does bounce, it doesnt bounce for 110* of crank rotation.

How could that be possible? Am I missing something?

 

One time i was cleaning my intake with intake cleaner and it says to spray while the car is running. I had the elbow off and sprayed a little and the thing shot a 5 foot flame out of my intake and almost burned me. I had something fueling the fire but, I'd say its possible.

 

Possible but not likely unless you get into high dosage of N2O. Stock timing advance can be a problem with N2O. Timing retard is usually recommended by N2O guys over 175hp shot or so.

 

i actually was sitting in front of my motor once with the elbow off and the car was idling. i pulled the throttle open really quickly and it shot a puff of smoke out into my face and sounded like it backfired. my motor was on its way out then tho.

 

A 2-1/2 year old thread rises from the ashes.