The car:
94 Camaro, 355, forged pistons, stock other internals, A4, n20 cam, P&P heads, headers, new ignition components (EVERYTHING), Crane coil and box, NX Nitrous Kit, Nitrous Works plate,etc....

The problem:
This engine will NOT take anything more than a 75 shot w/ out KR, I'm using 108 oct race fuel, and I'm programming the timing tables for nitrous specifically. AFR is 12.0 @ WOT and if I try to go with anything like a 125 or higher shot, all I get is a huge backfire (probably from the retard its adding) and when I try to take out the timing in that area, it does NOT help at all.... I've gone as far as taking out 18* from 3200-6300 and it gets me nowhere. Still a BUNCH of KR and a BIG backfire as soon as it hits..... Fuel delivery system is new w/ upgraded parts and N20 system is working flawlessly. I'm ready to give up. Anyone with an idea?

-cp

 

What plugs are you running? Did you try adding fuel. What is the total timing?

Rich Krause

 

NGK TR6, I've had the fueling down to 11.0 as an experiment with NO change in engine attitude and the total timing with the 18* retard I added was clear down in the teens, with no change what-so-ever....

-cp

 

Turn off the KR and run ~20 total timing. I would also use a colder plug.

Rich Krause

 

The NGK TR6 plug is two steps colder than stock and this engine shouldn't require a colder plug than that for just a small shot (under 125) to surpress detonation. I've already tried taking the knock retard function away from the engine only to still see the HUGE dip on the dyno graph, indicating detonation in that area AND audibly hearing pinging at the same time, so the detonation event is for real. That is wht I'm stumped. My only plausible explanation is the static compression ratio being too high (11.2:1) and 108 octane not being enough to surpress detonation.

-cp

 

I know what the TR6 is and AFAIK it is not 2 heat ranges colder than stock. Just 1. But in any case, if I were in your position it's something I would try. Do you have possible carbon buildup in your motor or some other reason for "hot spots" somewhere in the combustion space?

Rich Krause

 

Found the problem: I was using the Nitrous Works injection plate that's sandwiched between the T.B. and the intake manifold and now it's in the bottom of a trash can where it belongs...

I switched over to a Shark Nozzle and mounted it a few more inches away/ahead of the T.B. to try and soften the hit and BINGO, detonation issue solved!

Evidently, by using the NW Plate, the point of injection was far too close to the intake manifold throat for this engine to handle all at once and when that huge, cold shot hit the manifold, the rapid rise in cylinder pressure must have induced a burst knock event that the engine could not recover from, especially as it approched it's torque peak. (4500-4800 or so) Once I moved it a bit further upstream of the T.B., the burst knock event went away, (at least after a modified calibration) as it must have been just enough to "ease" into the nitrous hit, rather than "slamming" into it like it was before.

This thing is really marching now....! 487 RWHP/507 RWTQ w/ ZERO det.! WoooHooo! I wonder how much this thing can take.... Gonna find out!

Thanks for the help and if anyone else reads this and is using that POS trash can liner part for their N20 set-up, you may find the same resolution as I if you're having the same issues.


-cp

 

I love it. The NX stuff just keeps gettin' better.

 

nx is the way to go imo

 

Sounds like you know your stuff man ! Good job

 

I have a backfire problem on the spray as well,I thought it was hitting the rev limiter but now im having second thoughts.I have a NW kit as well and I am using the plate,You say you used a shark nozzle is that the same as a fogger nozzle?

 

Yes, that is correct.

-cp