TOTAL timing on nitrous, not how much to retard *I've searched*

[ebrow21]

I've spent a fair amount of time trying to find this out through search and have not found a direct reply, so I figured it would be best to ask. I know every vehicle is different, but I would like a frame of reference if possible.

A quick rundown.
06 Gt Convertible auto
HT0's gapped .31
NX stand alone fuel cell running C16 with nitrous, 93 octane in the car.
125 shot 57n/33f HSW plate with NX solenoids (11.0-11.2:1 AF)
Other expected assorted bolt on's.


The car was dyno tuned on nitrous and ran fine pulling 5 degrees of total timing full throttle. Datalogs show around 26 degrees total timing while on the nitrous tune. On two separate occasions, the car has run great the first half of the track, laid over the 2nd half of the track, and burned the plug under the fuel rail pressure sensor. My wideband is on the on the same bank as the burned plug, and throughout the entire run it never went more lean than 11.2:1. All the other plugs checked fine, and weren't changed after the first plug was burned.

I'm thinking the cumulative heat from the run is eating that plug at the end of the run, where it wouldn't do so on a single dyno pull. It just seems odd to burn the same SINGLE plug twice if its tune related.

I am getting the injectors flow tested, putting fresh c16 in the cell, and have a tune with the option to pull more timing. The car compression and leakdown tested fine. Before I run the car again, however, I would rather have some input from other nitrous users.

To give you and indication, the car went [email protected] in the 1/8th and then went [email protected] in the 1/4 on the run it burned the plug.

Those who have run nitrous on their car and datalogged, what has your total timing looked like?

 

[psfracer]

4 years ago when I ran the 125 shot, that would happen to me. The same plug would go away (under the fuel rail pressure sensor). I put a BAP on it and retarded the timing another 2 degrees and didn't have any more issues. And, like you, this only happened on 1/4 mile passes, in the 1/8th it was fine.

 

[WarFords]

I have burned a few on my 5.0 pushrod motor with A/F good. There was just to much timing.

 

[ebrow21]

4 years ago when I ran the 125 shot, that would happen to me. The same plug would go away (under the fuel rail pressure sensor). I put a BAP on it and retarded the timing another 2 degrees and didn't have any more issues. And, like you, this only happened on 1/4 mile passes, in the 1/8th it was fine.

I was hoping you would respond, as you have had a similar setup and track experience. Do you happen to remember what you ran for total timing?

I understand what you are saying, however, I have a seperate fuel system (cell, pump, regulator) running c16 on the fuel side of the nitrous system. The cell is rated for 800hp on gasoline, and from what I have seen, I do not lose pressure on either fuel setup at any point while spraying. My motor tune runs about 12.8:1 AFR.

My hope is the fuel in the cell went bad. I only topped it off from the time I installed it 8 months ago or so. I'm tempted to convert to methanol with the cell setup and drain/refill it every time I go to the track.

 

[KenB]

26* total on 93 octane is too much in my opinion and the fuel is too rich (if it's that way all the way down the track). Most people make the mistake of throwing a bunch of fuel at a nitrous car.

 

[ebrow21]

26* total on 93 octane is too much in my opinion and the fuel is too rich (if it's that way all the way down the track). Most people make the mistake of throwing a bunch of fuel at a nitrous car.

Thanks, you're correct about the A/F. I am mixing c16 on the fuel side of the nitrous system with the 93. The car made 313 on motor, 433 on nitrous. The mix should come out to be around 100 octane. I understand your where you are coming from with the A/F suggestion. The intent of running that rich is more to bump the total octane of the fuel, as they mix ethanol in our 93 here. I want to avoid pump gas variatons.

What would you suggest I should try timing wise?

 

[psfracer]

If you are burning up the same plug, but none of the others, and you are sure its not a fuel supply problem to that one, I would start at 22 degrees (vs the 26 you have now). How does the other plugs look? Can you see any small dots on the insulator nose (an indication of detonation)?

 

[KenB]

Thanks, you're correct about the A/F. I am mixing c16 on the fuel side of the nitrous system with the 93. The car made 313 on motor, 433 on nitrous. The mix should come out to be around 100 octane. I understand your where you are coming from with the A/F suggestion. The intent of running that rich is more to bump the total octane of the fuel, as they mix ethanol in our 93 here. I want to avoid pump gas variatons.

What would you suggest I should try timing wise?

Actually, the rich condition could be burning your plugs. Too rich on a nitrous engine is more dangerous than too lean IMO.

Anyway, I would pull the timing back to 20-22, then lean it out to 12-12.5

Once you have the fuel correct, then I would start adding the timing in slowing. If you want to give it max effort, read the plugs to let you know how much timing the engine wants.

 

[ebrow21]

If you are burning up the same plug, but none of the others, and you are sure its not a fuel supply problem to that one, I would start at 22 degrees (vs the 26 you have now). How does the other plugs look? Can you see any small dots on the insulator nose (an indication of detonation)?

The other plugs did not seem damaged based on a visual inspection, but I ran the car back to the pits and idled for a bit before pulling them. No compression/leakdown damage as well.

Actually, the rich condition could be burning your plugs. Too rich on a nitrous engine is more dangerous than too lean IMO.

Anyway, I would pull the timing back to 20-22, then lean it out to 12-12.5

Once you have the fuel correct, then I would start adding the timing in slowing. If you want to give it max effort, read the plugs to let you know how much timing the engine wants.

I appreciate the response and advice. I guess the c16 doesn't help that much. I need to spend some more time on the dyno then. Of course I didn't have time to set up the datalog on these runs at the track. I normally datalog every run.

This particular problem began recently, I have run the same nitrous jetting on multiple tunes. Before this, I haven't burned a plug since converting to a stand-alone. How much do you think I'm leaving on the table running that rich?

Seems like timing is the root of the plug issue based on everyone's advice.

 

[KenB]

The other plugs did not seem damaged based on a visual inspection, but I ran the car back to the pits and idled for a bit before pulling them. No compression/leakdown damage as well.



I appreciate the response and advice. I guess the c16 doesn't help that much. I need to spend some more time on the dyno then. Of course I didn't have time to set up the datalog on these runs at the track. I normally datalog every run.

This particular problem began recently, I have run the same nitrous jetting on multiple tunes. Before this, I haven't burned a plug since converting to a stand-alone. How much do you think I'm leaving on the table running that rich?

Seems like timing is the root of the plug issue based on everyone's advice.

Hard to say. My advice is more about keeping the engine happier while maintaining performance. I would tune a car like this on the track, not the dyno honestly.

I should have said it sooner, but I'm not a fan of mixing race fuel with pump gas. That could also be part of your problem. No way to ensure it's mixed well.

 

[ebrow21]

Hard to say. My advice is more about keeping the engine happier while maintaining performance. I would tune a car like this on the track, not the dyno honestly.

I should have said it sooner, but I'm not a fan of mixing race fuel with pump gas. That could also be part of your problem. No way to ensure it's mixed well.

Understood. I primarily tune Hondas and don't want to pay for the software license for one vehicle. I asked for a few specific things from the original dyno tuner but it seems yet again the car isn't right. Between the unlisted cam angle built into a NSR cam to another tuner simply being unable to lock my triple disc converter under full throttle I've had nothing but problems on the tuning side. This is the third tuner.

I appreciate you taking the time to respond, its difficult to get a direct response from someone who actually knows about these vehicles and nitrous setups. With an unlocked tuner I can at minimum band-aid this back to safety.

On the second part, from the standpoint of IM design or atomization in the combustion chamber?

 

[KenB]

Understood. I primarily tune Hondas and don't want to pay for the software license for one vehicle. I asked for a few specific things from the original dyno tuner but it seems yet again the car isn't right. Between the unlisted cam angle built into a NSR cam to another tuner simply being unable to lock my triple disc converter under full throttle I've had nothing but problems on the tuning side. This is the third tuner.

I appreciate you taking the time to respond, its difficult to get a direct response from someone who actually knows about these vehicles and nitrous setups. With an unlocked tuner I can at minimum band-aid this back to safety.

On the second part, from the standpoint of IM design or atomization in the combustion chamber?

Mixed well in the tank. Unless you are mixing it before you put it in. Still not a fan honestly.

Is the kit dry or wet? If it's wet I would just get a good NA tune and do all the tuning yourself with jetting at the track and your tuner should give you enough room on the custom parameters to take care of the timing.

And no problem on the help, I like to see people happy with their cars. Helps everyone.

 

[ebrow21]

Mixed well in the tank. Unless you are mixing it before you put it in. Still not a fan honestly.

Is the kit dry or wet? If it's wet I would just get a good NA tune and do all the tuning yourself with jetting at the track and your tuner should give you enough room on the custom parameters to take care of the timing.

And no problem on the help, I like to see people happy with their cars. Helps everyone.

It is a wet kit, and thats the plan.

I think you misunderstand what I meant by mixing fuel. I run a stand alone fuel cell with c16 running through the fuel side of the nitrous system. Two tanks, two fuel pumps, regulators, etc.

http://www.nitrousexpress.com/product-details.php?id=1488

It exclusively sprays c16 through the fuel solenoid and a plate setup. I do not physically mix the 93 and c16 in the tank.

 

[KenB]

Ah OK. I'm fine with that

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