Rolling road nitrous tuning

Why would they need to do / know special stuff to help you set up nitrous? I thought it was just a case of getting the car set up well in the first place (a bit rich if possible, to guard against detonation), and getting your extra nitrous / petrol in.

It is basically, but they are all a bunch of tarts.

After speaking to Mr. Williamson I'm fairly well convinced it's running a bit "too" rich, mention nitrous to garages and they s*it themselves. I just want to look at power and torque curves to gauge accurately what the engine is doing.

Another way.

Do a baseline run, time it and after the run dip clutch, coast to a halt with the motor turned off on a flat bit of road / runway. Start the run at 2500, end at redline every time and pull ALL the plugs and examine them. Look for a nice DARK to MEDIUM tan colour on the OUTSIDE ring! This will be the colour of the head. Ignore the electrodes for the moment. Make sure the bottle has some left in after each run!. Run 1. Time it (get another person!) with a stopwatch ACCURATELY as you pass

ETc...

But... Unleaded fuel does not colour plugs well like the old leaded stuff did... So be very careful...

And use old (carbon coated) plugs, not brand new ones! They take on the colours faster...

Also listen for any harshness that may indicate that the timing needs to be retarded. AND watch to see temperature of bottle, and engine does not vary much.

What you are after is controlled constant conditions.

Also if on a rolling road be careful that the operator does not try to "lean it" to the "correct" mixture! This will give best power but the least safe setup! Nitrous WANTS to be set up a bit onj the rich side, as bottle pressure varies and the slight over rich situation cools and prevents detonation etc.

But go rich enough and you get no extra power! Somewhere in between is what you are after.

Look at the graphs on my pages showing the effect of a slightly rich mixture compared to "correct"

This is a bike but you see what I am talking about.

Go to

I haven't got access to a secection of jets today but it won't stop me testing the ones i have in there.

Plug chop, going to do that today thanks. I spoke to highpower and one possibility they suggested is that I'm wellying it for extended periods and the bottle pressure is slowly dropping on full boost making the mixture richer and richer the longer it's on boost. This sounds plausible as well since i'm getting strong acceleration that's tailing off at higher rpm. It might well be a combo of all these factors on top of the torque falling off at higher rpm as expected.

If thats the case then a) it is a bit on the too rich safety side b) you need a bigger bottle. (14lb is about right for a car?)

I've got highpower's 11 lb bottle in the car. I think a lot of the brick wall effect I'm talking about is me over revving the car. Peak power standard with this engine is 150bhp at 6080rpm but peak torque flatlines between 3800 and 5500rpm, then drops off rather rapidly according to this power run printout. It's got high compression cylinders apparently.

Done several plug chops, the colour isn't changing noticeably. Ran it off boost and held it at 6000 rpm for a few seconds before killing the ignition, plugs were a creamy grey powder colour. Same colour on boost with 50bhp jets. Tried it with 75bhp jets (60 fuel/150nitro) and got a juddering misfire as the progressive built the power. It happened every time but only tried it 3 times before giving up. Put the 50 bhp jets back in and everything worked fine again.

So far I've had it suggested it could be an electrical distributor problem where the plug isn't getting enough charge to fire the spark across the gap because of the increased and increasing pressure in the cylinders. Or highpower suggesting it's just the fuel pump. Any thoughts?

Choices... Too rich Fuel pump too small Ignition breakdown (close up plug gaps and see if the "juddering" stops???)

The plugs will not colour very well at all with unleaded fuel...

Will do the plugs first, hopefully it's that. What long term effects on normal running? Am I right in thinking it'll just make them wear out (degrade) a bit sooner?

Well IF that stops the misfiring then you really need to find out whats failing and fix it. Could be coil, or HT leads, maybe an aftermarket ignition system is needed?