nitrous woes

[ekjim]

After a good weekend at the drag strip and with a few alterations to the car i managed a 13.2 at 112mph...trying to get this into the twelves I used a 50 shot of nitrous 2nd, 3rd and 4th gear, managed a 13.0 at 115mph but after crossing the line the car had dropped a cylinder. After checking at the pits number 3 spark plug had melted the electrode. I've changed the plug after giving ther car an overnight and there is still only 3 cylinders...Would anyone know what I have done?:

 

Thanks,

 

Jim.

[KJ 1320]

First of all m8 did you check the fuel pressure and jet the nitrous for the fuel pressure that you were using ?

Also what was your nos bottle pressure

[Toby]

 

I don't know about the nitrous but a compression check (with the throttle wde open) is a good place to start.

 

Hope it's no biggy!

[KJ 1320]

 

I don't know about the nitrous but a compression check (with the throttle wde open) is a good place to start.

 

Hope it's no biggy!

 

After he had told me about the nos setup,and if it wasn't setup correctly i would tell him what he has melted Toby

by the sounds of it,it's probably taken the edge off the exhaust valve

[ekjim]

i dont know the nitrous pressure the nitrous jet was 37 and the fuel 32 im going to do a compression check tomorow my mate wullie brown says the spark plug is like the fuse so if thats melted then that was the warning its went lean but i checked there wasnt any fuel in the oil tonight and put another plug in and its still the same

[mrmoo]

what brand of nitrous kit are you using??

ive got a wizards kit on my capri and am going to york raceway this weekend

 

what grade of plug are you using? at around a 50shot you need a colder grade

ive gone for 2grades colder, NGK B8ES you have to grind the earth strap down so it give the correct gap but they cost peanuts

 

anyway if youve got nos probs speak ask at www.noswizard.com

[dragaddict]

m8 first of all what are you running carb or injection?

[Toby]

After he had told me about the nos setup,and if it wasn't setup correctly i would tell him what he has melted Toby

by the sounds of it,it's probably taken the edge off the exhaust valve

 

Is it that predictable?

 

I've heard when an engine leans out on that stuff it is like having a flame cutter in the cylinder, and it happens real fast!

[Mk2Jo]

KJ is a nitrous expert so I reckon he would be best placed to give an accurate answer mate

[KJ 1320]

After he had told me about the nos setup,and if it wasn't setup correctly i would tell him what he has melted Toby

by the sounds of it,it's probably taken the edge off the exhaust valve

 

Is it that predictable?

 

I've heard when an engine leans out on that stuff it is like having a flame cutter in the cylinder, and it happens real fast!

 

That's why you need to know the fuel pressure that it's been jetted for m8

you can't just guess at it and when it goes bang blame it on the nitrous!

[KJ 1320]

i dont know the nitrous pressure the nitrous jet was 37 and the fuel 32 im going to do a compression check tomorow my mate wullie brown says the spark plug is like the fuse so if thats melted then that was the warning its went lean but i checked there wasnt any fuel in the oil tonight and put another plug in and its still the same

 

With those jets sizes m8 it should have 8psi fuel pressure and it would be 60hp increase

you can't just put a nitrous kit on and expect it to work properly if you don't set it up m8

[ekjim]

thanks .i did use a grade colder on the spark plugs ngk bpr8es .ill find out the fuel pressure tonight its an nitrous oxide systems single fogger nozzle for fuel injection cars. my engine is fuel injected, could i have held it on for to long ?

[dragaddict]

i dont know the nitrous pressure the nitrous jet was 37 and the fuel 32 im going to do a compression check tomorow my mate wullie brown says the spark plug is like the fuse so if thats melted then that was the warning its went lean but i checked there wasnt any fuel in the oil tonight and put another plug in and its still the same

 

With those jets sizes m8 it should have 8psi fuel pressure and it would be 60hp increase

you can't just put a nitrous kit on and expect it to work properly if you don't set it up m8

 

m8 like K.J. said check the fuel pressure first and then begin to work

[mrmoo]

im running a holley 350cfm twin barrel on the stock manifold using an adaptor plate

its fueled from a facet red top and has a filterking v8 reg set to 6psi

[Toby]

KJ is a nitrous expert so I reckon he would be best placed to give an accurate answer mate

 

Ok I'll shut up then!

 

But just before I do....

 

In my experience of no NOS power you need to ensure your fuel pump delivers enough fuel to the engine, a red top I believe is good for 200hp (through a big enough, non restrictive pipe). If your pump wont supply enough fuel for your power then you'll lean out even if you have enough pressure at tick over. Or is this fuel pressure measured at full chat?

 

I've said my bit....Over to KJ

[Mk2Jo]

KJ is a nitrous expert so I reckon he would be best placed to give an accurate answer mate

 

Ok I'll shut up then!

 

I've said my bit....Over to KJ

 

lol .... your answer wasn't there when I started typing my reply ... it was aimed at ekjim and not you Mr Tody

[mrmoo]

if facet can be believed at 5-8psi a redtop is good for 350bhp

they just give massive margains to make sure theyve got their ass`s covered

[ekjim]

i did a compression test tonight and got zero in number three cylinder the rest are 150 so ithink ill need to take the engine out in the next few days and take the head off and see what damage ive done

[KJ 1320]

i did a compression test tonight and got zero in number three cylinder the rest are 150 so ithink ill need to take the engine out in the next few days and take the head off and see what damage ive done

 

oops! it sounds like you've torched a valve m8

[joker]

may be a melted piston m8 from the top to the comp ring....

[Toby]

if facet can be believed at 5-8psi a redtop is good for 350bhp

they just give massive margains to make sure theyve got their ass`s covered

 

I take your word for the Red Top, as I'm sure you know, pressure is not the same as flow. On mine, when I ran the original fuel line I had enough fuel pressure but not enough coming along the pipe. I measured the flow by cracking the fuel pipe off at the carb end and cranking a litre out, timing it and seeing what is really being delivered to the engine.

 

I did this cos I melted a head gasket despite the "spec" of the pump.

You may find it does exactly what it say's on the tin

My solution was a bigger fuel line through the car.

[Toby]

 

lol .... your answer wasn't there when I started typing my reply ... it was aimed at ekjim and not you Mr Tody

 

Permission to speak please miss!

 

And stop calling me that!

[mrmoo]

good thinking toby, its a better to check than guess

the fuel pipe is a much bigger bore than the outlet from the fuel tank

so by my reckoning unless i fit a bigger tank outlet its going be flowing as much as it can?

 

the car and i will be at wizards of nos on saturday afternoon in prep for the won nationals at york raceway on sunday

[dragaddict]

m8 you said that the nitrous jet is 37 and the fuel jet is 32 if they are like that you mixed them around cause the fuel jet must be bigger than the nitrous jet on a carb system

[Toby]

the fuel pipe is a much bigger bore than the outlet from the fuel tank

so by my reckoning unless i fit a bigger tank outlet its going be flowing as much as it can?

 

Not true mate, the length of the pipe, boundry layer, wall friction etc come into it. If it is a bigger than standard pipe you'll probably be ok but best to check I think - it not hard.