How to spit flames?

[craig]

Mine has never flamed with a twin exit exhaust but with my old single I used to get flames only occasionally.

mine was the opposite....flames with a departure but none with a nur spec...

[craig]

so basically, if your flamming all the time, your running to rich and more than likely losing power because of this???
i certainly dont get massive bangs like some i here, like a gun going off......
never noticed flames....
only really get a little pop if changing gear hard, or just fully off the throttle while slowing down....little mini pops..

then again im running a little leaner than most....

when I had my Nur spec, I had loads of pops and bangs but no flames.

[jimGTS]

imagine a flame out of the nur spec!!

[craig]

imagine a flame out of the nur spec!!

yeah, like a giants blow torch

[bradda_gibbo]

mine used to flame quite a lot, then other week it started misfiring and i could get it to flame just by revving on tickover. turned out the plugs were screwed. changed them and doesn't do it much now, kinda makes me wanna put them back in

[Steve W2]

so basically, if your flamming all the time, your running to rich and more than likely losing power because of this???
i certainly dont get massive bangs like some i here, like a gun going off......
never noticed flames....
only really get a little pop if changing gear hard, or just fully off the throttle while slowing down....little mini pops..

then again im running a little leaner than most....

It depends, if your overfuelling, then your just wasting fuel. If your detting in the exhaust running the proper AFR's then it's likely your losing power since the fuel intended to create the energy to make your car go forward is combusting at the wrong point within the system. This, as indicated above, can be caused by poor condition ignition components.

This can sometimes also be caused by more 'racy' cam profiles too.

[Brian]

just a question..!!!!.

I know that these cars normally pop and bang, but anyway of making it more prone to happening.......?

After changing the spark plugs, dizzy rotor and cap, my old Rev4 started to pop and bang.

It scared the hell out of me the first time, as I thought having worn items would promote more unburnt fuel to enter the exhaust!

[Draven]

As the guys on the concrete cows meet know my car pops and bangs when the exhaust is hot.. all the time.. I find it happens every time if i peddal it and then lift of quick.. Exhaust has to be hot around 10 mins of driving normally sees to that.

I have a single exit straight through exhaust.. (i,e, no cat)

It was driving to my girlfriends a couple of days ago.. I pulled up to a junction as i stopped my exhaust let out a nice shotgun noise and the bloke waiting by the bus shelter ran for cover..

He musta thought someone was trying to shoot him he he.. I chuckled all the way home.. My girlfriend wasn't impressed when i told her said it could have been an old man had a heart attack.. Yadda yadda...

[MK_Steve]

As the guys on the concrete cows meet know my car pops and bangs when the exhaust is hot.. all the time..

Yup - sounded great.

Looking forward to treating my tubby to a decat this summer and hoping to get some pops myself.

Steve

[ioa1980]

OK, unburnt fuel being ignited by the hot exhaust tips - thanks Mark.

But it seems some people are saying that crap plugs make them pop, bang and flame, but others are saying new plugs make them pop et al.

Maybe its me, but I found less pop's while using Tesco 99ron compared to Shell optimax???

..and also more on cool and even damp days. (maybe, due to the crap weather I'm focussed more on the car instead of enjoying the scenery and drive )


Would air temp and density have an input too then??

[Mark Edwards]

Not so technical as to comment on air temp etc. but tesco fuel is higher octane so would be more resistant to burning. I should imagine if you were stupid enough to use 95ron it would flame nicely.

[ioa1980]

Re: using 95ron

..I had thought of that...that is, the amount of flames you would get, not using it.

[Mark Edwards]

Re: using 95ron

..I had thought of that...that is, the amount of flames you would get, not using it.

Yeah, don't even think about using the stuff.

[EarL]

Mine flames occasionally, even though I never use anything but Optimax.

Top tip! Get your exhaust nice and hot by going for a nice long blast in the late evening, then drive back through town and watch the peckerheads in their BMW 330ci's back off when a foot long flame lights the evening sky up!


...or maybe it's just me

[thai boxer]

so basically, if your flamming all the time, your running to rich and more than likely losing power because of this???
i certainly dont get massive bangs like some i here, like a gun going off......
never noticed flames....
only really get a little pop if changing gear hard, or just fully off the throttle while slowing down....little mini pops..

then again im running a little leaner than most....

when I had my Nur spec, I had loads of pops and bangs but no flames.

Dito mate. My Nur never flames......

[Steve W2]

Not so technical as to comment on air temp etc. but tesco fuel is higher octane so would be more resistant to burning. I should imagine if you were stupid enough to use 95ron it would flame nicely.

Lower octane level (RON) fuels don't burn better than higher RON fuels. They don't have the capacity to resisit detonation through compression like higher octane fuels, thus knocking and/or pre-detonation may occur (this is bad).

Higher octane fuels do combust better and provide a greater release of energy per unit of fuel in comparison to a fuel of a lower octane rating.

The point at which a fuel will ignite and it's combustion properties, or abilty to 'burn' are very different things.

The auto ignition temperature for both fuels is very similar (I think), so the fuel makes little difference when making a car go bang. Except that for the same mass of fuel the higher octane stuff might make a bigger bang.

The air temperature I don't think will have an effect as your cars ECU measures the air intake (accounting for differnces in density relational to ambient temperature changes) and provides the correct amount of fuel.

If the car runs rich it will overfuel and cause excess to pass through the exhaust potentially igniting the mixture and causing a pop. This is more likely in cars without a moggy as they absorb some of the heat from the exhaust.

Poor condition spark plugs and rotor arms may cause detonation in your exhaust as they may not have provided a sufficient spark to fully combust the fuel/air mixture within the cylinder. This scenario would result in reduced power output from your car.

Blimey, that was a long post, I'd better go do some work now

[Bibbs]

so
Dito mate. My Nur never flames......

I think it's due to the length of the pipe .. it's not hot enough.

My H&S is pretty short and the "Y" pipe gets VERY hot

[nutter]

just spend £2k on an over rich tune from Thor and you'll get enough flames to cook all the burgers you can eat!

[Mark Edwards]

just spend £2k on an over rich tune from Thor and you'll get enough flames to cook all the burgers you can eat!

I never said a word.

[Gav-GTS]

My Apexi GT pops/flames like crazy when its hot
Almost always get some action on overrun and when shifting at high revs, very addictive!! Only takes about 20mins of driving before the exhaust tip is extremely hot, tis a very short/free flowing exhaust!