Is overrun a bad thing?
Discussion
Obviously sound and attention-wise nothing beats the POP BANG of over-run, but after a boring stop-start drive home last night that had me revving to 3000rpm and releasing for maximum effect it got my wondering....
The noise (and flames if you're lucky
) are caused small explosions by unspent fuel somewhere in the exhaust (manifolds?).
Obviously if this fuel isn't being burnt in the engine its wasted, I can live with that for the
factor but does it cause damage to anything in the exhaust or elsewhere at all?
Not that I'd be persuaded not to make use of over-run, but I'm just curious.
The noise (and flames if you're lucky
) are caused small explosions by unspent fuel somewhere in the exhaust (manifolds?). Obviously if this fuel isn't being burnt in the engine its wasted, I can live with that for the
factor but does it cause damage to anything in the exhaust or elsewhere at all? Not that I'd be persuaded not to make use of over-run, but I'm just curious.
ncs said:
Its a bit like breaking wind - loads of fun for the person doing it - but it can be distressing for those in close proximity
Spoken by a man whose never had a wet fart
Tripps said:Remember to roll down your window so he can smell it
I'll bear that in mind whenever I see you in the my rear view mirror then
WILL bigger your pre-cats if you still have them.
this will cause them to break up causing blockages and associated damage.
will also cause probs to your cat (
), with possible bits of pre cat blocking and unburnt fuel cooking. with probable MOT failures forth coming.
then there's the damage to the silencer if you still have one...breaking up and burning the wadding causing a mettalic sound and more db's...
not all bad then!
top if you have a pre-cat!!!
this will cause them to break up causing blockages and associated damage.
will also cause probs to your cat (
), with possible bits of pre cat blocking and unburnt fuel cooking. with probable MOT failures forth coming. then there's the damage to the silencer if you still have one...breaking up and burning the wadding causing a mettalic sound and more db's...
not all bad then!
top if you have a pre-cat!!!
How are you generating the popping and banging on the overrun?
If it happens all by itself, then it suggests that the motor is running a bit rich. In extreme situations, this can lead to engine wear caused by the excessive fuel washing lubricating oil off the bores, rings and maybe valve guides.
It also allegedly knackers catalysts, but who cares about them?
I used to run a 4 litre Jeep with a Powerflow exhaust. The only way I could get it to spit, pop and bang was gently to rest my foot on the throttle whilst the car was on the overrun, preferably down a long hill. In other words, to provoke an artificially rich mixture.
The catalyst on the Jeep collapsed and used to rattle like mad, though whether this was as a result of my abuse is anyone's guess.
It is noteworthy that it still sailed through the emissions test at MOT time, even with the knackered cat.
Shortly afterwards, I took the exhaust off and knocked the guts out of the catalyst, leaving an empty box, followed by a straight through silencer.
I then sold the thing, so I have no idea whether it would ever pass a proper MOT test. It did, however, sound absolutely fantastic.....
Cheers
Pat
If it happens all by itself, then it suggests that the motor is running a bit rich. In extreme situations, this can lead to engine wear caused by the excessive fuel washing lubricating oil off the bores, rings and maybe valve guides.
It also allegedly knackers catalysts, but who cares about them?
I used to run a 4 litre Jeep with a Powerflow exhaust. The only way I could get it to spit, pop and bang was gently to rest my foot on the throttle whilst the car was on the overrun, preferably down a long hill. In other words, to provoke an artificially rich mixture.
The catalyst on the Jeep collapsed and used to rattle like mad, though whether this was as a result of my abuse is anyone's guess.
It is noteworthy that it still sailed through the emissions test at MOT time, even with the knackered cat.
Shortly afterwards, I took the exhaust off and knocked the guts out of the catalyst, leaving an empty box, followed by a straight through silencer.
I then sold the thing, so I have no idea whether it would ever pass a proper MOT test. It did, however, sound absolutely fantastic.....
Cheers
Pat
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