Pops and bangs
Discussion
The only way to get a hotwire to pop and bang is to gun it then release the loud pedal quickly...A flapper will pop and bang quite happily at most speeds..Even if you drive it conservatively...(Whatever that means)..Mind you Delilah used to pop and bang like an AK47 and she was Mechanical Fuel Injection...I still laugh at the bank holiday police horse saga...
Perhaps its a TVR thing...Although i have never heard a Griff or Chimaera do it...The best was a friends Cerb that popped and banged like a gatling gun and spat fire at the same time...
I believe its to do with a slight over fuelling but then mine passed the MOT with spot on emissions...???
Perhaps its a TVR thing...Although i have never heard a Griff or Chimaera do it...The best was a friends Cerb that popped and banged like a gatling gun and spat fire at the same time...
I believe its to do with a slight over fuelling but then mine passed the MOT with spot on emissions...???
Small leak in the exhaust will do that - my old V8 7 had a leaky slip joint and it sounded like a calvery volley on over run - bloody awesome!
When Caterham took on the K series engine they weren't happy about lack of pops and bangs on lift off as the ECU shut the fueling off - so they went back to Rover to get them to repgrogram the ECUs so that fueling wasn't shut off on over run.
When Caterham took on the K series engine they weren't happy about lack of pops and bangs on lift off as the ECU shut the fueling off - so they went back to Rover to get them to repgrogram the ECUs so that fueling wasn't shut off on over run.
Edited by smash on Wednesday 19th November 08:59
mrzigazaga said:
i have never heard a Griff or Chimaera do it
You should get out more Mark....here's an old (crappy) vid. of my car but you get the picture, sorry noise..
https://www.youtube.com/watch?v=8Cxt1kpxcCQ
Still doesn't sound as good as a Wedge though....
pjac67 said:
You should get out more Mark....
here's an old (crappy) vid. of my car but you get the picture, sorry noise..
https://www.youtube.com/watch?v=8Cxt1kpxcCQ
your griff sounded blinking great Paul at the NG event.......aural delight
Still doesn't sound as good as a Wedge though....
here's an old (crappy) vid. of my car but you get the picture, sorry noise..
https://www.youtube.com/watch?v=8Cxt1kpxcCQ
your griff sounded blinking great Paul at the NG event.......aural delight
Still doesn't sound as good as a Wedge though....
My Wedge having a few pops up Prescott hill climb. I know I was slow - it was pouring down and slippy!
https://www.youtube.com/watch?v=1X81ivkmJPk
https://www.youtube.com/watch?v=1X81ivkmJPk
KKson said:
My Wedge having a few pops up Prescott hill climb. I know I was slow - it was pouring down and slippy!
https://www.youtube.com/watch?v=1X81ivkmJPk
Sounds lovely... And roof down!!good work sir https://www.youtube.com/watch?v=1X81ivkmJPk
matt-man said:
KKson said:
My Wedge having a few pops up Prescott hill climb. I know I was slow - it was pouring down and slippy!
https://www.youtube.com/watch?v=1X81ivkmJPk
Sounds lovely... And roof down!!good work sir https://www.youtube.com/watch?v=1X81ivkmJPk
Here's how it's done - Roof down..in the rain..proper job!
Sounds good too..
V8 Fettler said:
Flapper pops and bangs are due - in part - to the lack of road speed info being communicated with the ECU, hence fuelling continues on the overrun (ECU "thinks" car is at rest and idling, therefore needs fuel), IMO.
Thanks.So while it sounds good, it's isn't really a good thing......?
So far as I am aware popping and crackling on overrun is caused by a lean mixture, not a rich one. The crackling is the continuation of combustion after the exhaust valve opens. The flame front travels more slowly across a weaker mixture than a stoichiometric one so the combustion does not complete until the whole shooting match is in the header primary tube. Not *terribly* good for the exhaust valve and seat in theory, but in practice I doubt very, very much it has caused any noticeable damage.
A rich mixture. i.e. raw fuel in the exhaust header will cause a f***ing great bang periodically as the mixture reaches both a flammable stoichiometry and autoignition temperature.
When the fuel pump on my old 390se died, I noticed it as I put the foot down and it crackled like a goodun due to a falling rail pressure as the injectors injected what was left of the rail pressure into the manifold, luckily not 50 yards from my house.
I understand the 14CUX system has an overrun cutoff? That would explain why the hotwire systems don't tend to crackle. The flappers were wild for it. When I Megasquirted mine I have to say I did play with the overrun bins on the map to retain the crackle!
Ed.
A rich mixture. i.e. raw fuel in the exhaust header will cause a f***ing great bang periodically as the mixture reaches both a flammable stoichiometry and autoignition temperature.
When the fuel pump on my old 390se died, I noticed it as I put the foot down and it crackled like a goodun due to a falling rail pressure as the injectors injected what was left of the rail pressure into the manifold, luckily not 50 yards from my house.
I understand the 14CUX system has an overrun cutoff? That would explain why the hotwire systems don't tend to crackle. The flappers were wild for it. When I Megasquirted mine I have to say I did play with the overrun bins on the map to retain the crackle!
Ed.
Hi All
Still look in a lot .. my 350 popped and banged, was great and I miss it something terrible nothing else will ever come close to that in my opinion, I had never heard it from behind until the day I sold it and the guy drove off down the single track road from my house and gunned it.. I said to the wife .. what the f..k have I done
Cheers all Deke
Still look in a lot .. my 350 popped and banged, was great and I miss it something terrible nothing else will ever come close to that in my opinion, I had never heard it from behind until the day I sold it and the guy drove off down the single track road from my house and gunned it.. I said to the wife .. what the f..k have I done
Cheers all Deke
ed_crouch said:
When the fuel pump on my old 390se died, I noticed it as I put the foot down and it crackled like a goodun due to a falling rail pressure as the injectors injected what was left of the rail pressure into the manifold, luckily not 50 yards from my house.
Hi mate...Thats what happened when mine failed on the 350i..But unluckily i was 6 miles from home...ed_crouch said:
So far as I am aware popping and crackling on overrun is caused by a lean mixture, not a rich one. The crackling is the continuation of combustion after the exhaust valve opens. The flame front travels more slowly across a weaker mixture than a stoichiometric one so the combustion does not complete until the whole shooting match is in the header primary tube. Not *terribly* good for the exhaust valve and seat in theory, but in practice I doubt very, very much it has caused any noticeable damage.
A rich mixture. i.e. raw fuel in the exhaust header will cause a f***ing great bang periodically as the mixture reaches both a flammable stoichiometry and autoignition temperature.
When the fuel pump on my old 390se died, I noticed it as I put the foot down and it crackled like a goodun due to a falling rail pressure as the injectors injected what was left of the rail pressure into the manifold, luckily not 50 yards from my house.
I understand the 14CUX system has an overrun cutoff? That would explain why the hotwire systems don't tend to crackle. The flappers were wild for it. When I Megasquirted mine I have to say I did play with the overrun bins on the map to retain the crackle!
Ed.
I may have missed something but who said it was down to rich mixture?A rich mixture. i.e. raw fuel in the exhaust header will cause a f***ing great bang periodically as the mixture reaches both a flammable stoichiometry and autoignition temperature.
When the fuel pump on my old 390se died, I noticed it as I put the foot down and it crackled like a goodun due to a falling rail pressure as the injectors injected what was left of the rail pressure into the manifold, luckily not 50 yards from my house.
I understand the 14CUX system has an overrun cutoff? That would explain why the hotwire systems don't tend to crackle. The flappers were wild for it. When I Megasquirted mine I have to say I did play with the overrun bins on the map to retain the crackle!
Ed.
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