Cold Start Daftness
Discussion
Quick question,
Does anybody know if the cold start theatrics from modern fast cars (M3/R type Jags/AMG/RS Audis etc) actually have any technical benefit in terms of warming the engine or Turbos/emissions gubbins. I know modern performance engines are wildly complex so maybe all the noise has some purpose. Surely it can't be just noise for the sake of it?
Neighbour has an M4. Lovely car but it's incredibly loud first thing in the morning. I've driven various performance Jags and Audis recently and they seem insanely loud on start up.
Just wondered if all the noise has a purpose other than theatrics.
Does anybody know if the cold start theatrics from modern fast cars (M3/R type Jags/AMG/RS Audis etc) actually have any technical benefit in terms of warming the engine or Turbos/emissions gubbins. I know modern performance engines are wildly complex so maybe all the noise has some purpose. Surely it can't be just noise for the sake of it?
Neighbour has an M4. Lovely car but it's incredibly loud first thing in the morning. I've driven various performance Jags and Audis recently and they seem insanely loud on start up.
Just wondered if all the noise has a purpose other than theatrics.
W124 said:
Does anybody know if the cold start theatrics from modern fast cars (M3/R type Jags/AMG/RS Audis etc) actually have any technical benefit in terms of warming the engine or Turbos/emissions gubbins. I know modern performance engines are wildly complex so maybe all the noise has some purpose. Surely it can't be just noise for the sake of it?
Just wondered if all the noise has a purpose other than theatrics.
Nope, none at all. If it did, then ALL cars would do it, instead of just the theatrical versions.Just wondered if all the noise has a purpose other than theatrics.
Raised idle? 1200rpm or so? Yes. A deliberate blat-and-blare? No.
Yep its a pita, i was delighted when my neighbour got rid of his rs5 because the damn thing would blip itself every time it started cold and it was loud enough to wake me some mornings. I thought he was being a t
t until one morning i watched him start it without even getting in the drivers seat and it still revved its noisy tits off at startup. His new sq5 is inaudible from inside my house now, happy days.
t until one morning i watched him start it without even getting in the drivers seat and it still revved its noisy tits off at startup. His new sq5 is inaudible from inside my house now, happy days.Not really needed, the manufacturers have over compensated on the Coolant temp startup tables. EG, this is my 600+ BHP Supercharged 6.2L V8 VXR8 GTS starting up from cold with the Bimodal exhaust fully open. Really not much difference to a warm start. Idles straight to 600rpm. https://youtu.be/aVdaKHiDw1s
kapiteinlangzaam said:
Isnt it for emissions, get the CATs up to temp ASAP.
That was my understanding too. My previous M135i did it, and current C63 does too. It definitely seems to be a modern trend with 'performance' cars but I was sure it was to do with warming the CAT, presumably so that the car can 'cheat' its way into a lower emission banding?TooMany2cvs said:
Nope, none at all. If it did, then ALL cars would do it, instead of just the theatrical versions.
Raised idle? 1200rpm or so? Yes. A deliberate blat-and-blare? No.
A great theory, but completely wrong... Just because some manufacturers don't do it, doesn't mean it's purely for theatrics...Raised idle? 1200rpm or so? Yes. A deliberate blat-and-blare? No.
It is done to get the catalyst up to temperature as quickly as possible (especially close coupled cats), as the performance of the catalyst is optimised with temperature - The high idles used now are generally done with the recycling of exhaust gasses to also increase cylinder temps, are are designed to increase the temp of the cats as quickly as possible after a cold start so that they can work effectively.
Superhoop said:
TooMany2cvs said:
Nope, none at all. If it did, then ALL cars would do it, instead of just the theatrical versions.
Raised idle? 1200rpm or so? Yes. A deliberate blat-and-blare? No.
A great theory, but completely wrong... Just because some manufacturers don't do it, doesn't mean it's purely for theatrics...Raised idle? 1200rpm or so? Yes. A deliberate blat-and-blare? No.
Quite a few (like the R8) have air injection pumps that dump fresh air into the exhaust system, ahead of the cats, to combust with unburnt fuel. The pump running and the fuel burning off results in that increase in volume, I believe. Helps the cats get up to temperature faster, cutting emissions (so they say). Presumably it protects the cats a little from the overly rich initial mixtures, too, if they are actually that rich.
And yes, I found it annoying - ran an R8 for two weeks and I felt very anti-social whenever I had to fire it up at 7AM in the morning... damned secondary air injection system.
A few of my old cars ('80s/'90s) have similar systems. Got one of 'em cheap because the seller thought the manifold had cracked, haha - but no, it was just the air injection pump running, hence the noise when cold.
And yes, I found it annoying - ran an R8 for two weeks and I felt very anti-social whenever I had to fire it up at 7AM in the morning... damned secondary air injection system.
A few of my old cars ('80s/'90s) have similar systems. Got one of 'em cheap because the seller thought the manifold had cracked, haha - but no, it was just the air injection pump running, hence the noise when cold.
Edited by theseoldcars on Thursday 19th January 10:42
TooMany2cvs said:
I'm talking about within manufacturers, and even model ranges, too.
There is more than one way to skin a cat.. Some manufacturers use different methods on different models/engines etc... But they are all trying to do the same thing - Get the cats up to temperature as quickly as possibleI guess the question is how much of it is for show. Can the cats be got up to temperature without the racket? I delivered a F-Type R the other day - start up, especially cold, was just over the top. My neighbour's M4 is insanely loud when he starts it in the morning. He always looks pretty embarrassed about it. His choice of course, can have whatever car he likes - but there is no doubt that it does wake everybody up in the near vicinity.
theseoldcars said:
Quite a few (like the R8) have air injection pumps that dump fresh air into the exhaust system, ahead of the cats, to combust with unburnt fuel. The pump running and the fuel burning off results in that increase in volume, I believe. Helps the cats get up to temperature faster, cutting emissions (so they say). Presumably it protects the cats a little from the overly rich initial mixtures, too, if they are actually that rich.
And yes, I found it annoying - ran an R8 for two weeks and I felt very anti-social whenever I had to fire it up at 7AM in the morning... damned secondary air injection system.
A few of my old cars ('80s/'90s) have similar systems. Got one of 'em cheap because the seller thought the manifold had cracked, haha - but no, it was just the air injection pump running, hence the noise when cold.
Yep my RX7 has one of these as well runs around 2k rpm when cold and drops to 1k rpm after 5 min. The problem with the rotary is the tenancy for the thing to flood if you switch off during it's warm up cycle so even when just moving cars around the drive I have to leave the bugger idling (granted I DO NOT do this late at night or early in the mornings)And yes, I found it annoying - ran an R8 for two weeks and I felt very anti-social whenever I had to fire it up at 7AM in the morning... damned secondary air injection system.
A few of my old cars ('80s/'90s) have similar systems. Got one of 'em cheap because the seller thought the manifold had cracked, haha - but no, it was just the air injection pump running, hence the noise when cold.
Edited by theseoldcars on Thursday 19th January 10:42
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