probably a stupid question on engine noise

[stinkysteve]

Hi chaps,

I've just had the exhaust on my standard K-series S2 fixed.

It was blowing at a break on the flexible pipe for some time.

I knew it was going, but left it as long a i could due to finances. The car was a bit stuttery whilst accelerating, and noiser than it should have been.

Now it's fixed, it's a revelation. Throttle response is much better, power delivery is much smoother, etc.

However, it's now got a different sound that's freaking me out a bit!

It's got a whistle! It genuinely sounds like a turbo when you give it more than half throttle under acceleration. The pitch of the whistle doesn't really change much. Just off, then on all the time whilst on throttle.

I presume this is just being made by the induction (standard airbox) and i can only hear it now because A) it's much quieter without the blowing exhaust, and B) because it's pulling air in better/faster due to the improvement in exhaust flow.


Is this a reasonable theory and has anyone else experienced the same noise? shall i just get used to it or is there something to check?

p.s. the car is standard except for a janspeed back section.

thanks for your help.

[JTBUSH]

Have you checked the induction system for any leaks?

[Gad-Westy]

Total long shot but you haven't put a new stereo in recently have you? I had a polo a few years ago and it made a very high pitched turbo like whistle that would change pitch with the revs. Spent months trying to chase a leak, even had a couple of garages look at it and nothing. Then one day I forgot my stereo face plate and the whistle had gone. I felt like a right plank. Turned out to be interference from the spark plugs.

[subaqua]

I have a K&N 57i on my 135 S1... and when your foot is hard on the throttle, I notice a whistle from the induction - which is suprising, as the zorst is rather loud!

[stinkysteve]

hmmmmm,

theories abound...

I'v checked the airbox and it's sealed as it should be JT. It isn't pulling air in where it shouldn't

No new stereo. I know the sound to which you refer Gadwesty, however this isn't it.

I do presume it's just the air inlet, but it's such a new and obvious noise it's hard to miss and quite unnerving.

Oh well, i can always stick a K&N on and see if that changes anything. Thanks chaps.

[RobM77]

Isn't this normal? My 111S has always made a high pitched noise under a steady throttle. It's very subtle, but it has always been there. I've been told that they all do it. I expect you just couldn't hear it beforehand with the broken exhaust.

[stinkysteve]

RobM77 said:

Isn't this normal? My 111S has always made a high pitched noise under a steady throttle. It's very subtle, but it has always been there. I've been told that they all do it. I expect you just couldn't hear it beforehand with the broken exhaust.

Cheers Rob. I was just wanting confirmation that 'they all do it'. I'm sure you're right that i just couldn't hear it before.

[RobM77]

stinkysteve said:

RobM77 said:

Isn't this normal? My 111S has always made a high pitched noise under a steady throttle. It's very subtle, but it has always been there. I've been told that they all do it. I expect you just couldn't hear it beforehand with the broken exhaust.

Cheers Rob. I was just wanting confirmation that 'they all do it'. I'm sure you're right that i just couldn't hear it before.

Glad to be of help. I'd contact the garage that service your car just to check (assuming they're a main dealer or Lotus specialist), but my car's certainly always had a very high pitched whistle on a steady throttle. That said, I've just driven to Brands Hatch and back in the Elise and I can't recall hearing it! It definitely interested me enough to call Bell and Colvill about it a few years ago though, and the response was that "they all do it".