HIGH PITCHED SCREECH AT 0.5 BAR BOOST

[Dovey]

I dont doubt the whistle comes from the front. My theory was a minute difference in back pressure between the two tailpipes, could create a noise under the bonnet. Apparently not all with inner tailpipes whistle anyway, so thats killed that one.

Now, my neighbour says he had exactly this problem on his Intergrale. He said it was the manifold gasket. Hammer the exhaust around a bit, then increase the boost and pop! Its another theory, but a good one.

[JIMBO]

It's good news and bad news again.
The bad news is the mother in law is still on board.
The good news is it's now boosting to 0.75 / 0.8 bar !
It's hard to tell exactly what the boost was as a lorry
changed lanes in front of me on the A14 and I had to
find an anchor or two to throw overboard.
The even worse news...... the radiater has started leaking.
Regards
Jim

[Dovey]

the radiater has started leaking

Hmmm. Mine has been running hot for a while, now its critical. Think its polished off the thermostat.

[GeoffSmith]

How are all the screaming banchees?

I've had a play with the Mountain range this last week and it seems to have made bugger all difference. It's still there from 5000RPM upwards under load and doesn't seem to be boost level related. The only good thing is that you don't spend quite so long above 5000RPM with the Everest

Just read your post about the manifold gasket Dovey - I'd been having similar thoughts myself. Maybe it's not the manifold gasket but the Peco supplied gasket? BTW has anyone followed it up with Peco Dave?

Geoff

[JIMBO]

Hi,
I emailed Dave and asked if he had any idea's or if I was in the area would he look at it, but that was 2-3 weeks ago and so far no reply.
I must also order an "Everest" chip now that I know it's not going
to make it worse.
Regards
Jim

[RatHead]

I phoned Dave about a week ago and asked him if he had any ideas. The only thing he could think of was that the turbo was the source as it was spinning faster than it was before.

[Dovey]

Geoff, I saw exhaust manifold gaskets the other day for the grand total of a pound. Might be worth getting one anyway at that price. They're here in fact:

http://www.bell-colvill.co.uk/LotusShop ... A100E6043F

[algirdas]

Dear All:

The turbo spining too fast? That does not sound right to me. We have had other guys in LEC get massive boost levels without screeching. We have other guys running even 2.5 inch exhausts which should also cause the turbo to spin much faster. They do it without screeching. Plus, not every person who has installed the PECO exhaust is getting the screech.

I'd like to know what you guys with more experience with turbocharged cars think about this.

Sincerely,

Algirdas

[GeoffSmith]

The turbo spining too fast? That does not sound right to me.

Must agree with Algirdas. My two favourites are gasket and wastegate valve as the source as the sound is similar to a woodwind instrument (essentially a reed vibrating in a pipe). The pitch does not change significantly with engine speed or, as far as I can tell, with boost whereas amplitude most certainly does. This to me suggests a resonance.

Don't laugh, but I had a whistling toilet after we extended the house. The plumber and builder couldn't stop this high pitched whistle which could be heard throughout the house as the cistern approached full fill. The best they could do was to fit a device to stop water knock which quietened it for a short time. As soon as the builder left, it started up full volume again of course. I eventually found that the valve had a large rubber seal inside a large cavity which tended to resonate at exactly the same frequency as the pipe run from the elbow under the floor (quarter wavelength of sound waves in water). The cure was to change the frequency of the oscillating valve which I did temporarily with a lump of blu-tak. It has never come back so I haven't had to do an epoxy resin permanent fix.

Back on topic, I wonder if something like the gasket is beginning to oscillate at the resonant frequency of some part of the new exhaust pipe. A quick trawl of the internet for "screech" and "turbo" and "exhaust" indicates we are not alone!

If I can find enough time this week to complete some development work, one thing I hope to be able to try is to dial in different levels of boost. I will be able to remotely switch between stock, Kili and Everest to check if the frequency or amplitude are boost dependent. More news as available.

Geoff

[RatHead]

It will be interesting to find out what it is. Algirdas might have a point with the exhaust repair tape around the flexible section but you would need ramps for that.

PS Elan just clocked up 100k!

[Dovey]

I will be able to remotely switch between stock, Kili and Everest

Fancypants!

[algirdas]

Dear Geoff:

You are going to be able to switch remotely between the three configurations? Wow. That is way, way, WAY cool.

Sincerely,

Algirdas

[algirdas]

Dear All:

Are there cars out there still experiencing the screech or (my theory) has soot from the exhaust sufficiently plugged the flex joint so everything is nice and quiet?

Just checking in.

Sincerely,

Algirdas

[GeoffSmith]

Sorry Algirdas. Still screeching like the mother-in-law. PROM hopping does nothing for it either. I still suspect the gasket.

Geoff

[rjbean]

not sure if i'm having the same problem or not...
got my car back after 20 weeks long story but it failed on rear sliencer and rear disks. Took a long time to get hold of parts and people at the garage being ill and them attempting to put in my speedo cable. Anyway, i digress... now when driving my car the boost gauge is working as it used to but i also get a whistly noise when i have boost. It's pitch alters with amount of boost and although cannot really hear it at .5 bar i thinks it's still there but above my hearing range. It's about the same volume and sounds as though it's coming from the same area as the fluttering wastegate but very annoying, especially if on motorway and a slight incline as it is constant.

sorry i'm useless at explaining things but does this sound the same as what others are experiencing?

[algirdas]

Dear Mr. Bean:

Have you installed a PECO exhaust on your Elan?

Sincerely,

Algirdas

[rjbean]

afraid not some back box the garage bought for me. look alright though but eventually i will get a peco i think

[JIMBO]

not sure if i'm having the same problem or not...

Hi,
I don't think you have the same problem because mine is unpleasantly loud, so much so that people in cars I pass are looking for the origin of the noise. I think I might get the gasket changed to see if that helps.
Jim

[Bobc]

Hi all, did this problem get resolved, because I have just had a Peco fitted and I am now a member of the mother in law club which is a real pain!

Cheers,

[Bobc]

Help!! Does anyone know how to solve this 'screeching problem? It defiantly only started happening since I had the Peco fitted.

Cheers