HIGH PITCHED SCREECH AT 0.5 BAR BOOST

[philip_sloper]

Just to add to the theory.

If the boost is higher than standard, it might be that characteristics of gas flow through the wastegate have altered causing a resonance which is heard as a screech at max boost. A small adjustment might change the gas flow enough to cure it.

[algirdas]

Dear All:

In talking to Marie tonight, she has come up with an unique theory-its the muffler/silencer. She is running the PECO pipes but with a Borla muffler/silencer. She is running more boost and now, with the turbo upgrade, she is running larger volumes of air through the motor. No screech for her.

And, at least to me, a muffler issue would be more noticeable from inside the car than from under the hood/bonnet.

Comments?

Sincerely,

Algirdas

[philip_sloper]

But wouldn't you then expect all the cars fitted with the Peco exhaust to do it?

[algirdas]

Dear Phil:

If it is a design flaw, then I would expect them all to do it. If it is just a production flaw, then I would expect some, but not others, to have the problem.

Sincerely,

Algirdas

[paulwatkins]

Dear Phil:

If it is a design flaw, then I would expect them all to do it. If it is just a production flaw, then I would expect some, but not others, to have the problem.

Sincerely,

Algirdas

Guys, I recently had a problem with my Peco exhaust. The inner tube in the exit pipe had come away and was rattling about within the oval pipe. (I hope you get what I mean).
Peco did say that they would look at it and repair it for me, but that would involve me removing it from the car, posting it off to them, them looking at it, repairing/replacing it, sending it back, me re-fitting it! All downtime during the summer!

So I decided to go to a local stainless custom exhaust shop in Bristol because
a) it would mean minimal downtime.
and b) I didnt like the oval exit anyway, and wanted something different.

Anyway, to cut a long story short, when the rear exit was cut off, it was found that the inner pipe (which had come loose) was only attached to the muffler by 3 small tacks, and not welded continually around the circumference. The guy commented that this was pretty poor manufacturing.

I dont know if this would be common to all systems, or if it was just mine, but if this inner tube is only tacked on, maybe the areas that are not welded may be letting the gases through and causing a screeching noise (similar to when you blow through 2 blades of grass)

Just a thought! Something to add to the pot.

Cheers, Paul

[Rambo]

Dear Phil:

If it is a design flaw, then I would expect them all to do it. If it is just a production flaw, then I would expect some, but not others, to have the problem.

Sincerely,

Algirdas

Guys, I recently had a problem with my Peco exhaust. The inner tube in the exit pipe had come away and was rattling about within the oval pipe. (I hope you get what I mean).
Peco did say that they would look at it and repair it for me, but that would involve me removing it from the car, posting it off to them, them looking at it, repairing/replacing it, sending it back, me re-fitting it! All downtime during the summer!

So I decided to go to a local stainless custom exhaust shop in Bristol because
a) it would mean minimal downtime.
and b) I didnt like the oval exit anyway, and wanted something different.

Anyway, to cut a long story short, when the rear exit was cut off, it was found that the inner pipe (which had come loose) was only attached to the muffler by 3 small tacks, and not welded continually around the circumference. The guy commented that this was pretty poor manufacturing.

I dont know if this would be common to all systems, or if it was just mine, but if this inner tube is only tacked on, maybe the areas that are not welded may be letting the gases through and causing a screeching noise (similar to when you blow through 2 blades of grass)

Just a thought! Something to add to the pot.

Cheers, Paul

Good theory Paul and I also tend to agree with Algirdas.

No problems with mine and it came from the 1st batch that Geoff organised. It would be interesting to identify if any of the original dozen or so people have had problems ? I know there was a slight delay for the second batch because of supply and demand. Perhaps they weren't made quite as well as the 1st batch?

Anyway mine is still performing well, looks good and makes the car sound as sporty as it looks.

PS The only screeching I get comes from the passenger seat when I approach corners a bit too fast !

[philip_sloper]

I have had a look inside the rear tailpipe assembly on mine. There seems to be a continuous bead of weld around the outside of the joint where the inner tailpipe is welded to the end plate of the silencer, no obvious holes visible from the outside. Looking inside doesn't help as the inside diameter of the tailpipe is slightly smaller than the hole in the endplate so you can't see the joint itself.

But the idea that a small hole somewhere there could cause some kind of noise seems plausible. Perhaps other people who suffer from the screech can have a look at their welds?

[GeoffSmith]

Some more for the pot....

Mine was from the first batch and it screeches.

My tail pipe is fully welded and it screeches.

[ESM]

Just to add another bit of data... I was talking to Chris Foulds (specialist Lotus garage owner) the other day. He has fitted three Peco exhausts and none have screeched. All have crept though.

[algirdas]

Dear All:

Here is a new definition of "hell". I'm not even married and I have a mother-in-law in the car. As feared, I am part of the screecher club.

I will gather more data on the way up to Aspen/Snowmass and will post up as the opportunity presents itself.

Sincerely,

Algirdas

[ESM]

I stand corrected - one of CFs customer's informs me his did screech!

[Rambo]

Some more for the pot....

Mine was from the first batch and it screeches.

My tail pipe is fully welded and it screeches.

Since we were amongst the first to have the PECO's fitted Geoff and yours screeches and mine doesn't the only discernable difference I can see is that you have an S2 and I have an SE. Don't think Monty has any problems with his SE either and his was fitted at PECO a few hours before mine ?

[GeoffSmith]

Some more for the pot....

Mine was from the first batch and it screeches.

My tail pipe is fully welded and it screeches.

Since we were amongst the first to have the PECO's fitted Geoff and yours screeches and mine doesn't the only discernable difference I can see is that you have an S2 and I have an SE. Don't think Monty has any problems with his SE either and his was fitted at PECO a few hours before mine ?

Good point Mark, although I'm pretty sure some SE's had the screech - makes me wonder if the pre-cat housing {exacerbated by being full of carp in the S2?} has anything to do with it though, as it isn't exactly free flowing.

[Monty]

If there is SE`s havimg the same problem, i`m still going with the welds theory as it seems some have problems whilst others don`t and since (IIRC) the welds are manually welded it would be a reason why it`s a hit `n` miss.

[Rambo]

Just out of interest, has PECO Dave any theories on this ? He also has an SE and I'm sure if his exhaust screeched he would have bottomed it by now.

PS Monty - if you get any screeching it's probably your Man Utd pal Dico when he's a passenger as you approach a corner too fast LOL

[algirdas]

Dear All:

Let me really go off the deep end here: I have an SE with the pre-cat. Probably all gummed up. I installed the PECO exhaust and it screeches. But it only does it around 6,000 rpm. I can be at .5 bar boost all day long with nary a wimper, but hit 6Gs and its showtime with Carmen Miranda at center stage!

The other day I was in the left lane during a stretch of highway where the concrete barriers that separate opposing lanes of traffic are fairly close to traffic. With the top up and the left window down, I noticed that I get a low pitched and low volume "groan" first and then the high pitched scream around 6Gs.

Now for the weird part-it seems to be coming from the left front corner of the car! Intercooler?

An exhaust leak should sound like a fart in keeping with the exhaust pulses of the car, but I guess the turbo evens out the pulses. The muffler could whistle. But something on the intake side could make more sense in terms of a whistle. I realize I am all over the board here, but it deem seem odd that it was coming from the front left of the car.

What do you guys think?

Sincerely,

Algirdas

[philip_sloper]

Perhaps we can summarise who has got what (amongst the screechers) in order to get a profile. i.e
1. SE, S2 or Fed
2. Standard Peco tailpipe or "circumcised"*
3. Standard downpipe or "stiffy"**

*Standard looks like the attached picture, "circumcised" was the term used in the original group buy for a tailpipe design without the inner pipe, just the outer oval.
**If you haven't changed the downpipe from the engine to where the Peco starts then you are standard.

I'll start off:
1. SE
2. Standard
3. Standard

[GeoffSmith]

1. Philip_sloper SE, standard, standard
2. geoffsmith S2, standard, standard

[algirdas]

Dear All:

For me its: California Fed, Standard, Standard and it screeches.

Sincerely,

Algirdas

[GeoffSmith]

1. Philip_sloper SE, standard, standard
2. geoffsmith S2, standard, standard
3. Algirdas CalFed, standard, standard