Piper Exhausts turbo downpipe development thread

[ccb056]

This is the best picture I have seen so far of how the OEM downpipe separates the 2 flows.
If anyone else can get better pics of the OEM showing just how far deep that baffle goes, then from a design standpoint we can start modifying the Piper downpipe to at least be equivalent.

What is the obsession with keeping things equivalent? Different approaches can give similar results.

Examples.

Standard hand dryer. Dyson air blade (if you don't have this in the US then google it)

Concorde, Harrier, Boeing 747

Apple, Microsoft.

Do you have a Piper downpipe? Being US based I doubt it. So how do you feel qualified to comment on something you have never seen or driven a car fitted with it?

I have this on my car and am very happy with it so please stop complaining about this product based on nothing but your personal preferences and theories.

If you read my last post, I have suggested several ways of collecting data, how about we do that?

I'm not complaining that Piper took a different approach.
I'm simply stating as a mechanical engineer my professional opinion as to why the Piper downpipe could be causing the overboost issue for so many people.

[Steve A]

lack of brackets for heat shields

I don't think the heat shield is needed, as the down pipe isn't a bulky heavy cast mass it replaced so brackets are not required.

i cannot understand why piper has not commented on the issues

Maybe because the thread has descended into a slanging match but it would be nice for them to "Pipe up"

I'm simply stating as a mechanical engineer my professional opinion as to why the Piper downpipe could be causing the overboost issue for so many people.

That's fair enough, but that's not get carried away by blaming the down pipe, in my case I had over boost before I fitted the down pipe,
I was hoping that by porting the waste gate whilst fitting the down pipe it would have sorted it.
Boost creep/over boost is a common fault with Elans that fit a larger bore exhaust, as we well know.
If we look at all the different set ups from people that have actually fitted the down pipe and then compare the results people are getting (good or bad) we can learn how we can improve things,
as Cliff's set up is similar to mine I am encouraged by the positive results he has been getting, and it proves to me that it's not the down pipe causing boost creep.

[paulsmithmk]

I have a full piper exhaust + precat , i had every intention to buy the down pipe, i would love to have a full system,
but after seeing the quality of finishing on HJ2 i decided not to

i have no knowledge of fluid dynamics or wish to,
i cannot understand why piper has not commented on the issues that have been brought up on the quality control , (rough arse internal finish , lack of brackets for heat shields

never mind the other issues

it looks to me like this product has had little thought apart from making sure it fits, i'm sorry this is my personal preference and theory.

I dont have photos but there was nothing wrong with the quality of mine...

[HJ2]

Then perhaps Piper did do something positive on the quality side of things.
I posted detailed pictures of what was wrong with mine, mainly on the inside, and what I have done to correct it.

Just to be sure, when i placed my Piper downpipe, my car was running perfectly with:
* S2 (so O2 sensor and everything)
* Everest
* Ported wastegate
* OEM downpipe
* OEM but empty pre-cat housing
* Piper 2.25" exhaust
* No Main CAT

After this I replaced:
* The exhaust manifold for another OEM (so no changes here)
* The first bend of the exhaust after the downpipe due to damage (for yet another one of Piper's finest, so also no changes here as well)
* The OEM lump + pre-cat housing for a Piper downpipe, where the internals of my Piper have been flowed.

After this, boost-creep returned. IMHO this can only be due to the flaw design of the Piper downpipe, which was confirmed by my flow-dynamics colleagues yesterday (it is not that hard to see)

Might I add to the overall discussion in this thread by stating that this is a FORUM, a discussion platform so to say. IMHO anyone is welcome to discuss an comment things even if they have nothing to go by than a picture and do not have the hardware itself. It is in my opinion good to have as much comment, meaningfully or not so meaningfully, as possible to chart the problem and derive solution directions. In my experience as a test engineer for rocket engines it happened multiple times that a solution direction was determined based on pictures and drawings ! So please everybody is welcome to discuss, and everybody who wants to bash will simply be ignored in time.

Anyway: so I took the Piper out and took it along with the OEM lump for comparison to my colleagues. The general opinion on matters is that the flow of the wastegate enters the main flow to steep, causing impinging problems (turbulence and pressure differences). DUH! The way to solve it is to let both flows mix at a minimum angle of 45 degrees. DUH!
You can't produce a baffle that reduces this to 0 degrees because it will take up too much volume of the main flow (and restrict it again) So I'll have to find an optimum.

My plan now is to dremel out a groove with the desired shape of the baffle. (both sides of the downpipe "head'). The sheet metal baffle is then bent into profile on a bench, inserted in the groove and welded from the outside. I am sorry, but I am not gonna place it back in order to do an Elanscan prior to the work.

We'll see what happens after replacement. I have to be quick as temperatures are rising and chances of boost-creep reduce.
As always, I'll keep you informed. Now go out and drive in stead of hanging around behind your keyboards!

[Steve A]

I posted detailed pictures of what was wrong with mine, mainly on the inside,

Yes I have to agree with you there, as mine was the same

After this I replaced:
* The exhaust manifold for another OEM (so no changes here)
* The first bend of the exhaust after the downpipe due to damage (for yet another one of Piper's finest, so also no changes here as well)
* The OEM lump + pre-cat housing for a Piper downpipe, where the internals of my Piper have been flowed.

After this, boost-creep returned. IMHO this can only be due to the flaw design of the Piper downpipe, which was confirmed by my flow-dynamics colleagues yesterday (it is not that hard to see)

So the down pipe for you is looking like the cause of your problems, this is where Piper could offer advise

Might I add to the overall discussion in this thread by stating that this is a FORUM, a discussion platform so to say. IMHO anyone is welcome to discuss an comment things even if they have nothing to go by than a picture and do not have the hardware itself. It is in my opinion good to have as much comment, meaningfully or not so meaningfully, as possible to chart the problem and derive solution directions. In my experience as a test engineer for rocket engines it happened multiple times that a solution direction was determined based on pictures and drawings ! So please everybody is welcome to discuss, and everybody who wants to bash will simply be ignored in time.

yes I totally agree with you, as long as nobody has an axe to grind and has a positive approach, there's banter and then there's abuse

Good luck with your grinding, I look forward to your progress

[cliff]

Good work HJ, hope you get some positive results.

Now go out and drive in stead of hanging around after your keyboards!

I wish I could, I am in Frankfurt & the car is in the UK getting a respray.

[ovi]

Might I add to the overall discussion in this thread by stating that this is a FORUM, a discussion platform so to say. IMHO anyone is welcome to discuss an comment things even if they have nothing to go by than a picture and do not have the hardware itself. It is in my opinion good to have as much comment, meaningfully or not so meaningfully, as possible to chart the problem and derive solution directions. In my experience as a test engineer for rocket engines it happened multiple times that a solution direction was determined based on pictures and drawings ! So please everybody is welcome to discuss, and everybody who wants to bash will simply be ignored in time.

[paulsmithmk]

if anyone knows of appropriate testing location not so far from Milton Keynes I am happy to pay and get it booked in and post results...

[Steve A]

Wilshers Garages
Automobile Engineers
Cambridge Road,
Wimpole
Royston
Cambridgeshire SG8 5QE

Rolling Road (Peter Baldwin) on: 01223 207217

I know it's not MK but it's not far.
It's a "proper rolling road" they let you stay with the car/help out.
Peter is a legend and knows his stuff, he's been going for years,he usually has a que of "interesting cars"waiting to go in, just google his name, he also races mini's

[rip]

That's not so far from Milton Keynes.
Not far off Paul's route home when collecting the car from having its new interior fitted.

[paulsmithmk]

That's not so far from Milton Keynes.
Not far off Paul's route home when collecting the car from having its new interior fitted.

This is true and not so far to pop over anyway - I will get in contact with him next week...cheers P

[HJ2]

Just now I Determined the free area where the flapper goes when fully open (25 mm's)
And sketched the outline of the baffle on the downpipe head. Let's see if i can finish it tomorrow and fold the steel and dremel the groove in the downpipe head so everything is ready for welding...

[paulsmithmk]

I recalled an out of touch friend had some contacts and I now have access to full test station in Milton Keynes (as long as I am not over 1000 BHP?!!) price OK so as soon as I have car back I will get it booked in...

[cliff]

Hi Paul,

I would be up for some of the same if your contacts don't mind. 2 cars on the same rolling road should give some clear figures. A comparison between cat & non cat will also be interesting.

I have a lot on at the moment, I've told the guy doing the respray to take his time as I am busy until the beginning of May. For me any time after that would be great.

Could you drop me a PM with prices & location.

Thanks

[Jeemy]

Following this with interest. I've had my wastegate bored out to 21mm and have the Piper ceramic downpipe sitting waiting to fit. I wasn't intending on Dremel-ing it having been told by Piper that was not necessary but am now considering that as the very least action to take…..

I've never opened the packet, if you need pictures I'd be glad of the excuse to do so!

[paulsmithmk]

it is so hard to say what will work here - I hope to post results in next few weeks but I am really happy with my set up no matter what the stats say! wastegate was ported to 20mm on basis it's hard to put some back but easier to take more off!

[Jeemy]

Piper were very clear that they had never heard of any problems. This was 4, 5 months ago? I am a bit worried. I really just want to set it and forget it…..enough other stuff to worry about.

[HJ2]

Never heard? I have an extensive email correspondence which obviously I won't share here.

No progress yet as I don't have the time to do anything being a fresh dad and all

[Jeemy]

Yes, I mentioned the concerns with you (not by name) and the Dremelling and also I think it was Steve made some cryptic comments about the ceramic coating being on the outside and therefore less use, possibly something else. I asked if they knew about those concerns and they acted baffled.

More importantly, congratulations! My little one turned 1 on Sunday and took his first steps the same day; I was absolutely beaming. You'll love it.

[ovi]

This weekend I was visiting Hj.
I've seen the original downpipe and clear that in the origin is indeed a distraction and that of piper not so I do follow the logic of Hj!

Hopefully your understand what I'm saying because much work on my englisch!