Piper Exhausts turbo downpipe development thread

[PiperRS]

We have not changed the design from the first one we sold.

We made these as a batch, this helped keep the cost down, they are very tricky to make and making them individually would be very expensive.

when we make the next batch, i will consider a re-design but my main concern will be the price of the part. As i mentioned before, im aware it may not be the best possible design but the downpipe we released is better than the stock downpipe it replaces, and (i think) is very well priced.

If we were to make the downpipe with this 'baffle' inside, but it was say £100 more, would it still be a part you would buy?

[HJ2]

Dear Tom,

Thanks for taking up the conversation again, appreciated!

IMO the pipe as is, is not better than the original until it does not cause additional problems over the OEM design.
Now it does, as the original downpipe runs OK, but your pipe does not, it is the root cause of boostcreep. That also implies that the price is not right as well @ the moment. Who wants to spend time and money on something that will cause problems with your car?

Therefore I would suggest that the baffle should be a part of the new batch, because if not, your product is the cause of more Elan's developing boost creep. This is not good for the Elan community AND not good for your business, so a loose - loose situation for all. That's my opinion at least.

The Baffle itself is easy and cheap to manufacture, but putting it in afterward is time consuming, thus expensive if you do this on a professional basis (like you).
However, incorporating it in the design and putting it in during the welding process makes everything a whole lot easier thus cheaper. I think it's possible to keep the additional cost way under 100 GBP you mentioned. If the design is corrected, then yes, the price is fair!

I am aware that not everybody is experiencing problems, but there are many many reasons possible why this does not come to the downpipe but something else.
I had the problem however, and cured it just by changing the downpipe. You do the math!

We had an extensive email correspondence already about the downpipe and the design being not complete. Give me some time and i will drop you a line with the details.
Anyone who has boost creep problems right now: drop me an email (not a PB please) and i will try to help you out as well

As the Dutch company Phillips already said in their advertisements: "Let's make things better"
Why not exactly do that?


Happy Elanning all!
Henk-Jan

[m100sandra]

In a nice way I still have mine here waiting for my better half to fit it, tbh i have been keeping a eye on this topic and am really reluctant to pester him to fit it
Surly when somthing is sold from a reputable company (the exhaust system is spot on) it should be sold as fit for purpose, or maybe with a health warning that this down pipe may not work It just seems wrong that somthing can be sold that doesnt work as it should.... ?
Come on Piper..... surly its better to keep your exelant reputation.....
Just my 2p's worth, i really want mine fitted
Sandra

[whippit]

just my 2 pence worth, sounds like HISPEC brakes all over again, bob brown sorts the design problem for them and gets no thanks from HISPEC

HJ2 does all the problem solving engineering and gets no thanks,
m100sandra comment ring true to me

piper admit its a compromise, what between working and not, it baffles me how a company can sell a product that might work, i understand there must be thousands of variables, but you just have to look at HJ2 photos to see something's wrong,
come on Tom, most of your exhausts have been sold on reputation and recommendation, i cannot fault your exhaust's for welding quality' finish and fit,
but to fob people off and say it will cost you more for a small baffle plate to be installed to correct a manufacturing failing
when your internal finishing of HJ2 down pipe was shocking, surly your quality control must be embarrassed at those pictures,

i would love to buy your down pipe but only if it fit for purpose,

[Jeemy]

Here's a picture of what I got. Is this OK? Normal? Flawed?

P1010466.jpg

[Steve A]

Here's a picture of what I got. Is this OK? Normal? Flawed?

I think you'll find we all got the same, it's time to get the dremel out

[Alan_C]

I'm not convinced it's all Piper's fault that their replacement downpipe is causing over boost. Changing pretty much any part of the stock exhaust for aftermarket parts can cause over boost, as we know. My car, for example, was bought already fitted with a stainless Peco 2.25" single silencer system. Everything else was still factory stock. I could easily provoke an over boost situation followed by fuel cut. Wasn't the factory fitted standard exhaust equipped with a squashed pipe for which we could not find a reason, and some surmised it was to restrict the exhaust and provide some back pressure in the system, possibly to prevent over boost? I'm pretty sure Lotus never confirmed this however. I fitted an Everest chip and converted to closed loop (actually running a Killi chip on a switcher now), and still got over boost. The turbo needed to be modified by porting the waste gate valve. Once I had my turbo on the bench, it was ported to the maximum while still allowing the flap to seal closed, this was measured at 21mm. I also gas flowed the area inside the waste gate valve before the flap. This area is rough and the casting doesn't provide a good path for fast flowing hot gases to pass into the port, it was quite angular. An hour with the grinder made a huge difference to the apparent flow characteristics to this area. While I don't hold a Phd in fluid/gas dynamics, it was pretty easy to see that a little work in the area is needed. On turbo refitment, I could not provoke over boost, no matter what I did, although I have not tried with the switcher set to factory mapping. I then fitted a ceramic coated "stiffy" downpipe, noting that there was no separation for the 2 gas flows at all, just a huge open flange that covered both. I experienced no over boost, and have never experienced it to date (some 2 years now). The downpipe change gave some performance increase, I haven't dyno measured it, but the acceleration is stronger and smoother, the turbo spools faster and maintains boost more progressively than with the stock cast iron dustbin. I can therefor only conclude that it's the turbo design limitation that causes over boost and changing parts of the exhaust from stock can provoke it. Piper have therefor not made a duff product, although careful redesign may be able to provide gas flow properties that help the waste gate gases flow into the exhaust better than the stock downpipe and so reduce the chance of over boost, but this is an area that Piper shouldn't need to research into, as the cost of the downpipe would then become excessive for a retail item. Even fitting a replacement exhaust from them most often produces over boost. Therefor I think the onus is on the owner to port and gas flow the turbo BEFORE the exhaust parts are fitted. The items produced by Piper in my mind are fit for purpose, but should be supplied with instructions on turbo modifications required prior to fitting the exhaust parts.

[HJ2]

Therefor I think the onus is on the owner to port and gas flow the turbo BEFORE the exhaust parts are fitted.

I did just that. 21 mm. Well, did not flow as i did not want to take the turbo apart
Although i can follow your story above, i still think a deflector should be an integral part of the design!

[Alan_C]

.... i still think a deflector should be an integral part of the design!

In an ideal situation, yes, I agree with you. Also perhaps the join should be further down the pipe too, but all this would add to the engineering costs for producing the downpipe and the overall retails cost would escalate until the product was no longer a viable situation. Would you pay a possible £400+ for a downpipe (and you'd still need to port and even gas flow the turbo). Piper have produced an item, at a reasonable cost (it's still not exactly cheap), that will replace the cast iron rubbish. I would be happy to use the Piper product, though like you, I may modify it. It an option we have as consumers.

[dapinky]

Hmmm, been thinking about this one since Alans post - and I think I agree with him!

....just for arguments sake, lets assume that Piper had made the downpipe first, and then after a year or 2 of good sales, they produced their free-flowing 2 1/4 system....

...what would be the likely outcome?

As no-one has (to my knowledge) fitted the new downpipe to an OE 2" exhaust I can only guess as to the outcome from my tongue-in-cheek scenario....

...perhaps the downpipe with OE exhaust would increase exhaust speed and turbo spool-up and give a nice power increase without boost creep....

....then when we add a 2 1/4" system it would end up with the overboost we now see.....


.....so would we all be saying that the 2 1/4" system was what was causing the boost creep and complain about it???

The problem in any given development is cost vs result - and can only be fully sorted with a lot of testing - as i see it, that is the situation we are now in - the testing phase!

It is the whole system which provokes boost creep (and i don't mean the whole Piper system, but the whole thing from exhaust valve to fresh air!) - Piper are just the company who makes a cracking exhaust pipe and a downpipe which *may* need a tweek, but work on the turbo wasn't in their brief. (even though it is beneficial).

[HJ2]

Sorry, but i just don't agree with you on this one, and i made in earlier posts clear why.
Of course everybody is free to decide for themselves if the current product is good value for money.
Can't argue with that

(I wrote this before your reply, dapinky ;/) )

[Rice crispy]

Ive got a standard 2" exhaust on mine with a everest and no overboost, if piper want to try a downpipe on it to prove the downpipe is ok then im happy to provide a car for test

[Steve A]

if piper want to try a downpipe on it to prove the downpipe is ok then im happy to provide a car for test

I think that puts you at the front of a very long Que Dave, I like your style

[Rice crispy]

Don't ask you don't get knew it was a long shot

[ashm]

Ok, question for those who have installed the downpipe.
How did you tighten the bolt on the lower front turbo/downpipe stud? It's in a recess in the downpipe, and there's too small a gap between the nut and radiator to fit a normal spanner in there.
Do I need some sort of cranked spanner? Crows foot maybe?
Thanks,
Adam

[HJ2]

I installed the pipe to the turbo before putting the turbo back in

However, i removed it later on to weld the deflector in.
If i recall right i shortened the stud a little so i had more play to fiddle around.

[m100sandra]

I think Steve cut a old spanner down to size

[surfboardfiller]

Sorry, but i just don't agree with you on this one, and i made in earlier posts clear why.
Of course everybody is free to decide for themselves if the current product is good value for money.
Can't argue with that

(I wrote this before your reply, dapinky ;/) )

The deflector you installed will reduce the flow, its your design based on the original Lotus part which is a horribly flawed piece of engineering.
My understanding of fluid dynamics from the books I have read and my experience with the McLaren 12c Turbo system favour the Piper design over the Lotus (whoever their supplier was) part.

You have to have a lot more understanding of fluid dynamics to just cut up the pipe and shove 'whatever you think is best' in place. The small deflector will mix the flows with an eddy which is exactly what you want, when the waste gate opens the gas through the WG will be faster as there is less resistance than through the turbine and both ports will have gas running through a much lower pressure than with the wastegate shut; as the surface area of the WG port is ADDED to the overall exhaust flow reducing the flow from the turbine.

There is no need to have the waste gate deflecting lots of gas or even mixing further down the pipe. The Piper down pipe is simply a lot bigger than the Lotus one so the mix isn't critical, we are not running a V8/V6, high displacement or high pressure turbo, its a 1.6 with a little turbo on a light car. The waste gate should not shut down the turbine as it is attached to the impeller which is still feeding the engine with air, if you stop the turbine the engine will stop.

If you have problems with overboost then your turbo may need rebuilding if you still have problems then you may want to fit a boost controller but there are cars running with this pipe without problems.

[surfboardfiller]

Ok, question for those who have installed the downpipe.
How did you tighten the bolt on the lower front turbo/downpipe stud? It's in a recess in the downpipe, and there's too small a gap between the nut and radiator to fit a normal spanner in there.
Do I need some sort of cranked spanner? Crows foot maybe?
Thanks,
Adam

Is this sorted now? Do you have air con?

[HJ2]

Sorry, but i just don't agree with you on this one, and i made in earlier posts clear why.
Of course everybody is free to decide for themselves if the current product is good value for money.
Can't argue with that

(I wrote this before your reply, dapinky ;/) )

The deflector you installed will reduce the flow, its your design based on the original Lotus part which is a horribly flawed piece of engineering.
My understanding of fluid dynamics from the books I have read and my experience with the McLaren 12c Turbo system favour the Piper design over the Lotus (whoever their supplier was) part.

You have to have a lot more understanding of fluid dynamics to just cut up the pipe and shove 'whatever you think is best' in place. The small deflector will mix the flows with an eddy which is exactly what you want, when the waste gate opens the gas through the WG will be faster as there is less resistance than through the turbine and both ports will have gas running through a much lower pressure than with the wastegate shut; as the surface area of the WG port is ADDED to the overall exhaust flow reducing the flow from the turbine.

There is no need to have the waste gate deflecting lots of gas or even mixing further down the pipe. The Piper down pipe is simply a lot bigger than the Lotus one so the mix isn't critical, we are not running a V8/V6, high displacement or high pressure turbo, its a 1.6 with a little turbo on a light car. The waste gate should not shut down the turbine as it is attached to the impeller which is still feeding the engine with air, if you stop the turbine the engine will stop.

If you have problems with overboost then your turbo may need rebuilding if you still have problems then you may want to fit a boost controller but there are cars running with this pipe without problems.

Ah! So i fixed a bad turbo in it's early state by adapting my downpipe?
I really don't think so.

My turbo is in excellent condition as are the bearings, compressor wheel and turbine wheel. Judging the state of these parts is now part of my job actually, now that i have a mini Jet engine to maintain.

Anyway, I partly agree about the size of the diameter (the V8 story ) so diameter is not the crucial flaw, it's overdimensioned for sure. No, the big gain of the piper design is the way that the minimal bending radius is reduced and the flow is smooth and more straight in stead of the nasty sharp angles and steps in diameter in the S2 OEM pre-cat lump + downpipe!

So this is where most of the gain comes from, not the bigger diameter.
Without the deflector the wastegate jet is injected at almost 90 degrees which causes violent turbulation, reducing the amount of flow that the main flow can cope. So it is not a matter of larger diameters, but optimising flowdirection and avoiding diameter steps.

The pipe did not work on my car initially, but after my modification it works perfect
Now the Knox design does a far better job with mixing the flows, but the Piper is what i had and thus what i had to modify to make it work.
I still have the benefit of the smoother flow and the OEM-like deflector i made cured the overboost on my setup anyway.

So it may reduce the flow without the waste-gate being opened, but the diameter was overdimensioned anyway so i won't notice that. However the flow with opened wastegate absolutely improved after the addition of the deflector. Hence my cured overboost.

again, my 2 cents