Piper Exhausts turbo downpipe development thread

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Re: Piper Exhausts turbo downpipe development thread

Postby ccb056 » Sat 02.11.2013, 22:10

Dapinky,

I think everyone in the thread agrees that the Piper downpipe provides for more flow through the turbine, giving better response when compared to the OEM design.
Therefore, by installing the Piper downpipe, your wastegate will have to be open more than it does in the OEM design to be able to adequately control the boost.
I think you will find a lot of information if you perform an elanscan of your car.
Specifically, make multiple runs through 3rd gear to redline at 100% throttle.

If you find that the wastegate duty cycle goes to 0% (0% closed, 100% open) then you will know that that Piper downpipe will likely [possibly?] cause boostcreep.
If you find that the wastegate duty cycle does not go to 0%, then you may be able to install the Piper without boostcreep.

I have attached my data on an OEM downpipe, with Piper PCE, Piper 2.5, Everest, and RC injectors.
3rd everest.png


As you can see, the X-axis is RPM.
The Y-axis on the left is boost pressure (blue dots).
The Y-axis on the right is wastegate duty cycle (red dots).

What this data is telling me is the car is capable of achieving 0.90 bar boost, but the wastegate must be completely open.
Any more flow through the turbine means less flow through the waste gate (replacing OEM downpipe with Piper).
Any less flow through the waste gate means boost creep.
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Piper 2.5 Resonator PCE; 21mm wastegate; Everest
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Re: Piper Exhausts turbo downpipe development thread

Postby dapinky » Sat 02.11.2013, 22:47

I haven't done any recent elanscan runs where I go to redline in 3rd as I haven't been on track in it this year :cry:

I see what you mean about the POTENTIAL improvement that a good downpipe may give, but what I'm really after is an answer to the $64,000 question "Will the downpipe give me a better driving experience than the system I already have" - and I believe that HJ is the only person to have gone from a Piper PCE to a Piper downpipe (but there may be others).

If i hadn't already got the PCE, i would be far more likely to get the downpipe, but having already bought what was the (then) best system availlable, will I see much of an improvement now for the money which needs to be spent.

It's not about top speed for me (and max power isn't at the red line anyway) - it's about the general 'pull' of the car.
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Re: Piper Exhausts turbo downpipe development thread

Postby DeeAitch » Sat 02.11.2013, 22:56

HJ2 wrote:Meanwhile, on the true Piper front:

I was thinking: Why not guide the wastegate gasses into a tube of a slightly larger diameter diameterthan the porthole, say 25mm. Then let it stick at a 90 deg. angle through the core flow (slightly flatten the tube where it goes through the core flow for less core resistance). after this section there is a lot more room to make a large radius and one could join the 2 flows at just a small angle at the end of the piper again. A bit of a hybrid between Piper and Knox ... The deflector can be ditched all together then. :poke:
Opinions please! (theory or evidence based ) :-D


I actually drew this up on the back of a fag packet a few months ago, even contemplated making it but 'we' did not have any 25mm tube and 'I' did not have a template.
Production would have been a nightmare - 2 half pressings or a lot of cut n shut.
So I decided to buy a Merc instead :-D
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Re: Piper Exhausts turbo downpipe development thread

Postby HJ2 » Sun 03.11.2013, 08:54

dapinky wrote:I haven't done any recent elanscan runs where I go to redline in 3rd as I haven't been on track in it this year :cry:

I see what you mean about the POTENTIAL improvement that a good downpipe may give, but what I'm really after is an answer to the $64,000 question "Will the downpipe give me a better driving experience than the system I already have" - and I believe that HJ is the only person to have gone from a Piper PCE to a Piper downpipe (but there may be others).

If i hadn't already got the PCE, i would be far more likely to get the downpipe, but having already bought what was the (then) best system availlable, will I see much of an improvement now for the money which needs to be spent.

It's not about top speed for me (and max power isn't at the red line anyway) - it's about the general 'pull' of the car.



Sorry to disturb the party, but i did not have a PCE, just an emptied OEM pre-cat housing :poke:
If you already have a PCE my guess would be that it is not that interesting to get the Piper downpipe. There might still be some gain in HP left, but not that much that you wil notice it like the step where the pre-cat get's ditched 8) But i think i wrote this somewhere earlier in this topic.

I will investigate the pipe / piper option once more as i have an unmodified piper in the garage for Peter's briljant car.


What i noticed after placing the Piper in stead of OEM downpipe and EMPTY pre-cat housing: Faster spool up time, thus earlier use of turbo power.
If now someone will tell me it is all between my ears, I cannot prove him (or her!) wrong (Where is LGM in this topic?).

However, i need to finish Peter's headgasket and several upgrades before i can even think of making another run with my car. Then there's the family saloon i recently obtained, a BMW 530i touring which has got bad valve lifters (Grrrr!) And the Elan's exhaust needs to be tweaked as well to get it gastight again so the Lambda probe does not mess up the mixture :bonk:

Meanwhile: Let's discuss possible options with the Piper pipe as this is still available :cheers:
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Re: Piper Exhausts turbo downpipe development thread

Postby dapinky » Sun 03.11.2013, 20:01

I've had enough now, and I've had PM's from a couple of people (one asking for a bit of 'moderation', and the other - well, I'm not really sure what it's purpose was, but I replied to it anyway)...

As a result, I'm TEMPORARILY locking this thread, reading it through from the beginning, and I'll no doubt be removing and/or editting some of the more contentious postings.

The first thing I've noted is that back on P2 (way back in 2011) I already asked for a bit of decorum, which happened for a while and progress continued quite nicely, unfortunately this has degenerated again and it has become unhelpful for most of us.

Whilst I'm all for frank discussion, I refer back to my earlier comments whereby if something isn't availlable it's pointless saying it is best and we all need it, and we need to be 'on topic' a bit more directly.

In the meanwhile, I ask everyone to chill out a bit, and if you don't like what I do, then feel free to post your opinions when I again unlock this thread (may take a few days), and If I don't like your opinions, I'll just delete them at that point :D
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Re: Piper Exhausts turbo downpipe development thread

Postby dapinky » Wed 06.11.2013, 14:37

Well, that was fun! - the thread is again open for posting.

I've gone through the thread, and the observant amongst you will notice that it is now 2 pages shorter than it was.

I have edditted [shown in red in square brackets] a number of other posts, either to explain why they may appear out of context, or just to tone down the seemingly abrasive comments where a total removal of the whole post would be counterproductive to the whole purpose of the thread.

Should anyone who has got those red bits on their posts wish to edit it themselves to make it read 'nicer' then it would be appreciated, but equally, should you wish to edit your own posts to read substantially differently just to cast disparagy at other forum users, then it will be viewed dimmly, and I WILL take further action.

Having gone through and PROPERLY read the whole lot, I would like it to remain on topic, so will state the following as a point of reference to anyone who wishes to make any further posts here:-

The thread is all about developing the PIPER downpipe - it is NOT about stating that the Knox pipe is better, or the Piper one is rubbish. Also, it is NOT the place to discuss theoretical physics - by all means start a new thread somewhere appropriate if that is what you want to do, but not here please.

[/Moderator input]

The following is MY personal assessment of where we currently stand:-

Piper make an 'off the shelf' product which is availlable to buy NOW.

When developed in consultation with all who took part, it fulfilled the design brief.
When tested on the 'mule' car [no dissrespect to Clive :D ] it worked and NO boost creep was caused, so it was marketed as 'fit for purpose'.
Those who purchased it (or are considering purchasing it) may or may not get boost creep with it fitted - often due to other things which may or may not have been changed.
The ONLY way to stop boost creep is to improve the wastegate flow - usually by porting it out to 20/21mm, but additionally by increasing the diameter a bit more, or improving the flow by cleaning up the flow before the wastegate (which I have done anyway - basic stuff for us old gits who have spent many hundreds of hours porting and flowing engines over the years to get the maximum flow rates - but maybe something not considered by many who have grown up in the 'buy-it-off-the-shelf' era.)
To say that the design is 'flawed' is incorrect, but to say it is perfect to fit 'out of the box' without any other considerations, without expecting the possibility of boost creep is equally incorrect.
Those who want an improvement can fit one on its own - those who want perfection need to accept that modifications will be needed to the basic unit.
Piper have already stated that a baffle plate can be incorporated into the basic design, but at a cost (as is reasonable to expect, given that it will involve more work to produce).
Boost creep in itself isn't a huge problem (but I may be wrong, and am open to correction), but only becomes an issue when it reaches the level where the fuel-cut operates.
I look forward to getting an elanscan run at WOT in 3rd gear to see what %age my wastegate is operating near the rev limit, now that ccb056 has shown me how to plot it to see what 'spare capacity' I may have (probably none!)

We have to remember that all the modifications being considered here at at the 'top end' of what is achievable with stock turbo/fueling components, and as such, any one component may well have an overall effect - each user can only really comment on what they have, and how it works for them.


In closing, I express my great thanks to most of the people who have expressed an opinion, and especially wish to mention the great work done by HJ2 in the spririt of the thread title :bowdown:
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Re: Piper Exhausts turbo downpipe development thread

Postby ccb056 » Wed 06.11.2013, 14:58

Thanks for cleaning up the thread a bit dapinky.

dapinky wrote:I look forward to getting an elanscan run at WOT in 3rd gear to see what %age my wastegate is operating near the rev limit, now that ccb056 has shown me how to plot it to see what 'spare capacity' I may have (probably none!)



I agree. I think what would be good to see now is some elanscan data showing how the Piper performs at high revs to see if there is or is not a problem.
I think it would also be informative to compare elanscan data between a Piper PCE (mine), a modified Piper downpipe (HJ's), and a stock Piper downpipe (surfboardfiller).

This data, in my opinion, would be valuable to anyone considering to upgrade their exhaust setup.
1991 Lotus Elan Fed, Monaco White
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Piper 2.5 Resonator PCE; 21mm wastegate; Everest
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Re: Piper Exhausts turbo downpipe development thread

Postby Steve A » Wed 06.11.2013, 16:20

:agree:

Then we can argue about the results :lol:
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Re: Piper Exhausts turbo downpipe development thread

Postby surfboardfiller » Wed 06.11.2013, 17:16

No, its no use comparing 3 different set ups on 3 different cars.

Comparing the same set up on 3 different cars: then you can test the single modification with more reliable results.
Comparing three different set ups on the same car: then you can compare the performance difference per modification.

It would be interesting to see and I would welcome anyone with a piper exhaust set up, to post their data, but most of us are using different exhaust pipes and the characteristics between 3 randomly selected 20 year old Elans throws so many variables into the equation the results are not going to pinpoint much, even if they were all standard equipment.

We have already seen cars get over boost without a piper product, non standard exhaust pipe (peco/miltek etc) or Mountain chip and then cars with non standard exhaust and piper down pipe running without overboost.
Last edited by surfboardfiller on Wed 06.11.2013, 17:21, edited 1 time in total.
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Re: Piper Exhausts turbo downpipe development thread

Postby ccb056 » Wed 06.11.2013, 17:20

You're assuming a lot of things in that statement and most of what you say is your own opinion. Let's post the data and let the people on the forum analyze it and draw their own conclusions.
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Re: Piper Exhausts turbo downpipe development thread

Postby surfboardfiller » Wed 06.11.2013, 17:59

ccb056 wrote:You're assuming a lot of things in that statement and most of what you say is your own opinion. Let's post the data and let the people on the forum analyze it and draw their own conclusions.


No I'm not assuming anything, I qualified my statement. To test reliably you remove as many outside influences as possible so you only have the thing you are testing; affecting the results, this isn't my opinion this is universally accepted and common practice in design and engineering.

The objective is to help piper develop the down pipe or determine what is actually happening in a specific setup as controlled as possible.
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Re: Piper Exhausts turbo downpipe development thread

Postby dapinky » Wed 06.11.2013, 18:09

I can see both points of view, here.....

...but as we "only" want to see what effect the Piper downpipe has, I can see little point in publishing MY data with PCE & 2 1/4 Piper pipe, other than to see if there is any 'spare capacity' with my current wastegate, or if I would only really see a benefit with the downpipe if I did more work in that area.

Either way, it wouldn't really show anything to anyone (other than perhaps 'bragging rights') else considering this upgrade.

The only real way to say how much improvement there is would be to fit one, and then publish before and after figures.

The next best thing is to rely on the likes of Hen-Jan (who has actually done the conversion, and whose opinion I respect) to say that the whole thing feels better!

He has done this many times so far throughout the thread, and as far as I know, he has elliminated the boost creep/fuel cutoff issue with a combination of wastegate work and pipe alteration....

....however, bottom line is "will I need to modify the pipe" - and without knowing what spare capacity the wastegate has got, I can't really assess that question with any confidence....

...and that isn't likely to happen anytime soon (next Spring)...

Individual P.max figures for individual cars mean little to me - I just want something which works for me.....

If Paul Watkins is still reading the forum, he can attest that at Llandow circuit I kept with him all the way, despite having 50+bhp (guestimate) difference in the cars - I have to admit, it was probably as much to do with the weather as it was my driving, but it just shows that individual cars are driven differently, and maybe I was a tad more 'enthusiastic' on the day (because my car is a tool not an ornament), and had the benefit of a shift light to keep me in the power band :?

Either way, it doesn't help anyone, except me, to assess the performance of MY car, so I'm back at the beginning :(
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Re: Piper Exhausts turbo downpipe development thread

Postby surfboardfiller » Wed 06.11.2013, 19:29

:agree:
I plan to test the same car (my S2) with a piper exhaust, then add a mountain chip to produce two sets of results.
Then those results can be compared to the car with a piper down pipe added with/without the same mountain chip.

Results for:
Piper exhaust
Piper exhaust with Mountain chip
Piper exhaust & down pipe
Piper exhaust & down pipe with mountain chip

All on the same car, so I am testing the upgrades not the car.

This won't be results that guarantee to help other people on their aged/mint cars, but it will give a good set of directly comparable data and a car I can analyse should any problems arise and that way it may well help other people with their cars.

There's not much point in me testing the track car; as it is so heavily modified the results would be irrelevant to anyone else's set up and any problems would be due to my abnormal set up.

I'll get back to you when I'm done......
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Re: Piper Exhausts turbo downpipe development thread

Postby Steve A » Wed 06.11.2013, 19:40

surfboardfiller wrote:Results for:
Piper exhaust
Piper exhaust with Mountain chip
Piper exhaust & down pipe
Piper exhaust & down pipe with mountain chip

All on the same car, so I am testing the upgrades not the car.


:agree:

This is the only way to test a product, but has not been practicably possible so far not to mention costly :roll:
It's a shame Piper couldn't do some before and after testing, it would certainly settle a few arguments either way and sell their product.
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Re: Piper Exhausts turbo downpipe development thread

Postby HJ2 » Wed 06.11.2013, 19:57

I'll see if Peter agrees to have 2 tests on his car.
An unmodified Piper and a modified (if needed!)

However, i already spend quite some time on his car, and i live by the day 8)


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Re: Piper Exhausts turbo downpipe development thread

Postby ccb056 » Wed 06.11.2013, 21:00

surfboardfiller wrote:Piper exhaust
Piper exhaust with Mountain chip
Piper exhaust & down pipe
Piper exhaust & down pipe with mountain chip

Thanks surfboardfiller! This is progress! :cheers:

Will you be using a Piper PCE for the first 2 tests?

If so, I think you will find your first 2 tests to be similar to mine, I have these 2 documented:
1. Piper PCE, Piper 2.5, 21mm wastegate, Lotus ECU: viewtopic.php?p=276742#p276742
2. Piper PCE, Piper 2.5, 21mm wastegate, Everest: viewtopic.php?p=277183#p277183
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Re: Piper Exhausts turbo downpipe development thread

Postby Peter D » Wed 06.11.2013, 21:41

HJ2 wrote:I'll see if Peter agrees to have 2 tests on his car.
An unmodified Piper and a modified (if needed!)

Totally up to you Henk-Jan.
If you can spare the time to do the comparison, it can only benefit other Elan drivers.
I'm very greatfull to be able to fall back on this forum for any questions, so if this can be a small contribution from my side, why not.
Please note that I'll still have the OEM cat and exhaust (same dimensions, though aftermarket replacement I think).
I would like to upgrade it to sportscat (or even without a cat if I can still meet Belgian MOT exhaust standards) in the future.
So the final modification will be close to what you have HJ2, and the downpipe modification as you've done on yours is very likely needed in the future.
Now is the best time to do so, as you're working on the car anyway.
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Re: Piper Exhausts turbo downpipe development thread

Postby HJ2 » Thu 07.11.2013, 21:30

Step 1: I Ported Peter's turbo to 21.5 mm just now :roll:
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Re: Piper Exhausts turbo downpipe development thread

Postby m100sandra » Thu 07.11.2013, 22:09

Think ill have to keep my fingers crossed, My Elan is currently away having a aftermarket ECU fitted, It as the uprated standard Turbo fitted (ported wastegate, bigger compressor side etc) Full piper exhaust including the downpipe, If all goes well ive asked Chris to keep the boost at 1.3 bar max, and i have mentioned to keep a eye open for the dreaded boost creep........
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Re: Piper Exhausts turbo downpipe development thread

Postby m100sandra » Mon 25.11.2013, 21:26

Just got a reply back from Chris who's doing the mapping, theres a prob :( :evil:

Quote:
Engine going strong, but houston, we have a problem..



Did you mention that sometimes guys struggle with boost creep ? We have a lot of it. 20psi by 5500rpm and climbing strong, so not good. The actuator is holding steady at 9-10psi until about 4500rpm, then the creep takes over.



Did you say the wastegate had been ported already ? And if so, was there much scope to go any larger ?
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