Piper Exhausts turbo downpipe development thread

[paulsmithmk]

No Boost creep?
Lucky you!

Wait for winter before you smoke the cigar...
As the air gets colder, it is getting denser and chances of experiencing boost creep increase.

As the air gets cooler the more she stays in the garage!!!

[HJ2]

Now there's an out of the box solution!
Haha

[ccb056]

Are there any temperature comparisons between the ceramic and non-coated down pipes? Perhaps Piper themselves could say how thick the ceramic coating is and how cooler the pipe is with it.

For 84 pound sterling (135 USD) I am not sure if a better deal for those in the US is to use Swain Tech ceramic coating on the Piper downpipe.

http://swaintech.com/advanced-coating-technology/

Swain Tech Coatings is the only company to offer a true insulating thermal barrier for exhaust parts. This external thermal barrier is applied approximately .012″ thick, has a white matte finish and does a tremendous job of keeping the heat inside of the pipes to improve scavenging and reduce under hood temperatures.

http://swaintech.com/race-coatings/auto ... ice-sheet/

Cast Iron Manifold (4, 6 or 8 cyl.) $150 – 235
Turbo Charger Housing $90 – 125
O2 Housing $50 – $100
Pipes, Down Pipe, Crossover, Collector, etc. $40/foot approx.

[surfboardfiller]

Ceramic coating on the inside (where it should be) was a lot cheaper.

I expect the GBP/USD exchange rate and usual higher prices here would lean in favour of getting it done locally in the US?

[paulsmithmk]

OK so as you clever lot predicted got my first boost creep at the weekend - cold weather, revving through the gears and boom - fuel cut off, warning light on for about 30 seconds then back to normal and no repeat. So question - is porting the wastegate my only option?

[ccb056]

Either port the wastegate or restrict the flow through the exhaust.

[surfboardfiller]

Either port the wastegate or restrict the flow through the exhaust.

Why would you restrict the flow through the exhaust? The whole point of the down pipe is to de restrict the flow through the exhaust to improve performance.

[rip]

Either port the wastegate or restrict the flow through the exhaust.

Why would you restrict the flow through the exhaust? The whole point of the down pipe is to de restrict the flow through the exhaust to improve performance.

Another option is to be a little more cautious with the accelerator. That defeats the object too.
With an Everest chip, the variation between target boost & overboost is very small so you won't be likely to see it on the boost gauge..certainly not in time to react with your right foot.

An alternative is to go the 'plumbing route' which fools the ECU. This goes against upgrading it with the Everest so you wouldn't need it. I prefer the ECU to know what is going on & make the appropriate adjustments so do not like this method, although many have done this with their Elan with no issues.

This leaves porting the wastegate.

[paulsmithmk]

or I guess only drive it on a warm day?!!

mmmm porting it will have to be I guess thanks guys

[Steve A]

The only thing I need to do now is alter the short section of pipe from the Piper down pipe to the exhaust,
I will be adding a flexi to take some of the strain and vibration away from the Piper down pipe, it's probably
why my exhaust sheared in the first place

I've now done this, it's all on and running (photo's to follow), I feel much happier with a flexi in position it will help protect the down pipe.
Just got to live with it now and see how I get on, feels good so far

[Steve A]

Went for a blat in the cold air today it was over boosting like a
and to make matters worse it happened whilst fending off a large 4X4 that fancied his chances
I was left eating his dust FFS

[ccb056]

I'm starting to think the Piper PCE is a better choice than the Piper downpipe.....

[HJ2]

Same here.

I finally hope that I can remove it next week and see what I can improve Flow-wise without a redesign of the whole thing.

[paulous]

After reading this and other related threads I decided to go with the PCE. So I currently have a PCE and full 2.25 system with sport cat waiting to be fitted the week after next. I'm hoping I don't get any overboost issues. My car is an S2 but not chipped yet...altho considering a Kilimanjaro chip.

By the way does the piper tailpipe really fit? It's huge!! Nice tho.

[wayne]

OK so as you clever lot predicted got my first boost creep at the weekend - cold weather, revving through the gears and boom - fuel cut off, warning light on for about 30 seconds then back to normal and no repeat. So question - is porting the wastegate my only option?

Sounds like the Piper downpipe is doing it's job ..... Increasing the airflow....

How about getting Alan to review his mountain chip and raising the fuel cut off to more than 1 bar? would the stock injectors be able to deliver enough fuel? (or maybe upgrade fuel injectors to suit)?

Seems a waste getting all of this extra airflow to spin the turbo to just vent it off in a different direction?

Knowing nowt about turbochargers and airflow....... At some point in the near future I intend to change my downpipe for something along the lines of Steve Mathews pipe (I have found a company that will make it locally). As I know my precat has been previously cracked and repaired and the OEM downpipe and precat must weigh alot more than the piper downpipe. Has anyone weighed both parts? I currently have 2 1/4" exhaust aft of the precat with no boost creep with just a standard mountain chip.

I do have an old BBR kit laid around which would probably solve any overboost problem. But have never fitted it due to concerns about damaging the engine due to low air / fuel ratios.

Prior to fitting Alans Mountain chip. I previously used a MBC. I can conferm that with a stock exhaust and downpipe the Turbo can still produce more than 1 bar at way over 40C OAT.

[GeoffSmith]

Wayne, the cutoff is at its highest level (0.95 bar overpressure) as the stock MAP sensor only reads to 2 bar. There are equivalent 3 bar MAPs however. I think the stock injectors are pretty much maxed out as well.

[wayne]

Oops, Sorry. ... Thank you for the reminder Geoff. I guess it's back to the 3 bar map sensor and 550cc injectors?

A bit off topic but. Does anyone still supply 3 bar map sensors that will plug into the existing wiring?

[Steve A]

The question(s) for me now is:

Do I now have a car that is only good for when the temperature is warm

What can I try to improve the situation ?

Just to summarise :

Who is running the Piper Down-pipe and what is your set up and findings :

Steve A: 91 SE Turbo , 2inch Paul Matty exhaust , standard chip, waste gate ported to 20mm, over boost in cold weather , hot weather ??? generally hesitant when I put my foot down like it's holing back.

[rip]

Sounds like the Piper downpipe is doing it's job ..... Increasing the airflow....

I agree. It is working too well.

How about getting Alan to review his mountain chip and raising the fuel cut off to more than 1 bar? would the stock injectors be able to deliver enough fuel? (or maybe upgrade fuel injectors to suit)?

As Geoff pointed out, the overboost cut is there because the injectors are close to their limit. Any higher & the stock injectors will not be able to deliver enough fuel. I doubt Alan will write a boost profile which he knows will cause the injectors to underfuel.
The injectors work by pulsing & maximum will be 100%. Larger injectors can deliver more per cycle but the ECU either needs to be modified to allow for the extra capacity or you would need to go down the 3bar MAP sensor route.

Seems a waste getting all of this extra airflow to spin the turbo to just vent it off in a different direction?

& make the car harder to drive. You are boosting high because you want to go faster. The last thing you want to be doing is lift off. You'll then find an un-chipped Elan will have nipped past

Knowing nowt about turbochargers and airflow.......

I think you underestimate yourself.

[ccb056]

Sounds like the Piper downpipe is doing it's job ..... Increasing the airflow....

I agree. It is working too well.

I don't think the pipe is working too well. Because the wastegate flow isn't separated from the turbine flow, we are getting a lot of high pressure turbulent air directly downstream from the wategate port. This is causing less air to flow through the wastegate (something porting the wastegate can't fix).

To make the piper downpipe work well it would need to be modified with a baffle to keep the wastegate and turbine flow separate for some distance, much like the OEM and Knox downpipes have.