Piper Exhausts turbo downpipe development thread

[HJ2]

Still potentially very interested , but i would like to see some piccies first and some additional testdata would be helpfull deciding....

[Steve A]

I could be tempted to buy a whole system if the data and price is favourable

[rip]

:agree:

I could be tempted to buy a whole system if the data and price is favourable

You mean you're not going to add yourself to the list...just because it is a list.
I nearly put you on by default

Someone pick me up off the floor!

I am sure the option is still there for us to say 'you must be kidding - I'm out'
But I'm also sure Piper won't mess us about. They certainly didn't with the 'zaust.

[cliff]

So here it is. Fitted on a 91 SE with Aircon.

CIMG0943.jpg

CIMG0944.jpg

Fitted along with a 2.25 in pipe with single silencer box. (excuse the state of the engine bay - it's on the winter list!)

CIMG0952.jpg

From underneath:

CIMG0948.jpg

CIMG0947.jpg

The pipe is not as close to the sump as it looks. In fact the whole system fits really well.

CIMG0953.jpg

The lower heatshields are not fitted, Dave at Piper said that this should not be a problem as there is plenty of clearance & when the turbo is in use then there should be enough cooling air coming in. I did fit the top heatshield as it looked so bare without it. I checked it several times on the journey north (about 230 miles) and heat did not seem to be an issue. Ceramic coating might be an option though, Piper use a specialist company for this.

The exhaust sounds fantastic! For me it, is exactly how a sports car should sound. At low revs & around town it is quite unobtrusive, opening the throttle produces a wonderful growl. At steady motorway speeds, top up or down, it is not too noisy - in fact quite refined. I will find out about autobahn driving on Tuesday. Accelerating is a different matter though, a loud roar & away we go.

I find the car is much more responsive now, it feels like there is definately more power available. Not having driven a car with a Piper exhaust before, it is difficult to know how much of this is the downpipe & how much from the rest of the system.

As it rained for most of the trip, it was only coming on to the M180 that I could floor it. That was my first encounter with boost creep, classic over fuel, CEL light & loss of power. I had the car out today on a few nice back roads, now I know about it, I keep a good eye on the boost guage. As soon as I see it going past .7, I back off the gas a little. Porting the wastegate is the next job on the list.

I was hoping to have the car on a rolling road while I was in the UK but I really want to sort the overboost first. I have an everest chip screaming out to be fitted so ideally I want to do the porting, then rolling road it pre & post chip.

I am very happy with this system, to my mind it has really improved the performance of the car.

As an aside, I went for an MOT today. CO2 was 3.9 (max 3.5) & HC was 145 ppm (max 1200 ppm). Since I have had it, the car has always seemed to run a bit rich so I am not sure if this has anything to do with the new exhaust. Unfortunately the tester did not give me a chance to tell him how to adjust it so it will be done on the retest on monday.

[trig]

[quote="cliff"]So here it is. Fitted on a 91 SE with Aircon.

CIMG0943.jpg

CIMG0944.jpg

That looks like they have done a brilliant job

Was a shame you couldn't have the porting work done at the same time but hopefully you we have this done soon and the put her on the rollers to see what gains you have before and after chip , ,,, would be nice to compare standard down-pipe against your new shiny Piper..

I would love one of these but cant justify the outlay having only recently fitted one of there PCE, just wish the down-pipe was available at the time

I wonder would Piper be interested in offering a part exchange to owners who have purchased there PCE ?? maybe send back your PCE and get £50 of the new down-pipe

[Karl Martin]

Firstly, I would like to thank Piper and all those involved for their efforts. As with their exhaust, this looks to a very nicely made fabrication.

However, I would like to ask them about the thinking behind this design. Apart from the nicely curved exhaust section, the waste gate part appears to meet it at almost right angles, which is no different to the original.

I have been researching this ever since I first starting seeing how much power could be gained from the original Turbo, using upgrades which would significantly improve, but keep things civil and easy to drive and have spent a huge number of hours asking many different engineers lots of questions, with many different , often conflicting answers.

But, when it came to a downpipe, ALL of them have said that the further away you can join the two pipes and the smoother the two integrate the better, even to the point of separating them completely, if you can.

This design seems to be showing the opposite.

[whippit]

i totally agree
Karl Martin said
But, when it came to a downpipe, ALL of them have said that the further away you can join the two pipes and the smoother the two integrate the better, even to the point of separating them completely, if you can.

even piper agreed this on page two, then have gone for a single pipe ???, maybe because of the aircon issues,
i maybe wrong but the new design looks more restrictive for the waste gate than the original, the larger down pipe must help but,
it looks nice but a dyno before and after might have helped people decide,
i hate to say it but the knox motorsport design looks to have the edge

[bobbrown]

Piper also said early on
"I think the better design will be a separate wastegate tube, but bore size, length and re-entry point are still to be determined"

Never mind the fact that Piper commented on the Knox pipe with regards to how the waste gate flow meets the main flow and was likley to cause turbulance and promptly do the same!
As a note the Knox pipe was version 1 and has been refined some what in version 2.

Ok it looks good and saves weight, allways a good thing but at what cost both £ and power, is there any power gains, as it stands unknown.

[surfboardfiller]

You'll never know bob because you drive an NA!

On a more serious note, the Lotus original never gave the characteristic problems that all the 'self proclaimed experts' say is the reason to separate flows: a stalling turbo.

I originally wanted to replace the Lotus down pipe because the Bore size was the restricting factor, when the bore size was increased throughout the rest of the pipe with the Piper upgraded exhaust. Also further down the pipe/pre cat - the change in bore size meant the gas flow would change speed/velocity which restricts flow as the gasses compress, expand and collide as they travel down the pipe.

A good design solves the existing Lotus downpipe problems:

1/ Initial bore size
2/ Complexity of varying bore size and uneven flow
3/ unnecessary weight

The problem of a stalling turbo on oem pipe never existed The graphs show that and if you look at an Elanscan graph it's a smooth curve!

Whilst Nox designed to solve that problem they may have introduced other problems but certainly raised the cost of manufacturing.
If you have this concern and you may if you are building a race car you can have a very good head start by buying a Piper down pipe and doing your own modifications to your own expert opinion. I may do this for my race car as I have a lot of room next to the turbo for stuff like this, but for my road car I doubt I would see the benefit of a separate waste gate pipe compared to the cost.

Please also bear in mind that this is a prototype for testing!

[HJ2]

So, for the nit-wit's (being me...):

There are now 2 proto's, one being dyno-ed before and after, and the other one not (yet?)
I already decided I want an alternative for the stock lump, but which one?
Now I need to know more about availability and price for both alternatives.

In the end the selection will be made on price and (proven) gain (perhaps gain / Euro? )
If there will be only one alternative for sale (for real), than choosing however is easy

[surfboardfiller]

Nothing is more relevant than the statement of 'how fast this car can go' which can only be done with timing a run.

Power curves are less relevant as they are affected by the equipment and operators, and don't tell you how fast the car can go which is what people want to know.
0-60 is real world which is why the automotive industry and everyone else refer to them as a bench mark of a cars performance.
A better test is in gear acceleration times which have less variables from driver input (through gear changes).

So in summery we have no 'real world' timing of either down pipe yet.

[HJ2]

Real world as in: 2 identicals cars, one driver and the same testtrack / time of day! 0-60 time on a FWD doesn't mean a lot to me to be honest.
To eliminate (most, I agree not all) influenceable parameters on a dyno run: Use same parameters on the run before and after the downpipe swap from stock lump with empty pre-cat to new design, and just look at the delta
As with everything else this is no guarantee to rule out sabotage, but then again we are all grown ups here, so this won't happen, right? ...

[surfboardfiller]

Real world as in: 2 identicals cars, one driver and the same testtrack / time of day! 0-60 time on a FWD doesn't mean a lot to me to be honest.
To eliminate (most, I agree not all) influenceable parameters on a dyno run: Use same parameters on the run before and after the downpipe swap from stock lump with empty pre-cat to new design, and just look at the delta
As with everything else this is no guarantee to rule out sabotage, but then again we are all grown ups here, so this won't happen, right? ...

I agree but to people who aren't engineers and do know a thing or two about performance cars, Dyno runs are treated with huge scepticism here and seen to be an industry for making money not making reliable data.
I am sure motorsport tuners find them useful but theoretical when compared to the cars actual performance.

Why do you say "0-60 time on a FWD doesn't mean a lot to me" Is this because you are interested in the power output of the engine rather than the cars performance?
An engine can produce power that the car cannot use, so if the performance upgrade characteristics are not delivered through the car, then that surely is the most important information which the Dyno cannot tell you.

Why would you spend £250 on an upgrade that isn't use able when you can spend the same money making your car go faster. I want my car to go faster, I don't care how big my BHP is only how fast my car can go.

No one is going to be impressed with you waving a graph print out of you window as they leave you for dust in a 0-60 race.

[HJ2]

It's the '0'that worries me in 0-60.
A whole lot of it has to do with the driver in question as well as the conditions. For instance, when you do it on wet, you'll see that the custom downpipe won't do a lot
on he dry, perhaps you'll see most gain from 20-80 or whatever On a dyno you'll have the same conditions over and over again. True, measuring may not be that accurate, but the delta can easily be visualised without as many question marks as with a 0-60.

But why not do both!

[surfboardfiller]

Yes, I did say a better test is in gear acceleration times which have less variables from driver input (through gear changes).

But you are right both sets of data would be ideal.

[knoxmotorsports]

Well, this has turned a bit ugly...

I am glad that Piper's pipe fits a RHD car with aircon. What is the diameter of the downpipe now, looks to be 2.5"? I wonder if there is any provision for a smooth transition in between the downpipe and the exhaust?

Phil, dyno readings are hardly an industry for making money. Maybe in the UK, where tuners seem to swoon over BHP, as in Crank HP, which is nigh on impossible to truly measure from a chassis dyno with any accuracy. But here in the states, we don't give a damn about BHP unless the motor is on an engine dyno, where it can be accurately measured. We use the same dyno with as close to the same conditions (mother nature permitting) and then standardize them back to one another in order to quell variation. I don't care what the actual number is, that is the part for bragging. What I am interested in is the delta, as many have said. If it is taken on the same day with the car strapped down the same way between runs, and there is a correction factor in place to ensure repeatability, and my pipe makes +18whp more than the stock pipe, no reason the numbers couldn't be compared with one another.

And our car doesn't overboost.....ever. Sounds like the tester did this on his first foray onto the motorway.

I could care less about having a monopoly for a given performance mod. I will let the dyno and other media speak for itself. Given exchange rates and shipping and whatnot, I don't expect to ever monopolize the British market anyhow.

We may just have to schedule some drag strip time to get you the numbers that you desire. 0-60 is hardly a benchmark of performance in real world conditions. Published 0-60 times are the best single run over a testing period, at a prepared drag strip, with an expert driver. Hardly real world. But I digress.

Oh, and in case anyone is interested, here is a pretty informative/comprehensive intro to fluid dynamics. It has been translated so perhaps some things are not correct, but if you can comprehend what is being said, then the whys and hows of downpipe theory should be more clear.... http://translate.googleusercontent.com/ ... QbeErfdUeg

[Avonvilla]

Well, this has turned a bit ugly...

I am glad that Piper's pipe fits a RHD car with aircon. What is the diameter of the downpipe now, looks to be 2.5"? I wonder if there is any provision for a smooth transition in between the downpipe and the exhaust?

Phil, dyno readings are hardly an industry for making money. Maybe in the UK, where tuners seem to swoon over BHP, as in Crank HP, which is nigh on impossible to truly measure from a chassis dyno with any accuracy. But here in the states, we don't give a damn about BHP unless the motor is on an engine dyno, where it can be accurately measured. We use the same dyno with as close to the same conditions (mother nature permitting) and then standardize them back to one another in order to quell variation. I don't care what the actual number is, that is the part for bragging. What I am interested in is the delta, as many have said. If it is taken on the same day with the car strapped down the same way between runs, and there is a correction factor in place to ensure repeatability, and my pipe makes +18whp more than the stock pipe, no reason the numbers couldn't be compared with one another.

And our car doesn't overboost.....ever. Sounds like the tester did this on his first foray onto the motorway.

I could care less about having a monopoly for a given performance mod. I will let the dyno and other media speak for itself. Given exchange rates and shipping and whatnot, I don't expect to ever monopolize the British market anyhow.

We may just have to schedule some drag strip time to get you the numbers that you desire. I think you are being rather naive with saying 0-60 is a benchmark of performance in real world conditions. Frankly, that's bull****. Published 0-60 times are the best single run over a testing period, at a prepared drag strip, with an expert driver. Hardly real world. But I digress.

Oh, and in case anyone is interested, here is a pretty informative/comprehensive intro to fluid dynamics. It has been translated so perhaps some things are not correct, but if you can comprehend what is being said, then the whys and hows of downpipe theory should be more clear.... http://translate.googleusercontent.com/ ... QbeErfdUeg

Are you actually selling your pipe ?

[knoxmotorsports]

Now that we have some legitimate testing data on the durability of our pipe, we plan on doing a production run.

But this thread is about Piper, so I won't clutter it any further.

[HJ2]

thanks for the update!

I must admit I tend to clutter both threads with my surplus comments on the system from the other tread, but that is just my nature. I tend to react on the most active treat as my LEC homepage is the one with the search results 'new' so my excuses as well

Reading the page about fluid dynamics makes me think out loud:
Piper has a design and room for experimenting with another set-up with incorporates swirl injection of the by-pass gasses into the main exhaust flow!
Although calculations is not my strong point (understatement) My experience with rocket engine systems testing makes me confident that this priciple can be easily incorporated in the piper design!

Needless to say i am still very interested in availability of both systems and fitment for my S2 with 2,25" exhaust, LHD and Aircon
I don't want to push anything, but Euro's are burning in my pocket here (well, my banker's pocket anyway )

[surfboardfiller]

I was actually interested in what you had to say right up to the point when you wrote this

I think you are being rather naive with saying 0-60 is a benchmark of performance in real world conditions. Frankly, that's bull****. Published 0-60 times are the best single run over a testing period, at a prepared drag strip, with an expert driver. Hardly real world. But I digress.

This hadn't turned ugly as you put it, it was a topical debate until of course you posted up insulting me by calling me naive and stating my opinion was bull****.