Piper Exhausts - Products now avaliable online

[PiperRS]

Hello all.

Just thought i would update you all to let you know that i have updated our website with the products for the Lotus Elan.

These are all available with 1-3 days delivery.

See here : PIPER EXHAUSTS - LOTUS ELAN

The price has gone down a little since we first developed them all for you thanks to Mr Browns nice Tax cut

[ektrolleyboy]

Can anyone explain the difference between the two sizes before I order.
It is just airflow and therefore power potential.

In order to minimalise boost creep would the smaller system (2.25) be a better option for my S2. Was thinking the 2.25 with sports cat' is the one for me?

[Monty]

Can anyone explain the difference between the two sizes before I order.

1/4 off an inch

[dapinky]

Area = Pi x r 2

2 ¼ “ diameter pipe:-
1 1/8 x 1 1/8 x Pi = 3.98 in2 = 25.68cm2

2 ½ “ diameter pipe:-
1 ¼ x 1 ¼ x Pi = 4.91 in2 = 31.68cm2

Volume of a cylinder = [Pi x r 2 x height], and I litre of volume is 10cm x 10cm x 10cm.......
By using a bit of arithmetic, with a cross section of 25.68cm2, one litre will occupy:-
1000/25.68 = 39cm of exhaust pipe,

But by increasing the cross section to 31.68 cm2, one litre of exhaust gas will occupy:-
1000/31.68 = 31.5cm of exhaust pipe,

So you can get a lot more exhaust gas out of a slightly wider pipe!

Assuming that the engine is running at 3000 rpm, the volumetric displacement of the engine will be 1.6 litres (cubic capacity) for every 2 revolutions, = 2400 litres per minute (off boost).

With a turbo boost cutting in at 3000 revs, it can be twice that amount (at 1 bar boost), but lets call it 0.7 bar, so you can have a sudden(ish) jump from 2400 litres/min to 4080 litres/min, and that gas has to go somewhere, so the wider the pipe by even ¼” diameter will improve things by over 12% volumetric capacity.
I can’t be bothered to incorporate air speed losses, friction, temperature losses, direction changes and all the other variables, but they all have an effect.
Overall, think of a river, flowing down a slight gradient – where it is wider, the water flows slower than where it is narrower, even then it is slower at the sides than in the middle, due to drag on the riverbank, but back to the pipework, there is (proportionally) less circumference to area ratio on the wider pipe, so less air drag.

That said, unless you are aiming at 300bhp, with big boost, the 2 ¼“ will be enough

To put it into context, it is still a 12.6% improvement over a standard 2" system, not counting the 'squish' restriction, and other crap in the way due to the way the pipes are bent! - realistically, i would estimate the improvement in airflow to be in the region of 20-25% with a mandrel bent system with a PCE.

[ektrolleyboy]

Well that clears it right up...
Huh???

So it won't be as powerful as the 2.5 is what you're saying? But irrelavant on a standard engine?

[dapinky]

The exhaust doesn't 'make' power, but it lets the engine develop more, until it reaches it's limit, then you need a bigger one!

[ektrolleyboy]

Right oh.

So I'll order the 2.25 system then with the sports cat'.

I hope it sounds the beez neez! But I guess anything sounds better than the original which sounds like a family hatch-back with half a hole in the pipe...

[max and andy]

Have you thought about going without a CAT ? Andy

[ektrolleyboy]

Two reasons why I wouldn't...

One it reduces the chance of boost creep Paul Matty tell me. And two, it saves any worry come MOT time. As you can probably tell, I'm not one that likes hassle or potential for disaster !

[GeoffSmith]

A sports cat is designed to be free-flowing so don't expect to avoid boost creep just by having one. If you want to avoid boost creep, stick with a factory fitted 2" pipe, after all, that's what the wastegate is designed for - you can't going reducing the exhaust 'resistance' by 20% and expect the wastegate to cope.

[nitroman]

I can't think of anyone using a cat who has had the boost creep problem.

[max and andy]

We are thinking of putting an order in for a 2 1/4 inch no Cat single box exhaust + PCE from PiperRS .At the end of next week.We are hoping that porting the waste- gate would be as good as a free flowing sports Cat.To stop the boost creep .We have read a lot of the back posts .And decided that to go with out the Cat, would be a risk worth taking .With emissions in mind.We thought that we had taken all the pro's and con's into mind and decided .But reading the last posts I'm having second thoughts .Do you think i should take a punt ?Or get the sports Cat ?We're trying to budget where possible, as the brakes are on the list as well.And we didn't want to take any shortcuts with them .Any comments might help put my mind at rest .Until buying time .Id like to try and go without,or am i being greedy ? Thanks for all the advice and reassurance . Maxine & Andy

[bobbrown]

My philosophy is always to start at the corners and work in.
So tyres come first on the list followed by brakes, up rating the power without at least taking the brakes into consideration is never a good thing.

dapinky,
very simplistic view of exhaust volume, hot gases more volume, burnt fuel more volume, more power (more fuel) more volume and it does assume 100% of the gases get in and out, but I think the general idea is ok. With Turbo charged engines bigger is always better but you can hit limitation of other OEM components like waste gate and ECU. It is commonly accepted that aftermarket exhaust systems do release more power, they do not actually produce more power just release what is there, reducing backpressure for better flow more power.

Bob

[max and andy]

Ive been reading the back issues .Lack of boost not over boost and the like.I feel a lot better about it.I must of been having a mad five minuets,when i got up this morning.Cheers Andy

[dapinky]

dapinky,
very simplistic view of exhaust volume, hot gases more volume, burnt fuel more volume, more power (more fuel) more volume and it does assume 100% of the gases get in and out, but I think the general idea is ok. With Turbo charged engines bigger is always better but you can hit limitation of other OEM components like waste gate and ECU. It is commonly accepted that aftermarket exhaust systems do release more power, they do not actually produce more power just release what is there, reducing backpressure for better flow more power.

Bob

If I'd written it out fully, it would have been a lot of writing! When i did a similar paper for a dissitation many years ago, it took up more than a few paragraphs! I think the final piece was about 25 pages long - and the general idea is to make it readable, not too scientific theorist. (if you want to read the original, full article, look on the Cardiff University Post-graduate website).

I do however disagree with your statement of "With Turbo charged engines bigger is always better....." I believe that if the pipe is too big, there will be such a velocity variance throughout the system that resonance will cause more problems than the flow potential can realise. That said, we are talking small amounts here, not 2 meter diameter pipes, so realistically, I stick with my earlier statements that the standard pipe is okay for a standard state of tune, 2 1/4 would be (and is) my choice for an output in the region of 250 bhp, then a 2 1/2 becomes necessary.

[Monty]

max and andy

If you`ve got an S2 and you intend on buying Pipers PCE then you will need the Main cat to past the emission test for the MOT.

[GeoffSmith]

I'll say it again: I ain't got no cats at all and keep passing no problem.

[bobbrown]

If I'd written it out fully, it would have been a lot of writing! When i did a similar paper for a dissitation many years ago, it took up more than a few paragraphs! I think the final piece was about 25 pages long - and the general idea is to make it readable, not too scientific theorist. (if you want to read the original, full article, look on the Cardiff University Post-graduate website).

I do however disagree with your statement of "With Turbo charged engines bigger is always better....." I believe that if the pipe is too big, there will be such a velocity variance throughout the system that resonance will cause more problems than the flow potential can realise. That said, we are talking small amounts here, not 2 meter diameter pipes, so realistically, I stick with my earlier statements that the standard pipe is okay for a standard state of tune, 2 1/4 would be (and is) my choice for an output in the region of 250 bhp, then a 2 1/2 becomes necessary.

I did think that was the case of keeping it simple other wise as you say it gets very very complex, fluid dynamics?
"bigger is always better" was more of a generalisation I did not mean dustbin size, and we still have to remember a couple of reasons the exhaust is there is to get the stuff from the front to the back and keep the noise levels to an acceptable level.

Bob

[max and andy]

I'm starting to panic again.Ive just been and had a quick look at the exhaust forums.And i think Ive got it right in saying that Jon, Geoffsmith, Nickb, Rip, Dapink(And by the way i thought your post on Exhausts,Turbos,Wastegates ,PCE. The bottle thing.Was really good and easy to understand.)Tigerdog. Are all running with no cats.And I'm sure Ive read somewhere the Everest chip is designed to keep things running within emissions regulations. Andy

[dapinky]

Andy,

The list you have may well be as per posts, but there is only a bit of relevance - it is all down to the age of the car and it's intended market when originally sold.....

A UK registered SE (or any other car of its era) only needs to reach an emissions test which allows 3.5% CO, and 1200ppm Hydrocarbons.
By the time the S2 hit the streets, the rules had changed and it needed to have emmissions of a maximum of 0.5% CO, hence it needed a catalytic converter fitted.

However, the cat brought the levels well below the limit, and many have found that even without one fitted, the levels are still okay enough to pass an MOT test.

Geoff has no cat fitted in his S2, and it still passes the MOT.

Mine has no cat, but doesn't need one anyway.