PiperRS 2.25" or 2.5" Exhaust for all M100s

[rip]

Emissions should not be a problem for you because your S2 is a '95 & therefore has to conform to the 'old' emmission standards.
Your sports cat may protect against overboost a little more than a straight-through system though.

[CJ101KT]

Emissions should not be a problem for you because your S2 is a '95 & therefore has to conform to the 'old' emmission standards.
Your sports cat may protect against overboost a little more than a straight-through system though.

I see ... I thought the new regs came in earlier than 95-96 and therefore affected all S2's.

[speed-demon]

I was running a 2.25 with pre-cat eliminator and sports cat and an S.E ECU on an '94 S2 car. My car failed it's emissions!
I replaced the S.E ECU with the original S2 one and the car sailed through...

Also Max and Andy were running an S2 car with a 2.5 system and no cat'. Their car also failed and they had to retro' fit a cat' to pass...

I think anyone with an S2 should just buy the Piper with a cat' as it's clearly required. Perhaps some MOT stations are twisting somewhat. Who knows? I think Geoff was running an S2 with no cat's and passing emissions...

And you will get overboost in certain situations. On the road, maxing it I never got any! Motorway journeys saw boost creep though when allowing the car to torque through the rev's in a single gear or two, like you do on the motorway. I genuinely think it's unavoidable 100 % of the time. There will always be a day when you'll get creep unless you port. But you'll lose power porting. I did.
One thing I will say about porting. Is that after, the drivability of my car returned to that of pre messing with the exhaust etc. So now I have all the benefits of the Piper but with a car that feels like Lotus intended. But less power than prior to porting but more power than when the bloody thing used to go to fuel cut in the outside lane of the motorway. Not good!

[rip]

I think Geoff was running an S2 with no cat's and passing emissions...

Correct. It was indeed there's only on f in Geof Smith who discovered this. He had a Peco fitted to his S2 & was getting through MOTs with just the pre-cat. When he stripped off the front section to port his wastegate, he found that the pre-cat had already been removed.
Others questioned how he could get through an MOT, accusing his tester of being dodgy etc, which simply was not true: his tester was an ordinary local garage with no bias at all. It was then that the July '96 issue came to light.

One thing I will say about porting. Is that after, the drivability of my car returned to that of pre messing with the exhaust etc. So now I have all the benefits of the Piper but with a car that feels like Lotus intended. But less power than prior to porting but more power than when the bloody thing used to go to fuel cut in the outside lane of the motorway. Not good!

The extra power is caused by boost creep. If you like the extra boost, get an Everest.

[Breed]

I have a early 96 S2 with 2.25 Piper with just a pre cat. Passed MOT no problem.
Do not know if there is any stuffing in the pre cat but suspect there is as no boost creep.

Bill

[speed-demon]

I have an Everest chip. K&N filter. Bailey dump valve. Piper pre cat' eliminator and Piper 2.25" exhaust with sports cat' ... But the power of the boost creep was amazing! Unfortunately not always very practical when it went to fuel cut. After fitting the Everest Chip it made the boost creep almost absent, but every now and again it would rear it's ugly head.
Now my car is ported it feels sorted but not hugely different to standard. Before the porting it was mad! I wish I could have the madness with the driveability of the ported car.
I must get it dyno'd at some point soon to check what power I am getting. I wonder if the magnorcore leads and a set of split fire spark plugs would also help?

[rip]

I have an Everest chip.....

I wish I could have the madness with the driveability of the ported car.

Everest target boost is 0.9 bar.
IIRC, Overboost with an Everest is 0.96 bar (0.94 with stock chip)..so you should only have 0.06 bar of boost creep.
When the turbo spools up, the Everest should aim for 0.9bar of boost instantly. With a stock chip, this will aim for 0.65 then slowly creep towards 0.94, so the ported Everest should be faster than un-ported stock.

My guess is that your ignition timing needs advancing.

Don't think that 'correct is best' because that may not necessarily be the case. My Piper-fitted SE ran very poorly when set 'by the book' at 16btdc. Overboost occurred very readily at 4100rpm, boost gave me very little power, the exhaust was very sooty & the car spluttered to life. I set my timing by stopwatch, used Elanscan to check that I am getting no knock & found it now runs best at 32btdc??? The difference has been amazing: overboost now occurs at 5500-6000rpm, but only in cold weather, the car purrs to life, the exhaust is cleaner & boost now gives me quite a whack in the back.

[ailwyn]

I set my timing by stopwatch, used Elanscan to check that I am getting no knock & found it now runs best at 32btdc???

How do you set the engine by stopwatch?

Seems quite a coincidence that your timing has ended up at exactly 2x the handbook

Can anyone explain?

[rip]

I set my timing by stopwatch, used Elanscan to check that I am getting no knock & found it now runs best at 32btdc???

How do you set the engine by stopwatch?

Seems quite a coincidence that your timing has ended up at exactly 2x the handbook

Can anyone explain?

I can because it was me who tried it after Geoff commenting that excessive overrun was caused by incorrect timing.

I know, it sounds absolutely bonkers, but it ran like a dog when the timing was set by the book.

I picked a quiet, level dual carriageway & accelerated full throttle from 25-70 in 4th gear, starting my stopwatch as the speedo hit 30, stopping it at 70.
I marked the position of the CAS using duck tape & a pen so I knew where to set it back to if everything went belly-up.
I then advanced the timing a little & re-did the test on the same piece of road.
I marked this new CAS position, advanced again & re-performed the test.
30-70 dropped from around 13.5 to 7.5 seconds. As you can imagine, this transformed the car. Overrun had virtually gone, overboost was no longer an issue & the engine purred to life rather than spluttered to life (which I actually quite liked).
Over time, I found the exhaust to be a lot less sooty than when the timing was set by the book.
The CAS was advanced almost all the way & Elanscan showed no knock.
I then checked the timing by strobe & found it was 32btdc.

[CJ101KT]

Do Piper offer us any discount on their prices for quoting LEC?

[CJ101KT]

Piper exhaust arrived this morning ... just 2 days after ordering!!! Was brilliantly wrapped and protected. I have gone for the 2.25" system with the sports cat and will be having it fitted this weekend/Monday so will share some more photos once it is fitted. I know a lot of people have gone for the Piper decision but I couldn't find a lot of photos of the system.

[BFG in the BRG]

Wow, that does look nice - I almost want my exhaust to fail so I can get one

[MPx]

Faced the same dilemma when I bought mine. I went conservative cos I'm not chasing the last n BHP or db. In fact I dont yet know if its paid off cos I've not had my next MOT yet...but I'm hoping my decision to use the 2 1/4 with Sports Cat will see it sail through (despite also removing the pre-cat and porting). Of course if it doesn't then the rest of you guys with 2 1/2s and/or no sports cat are in deep doos !

Well that's a shame. Just got a call from Phil at SWLC to say my car did fail its test on emissions. He's not yet had it back on the ramp to check it out, but that will be annoying if a Piper 2.25" with Sports Cat on programme 1 of the switcher wont pass! He also said that the regs changed in 1992 so everything registered since and some from 1992 have to be tested as catted. I mentioned the threads on here which quote a date later in 1995 and he just said they were wrong....this could get tricky!

[DaveB]

If you need any confirmation on MOT questions/answers let me know...

I work for a dealership with several MOT testers, and I'll ask 'em...

David

[lotos]

You got the cat and still failed on emissions?

[rip]

You got the cat and still failed on emissions?

But no pre-cat if I read it correctly.

[MPx]

Yup...no pre cat, ported to ~20mm, Piper PCE, Piper 2.25" system with sports cat, Mountain switcher. Its done less than 2k since its last serrvice and MOT where it had no problem...but of course I've done all the mods since then. Really didn't expect to have an issue given others experience, but it may still just be some other prob - timing, sensor, whatever thats nothing to do with the mods.

Thanks for the offer David...I'll report back what Phil says tomorrow.

[rip]

He also said that the="MPx"] regs changed in 1992 so everything registered since and some from 1992 have to be tested as catted.

Sorry, I didn't notice this bit before.

1992? Query that. I read somewhere on this very forum (maybe in the Peco thread?) that cars registered/built (whichever is earlier) after June 1996 were subject to the stricter regs.
Weren't SEs built until 1993? They had no cats or O2 sensors.

I am 100% sure that Geoff's S2 is cat-less & has never had a problem at his local (impartial) MOT station.

[MPx]

1992? Query that. I read somewhere on this very forum .........

Yeah I've read those posts too...that's what I mentioned to Phil. It does look like one of those annoying changes where there's more mis-information than fact both within the trade and public fora. As long as we all keep having different experiences which we report back and compare, the uncertainty will continue - but that still the best available outcome. Where's Steven Fry when you need him for a definitive answer...

No word yet on the cause of my high emissions....

[MPx]

Well my car has been made to pass its emissions test but its not a very good situation. Phil had to remove my rear box and he made up a section with an Elise cat and a connector pipe instead, just to pass the test. He says that the sports cat does the job at tickover and when cold, but at fast idle there just way too much CO2. He was a bit scathing about me removing the pre-cat. His experience is that any Elan is marginal on emissions and any that have had exhaust or ECU mods always fail. That is completely different experience to what I've consitently read on LEC. How can experiences be that different? Is there something else that should be investigated? Once I get the car back, I'd really like to sort this before next year - I'd not have done the mods if I'd thought it would be this hard/expensive to get an MOT!

Does the switcher programme make any difference to CO2? Its currently set to 1 (Standard S2) but maybe it would be better on one of the other MAPs given the lack of cats and bigger pipe?

The Lamda sensor has been replaced - which made no difference. Is there anything else that could affect CO2?

Timing is set on the marks. Some posts on here seem to suggest that making it further advanced may improve matters is that worth trying?

I'll be interested to see the fail certificate - specifically to see what numbers they tested against and how far over the car is.