I'm new to the Elan M100 and wish to upgrade exhaust system

[bxs]

Will have my red Elan M100 delivered in next few days, and it only has some 10,246 original miles. My goal is to upgrade the exhaust system from its stock system having CATs to one without CATs.

I've contacted PIPER and they are offering me this.

https://www.piperexhausts.co.uk/product ... liminator/
Pretty darn expensive, but maybe understandable due to its manufacture effort)

...and this

https://www.piperexhausts.co.uk/product ... ystem-149/

As I'm located on U.S. west coast the S&H is high having to have it shipped from UK.

This is the cost for the above....
CLOT8CJ - LOTUS ELAN 2.25" SYSTEM WITHOUT FRONT SILENCER TAIL PIPE J £355.17 (no VAT)
LOPCE1 - LOTUS ELAN - PRE CAT ELIMINATOR - SUIT 2.25" BORE SYSTEM £230.71 (no VAT)
Carriage S&H to my location £215.95

Thus Total comes out to be some £801.83 or some $1,065 USD

I'm curious to know if installing this exhaust system is a DIY task. I've done similar exhaust replacements on my 2004 Volvo S60R (Halo car) and it was doable but not easy.

Also, I'm under the impression that this PIPER exhaust system will not require me to modify the turbocharger.

A sports exhaust replacing a stock exhaust system is said to increase car's HP..... comments about this would be appreciated.

Thanks....

[dapinky]

Hi, and welcome to LEC.

There are 3 known aftermarket exhaust systems for Elans (plus endless other bespoke options) - Piper, Cybox (used to be known as Peco) - now sold mainly by PNM and listed under their own brand, and Quicksilver.

Only the Cybox is available 'off the shelf' with the others being made to order - but with a short lead time it isn't a big problem.

The choice comes down to what you want it for, and which bits you want/need.....

basically, Quicksilver is pretty much a straight replacement for the OE system, but in stainless (2" pipework)....
Cybox is a 2 1/4" fully-stainless system with some options (1 or 2 silencers, cat or not)
Piper is either 2 1/4" (CLOT8) or 2 1/2" (CLOT7), with a bigger choice of options for a more bespoke system.

First off, the Quicksilver was the first system to hit the market, and has really been superseded in popularity since the others hit the shelves 20 years ago - not so easy to get these days, and really not as good as the other 2 (but nothing actually wrong with them).

The Cybox and Piper are similar, but some people prefer one over the other....... personally, I love Piper, and have used the company for many years (about 40!) for various stuff - I was also part of the initial group who managed to get them to build the Elan systems for us..... so if I seem like I'm pushing their products, it's because I like them!!!

If you are NOT going for a really high output from the engine, then you can disregard the 2 1/2" system as it is only worthwhile if you are looking to go over 300bhp which requires a bigger turbocharger, injectors and other work.

So, we are back to the 2 1/4" system that you reference in your links above.

I have that same system on my green car (PCE, CLOT8, Single silencer) and it is perfect for what I wanted at the time..... a car that was used mainly on the road, but with an occasional trip to the track.

For the blue car, I am not worrying about the PCE as that isn't really necessary on a purely road-going car....... yes, it saves a chunk of weight, and does improve the gas flow, but not enough to matter in a meaningful way.

However - as you are talking about a FED car, the pre-cat on your system will contain the honeycomb structure which will restrict the exhaust flow (the housing is hollow on a UK SE), so I can see why Piper are suggesting the PCE for you.
This brings you to a choice, you can either keep the "stuffing" in your current Pre-Cat, to give some reduction in emissions, you can hit the contents with a hammer to break it up and then throw it away, thus leaving it hollow like a UK system.... but it needs doing safely due to tiny sharp shards of ceramic breaking off - you don't want them in your eyes or lungs.
Or you can replace the downpipe completely with a straight pipe (not so easy to source these days).

I suppose it comes down to what your car requires to pass any emissions/smog test where you live (or may potentially relocate to in the future) - I assume from what you ask, that a Cat isn't needed to be present.

If it were me, I'd hollow out the current housing, then bolt on a full 2 1/4" system to the hollow unit, with a single silencer, and call it a day - but if I thought that I may need the Pre-Cat in the future, then I'd remove and store it, and fit a PCE.

As for the second part of the question - I fitted mine without lifting the car from the ground and it was possible...... far easier with it up on axle stands, and if you have a lift or a pit, it is laughably simple!

The hardest part was removing the old system as some of the Pre-Cat bolts snapped and needed to be drilled out, and I had to chop the old pipe off at the back to get it out of the car - but actually fitting the new system was very quick and simple.

As for increasing the BHP, it is arguable as to whether the exhaust does that, or simply allows the engine to do it itself (chicken & egg situation)..... I assert that the engine is capable of higher power anyway, but the 2" exhaust system restricts it - so the freer flow of the 2 1/4" allows the engine to breathe better and release more power..... probably something like 15-20bhp.... but as you will be removing the Cat, then that strangles 10bhp anyway, so your 'stock' car at 155bhp will become 165bhp+whatever you get from the bigger system.... so you should get a noticeable jump in output (20bhp is noticeable).

You may well find that the best way for you is to find a local bespoke exhaust shop and ask them to make something up for you - I have no idea of costs, but with shipping involved, it should be much more in your favour.

[MPx]

Dave's really covered all the ground but just to add :

I have the Piper 2.25 system with a sports cat and PCE. That makes it marginal on passing the UK emissions test, but if the car is well tuned it does. Its a great exhaust!

I have a mountain (replacement ECU) chip and mostly run the everest programme. Its a cheaper way to more power (even with a standard exhaust) - and Ron is making them available again now that Alan has shut up shop.

IMO (and I accept others disagree with me) the OEM brakes are marginal in the M100 even at standard output. If you like to press on then you should consider a brake upgrade before increasing the power.

Enjoy!

[bxs]

@dapink & @MPx .... many thinks for both of your responses to my exhaust system upgrade enquiry.

I've been a fan of Lotus ever since 1966 when I briefly worked with Colin Chapman on the preliminary design for a small airplane Colin was thinking about. After long design meetings at Colin's house that lasted well into the early morning hours I would miss my train back to London.... but no matter, Colin would drive me back home in his personal Elan. So as you can imagine, I have a close association with Lotus.

My new to me Elan M100 will not be used for track, but will be used for local driving and attending TSD rallies in my PNW area with my 17 yr old grandson navigator with granddaughter as my backup navigator.

My WA state here in the U.S. does not require emission testing any more, and this 1991 Elan M100 is considered a Classic car being over 30 yrs old, and is expected to be driven not more than around 3,000 miles per year.

Upgrading the stock exhaust system is a simple way IMO to increase the fuel efficiency and engine performance by maybe a few HP. The ISUZU-LOTUS turbocharged engine from all my readings is a solid performer, and if treated nicely should last a long time doing proper maintenance intervals. The fact that my M100 has a mere 10,246 original miles brings a big smile on my face knowing this Elan will last a lifetime if cared for.

I do think my decision will be to opt for what PIPER is recommending for my exhaust system upgrade, along with the two responses here agreeing they are reputable, trustworthy, and knowledgeable about the Elan M100..... Plus I lived as a child in Broadstairs which is just up the coast line from Folkestone where PIPER has their facility.

I've eMailed PIPER several times and get responses within 24 hrs each time from a fella named Anthony Jewkes who has provided excellent info and advice to me. I'll just have to swallow the stratospheric S&H cost. I should ask Anthony Jewkes just what is the weight of this recommended exhaust system.

Anthony was kind enough to forward a drawing of the stock exhaust system and indicate the parts the recommended system would replace. See the attached photos.

His eMail and excellent information to me is contained here.... https://www.icloud.com/sharedalbum/#B2NGlKcM6GTN18O

[dapinky]

I'm sure that you will be pleased with the Piper system (I've never heard of anyone who isn't).

so, with that decision in mind, 2 further things come into play......

.... There is a 'fitting kit' which they offer, CLOT8/FK, which makes it a whole lot easier with everything you require in the bag - sometimes they include it in the deal, sometimes they don't, and it needs a separate mention...... there is nothing in it which you couldn't get locally anyway, but it is nice to have at the start.

...... Now the better bit..... if you mention to them that you are a member of LEC they should offer you a discount (it used to be 10%). That will make the whole thing slightly less upsetting on the initial shipping costs!!!

I would suggest that you 'expect' at least some of the M8 bolts that hold the Pre-cat to the cast downpipe to be seized solid, and prone to snapping off. I would suggest giving them all a good soak in plus-gas (or US version!) between now and when you plan to do the job.... even if it is months away.

I replaced all the bolts in my system for stainless steel ones to (hopefully) stop them ever causing me problems in the future.

[bxs]

Thanks Dave..... Maybe this is equivalent to the PlusGas
https://www.acehardware.com/departments ... ls/1004892?

I'm likely to take the Elan to my local professional car exhaust system facility to have the PIPER installed, and in mean time will crawl under the car some and give the M8s a good squirt ahead of time. I downsized some 14 yrs ago from a house with 4 garages and now have garage-less house.

Thanks for the additional AAA+ recommendation for the PIPER system, and will certainly explore the 10% discount with Anthony at PIPER.... that in itself is ~half the S&H cost.

As an aside.... I asked DeepSeek AI to give me some information on Turbocharger boost creep, and this was what spat out....

============= Below is DeepSeek's information about boost creep!

Turbocharger boost creep is a phenomenon where the boost pressure in a turbocharged engine rises uncontrollably beyond the predetermined target level, typically at higher RPMs, despite the wastegate being fully open. This occurs due to the wastegate's inability to divert enough exhaust gas away from the turbine wheel, causing the turbo to spin faster and generate excess boost pressure. Unlike boost spikes (temporary overboost) or general overboosting (sustained high boost due to control issues), boost creep is a mechanical limitation tied to exhaust flow dynamics and cannot be resolved through tuning or electronic boost controllers alone.

Key Characteristics of Boost Creep:

Uncontrolled Rise in Boost: After reaching the target boost, pressure continues to increase with RPM, often peaking near redline. For example, a stock Subaru STI set for 8 psi might creep to 18+ psi under certain conditions.
Mechanical Root Cause: The primary issue is insufficient wastegate flow capacity, often exacerbated by modifications like high-flow exhausts or intakes, cold ambient temperatures, or restrictive wastegate port designs.
Dangerous Consequences: Boost creep can lead to:
Lean air-fuel ratios (AFRs) as the fuel system maxes out.
Engine knock/detonation, risking severe damage.
ECU limitations, where traditional safeguards (e.g., reducing timing) fail to prevent overboost.

Common Causes:

Exhaust Flow Upgrades: Aftermarket downpipes or catless exhausts reduce backpressure, increasing exhaust gas volume that overwhelms the wastegate.
Cold Weather: Denser air improves engine efficiency, generating more exhaust energy that the wastegate cannot bypass.
Wastegate Design: Small or poorly shaped internal wastegate ports restrict flow, while external wastegates may suffer from installation or manifold design flaws.

Solutions:

Porting the Wastegate: Enlarging the internal wastegate port and improving its flow path can mitigate creep, though results vary by application.
External Wastegate (EWG): Offers greater flow capacity but may require significant modifications and is often non-compliant with emissions regulations.
Reintroducing Backpressure: Using catted exhausts or retaining stock intake components can help balance flow.
Fuel System Upgrades: Larger injectors or methanol injection can address lean conditions caused by creep but do not fix the underlying mechanical issue.

Example Scenario:

A modified Subaru STI with a catless downpipe might experience boost creep in cold weather, where boost climbs from 8 psi to 18 psi by redline, risking engine damage. Solutions could include porting the wastegate or switching to a catted exhaust.

For further details, refer to technical discussions from Garrett Turbo or Cobb Tuning

[MPx]

information about boost creep!

Its certainly a thing for some, particularly those of us that have upped the exhaust diameter. Many of us have ported the wsstegate - usually from 16mm to 20-21mm. Not something I ever get having done that.

[bxs]

@MPx: Thanks for your insights about the boost potential issue.

[FunElan]

Being that you're stateside, it's probably most cost effective to just go to a local exhaust shop and have them fab something up. Keep your cats though, to not introduce any variables. I have a magnaflow muffler on my car (with both cats) and it's plenty loud.

[bxs]

@FunElan: I went to the Magnaflow website for their exhaust systems and they do not list Lotus in the Car makes drop down list. So what did you select for your Magnaflow exhaust system? Did you simply replace the Elan's stock rear muffler? ...and what was the cost for whatever you purchased from MagnaFlow ?

You're CA based so I understand why you've elected to keep the stock CATs. However, in WA there's no such requirement for Classic cars, such as this 34 yr old Elan M100, to have CATs.

Yea... understand a complete exhaust system replacement is expected to be more costly than replacing just the muffler. The exhaust sound is not my concern here, but rather overall a preferred performance improvement along with better fuel efficiency.

I appreciate your insights and welcome any further thoughts you may have.... Cheers

[FunElan]

If you remove the cats, then you probably will have to remove the turbo and port the wastegate, as mentioned here before.

I got my magnaflow from another M100 owner for cheap, it was too loud for him. But an exhaust shop can easily fab up a pipe with an off the shelf high performance muffler.

My car with the chip and both cats is NOT slow. Does yours have a boost limit increasing chip?

Keeping the cats I think is better for your mpg!

[chipp]

1018.jpg

I put the Piper 2.25 on my S2 which has the precat. This was replaced with the pce and the wastegate didn't require any fettling.
It has a lot better sound than stock and seemed to pull through the rev range a lot smoother and quicker, down to better flow I expect.
They also have a nice stamp on the tailpipe.

[bxs]

I've decided to go with the Piper exhaust system, along with the LEC10 10% discount coupon. I suspect it will take a month to get to my doorstep from the UK once Piper has manufactured it for me. I understand they require 2 weeks for pre-orders to make the system. I hope it all comes in one box, and that Piper provides S&H tracking so I know when to expect to have it delivered.

I had to have Piper send me a specific ordering URL link for payment as their standard web site insisted on an excessive S&H (Carriage) fee. The fella at Piper (Anthony) was kind enough to facilitate and help me with the ordering and payment.

The main reason for ordering this Piper exhaust system is that after having my M100 inspected by my local Lotus service shop I was told the stock exhaust was showing severe signs of spot rusting (presumably from condensation water inside the pipe) that once opening up to be small holes will then require repair and/or replacement. Let's face it, my M100 is 34 yrs old has a mere 10,300 original miles and has likely been sitting in stables for these 34 yrs.....

BY THE WAY.... My local Lotus service shop gave the M100 a thorough checkout and the Bulgarian technician said it was the best convertible he's ever ridden in (from a structural perspective). The engine was strong and ran smoothly, just one or two bulbs were burned out, and that a cover plate at front under the radiators was missing. I was advised to have wheel alignment and for the exhaust system to be replaced.

IMG_3795 (2).jpeg

[TorqueHorse]

Nice! Can't go wrong with a Piper. Are you going to take the pre-cat off too and try to overbore the wastegate, or just wait to see if overboost is a problem first? If you are already taking off the pre-cat, you will have direct access to that area and should be easy to do. But if you are leaving the pre-cat in place, then you will be opening up another can of worms with seized heat shield bolts that you might want to avoid, if not necessary

...and that a cover plate at front under the radiators was missing.

I just went back and looked at the photos on BAT and looking at pics 217/218, and you have all the "cover plate" that came stock on the FED version (unless something changed between those photos and now). You are missing the lower lip, which would hide that area from view, but there is no cover plate, just the tiny little fibeglass strip that has the comb notches towards the front, and hold the support for your rad fans. The UK version has a larger one, but that's because their rad setup is different.

[bxs]

@TorqueHorse

Yes the exhaust kit I purchased form Piper is for a cat-less system. So yes, the pre-cat will be removed and replaced with Piper's PCE.

I understand with the Piper's cat-less system there should be no issues with overboost.

If the Piper system provides a +20bhp that will be a bonus for my style of driving and with a smoother RPM engagement with the engine having improved 'breathing' due to the extra pipe diameter of 2.25", along with its SS pipes and muffler with the stamped PIPER on the tail pipe.

This M100 is going to be driven top-down in all weather conditions.... except for rain..... The top goes up in a jiffy..... also replaced the aging wipers with some more modern BOSCH ones.

Thanks for researching the issue of the front cover plate. So that gives me some comfort not having to be concerned about that.

Yes, the rubber lip is missing and I have secured a suitable black silicone lip I found on eBay that I will install myself. You mention this as "missing the lower lip" and ask if this is same as the lower front bumpers rubber lip?

Lotus M100 1.6L 16v (89-95) 2.25 - 1 Silencer System - J 5" x 3" Oval - SKU: CLOT8C-J
Lotus M100 1.6L 16v (89-95) 2.25"- Pre Cat Eliminator - SKU: LOTPCE1

[TorqueHorse]

@TorqueHorse
I understand with the Piper's cat-less system there should be no issues with overboost.

I am not an expert on this and could be reading the table wrong, but you may want to just double check the wiki page ...https://wikilec.com/view/Boost_Creep

Yes, the rubber lip is missing and I have secured a suitable black silicone lip I found on eBay that I will install myself. You mention this as "missing the lower lip" and ask if this is same as the lower front bumpers rubber lip?

Yep! That's a great find that you don't have much else to worry about now

PS, if you really want to have different wipers, you should check out the single wiper conversion

[bxs]

@TorqueHorse

Thanks for the ref related to over-boost. At this time I'm of the opinion that I should not worry about this based on others who have the Piper and that Piper itself told me not to be concerned.

I'm a person who values 'redundancy' and having two wipers meets my requirements. The one wiper is interesting and seems like an easy DIY task and maybe brings a modern look to the M100. However, I'm more interested in holding onto some authenticity for the M100 as best I can.

I do have an issue with the outside driver's electrical operated rear view mirror. It can be set for correct viewing but a few moments later it gets lazy and the mirror droops down and points at the ground. I've not found a fix yet, so have two spongy pieces jammed into the mirror's edges to fix the mirror into a single position for my driving. It looks a bit ham-fisted, but works without issues, and of course provides safety for driving.

My grandson and I were able to remove/wrestle the cover lid off on top of driver's dash console to reveal wire looms, fuses, and relays etc in the hopes we could find the bulb(s) for the turn signals and right side of the speedometer display. The L & R turn signals work but there's no tell-tale light in the row of dash lights. I can hear the clicking relay but it's awfully quiet and cannot hear it when driving. We are struggling with finding a solution for this at this time. The 4-way emergency flasher does cause a dash tell-tale light to flash though.

There's one bulb out in the spoilers 3rd brake light. Removing the 34 yrs of rusted screws/bolts holding the 3rd brake light casing to get to the bulbs proved impossible, plus the rear two screw/bolts are almost impossible to get at without damaging the adjacent body surfaces. It may require removing the complete spoiler to deal with this! I believe there are 4 or 5 bulbs in the 3rd brake light, so having just one out is not a serious issue at this time.

I'm really impressed with the trunk space in this M100.

There's very little wrong with my 34 yr old M100 with its 10,246 original miles, and this is very comforting given it was purchased sight-unseen and as-is from a remote seller.

[bxs]

I'm still having no luck in determining why I'm not seeing the Tell-Tale light in the dash for when the L & R turn signals are activated.

I can hear the relay clicking and the L & R turn signal lights are operating correctly for bot iron and rear when activating the steering wheel turn signal stalk lever.

I've check the bulbs for the turn signal lights and they are not LEDs and are the correct wattage.

I've checked the 4-way flasher switch on the console and it operates all four lights correctly, and its Tell-Tell light <--> does flash in the dash. I managed to get hand to backside of the 4-way emergency switch via the glove box opening and all connections are secure. I check the clicker relay in driver foot well and it's working correctly.

Any ideas on what next to check ? Thanks, Cheers.

[TorqueHorse]

That's pretty weird. Tuga has made a custom buzzer to help hear the signal while driving and he likes to tinker on the electronics side, so he'd be a good person to get some next ideas from. He might not be looking in this thread though, since the title is about your exhaust.
Try creating a new post specific to your turn signal, or try PM'ing him directly.

Also, fwiw, even though my dash indicator does come on, with the top down its usually so bright out that I don't see it, and like you, there is so much road noise that I can't hear the relay click. So I've gotten in the habit of using my fingers to check the stalk position after each turn

[Saltire]

I'm still having no luck in determining why I'm not seeing the Tell-Tale light in the dash for when the L & R turn signals are activated.

I can hear the relay clicking and the L & R turn signal lights are operating correctly for bot iron and rear when activating the steering wheel turn signal stalk lever.

I've check the bulbs for the turn signal lights and they are not LEDs and are the correct wattage.

I've checked the 4-way flasher switch on the console and it operates all four lights correctly, and its Tell-Tell light <--> does flash in the dash. I managed to get hand to backside of the 4-way emergency switch via the glove box opening and all connections are secure. I check the clicker relay in driver foot well and it's working correctly.

Any ideas on what next to check ? Thanks, Cheers.

If the turn signals are operating correctly, I’d be inclined to start from the warning light bulb and work backwards, as it were.

First off, have you checked that the tell-tale bulb is a) working, and b) isn’t an LED?

Assuming the bulb is OK, next check the contacts on the back of the instrument panel, where the harness connector plugs in - it’s not unusual for them to become tarnished or slightly displaced. From memory, its terminals B6 and B7, but I can’t recall which connector is B You’ll find out by tracing the copper tracks back from the tell-tale bulb.

If the connectors are fine, then the next port of call is the green/red (LHS turn signals) and green/white (RHS) cables from the direction indicator switch on the steering column. I’d expect you to have 12 volts there, because you say the actual turn signals are working correctly, but it’s worth just checking.

If all that checks out fine, then I’m stumped too - for the moment

Two points to note:

- I’m familiar with UK cars, but not the Federal ones, so treat my comments appropriately
- all the manuals, including the electrical ones and wiring diagrams, are downloadable from the tab at the top of this page, if you’re logged in. The direction indicators wiring diagram is on Page 15