Grandpa's Fast M100 (Red)

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Grandpa's Fast M100 (Red)

Postby TRAK » Mon 28.04.2025, 03:45

Hello! On the flip side of the Stock White Elan, I am also working on Grandpa's Red Lotus that I suspect to be a more exciting ride (if I can get her running).

Background: This was Grandpa's second Lotus that he drove for the past 10 years in conjunction with White, to combat the 5k mile limit for classic cars in my state. (78k miles on the engine) The car last drove the streets 1 year ago before sitting in the yard for no more than 6 months before I started fiddling with it. It was given to me with the phrase "Runs great! Think it just needs an alternator"

What I've Done:
-Replace the Alternator
-Clean and Replaced IAC Valve
-Compression Test (165 across all cylinders)

What I've Found:
-CAT Converter removed
-Upgraded Fuel Injectors
-Aftermarket Fuel Pressure Piggyback Controller
-Stock Boost Gauge Transducer is electrically connected and still in engine bay, yet the vacuum tube is not connected to engine. In fact, the port where the tube should go is capped.
-Needless to say, I believe there is a Mountain Chip installed.

Issues:
-After replacing the Alternator, I was able to get the car to turnover. Although, the engine would not idle without opening the throttle. Figured the IAC valve was stuck from sitting in the Vegas heat.
-Once I cleaned and replaced the IAC, went to start the engine and it would crank, but not turnover.

Can anyone point me in the direction of how to work on an upgraded Elan with Mountain Chip? I don't seem to have access to the Mountain Chip section of the forums.
1991 Lotus Elan M100 White (FED, Stock)
1991 Lotus Elan M100 Red (FED, Upgraded)
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Re: Grandpa's Fast M100 (Red)

Postby TorqueHorse » Mon 28.04.2025, 06:59

Good news is that if you have a mountain chip, it won't affect the running of your engine until it's over ~3k rpms and already under boost. (If you want to read more about the history of the mountain chip, I think you have to rely on the way back machine to get the link to work.)
So that just leaves all the other issues that could prevent a car from running ;)
Fuel supply/stuck fuel injectors are often a likely culprit for cars that have been sitting and would turnover one day, but not the next. You know about the little fuel cutoff switch behind the seat right? I've tripped that before and forgotten to check it.
-Matt N
'91 FED M100 -rolling resto

...and come to Salt Lake City, for the very first truly national Lotus Car Club event for the USA: LUG September 24-28, 2026
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Re: Grandpa's Fast M100 (Red)

Postby RonR » Mon 28.04.2025, 10:58

You can remove the Mountain chip and revert to the original Memcal to eliminate it from your list of suspects:

If you open up the ECU you should find that the mountain chip board (usually has Moates written on it) can be removed from it's slot and the original Memcal (blue thing should be attached to the Moates board) can be put back in.
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Re: Grandpa's Fast M100 (Red)

Postby TRAK » Tue 29.04.2025, 03:50

Ahh yes... the pesky inertia switch. I did not check that before turning the key. It should be at the top of my checklist by now :lol: Thankfully, I have a couple sets of the upgraded injectors to try out.

RonR: With my family saying it ran fine, I'd like to keep the mountain chip in the car and get it running again since it seems like the necessary aftermarket help the engine needs to handle the extra power is already installed. Would the aftermarket parts interfere with the ECU if I were to remove the Mountain Chip?

I'm mainly curious about what aftermarket support the forums recommend for the engine once a mountain chip is installed since I inherited it post-install. I've found a few parts in the garage that don't fit a stock Elan, like a 60KV Ignition Coil, that I can only assume is for Red. My main issue is not knowing where Grandpa left off in this project and not knowing what our engine needs to handle the extra power.
1991 Lotus Elan M100 White (FED, Stock)
1991 Lotus Elan M100 Red (FED, Upgraded)
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Re: Grandpa's Fast M100 (Red)

Postby Tuga2112 » Tue 29.04.2025, 09:48

theres very few recorded cases of people going over the mountain chip upgrade. and when they do. its basically a situation where every person goes in their own direction.

I Know of 2 folk that took M100s further than a everest/elisium chip. but neither is active in the forum these days.

you may strike luck and come across people here who can and are willing to help, but i suspect thats not likely

my suggestion is to start learning about the topic in depth, if you dont have the motivation to learn the topic from scratch. i strongly recomend to bring the car back to stock.
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Youtube Channel @Tuga2112 M100 repair videos
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Re: Grandpa's Fast M100 (Red)

Postby dapinky » Tue 29.04.2025, 10:13

Trak,

I think you are looking at the 'handling upgrades' question the wrong way round......

.... the 'upgraded parts' don't give it extra power, they allow the engine to survive at the inputs that the ECU demands.

So, lets start with the absolute basics (and I don't mean to sound at all condescending by starting at basics) - The actual lump(s) of metal that are bolted together to make the engine - well, Lotus already dictated a load of changes from 'stock' Isuzu lump to make it cope with a higher power and torque output - but it can still be taken further, if needed.

Personally, I wouldn't ever need to do anything like that, as what is already there is good enough for 350bhp, and to go to 450bhp the only thing I would change would be the head gasket (to a MLC unit)..... as these cars start to become undrivable once you get over 250bhp, not many people have the need to go higher.

Of course, there are always those 'left field' cars that go higher, but at that point it is not really a practical car for street use.

In 'OE' form the engine will make 165bhp (possibly slightly less on a FED car because of emission rules), and this is easily increased by fitting a 2 1/4" exhaust, allowing the standard engine to breath much better...... you will then be able to see ~180bhp.

An 'Everest' chip will allow the engine to develop ~205bhp

That is the point at which the other bits bolted to the engine become marginal - the turbo was selected to be small enough to give a rapid boost with little lag, but that comes at the expense of total airflow volume - so it will run out of puff not long after this point.... but before it does, there is a little bit more gain to be had from it.

Before you can increase the boost beyond the 0.92 bar "limit", you need to improve the fuel volume - the stock injectors run 325cc/min at full capacity, and once you go over the 0.92 bar boost, they simply can't physically provide enough fuel to prevent running lean, and engine detonation because of that.

So, with bigger injectors, you can then safely increase the boost level........ the standard turbo will go beyond 1 bar of pressure, but the MAP sensor will need to be changed at the 1-bar point, as the Elan uses a 2-bar sensor, but will then need a 3-bar sensor (1 bar atmospheric, plus 1 bar boost), but the turbo then becomes the limiting factor.

It is possible to fit a bigger/better turbo unit (Garret 2554R) but it isn't a bolt-in thing as it needs an adapter plate. All the development work was done many years ago by Lotusgirlmarie, and if you search the forum it will tell you how she did it all (and she did it properly!).

Of course, to control all that you need to change the ECU - this is where you can choose between getting the most out of it, and making do but keeping it useable......

..... to 'do it right' you would need to throw out the current ECU and replace it with a modern programable unit (Others have used Haltech or Microsquirt - I only have practical knowledge of Megasquirt from many years ago, and I'm sure things have moved on a hell of a lot since I last installed a unit on a car).

BUT

The thing is that the current ECU will work quite adequately if you use the simple maths (spelled for the UK, with the correct 's' at the end :lol: ) - if you increase the MAP by 50% (3-bar, from 2 bar), and then increase the injector volume by the same 50%, ie fitting 490 cc/min, it 'should' run the same - except it isn't quite that simple, as getting a 495 injector isn't possible, so the 'best' is a 550cc unit (easily available). This is why the programmable ECU will give a better end result, as it is infinitely variable for whatever you fit.

By this point, you will have maxed out the exhaust flow volume again, so will need to go to a 2 1/2" system, possibly with a custom downpipe (which would be needed for the turbo swap anyway).

After that (which can have you somewhere over 300bhp) it starts to get much harder, and the only Elan I've known to go above 400 was Costas' "Sh4rk" which is documented on the forum from 20 years ago, and got there using Nitrous Injection.

So, it depends on what you want to use the car for, and much of it depends on whether you want to follow someone elses ideas, or try to develop new ones - if I were to be building a pure track car I would use a standard engine, 2 1/2" exhaust, Garret 3554R, 3-bar sensor, Megasquirt ECU, 550cc injectors, oh, and fit a Quaiffe LSD in the gearbox along with a 3-puck clutch......

...... but if I "just" wanted a car to use on the road, with a fair few track days, I would stick to 2 1/4" exhaust, standard turbo, Everest chip and spend my money on good Yokohama AD052 tyres, Ferodo DS3000 brake pads and reduce the weight as much as possible.....

..... as it is, my car is built for road use, with (previous) occasional trackdays, and has the same as above, but with Yokohama 008R tyres, Ferodo DS2500 pads and I would empty the boot when I got to the track...... the limiting factor on track times was usually other people getting in my way, tyre grip, brake fade and running out of talent - not necessarily in that order!!!!

I never got to a point where I NEEDED more power, although I did get to a point where it may have made life easier.
Dave

Just the one now, but this one's mine! - and it will be finished eventually..... - but also temporary custodian of a project until it is finished enough for Angie to drive it


...oh, and a 2006 Freelander destined for the jungles of The Gambia - 4500 miles across roads, desert and tracks - what could possibly go wrong?
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Re: Grandpa's Fast M100 (Red)

Postby TorqueHorse » Tue 29.04.2025, 14:04

For the Mountain chip, there aren't any parts different from stock in the engine bay. It's just a chip that plugs into the ECU like RonR explained.
Here is a link to the old site to read the details https://web.archive.org/web/20160220134 ... -data.html
You may want to post a photo of your engine bay if you want input on if your setup is stock or not. People have done other things to increase boost, without using the mountain chip (like blow offs, micro-squirt, etc.) if that's the case, then yes, your troubleshooting procedures may be different than what is in the main service manuals.

Edit
Was having trouble posting this earlier, but just saw there are now more comments with more detail when mine finally loaded. Good luck
-Matt N
'91 FED M100 -rolling resto

...and come to Salt Lake City, for the very first truly national Lotus Car Club event for the USA: LUG September 24-28, 2026
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