Lotus Elan

EFI solutions and comments

PostPost by: gav » Tue Jan 21, 2020 7:20 pm

Meant to mention, I also bought Dave's extendable trumpets. We used the longest setting that we could because it helps with torque but the length is controlled to some degree by the air intake box.
The photo is the twin cam on the rollers. It produced 150 BHP and 129 ft lb
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PostPost by: HCA » Tue Jan 21, 2020 10:31 pm

Thanks!

Yes, I was intrigued by the extendable trumpets that Dave Walker outlined the theory. They are part of his main kit. I am not sure what the maximum length I can get though on a +2. It is dusty down here so imperative that I use an air box.

So the concensus is to use the 'top linkage' - I will ensure this is what he has as the option and add it to the list.

I reluctantly take your point John about the absence of a shared manifold, but was not sure this was the reason for a MAP delete - my logic thinks that if one has four ports all in good tune so to speak, then one could take a sample from one port and assume the others are the same and apply the necessary squirt across all four injectors... I think maybe I have a lot to contemplate in comparison to the lowly MGB..!

Appreciate the comments!
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PostPost by: mbell » Tue Jan 21, 2020 10:52 pm

HCA wrote:I reluctantly take your point John about the absence of a shared manifold, but was not sure this was the reason for a MAP delete - my logic thinks that if one has four ports all in good tune so to speak, then one could take a sample from one port and assume the others are the same and apply the necessary squirt across all four injectors...


I think the problem is more that you get a lot more variation in the MAP reading from a single cylinder. The manifold sort of average the vacuum level so you can get a reasonable reading at any point in time. From a single cylinder you get a lot more variation over the enegine cycle and therefore very variable reading depending on when in the cycle it is sampled.

In theory if you can control the ECU sample timing you could work around it and read one cylinder at same point in the cycle all the time and get a reasonable reading.

I think some people have rigged up a vacuum tank on a restricted feed to provide a averaged vacuum signal.
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PostPost by: HCA » Tue Jan 21, 2020 11:06 pm

Thanks!

I confess that I know very little on these finer points, so I am sure you are right!

I am interested in what you say about providing an average vac signal. Not for the injection, but so I might be able to fit a vacuum gauge! I have had a vac gauge on pretty well every [older] car I have played with - but these have all been BMC A or B series lumps. I am going to seriously miss one on the Elan :( :(
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PostPost by: Bahtatboy » Mon Jan 27, 2020 8:09 am

Newbie and potential +2S owner...

Could someone give me a ball-park price for having a +2S converted to EFI? All work to be done by an experienced and reputable company -- full turn-key package.

Thanks in anticipation.
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PostPost by: HCA » Mon Jan 27, 2020 9:13 pm

Back again begging some info if I may?

Ae there any photos of how EFI users with purpose made alloy fuel tanks have installed the hp pump and filter on a +2?

I was wondering how they might be on the back board behind the carpet, but afraid the pump noise would permeate into the cabin.

Thanks, Hal
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PostPost by: HCA » Mon Jan 27, 2020 10:38 pm

Bahtatboy wrote:Newbie and potential +2S owner...

Could someone give me a ball-park price for having a +2S converted to EFI? All work to be done by an experienced and reputable company -- full turn-key package.

Thanks in anticipation.

Depends on the hourly rate charged - allow 5k
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PostPost by: h20hamelan » Tue Jan 28, 2020 1:48 am

For me, I would not hesitate and use a fuel cell or aluminum tank with a bladder.
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PostPost by: Bahtatboy » Tue Jan 28, 2020 12:50 pm

HCA wrote:
Bahtatboy wrote:Newbie and potential +2S owner...

Could someone give me a ball-park price for having a +2S converted to EFI? All work to be done by an experienced and reputable company -- full turn-key package.

Thanks in anticipation.

Depends on the hourly rate charged - allow 5k


Thanks. And ouch! I see kits advertised, for less than £2k, that say someone with average diy skills can fit themselves. But the various posts in this thread seem to suggest there's a lot more to it. What am I missing?
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PostPost by: elanman999 » Tue Jan 28, 2020 1:35 pm

Bahtatboy wrote:
HCA wrote:
Bahtatboy wrote:Newbie and potential +2S owner...

Could someone give me a ball-park price for having a +2S converted to EFI? All work to be done by an experienced and reputable company -- full turn-key package.

Thanks in anticipation.

Depends on the hourly rate charged - allow 5k


Thanks. And ouch! I see kits advertised, for less than £2k, that say someone with average diy skills can fit themselves. But the various posts in this thread seem to suggest there's a lot more to it. What am I missing?



You are missing :-
Tank
Pipe work
Filter
Fuse box for EFI
Mapping
X pound an hour.
You'll probably need a friend with a lathe as well. :lol:
VAT.
£5K would be quite cheap for a turn key job IMHO.
Lots of the conversion kit prices assume an injected car to start with.

YMMV
Cheers
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PostPost by: HCA » Tue Jan 28, 2020 3:05 pm

Yep! I am putting a kit together as we write. Do not be fooled by some ‘all in’ prices. As John says there is more to it. I break it down so:

Components for EFI and EDIS: 2500
Aloy tank with collector: 500
Pipework and fittings; 200
VAT: 600
Labour and rolling road: 1000 minimum
Spa weekend for Mrs Bahtstboy and friend: 500
Gotcha fund: 500

- and could be more..!

Bon chance. Hal
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PostPost by: elanman999 » Tue Jan 28, 2020 4:01 pm

""Spa weekend for Mrs Bahtstboy and friend: 500""

Hal,
I Just love that! :lol: :lol:
Cheers
John
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PostPost by: disquek » Tue Jan 28, 2020 4:39 pm

There are two types of EFI tunes.

Speed Density - this is where the load is determined by the vacuum level in the manifold
Alpha-N - this is where the load is determined by the TPS.

You cannot (and I know folks will say they've done it - but it's not possible to do such that the car runs well at all RPM/load combos) do Speed Density on an ITB engine. There are many approaches to it. None work. The most common is an aggrigation chamber where all four vacuum signals are brought together. This wont work. The reason being that the one cylinder that's in it's intake cycle and thus generating a vacuum is drowned out by the other three were the intake is at atmospheric pressure. So the signal is lost/diluted. The range of pressure you will have to tune with is only a few kPa.

If you could design (and some have done it) a system with four map sensors and a circuit to average them, it could work. But unless you're an EE with tons of time on your hands for a one off ....

Motorcycles (the most common ITB EFI) use a hybrid system where they do Speed Density in part of the range and Alpha-N in the other.

You might ask "who cares which method is chosen?" The answer is that Alpha-N is far more finicky. Where Speed Density can be done by hitting a few map/rpm points on the dyno and extrapolating between them, Alpha-N requires that you hit EVERY point in the TPS/RPM map and tune it individually (because VE is non linear).

Most ECUs now have an auto-tune feature which makes this easier. But it's still far from easy. You need a load bearing dyno (not an intertia dyno), and very competent tuner, and ... loads of dyno time. One big factor is that this tuning generates a lot of heat and so you can't just go from cell-to-cell. You can only do a few cells at a time and then let it cool. All while being charged $250/hour for the dyno.

I've done this a few times now. It does produce an amazing tune. But also know that _any_ change to the engine after it's tuned will require a full retune.

If I were to inject my Elan (and I may) I would seriously consider fabricating a single throttle body style manifold. They have been shown to make at least equal power to ITBs and they can be tuned using Speed Density. And I have access to two load bearing dynos!!

Just my .02c.

-Kyle
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PostPost by: nmauduit » Tue Jan 28, 2020 8:16 pm

disquek wrote:
Just my .02c.

-Kyle


thank you for your 0.02c - well earned, and worth quite a bit more imho...
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PostPost by: h20hamelan » Tue Jan 28, 2020 8:33 pm

disquek wrote:There are two types of EFI tunes.

Speed Density - this is where the load is determined by the vacuum level in the manifold
Alpha-N - this is where the load is determined by the TPS.

You cannot (and I know folks will say they've done it - but it's not possible to do such that the car runs well at all RPM/load combos) do Speed Density on an ITB engine. There are many approaches to it. None work. The most common is an aggrigation chamber where all four vacuum signals are brought together. This wont work. The reason being that the one cylinder that's in it's intake cycle and thus generating a vacuum is drowned out by the other three were the intake is at atmospheric pressure. So the signal is lost/diluted. The range of pressure you will have to tune with is only a few kPa.

If you could design (and some have done it) a system with four map sensors and a circuit to average them, it could work. But unless you're an EE with tons of time on your hands for a one off ....

Motorcycles (the most common ITB EFI) use a hybrid system where they do Speed Density in part of the range and Alpha-N in the other.

You might ask "who cares which method is chosen?" The answer is that Alpha-N is far more finicky. Where Speed Density can be done by hitting a few map/rpm points on the dyno and extrapolating between them, Alpha-N requires that you hit EVERY point in the TPS/RPM map and tune it individually (because VE is non linear).

Most ECUs now have an auto-tune feature which makes this easier. But it's still far from easy. You need a load bearing dyno (not an intertia dyno), and very competent tuner, and ... loads of dyno time. One big factor is that this tuning generates a lot of heat and so you can't just go from cell-to-cell. You can only do a few cells at a time and then let it cool. All while being charged $250/hour for the dyno.

I've done this a few times now. It does produce an amazing tune. But also know that _any_ change to the engine after it's tuned will require a full retune.

If I were to inject my Elan (and I may) I would seriously consider fabricating a single throttle body style manifold. They have been shown to make at least equal power to ITBs and they can be tuned using Speed Density. And I have access to two load bearing dynos!!

Just my .02c.

-Kyle



Seems great to me, please. When You get further, keep us posted. If you or someone you know that can put together kits, I am sure they will sell.

Thanks Kyle
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