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Injector replacement and what not to forget...


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  • Gold FFM
30 minutes ago, Chillidoggy said:

Just a thought - how do those injectors match up to the originals resistance-wise? I seem to recall someone mentioning that ECUs can sometimes be a bit choosy.

2 Ohms apparently for the originals. The new ones are now Royal Mail bound back to the supplier so can't measure them (how would one measure it?). Can only assume that if the new ones were much different an Error 65 would have been thrown:

  

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  • Gold FFM
39 minutes ago, RobinB5 said:

2 Ohms apparently for the originals. The new ones are now Royal Mail bound back to the supplier so can't measure them (how would one measure it?). Can only assume that if the new ones were much different an Error 65 would have been thrown:

  

Ah, yes, that's scratched the itch I couldn't get to. I knew I remembered something about it!  Yes, I suppose if there's no error code set, then you're home and dry. I'd love to see a back-to-back test on the dyno on the effects of the change. If they are more efficient, that's a good thing.

Margate Exotics.

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  • Gold FFM

Ian, all I can honestly say is that the idle tick over is noticeably more lumpy with the old injectors (having now put them back in). I'm minded of this comment from Dermot's great page at https://users.ox.ac.uk/~ohare/engine.htm

"Fuel injectors _ Primary The stock primary injectors are low impedance (2 ohms) 370cc/min or 36lb/hr "peak and hold" injectors. The Lotus OEM ones have been frequently been deplored for their poor design and spray pattern."

and after 95k miles I can only assume they haven't got any better! :) 

Also came across a reference to the general advice to replace them after 60-70k mile (though any and all such advice is cheap of course). Either way, atomization of the fuel prior to combustion is one of the most important aspects of effective ICE operation (that I do remember from my Mech Eng degree (not much else mind)). 

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  • Gold FFM

When the revs go up - those original 370cc injectors struggle to keep up with fuelling the car and it leans out - hence the flood secondary injectors.

with 320cc injectors you risk having a lean running issue. They simply are not correct. the fuel pressure is a bit of a red herring - yes you can adjust that to increase the fuelling should you choose - but the Ecu sure cannot do that in the esprit 

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  • Gold FFM
3 hours ago, RobinB5 said:

Ian, all I can honestly say is that the idle tick over is noticeably more lumpy with the old injectors (having now put them back in). I'm minded of this comment from Dermot's great page at https://users.ox.ac.uk/~ohare/engine.htm

"Fuel injectors _ Primary The stock primary injectors are low impedance (2 ohms) 370cc/min or 36lb/hr "peak and hold" injectors. The Lotus OEM ones have been frequently been deplored for their poor design and spray pattern."

and after 95k miles I can only assume they haven't got any better! :) 

Also came across a reference to the general advice to replace them after 60-70k mile (though any and all such advice is cheap of course). Either way, atomization of the fuel prior to combustion is one of the most important aspects of effective ICE operation (that I do remember from my Mech Eng degree (not much else mind)). 


I’m always wary when unsubstantiated claims are made about performance engine parts. The American chaps are superlative at this, and if you believed their every claim, then you would end up with a 1,000 bhp motor.

This is, Dermot provides no hard evidence which backs up his claim. He may well be right but if so, to me he needs to prove it.

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Margate Exotics.

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  • Gold FFM

A proof based system of truth is always desirable. Intuitively however, injectors from 1/4 century ago are likely to be less effective than modern day equivalents. Factor in degradation, wear and tear, then even more so. Proof of the pudding is in the eating though! Apparently it's about £15 per injector to be tested for flow rate and spray pattern. Half tempted, in the name of science and the scientific method, to have one stock one and one new one tested, just to see what the findings are. Cheaper but albeit not as conclusive, as a full before and after dyno test, but would be fun nevertheless :)

 

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  • Gold FFM

Spray patterns etc have changed dramatically over the last 30 years - modern injectors atomise fuel completely differently. Best case - more bhp - worst case - better mpg.

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  • Gold FFM
12 hours ago, RobinB5 said:

A proof based system of truth is always desirable. Intuitively however, injectors from 1/4 century ago are likely to be less effective than modern day equivalents. Factor in degradation, wear and tear, then even more so. Proof of the pudding is in the eating though! Apparently it's about £15 per injector to be tested for flow rate and spray pattern. Half tempted, in the name of science and the scientific method, to have one stock one and one new one tested, just to see what the findings are. Cheaper but albeit not as conclusive, as a full before and after dyno test, but would be fun nevertheless :)

 


I have a feeling that Espritmon can calculate a power figure, so it might be worth checking that. Yes, costs can mount up on a dyno, but most will give you a ‘power-check’ for not a lot of money. There’s one local to me that will do so for £50 or so. Because there’s no ECU adjustments to be had, a check is all that can be done anyway.

As I said before, efficiency is key, and increased efficiency will not only mean your engine smells nicer, but should give a performance increase, and (if you keep your foot out of it and drive like an old fart according to my wife), increased MPG!

 

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Margate Exotics.

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  • Gold FFM

Defo 370cc units. Even come with a sheet just like yours.

these could be fake though since they haven’t come from a well respected lotus specialist 🤪0125207F-C163-4AB9-A249-B65F3E91EF18.thumb.jpeg.e614607cf8041d83a1927e96d42da9e5.jpeg

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  • Gold FFM

They are now installed. Cold idle initially sounds much the same but I’m sure there will need to be a relearn to get the best out of them.

Driving up the road - there’s a definite improvement - acceleration does seem smoother and power delivery more refined. Only time will tell - but the old units were probably original to the engine.

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I just received new RC fuel injectors from JAE this week,  they are a tad shorter than the originals, can’t bolt down the fuel rail now, this makes it impossible to get a seal. I have read about this situation before but can’t find the post. I realize i am going to have to do some kind of modification, Anyone out there dealt with this before?  Any insight would be greatly appreciated.                                                                                        Chris Herbert.                                                  1989 Lotus Esprit Turbo

45449B1E-7D42-40CC-B501-954613381078.jpeg

Edited by harveysalgadopix
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  • Gold FFM

@harveysalgadopix, the distance between the groove at the top where the circlip thing goes and the bottom of the injector is almost identical so are you saying the rubber o-ring doesn't seal properly at the top? How can you tell? Do they leak when working? The injectors can be rotated by hand once installed but if the o-rings weren't in properly then it would be possible to wobble the injector by hand.

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Yes they leak when working, the holes that hold the fuel rail on top are now misaligned, if i run the bolts thru them it pulls the fuel injectors up the equivalent to the difference between the injector heights. It seems i need fuel injector extenders.

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  • Gold FFM

The o-rings should stop this being an issue. Are you sure you have removed the old o-rings from the rail? The old rings are often left behind in there.

 

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  • Gold FFM

Chris, saw on FB that you have an 89 Esprit. Is it an X-180 or SE? Both Barry and I have successfully replaced injectors recently on an S4s and S4 respectively using the RC PL2 injectors. Wonder if the fuel rail was mounted slightly higher on your earlier car??

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  • Gold FFM

Mine were the same as the photo above. Make sure the seating holes are free from debris and use some slippy to locate them. Sounds like you have a damaged o ring

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The injectors that were in my Esprit Turbo (non se) are original, the injector closest to the firewall would not open when I put power to it. The other three worked fine. Jay at JAE knew exactly what car I have as I asked Him if not having a SE or chargecooler would make a difference on what injectors I ordered? Hey His reply was they call for the exact same injectors that go in a SE. I did my best to measure both injectors and the RC injectors are 1/8 shorter than the originals, this may not sound like much difference, however it is just enough to pull the RC injectors out of socket when I bolt down the fuel rail. I am sending inquiries to JAE and RC fuel injection. I will post what kind of resolution I come up with. Thank you everyone for your comments. 

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my understanding is that my injectors are original, I know that Lotus commonly made small changes on these cars even mid production. I’m not  surprised that my injectors are different than Robinb5’s    I sent and email to JAE and Joe tells me that if I use the lowest clip mount on the fuel injectors all will be fine. I don’t understand how this will help bolting down the fuel rail. I am going to fiddle with it today, I will report back my findings with pictures for the next Esprit Owner who finds themselves in this situation.Thank you once again for all of your comments. Chris H.

 

Good Morning Christopher,

Thank you kindly for your email.

There are two spots to insert the retaining clip. If you use the “lower” clip, it should hold the injector in just fine.

 

Best Regards,
Joe

 > 

Sent: Monday, September 13, 2021 12:00 AM
To: Jay JAE. Makwana
Subject: Fuel injector spacer for RC injectors

 

Hello, I just purchased 4 RC fuel injectors for my 1989 Lotus Esprit Turbo. These new RC injectors are slightly shorter than the originals so when I attempt to bolt down the fuel rail it pulls the injectors out of socket so to speak.  Do you have spacers for this?   Thank you in advance for your 

 

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  • Gold FFM

Chris, don't know how that's going to work out. The RC injectors have one clip mount (potentially a lower one but not designed for per se as the clip would interfere with the electrical connection). And that's even lower than the other one, which in turn is lower than the the stock one:

 

image.png.6851da7e18f9ed714c2911bce600cd70.png

Might be easier just to buy an S4, S4s or GT3? :) 

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  • Gold FFM

I’m not sure if this will help, but I found a photo of my Rochester injectors from my S4s. Apologies for the text pasted over them, and you might be able to see better if you scroll in, but to me they don’t look like the ones you have.

 

25A17D2B-A24A-451E-8BBA-30923B936680.jpeg

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Margate Exotics.

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