Injector replacement and what not to forget...

[Barrykearley]

5 hours ago, RobinB5 said:

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:

 

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

Fit them just like the top red line. They ain’t gonna fall out or leak if the orifices are clean and the o rings not fouled. Even me and @RobinB5 along with dozens of other folks have managed to fit these.

[RobinB5]

The problem though Barry is that there is no groove for the clip on the top red line on the RC injector.

[Barrykearley]

Ahh yes sorry I wasn’t clear @RobinB5 If you fit them with the clips - and bolt the rails on - then the injectors are seated into the engine block and rail just fine. 

[RobinB5]

For sure if it wasn't for @BarrykearleyI wouldn't have released they sent the wrong (reduced) flow rate RC injectors. But good on the supplier to acknowledge their error and supply the correct ones after I returned the PL2-320s that they'd originally sent (4 day turnaround):

Cajoled #3 son to help me remove the stock injectors yesterday evening, will do more cajoling this evening for him to help put these new beauties in. Don't think he's really interested in car maintenance, but the experience won't hurt  

5 hours ago, Barrykearley said:

Ahh yes sorry I wasn’t clear @RobinB5 If you fit them with the clips - and bolt the rails on - then the injectors are seated into the engine block and rail just fine. 

But apparently not on @harveysalgadopix's injectors that seem to be longer than yours, mine and @Chillidoggy's. 

[Barrykearley]

@RobinB5mine looked just like what he has posted above.

[RobinB5]

Right, new ones in, idles lovely, will take her for a spin tomorrow! And that is the end of the injector replacement. (and no, I don't know why one of the 2 below is marked '2660' and the other '2930', both are marked as PL2-370 so I'm not going to get fussed). 

[tomcattom]

14 hours ago, RobinB5 said:

and no, I don't know why one of the 2 below is marked '2660' and the other '2930', both are marked as PL2-370 so I'm not going to get fussed

Batch number or similar I expect.

[sailorbob]

The overall length of the replacement injector can vary a little bit and not be a cause of concern. The OE injector positions the O ring higher up into the fuel rail than most modern injectors. Having a reduced distance between the retaining clip groove and the upper O ring groove is not generally a problem on the Delco injection system because the bore for the injector in the fuel rail only has a short chamfer on it.

A critical dimension is the distance between the bottom of the upper O ring groove and the top of the lower O ring groove on the injector. When inserted the upper O ring is pushed downwards and the lower O ring is pushed upwards and if the grooves are too close together then the O rings may not get seated deep enough to seal.

[snowrx]

On 10/09/2021 at 03:00, Barrykearley said:

 

Anyone else have an issue with this spec? Without a fuel pressure input, how would the ECU determine pulse width vs. fuel flow at varying pressures?  55psi is 83% more than 30psi, mixtures can't vary by that much.   I suspect the spec. range is for absolute to atmosphere, but there must be a static pressure target referenced to to the manifold pressure, probably mid range around 1 Bar or 43psi.

Running 320's in a 370 engine probably gave Robin a bit of a "lean is mean" tune, the shaking hands knew that something was wrong, glad they got pulled out in time!

 

[harveysalgadopix]

Joe at JAE initially told me to use the bottom clip, which doesn’t fit due to the electrical connector, after speaking with RC Joe advised me to use the top clip, went with His recommendation and everything seems to be running fine. Seems to have a new little rattle noise, maybe I am being overly cautious. Hate any mystery noise.  

[RobinB5]

21 hours ago, snowrx said:

Running 320's in a 370 engine probably gave Robin a bit of a "lean is mean" tune, the shaking hands knew that something was wrong, glad they got pulled out in time!

 

Well, took her out with the 370s installed, not as manic to be sure, but still felt better than the old stock ones (probably psychological). @Barrykearleyalso mentioned that if the car was running lean it would be more responsive (at the expense of it buggering up at some point). Why is it that a leaner mix results in more response and what happens to the engine if run too lean?

[Barrykearley]

It all gets very hot in the combination chamber - yes more power - but at the expense of melting expensive engine parts

[drdoom]

There is a corollary for this is the tuning of air-cooled engines, where sufficiently rich fueling is critical to engine life. In fact it is reported that modern high performance OEM machinery, the Honda S200 for instance, are ECU mapped rich in the upper reaches of operation for the sake of longevity. In any turbo'd engine of prior era it will be that much more critical owing to elevated air inlet temperatures.

As to response I'd wager the new 320's better atomisation would account for perceptible improvement over well aged originals. As stated in an earlier posting there's been quite some improvement to injector performance over the years as well. Absent rolling road test would we be certain of leaner mixtures in operation on 320's, given closed loop feedback via O2 sensor?

[snowrx]

Making up a possible 15% fuel shortfall in wide open throttle would depend on the authority range and response speed of the ECU's O2 feedback loop, and whether closed loop is used in the WFO condition. To many variables for any  certainty, I was talking off the top of my head given the surprising performance difference described by the OP.

RC is not very descriptive on  injector specs on the website, I would hope these would be a modern multi hole spray to replace the old pintle style.

[Barrykearley]

3 hours ago, snowrx said:

Making up a possible 15% fuel shortfall in wide open throttle would depend on the authority range and response speed of the ECU's O2 feedback loop, and whether closed loop is used in the WFO condition

My understanding of the esprit Ecu - at close to WOT - the secondary injectors are turned on - and it goes open loop and there is no O2 control. It’s at higher revs and throttle opening that the risk of lean running exists - hence those flood secondary units.

[drdoom]

Agree utterly with @Barrykearley 's points above. Closed loop status is used for emissions control and is subject to going out of parameters when an O2 sensor is failing, not worth risking engine meltdown at full chat in such an instance. Driving along moderately when the system is in closed loop is where I'd speculate compensation for the differing injector flow rates might occur.

[Giniw]

On 19/09/2021 at 07:58, Barrykearley said:

hence those flood secondary units.

 

[RobinB5]

@Giniw, the sci hub links are all broken. Do you have any updated links?

[Giniw]

Even the updated one I posted moments ago? This one is working from France right now.

(I can upload the PDF too of course)

 

Here it is!

@Bibs>Not sure if it's OK to upload it here on TLF?

900269.pdf

[RobinB5]

Thank you @Giniw!

[drdoom]

I note the page 13 specs on power output with use of 95 RON petrol, which over here would be 91 and so the lowest rated premium to be had in N.A. Thanks for the PDF, various points of technical merit for the petrolheads!

Cheers

[Giniw]

From https://www.etuners.gr/fuel/ I understand the 95 RON is equivalent to the "91 PUMP" found in North America indeed (average between the RON and MON ratings)

Now this paper applies to the injection charge-cooled engine, maybe it's not the same recommended octane rating for your S2?

[drdoom]

Engine spec for my S2 remains to be settled, though likely high C/R N/A 2.2 if feasible. 

Cheers

[harveysalgadopix]

I went ahead and put the RC Injectors in using the top clip, don’t like that they are barely seated into the fuel rail. RC claims that the Injectors were specifically designed for Lotus Esprit’s, Why not make them slightly taller? The injectors would be properly seated in the combustion chamber and the fuel rail. If you are installing RC Fuel Injectors you will see what I am talking about. When you bolt down the fuel rail your now out of alignment, drive the bolts thru and now the fuel rail has pulled the injectors out of the combustion chamber slightly  My Esprit seems to be running fine, however it bothers me that I cannot have my Injectors seated properly top and bottom. 

Edited September 27, 2021 by harveysalgadopix

[harveysalgadopix]

RobinB5 your fuel rail is looking crusty, I’m kinda surprised you didn’t clean it up while you were putting in your injectors, I would be more than happy to mail you some steel wool.

Edited September 27, 2021 by harveysalgadopix