Rover 14CUX: Alternative injectors, any improvements?

[GDCobra]

With Winter either upon us or fast approaching (can't keep track of when seasons change) and my car (semi) off the road I'm looking at what "improvements" I can make, or things I can fiddle with.

I don't want to do any major jobs as I'd like to keep the car roadworthy as I no longer have to SORN it to save money on the RFL as it is now £0/year so if we get any dry weather (and I have any time) I'd like to be able to drag it out and have a play at short notice.

One area I have wondered about is the injectors used in by the 14CUX system. I have the original, standard "Green" injectors which obviously have the appropriate flow rate for the system, I'm not really looking to change that but I have heard that more modern injectors improve atomisation via a better delivery orifice design, seems to be a greater number of smaller holes.
I'm just wondering if anyone can recommend alterntive injectors which can be used without modification of the fuel map (although I can do this I'm not in a posiiton to get it on a rolling road right now) so it is spray pattern I'm looking to improve rather than flow rate, my understanding is that the standard flow rate is good for way more power than my engine will make so not needed anyhow, could even be detrimental.
I'm not necessarily looking for (or expecting) an improvement in overall power output, but if I get better low speed running (smoother, improved throttle response and so on) and possibly (slightly) better economy this would be worthwhile.

Has anyone experimented with this and if so what results did you see?



I'm also looking at creating a rig to test and clean up my existing injectors (thinking of a pressure vessle to hold some cleaning fluid and feeding to one an injector at a time), I've seen some YT clips of this but if anyone has any suggestions I'd be glad to hear them, particularly on controlling the opening/closing of the injector.

As always any help gratefully appreciated.

[Richard P6]

I bought some Vauxhall ones from fleabay and had them rebuilt/serviced - the injector service chap said the spray pattern was much better than the single hole ones. They are the red GM90501588 ones and were used in Vauxhalls including Vectras for many years.

I did look at some four hole Bosch ones but they were rather pricey and I managed to get the Vectra ones, including servicing/testing for under £200 for the set of 8

[GDCobra]

I bought some Vauxhall ones from fleabay and had them rebuilt/serviced - the injector service chap said the spray pattern was much better than the single hole ones. They are the red GM90501588 ones and were used in Vauxhalls including Vectras for many years.

I did look at some four hole Bosch ones but they were rather pricey and I managed to get the Vectra ones, including servicing/testing for under £200 for the set of 8

Hi Richard, thanks for the information and particularly part numbers. That is exactly the kind of informaiton I've been hearing, increased number of smaller holes giving improved atomisation hence a better, more complete burn which should either give more/better power or improved fuel consumption or even both at the same time. I think there may also be some difference in valve type which adds to the atomisation improvement but can't recall the details just now.
Were they a straight replacement or did you have to re-map for them?

[Richard P6]

I should have just installed them then checked any difference between them and the single hole ones, but that would be too simple

I took the engine out and stripped it down, had the bottom end balance and top hat liners fitted, then fitted a V8D Stealth cam, and had V8D take my heads out to Warrior spec. After rebuilding and reinstalling, then a re-tune on my megasquirt, the car is a lot smoother, and much more powerful.

To answer your questions, they are a direct swap, but I have no idea what difference they made to the power/smoothness or whether they need a retune

Sorry that's not very helpful, but from my research they are a good upgrade from standard and aren't too expensive.

[GDCobra]

I should have just installed them then checked any difference between them and the single hole ones, but that would be too simple

I took the engine out and stripped it down, had the bottom end balance and top hat liners fitted, then fitted a V8D Stealth cam, and had V8D take my heads out to Warrior spec. After rebuilding and reinstalling, then a re-tune on my megasquirt, the car is a lot smoother, and much more powerful.

To answer your questions, they are a direct swap, but I have no idea what difference they made to the power/smoothness or whether they need a retune

Sorry that's not very helpful, but from my research they are a good upgrade from standard and aren't too expensive.

That sounds familiar, I have a similar approach of not doing things the simple way when a more complex solution is available!
Mind you I wish I could afford the work you have described, mind you I'd want to convert to a 4.6 if I did that too.

I'll look a bit deeper into the spec' of the injectors you've mentioned and see if I can find the flow rate for comparison.

[GDCobra]

Just did a bit of digging and found some information on the GM90501588 injectors


Twin port brick red body (Vectra) injectors:
Application: Vectra B, Astra, Omega with x18xe & x20xev engines (1995-2002)
GM part no: GM 90501588
Siemens OEM part no: 5WK90761
Flow: 250cc @ 3.0 bar
Impedance: High (14.2 – 15.3 Ohm)
Good for 343hp @ 3.0 bar



No idea how reliable that is but if it is then they are quite a hike in flow rate from the standard 3.9 which are :

Standard injectors:
Application: All Rover V8 Land Rover & TVR models running the Lucas 14CUX system
Land Rover part no: ERR722
Flow: 200cc @ 3.0 bar
Impedance: High (16.2 Ohm)
Known to max out around 285hp if sticking to the 90% duty rule at the standard 2.6 bar


Great in your case as you have re-mapped but I'm guessing I'd be running rich unless I did also.
Also these are a 2 port design, there are designs available with 4 ports which would probably be even better.
For example:

Four port grey body injectors:
Application: Vauxhall Opel Omega & Vectra 2.6i & 3.2i V6 2000-03. Cadillac CTS 3.2 2002-04
Vauxhall part no: 93170386
Bosch OEM part no: 0 280 156 045
Flow: 208.9cc @ 3.0 bar
Impedance: High (14.5 Ohm)
Good for 310hp @ 3.0 bar

Just a slight increase in flow (which I could probably dial down with lower pressure) and I like the 4 port design too.

[Richard P6]

I toyed with the idea of going to a 4.6, even discussed it on here, but I do like the revvy 4.0. The engine is for a fairly lightweight car and I was looking for a bit more zip, and not so much the ability of dragging Billy Smarts Circus up Ben Nevis.

Strangely when I had the red ones tested they came out at 232cc/min, whereas the old ones were 240cc. Both of them were tested by the same garage on the same machine so a bit confusing? I was assured though that the dual port red ones had a much better spray pattern and would handle 300bhp comfortably.

I'm sure I looked at the 4 port grey ones but they only flowed 150cc/min. I may have got this wrong but the research I did, mainly reading forums was the red ones were the best for the price and would handle what I was looking for unless I wanted to spend some serious cash and get some newer Bosch items.

[GDCobra]

That's an interesting result you got, I've looked at information from a few sources and all seem to suggest that the 4 port greys are slightly up on the standard and the 2 port reds are greater again. But you can't argue with a physical test. I wonder if your standard ones were running high for some reason? Although it's hard to imagine how all 8 would.

As I said in my first post I'm also thinking of making up some sort of rig to clean the injectors and check the spray pattern, I could also check the flow rate at the same time.

If the EFi is running in closed loop mode the actual flow rate should not matter too much as the system will simply wind the trims up or down to achieve the correct output however my system is running an open loop map (map 2, green resistor). My understanding is that the fuelling uses a 2D, load-vs-RPM map to work out a value for the fuel required and then multiplies this by a constant value so presumably if I have a flow rate which is a constant amount above or below standard I should just be able to tweak the multiplier, would only be an issue if the flow rate is different depending on the input signal frequency.

[DaveEFI]

Other thing you need to consider is dead time - the time the injector takes to react to a pulse. If you increase the flow rate, this becomes even more important at idle and low throttle openings.

[GDCobra]

Other thing you need to consider is dead time - the time the injector takes to react to a pulse. If you increase the flow rate, this becomes even more important at idle and low throttle openings.

Hi Dave, thanks for your input.
I have been thinking of that hence my (probably poorly worded) comment in my last post. My thinking is that although the injector I'm looking at may flow around 5% more fuel over a minute when held fully open that does not mean that it will do the same when pulsing many times a second and the variation may be more or less at different frequencys, there will be no way to tell unless I try it.

I don't know enough about how the injectors are fired, I'm assuming that when the engine is at high RPM there will be a single "on" time in the cycle due to time available but at lower RPM there may be more, I have heard of 2 injection events per firing event.

If a new injector takes longer to open the flow rate would reduce with opening frequency and obviously go the opposite way if it opens quicker.
Would you expect a later injector to react quicker or slower?

I'm thinking quicker as it seems more likely that a more developed device will more closely follow the trigger requirements which of course would "add to the richness" and I suspect this would be more apparent at lower RPM where the opening time is a greater proportion of the total open time.
The other alternative is I could be completely wrong and talking total garbage. Not for the first time!
I guess the only way to tell is decide on the best alternative and give it a go.

I have a wideband lambda sensor which I can hook up and a piece of software I can use to monitor the output with, I'll hook this up when/if I decide to make the change just to see where I am and if necessary have a play with the map and multiplier.

I think it's worth looking into as the original injectors were very early in the EFi lifecycle and (aparently) there was quite a bit of development between these single orifice style (with a disc valve) and the 4 hole type with pintle valve, the valve probably also has implications for the flow characteristics particularly during open/close phase. That's my guess anyhow.

[stevieturbo]

If any injectors you have perform in any way "better" to make it even worthwhile, then the fuel map will also need optimised.

Otherwise it's just a waste of time.

Largely though, swapping injectors that are already known working ok, for others the same size.....hard to be convinced it will really be worth the effort unless it's for some economy challenge or something

[GDCobra]

If any injectors you have perform in any way "better" to make it even worthwhile, then the fuel map will also need optimised.

Otherwise it's just a waste of time.

Largely though, swapping injectors that are already known working ok, for others the same size.....hard to be convinced it will really be worth the effort unless it's for some economy challenge or something

Hi Steve. You could well be right but I guess you could say that about many of the things we do when we get involved with cars and engines.
The thinking behind this is that there are improvement made since the original injectors were specified, the main one being better fuel atomisation which should give better burn characteristics and deliver either more power for the same amount of fuel or less fuel for the same amount of power. More bang for you buck if you like. Obviously if I was too interested in maximising MPG I wouldn't have a 4L petrol engine but if I can get a few more miles to the £ when I'm not using the power I'm not going to complain, my main focus was that the injectors in my engine are 20+ years old and although they haven't done many miles could probably at least do with a clean, and new O rings wouldn't go amiss particularly with this high Ethanol fuel we have to use these days. So "while I'm in there" it may be worth swapping for something newer, even a full set of 8 are not super expensive .

[stevieturbo]

It is pointless making any changes of what is a major component if you do not re-tune to optimise for those changes.

It's as simple as that.

If you are just getting your own injectors cleaned/serviced, then that is fine

[GDCobra]

It is pointless making any changes of what is a major component if you do not re-tune to optimise for those changes.

It's as simple as that.

If you are just getting your own injectors cleaned/serviced, then that is fine

Totally agree Steve, but given that I am going to be getting the car onto a rolling road (Spring onward) it would be better to do so with the best set of components on it. I'm just looking to make sure I'll be close enough to actually use the car.

[stevieturbo]

Wouldn't see any problems in driving it normally to get it tuned, even if it was a bit larger injectors.