Later fuel rail
Discussion
Hi Adam
What style of injectors do you have...The type with the jubilee clips at both ends of the injector hose or the one clip and ferrule type?...I have a fuel rail for the latter and wanted to replace mine ..
Its fitted with the same grey top injectors but was told that they might need a different signal from the ECU being from a 4.0 RR, the 4CU lacks that capability as I understand it...I mainly wanted to do it as the old connectors on mine are very brittle and a couple have chipped where the clip is, This later one I have has the heavy duty clip and shielded cables...
I guess you would be okay with your new ECU...
What style of injectors do you have...The type with the jubilee clips at both ends of the injector hose or the one clip and ferrule type?...I have a fuel rail for the latter and wanted to replace mine ..
Its fitted with the same grey top injectors but was told that they might need a different signal from the ECU being from a 4.0 RR, the 4CU lacks that capability as I understand it...I mainly wanted to do it as the old connectors on mine are very brittle and a couple have chipped where the clip is, This later one I have has the heavy duty clip and shielded cables...
I guess you would be okay with your new ECU...
Yes, when I fitted megasquirt I went to the later injectors. You have to change the manifold as well, the sealing method is different (some websites say they are interchangeable, but I disagree - one seals axially and the other on the circumference). You'll also have to replumb the heater connections if you switch to a later manifold. I assume you have an aftermarket ECU? I don't believe you can put later injectors on a flapper ECU without problems. I guess you could convert to a full hotwire system.
You say 'upgrade'. I'm not sure about that. I've now gone back to the flapper injectors; but I'm running them on PWM peak/hold so I can bang them open on 12Volts and hold them open on 5V. I get much better control that way as they open and close quicker and cleaner. A common misperception is that newer is better - not necessarily so, there's constant efforts in the industry to reduce cost and sometimes reduced performance is accepted in the drive to reduce cost. Current trends are leaning back towards pintle injectors as the atomisation takes place over a larger area when compared to injectors with holes, but they are more expensive. It's also worth noting that on the RV8 at full chat you're mostly injecting fuel onto the back of a closed valve anyway, so atomisation out of the injector is probably not as important as you might think.
The jury is still out on my car as I haven't sorted the tune out yet, I need better weather!
Are you running out of flow on your current injectors? you could try Jag flapper injectors if that's the case, although they're quite rare I think.
You say 'upgrade'. I'm not sure about that. I've now gone back to the flapper injectors; but I'm running them on PWM peak/hold so I can bang them open on 12Volts and hold them open on 5V. I get much better control that way as they open and close quicker and cleaner. A common misperception is that newer is better - not necessarily so, there's constant efforts in the industry to reduce cost and sometimes reduced performance is accepted in the drive to reduce cost. Current trends are leaning back towards pintle injectors as the atomisation takes place over a larger area when compared to injectors with holes, but they are more expensive. It's also worth noting that on the RV8 at full chat you're mostly injecting fuel onto the back of a closed valve anyway, so atomisation out of the injector is probably not as important as you might think.
The jury is still out on my car as I haven't sorted the tune out yet, I need better weather!
Are you running out of flow on your current injectors? you could try Jag flapper injectors if that's the case, although they're quite rare I think.
Can I just add ...I have heard the results that Martin is achieving with his MS project and I have to confess I have never heard an RV8 let alone a Wedge sound so sweet at under 700rpm idle...It does actually "Purr"...And is subduedly hypnotic...For me at least...
There aren't so many pops and bangs but I think he has another setting for that and it also spits flames....
...I know what setting id have even if it is only 8 SPG....Well done Martin, I really think you are taking the Wedge into the future....
There aren't so many pops and bangs but I think he has another setting for that and it also spits flames....
...I know what setting id have even if it is only 8 SPG....Well done Martin, I really think you are taking the Wedge into the future....I use the later style injectors (the O-ring plug-in type) on an early fuel rail.
Cutting the plastic inlet end off with a saw reveals a steel inner core to which you can crimp a length of fuel hole that then fits the rail.
My injectors are 220cc/min, up from the 180cc/min of the standard type.
As the ECU duty cycle remains unchanged I run a much lower fuel pressure setting to get the same flow rate; the theory was that a solenoid valve and restrictor could be fitted in parallel with the FPR and switched in/out as required for WOT pressure boost... I just never got around to it (like a lot of jobs these days).
Cutting the plastic inlet end off with a saw reveals a steel inner core to which you can crimp a length of fuel hole that then fits the rail.
My injectors are 220cc/min, up from the 180cc/min of the standard type.
As the ECU duty cycle remains unchanged I run a much lower fuel pressure setting to get the same flow rate; the theory was that a solenoid valve and restrictor could be fitted in parallel with the FPR and switched in/out as required for WOT pressure boost... I just never got around to it (like a lot of jobs these days).
I've got the later (high resistance?) injectors in a hot wire fuel rail fitted to an early inlet manifold. No problem sealing anything, although the new rail fouls the plug on the CTS. One other drawback is that the later rails have the FPR built in, so using anything else would require some modification.
Hi Adam, I haven't put a scope on to check it's doing what it's supposed to, but the idle is much improved. It's a good idea though so I'll put a scope on it at some point. These are the settings I have to play with:
Dead time is a fixed adder to the pulse width and is intended to be the time it takes the injector to open. Time threshold is how long it sits at full battery voltage and current limit is the % of battery voltage it drops to after the threshold has been exceeded.
Loads of parameters to play with!
Dead time is a fixed adder to the pulse width and is intended to be the time it takes the injector to open. Time threshold is how long it sits at full battery voltage and current limit is the % of battery voltage it drops to after the threshold has been exceeded.
Loads of parameters to play with!
The Hatter said:
Interesting Ian... did you just bypass the injector resistors?
No, the injectors I used are from a later-series Jaguar but have the same resistance as the original '105' type so the electronics remain the same.The theory was that a Jag AFM would give me more air and the fatter injectors more fuel, but although I had the Jag AFM fitted, I removed it when the car developed a rev-limiting fault that turned out to be the ignition pickup coil in the distributor failing (over several months). By the time the pickup died completely I'd changed all bloody sorts including refitting the original AFM. Replaced the pickup and away she went. The 256bhp it recorded on the BBWF dyno (2010?) was with the fatter injectors but not the Jag AFM - and I've left it alone ever since
More important was the relatively flat air:fuel curve - many V8s' fuelling looks like a map of the Andes, mine's more like the Pennines
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