supercharged 4.0 chim with hole in bonnet..
Discussion
hi guys..new to this as work takes up too much time..but..any of you had exp of sprchgin'a rover v8..? all very fine till 5500 revs in 4th..then loads of "pinking ????" obviously ease off a tad then do 5th..but..as 5000 revs(approx 150 mph on clock)same pooh happens. have tried tuned chip but thats worse than std one !!! could it be larger injectors needed?? dont want to hand over to a garage yet,as could be a licence to bankrupt me!!! strangely tho..all fantastic till this point
Ed to add by Big Al.
Had a bit of a clean up!
Ed to add by Big Al.
Had a bit of a clean up!
Injector saturation sounds like a pretty likley cause if air flow is outstripping max fuel supply, but the same thing would happen at full throttle in any gear at a given rpm (IIRC max injector period usually happens around peak torque rather than max power, though of course air flow will be max at peak power). I presume the ECU is appropriately re-mapped, both fuelling and ignition timing?? if it were injector capacity then a quick and crude fix would be upping the fuel pressure ( could help as a diagnostic trial anyway). If its not that then it must be timing....
You mention a tuned chip, sounds like you are referring to something off-the-shelf? I would have thought you would need a custom designed map and or an adjustable set up for something so exotic, IIRC Mark Adams does a range of very special ECUs.
>> Edited by tahiti450 on Wednesday 27th April 01:21
>> Edited by tahiti450 on Wednesday 27th April 01:23
What is happening to the boost at that point? If the boost is going up then you could be hitting thermal runaway, where the breathing limitations of the engine start to cause back pressure, which puts more heat into the charge, which increases the back pressure, etc etc. Eventually the increased temperature and pressure will cause detonation.
pre ignition, would end up holeing the pistons 
compression needs to be very low for charging, could charge cool to help this, but low compression engine is key.
could also add thicker head gasket to reduce compression, thats what they did in the old days.
did you build it, what charger?
compression needs to be very low for charging, could charge cool to help this, but low compression engine is key.
could also add thicker head gasket to reduce compression, thats what they did in the old days.
did you build it, what charger?
tahiti450 said:Hmmm - slightly mixed up here. Injector duration should be longest at peak torque, yes, but there are more injector events at higher revs, so you will still be pumping most fuel at around peak power. Therefore the point at which the injector is mostly open could be after peak torque. You should generally not run close to maximum duty cycle anyway - most management systems will warn you I think.
(IIRC max injector period usually happens around peak torque rather than max power, though of course air flow will be max at peak power)
dannylt said:
tahiti450 said:
(IIRC max injector period usually happens around peak torque rather than max power, though of course air flow will be max at peak power)
Hmmm - slightly mixed up here. Injector duration should be longest at peak torque, yes, but there are more injector events at higher revs, so you will still be pumping most fuel at around peak power. You should generally not run close to maximum duty cycle anyway - most management systems will warn you I think.
absolutely right, of course max air flow determines max fuel flow also - to maintain stoichometric ratio etc, but I didnt want to get into a long discourse on fuel injection! 
PS: I admit I am a bit mixed up - but thats another story!
>> Edited by tahiti450 on Thursday 28th April 11:27
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