hana v valtek

[LPGC]

Most manifold side nozzles (manifold end of pipe between injectors and manifold) use an M6 thread (a few hardly worth mentioning here use M8 thread) but the gas pipe stubs on M6 manifold nozzles may be 4/5/6mm to suit the gas pipe connection stub sizes at the injector side of the pipe.

V30 injectors may have 4mm or 6mm stubs and the supplier may not mention which size stubs will be supplied - If you would prefer a certain size injector pipe stub I would advise ordering them on the phone and be very clear in stipulating the size you want (if they have that size in stock). All V30 injectors supplied with 4mm gas pipe nozzles (injector end nozzles) will have internal restrictions (in the injector body itself) of around 2.5mm, with these injector end nozzles you couldn't drill them to 3mm because they're too narrow to take the drilling. Some V30's supplied with 6mm gas pipe nozzles will have internal restrictions of 2.5mm, some will have internal restrictions of close to 3mm (probably 2.9mm), the internal size won't be listed anywhere in the parts description and the supplier won't know, a case of suck it and see. But there is no point fitting bigger injector side nozzles than injector internal restriction size - usually the injector side nozzles are the metering jet but in case injector internal sizes are smaller than injector side nozzles it will be the internal restriction that does the gasflow metering and usually less accurately than injector side nozzles. Whether 2.5 or 3mm (2.9mm) internal sizes won't matter if the install needs injector nozzles of 2.5mm or less but will matter if the install needs > 2.5mm nozzles.

The difference between 2.5mm and 3mm may not seem much but flow rate through a nozzle is dictated by the area of the nozzle not it's diameter and the area of a circle (nozzle jet cross section) is the old Pi R squared. For our comparative purposes Pi can be disregarded as it's just a factor in both cases, so we end up comparing 1.25 x 1.25 (1.5625) to 1.5 x 1.5 (2.25), so 2.25 /1.5625 shows the 3mm nozzle will flow 1.44 more times as much gas as the 2.5mm nozzle. It may seem that if we substituted 3mm nozzles with 2.5mm nozzles we could keep the same LPG fuel map just by increasing the reference pressure point to 1.44 times current reference pressure and increasing actual pressure by 1.44 times... and in a lot of cases (suitably quick in terms of suits the engine in both injectors cases) this would indeed give very similar results but this doesn't account for aspects such as injector response time (closing / opening / partially open flow) or the effect pressure has on response times and flow (particularly at lower pulse duration), or the effects of different injector responses at different temperatures, or the effects of phase change between liquid LPG and vapour LPG at temperature/pressure. I could see an old (good / accurate) LPG fuel map and probably wing it for a different nozzle size for similarly performing injectors (or same spec same performing) injectors with a different nozzle size bt I doubt many others could... and even I would rather check the results by seeing the car, especially if I don't trust the original map is correct (which I won't unless I or only literally a couple of other people in the world set the original map).

Simon

[superkp]

I think its best to see if it runs well after I fit another coil pack