I was hoping for a pic of the engine without the covers on. Is it a proper V6 or are they using the latest incarnation of the old VW 2.8 VR6? That's a very narrow angle Vee with the cylinders almost overlapping and a single cylinder head to keep the size down.
Yep, it's the VW derived VR6 (I mentioned VR6 in the title mate)... As you'll probably know, the German VR translates to V Straight (which, like you said, is the narrow angle single cylinder head design), the design has all inlet ports on one side, all exhaust ports on the other, so is more like a straight 6 really... Due to the design, even without the covers on there are still no LPG components to see because the injectors are all on the outer side of the inlet manifold (petrol injectors all at the same side of the engine too), can see the tops of LPG injectors in the pics. They're more of a pain to convert than most straight6 or V6 engines because the only place to fit injector spuds is under the inlet manifold, opposite side of inlet runners to petrol injectors as petrol injectors position is enclosed within the arc of the manifold, best place to fit injectors is on the outside of the manifold (or injectors might fit within the manifold arc but this would add an extra layer of unnecessary hassle when it comes to accessing injectors during servicing etc). Cyl 1 is particularly difficult because the alternator is in the way. At least the newer VR6's in Porsches have an easier design manifold regards conversion than the earlier design, which was boxier and made of metal (this is plastic). The 6 black plastic pipes you see atop the engine simply connect the plenum after the throttle body (drivers side) to the plenum on the passenger side (inlet side) of the engine, the passenger side is where all the injectors and variable length inlet tract gubbins are (usual type variable inlet tract gubbins to tune tract length according to rpm to increase torque, nothing special here regards the VR design). I reckon the V8 models are actually easier to convert than the VR6 models due to the design of the VR6 inlet manifold, though the V8 models are more demanding in terms of spec of components and accurate setup.
I might agree with your (reading between your lines) sentiments on the VR design - VW make such designs to fit more cylinders in tight engine bays but the design means an engine with an odd firing cycle and with valve timing that needs to differ between cylinders to compensate for the different length inlet tracts per cylinder bank (to avoid unequal cylinder charges)... this wouldn't seem a good starting point for an engine design but still they're are a good lump, just have their own unique sound and arguably can't be as smooth as a straight6, flat6 or 60 degree V6 (especially at low rpm) due to the odd firing cycle... Way better than some of the old Yank 90 degree V6 'shaker' engines though(!) and in practice you can't tell they're odd firing except for the distinct engine note. In my opinion a proper straight/flat/V6 or V12 is better because I don't like the idea of odd-firing (bang bang pause repeat) engines, but such usual designs wouldn't fit in the engine bay of some of the VW's / Audi's / Porsche's where VR6's live while a supposed good point of the VR design is a stronger crank. But if all engine designs are a compromise and the whole point of a 12 pot is smoothness, then W12's (which are pretty much two VR6's) are probably the most misleading of the VR designs because they too cannot be as smooth as a 'proper' even firing engine like a proper V12. Some people think VR is one up on V and W is one up on VR, some like the V5 VW engine designs (I've converted those too)... you and I would probably prefer 'more normal' designs with even firing / without need of special crank counterbalances etc. V8's not mentioned because we don't see many none 90degree odd firing V8's (except in WW2 tanks etc), there are no VW VR V8's, I have converted VW V8's in e.g. Audi R/S4's, A8's, etc, but they're just a fairly normal 90deg V8.
The owner is still away on holiday, he had his mates come collect it while he was away (which is when I found out he's in the band I mentioned).. He says he'll call me when he's back from holiday and then we'll probably arrange for him to return for his free 1000 mile check at some point... I might have opportunity to take a pic with the engine cover off then but there wont be much more to see as the only part of the LPG system under the engine cover is the vac pipe which runs between those 6 runners (atop the engine) and the engine to the reducer which is at the back passenger side of the engine (probably just see the reducer in the pics).
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