Went to replace an olive on the main tank to vapouriser pipe today and found the it's a 6mm rather than 8mm pipe (plastic coated so size wasn't obvious before). 8mm is recommended for 2.0 litres and above engines, I believe?
I take it that this will significantly reduce gas flow, send high RPM mixture weak and thus lose peak power?
It's a pain 'cos I've just spent a significant amount of time lovingly P clipping the whole installation...
Way more than 2.0 litre but I can't find anything that definitely says what size you need. Simon will probably drop in and confirm but I've always understood 6mm pipe is good enough for up to around 250 bhp so you should be OK. Even if you changed for 8mm pipe you'll probably find that the outlets on the solenoids are only 6mm anyway.
Found this in the Installation Manual today:
The “regular”model (shown in fig. 1.5.9-1) is connected to the regulator by means of a Ø 6 copper pipe, while the 5-8 cylinder “regular” model is connected directly to the regulator by means of a specifically designed valve (see fig. 1.5.9-2). With all “super” models, the type of
connection used is similar to the 5-8 cylinder model, with the exception of the tube, which in this case is a Ø 8
We identified mine as an S model regulator in my main "What wears out" thread
Sort of implies that I really should have 8mm pipe fitted, I suppose.
Ho hum. Wish I hadn't fitted those P clips with pop rivets!
I just noticed this thread...
I generally go with 8mm for just about everything I convert these days, but that's just because I stock loads of 8mm Faro pipe and many various types of Faro fittings for this diameter, including fittings that (for 8mm Faro) emulate 6mm copper pipe ends.
Like Gilbert said, 6mm is considered OK to around 250hp. Very unlikely there'll be problems due to 6mm on a P38, even running a sequential system (instead of a mixer system).
Even on most stuff that needs 8mm pipe, 6mm fittings are usually ok unless you're dealing with something a fair bit over 300bhp. Even on a 310hp vehicle, which might use a reducer with 8mm inlet, it would be unusual to ask a supplier for a tank valve with 8mm outlet. For reasons that I don't fully understand but have a bit of an idea on, flow of liquid LPG through pipes isn't totally related to minimum diameter within that feed, an 8mm pipe with 6mm fittings will flow more than 6mm pipe with 6mm fittings.
Because tank pressure fluctuates with temperature and pressure versus diameter dictates flow capability, if you don't have problems in the depths of winter you're unlikely to have problems all year round. The first point here also explains 'even running a sequential system' - A mixer system supplies gas at near atmospheric pressure while a sequential system might supply gas at 1.5 bar. Tank pressure minus supply pressure is the pressure that pushes gas down the pipe, so it's possible to get away with smaller diameters on mixer systems for any given bhp.
Simon.
Thanks Simon- I'll stick with the 6mm for now then.
One less thing to do!
You're welcome. I also meant to include... I would never fit 6mm on a P38, even for a mixer system, but wouldn't replace 6mm with 8mm if I was, say, replacing a mixer system with a sequential system on one. I've driven loads of P38s using 6mm with sequential systems and none of had a problem.
Simon
My '95 has a mixer system and 6mm. Maybe that's why it's very sensitive to low(ish) gas levels and air temperature. Ah well, nice to know, even if I am selling it :)