Right, I’m just in the process of connecting the LPG to the P38 that had the new engine fitted. I’ve got the wiring all done, rerouted the gas pipe and repositioned the reducer. I’ve run a second gas feed pipe so each set of injectors now has it’s own gas feed. The little vacuum/pressure pipes have got me confused though...

Art was never my strong point so excuse the quality of the drawing below.

As you can see, the pressure switch has 2 ports plus the electrical connection. One of the ports goes to the gas injectors. The other one has a Y in it that connects it to the pressure port on the reducer and to the inlet manifold. All simple enough, no problems there!

My inlet manifold has a gas injector on it on the banana for cylinder 3. You can’t see it in the picture below so I’ve put a red circle around where it is. The reducer was originally on this side of the car and I’m sure that pipe went to the pressure point on the reducer to give the pressure switch a reading.

I’m using the spigot on the front of the inlet manifold to get a pressure/vacuum reading from so I’m thinking I’m just going to put a bolt in the hole in the manifold to blank it. Anyone got any thoughts?

(God I hope this makes sense)

David.

The pics aren't working but I understand. Yes that will work fine.

Edit - Strange, the pics are working now.

Thanks Simon, I forgot to put .jpg at the end of them so was probably correcting that as you were reading.

So I should be good just to block off that port in the inlet manifold?

David.

dhallworth wrote:

Thanks Simon, I forgot to put .jpg at the end of them so was probably correcting that as you were reading.

So I should be good just to block off that port in the inlet manifold?

David.

A coincidence we're both on forum at the same time.

The pics are what I expected.

Yes absolutely.

Excellent :)

In that case, thanks to your advice on the selection of the reducer, this car is now running perfectly on LPG again as well!

Just got the heater matrix to get done at the weekend and she’s finished now.

Thanks again, Simon.

David.

One more question...

On the Magic 3 Power LPG reducer, does it matter which side is coolant flow and coolant return? I know which is which on the cooling system on the car but don't know if it matters on the reducer. The reducer didn't come with a manual and I can't find anything online.

Thanks,
David.

Shouldn't make any difference. I tend to plumb them so the inlet is at the top so more heat is absorbed as it flows through. My theory being that if the inlet is at the bottom the heat will cause it to rise to the top faster. No idea if it makes any difference, that's just how I do it, same as the radiator has the hot inlet at the top..

Well, the vacuum lines were all tidied up tonight with the extra hole in the manifold blanked. I’m going to order a little grub screw rather then using a bolt with a hex head on it as it’ll be neater.

Other then that, it’s running perfectly on gas and LPG and the changeover is barely noticeable other then when the injectors start rattling.

Heater matrix tomorrow and reconnect the pipes and the car is pretty much finished thankfully.

David.

I guess if you use a grub screw you should stick a bit of thread locker or something on, so it definitely can't go all the way through if it rattles loose and get sucked into the engine.

gordonjcp wrote:

I guess if you use a grub screw you should stick a bit of thread locker or something on, so it definitely can't go all the way through if it rattles loose and get sucked into the engine.

Yes, some suppliers sell 'injector hole blanking screws' which are really just grub screws, I wouldn't use a grub screw because there's potential for it to be ingested by the engine, a bolt head cannot be pulled through. A bolt (set screw) will be too long but can be cut short so it doesn't affect airflow.

dhallworth wrote:

I’m going to order a little grub screw rather then using a bolt with a hex head on it as it’ll be neater.

I wouldn't be able to sleep if I did that on a customer vehicle.

Reducer water flow direction doesn't matter if the reducer is below the tide line (you get the gist) when the engine is turned off. Best not to fit a reducer above the tide line but if it is it is better if the intake is at the bottom as this will keep the water channels full (as opposed to an internal waterfall) and lessens the potential for airlocks in the reducer.

Yea, i was going to put a load of thread lock on it so that it set tight in the hope that it wouldn’t rattle loose and suck through.

Given that it’s not really visible, maybe I should just stop being fussy and use a normal bolt.

David.

Or even a round head machine screw? Arguably neater than a bolt head but still no chance of being ingested.

A number of years ago I drilled my manifold while it was off in anticipation of fitting a multipoint. Never did and decided to stick with the singlepoint but I plugged the holes with M6 pan head screws, Loctited and with a fibre washer under the head.

i think they are called pressure plugs , basically a tapered hex plug , will not wind all the way in , just another option to look at.