Volvo Owners Club Forum - View Single Post - LPG on the yamaha V8 engine

Volvo_Grip · May 22nd, 2013, 23:04

Hello gentlemen,

I have been away for the best part of the month and did not have time to convert my S80 V8 yet.

While I was away I was searching through the net and found this:

http://www.bigastech.com/rootsgis/Sc...4S_LPG_ENG.pdf

It does not seem to be neat and I, personally, don't like 25-35cm runners and then having further 20-25cm of convoluted manifold duct i.e nearly half a metre for a gas to pass from injector to cylinder with half of this 'journey' being in a premixed state. However, such arrangement makes conversion much easier without a need to take off petrol rail & the bottom part of the manifold. I guess, it would have been neater to put individual injectors on each or the ducts.

Last weekend I took the upper part of the inlet manifold off just to see where would be the best places to drill the lower manifold. Not too much space here and there are a few alternatives. They are as follows:

1) Drill the wholes and install injectors directly between the lower and upper parts of the manifold. I completely agree with Dai that in such case one needs to go for extremely reliable LPG injectors. However, the space is tight there and the only way to make this option to work is by using 90 degree bent lpg hoses. Any attempt to bend a 12mm (6mm - i.d.) lpg pipe can collapse it.
There are silicone hoses with 90 and 135 degree tight bends, but I have never used silicone hoses for lpg and will not do this unless I am completely sure that they are lpg-friendly. Any advice on their compatibility is greatly appreaciated? The upstream hoses need to be fed through the gap openings at the front(left) bank

2) Drill the holes in the lower part of the manifold and feed the lpg hoses through the gap openings at the front(left) bank. A couple of the injector rails need to be located outside the front bank and connected to the lpg hoses.

The same problem as in (1): to keep the length of lpg hoses more or less equal one needs to use 90 degree hose bends so that the runners to the rear bank are not twice as long as the ones leading to the front bank.

3) Connect individual injectors to the ducts at the upper part of the inlet manifold as shown in the link above. The use of individual injectors will allow me to use 4-5 cm connecting hoses instead of 25-30cm thus reducing the length between the injectors and the inlet valves.

Problem: a substantial part of the manifold will be filled with the premixed gas and there might be a risk of backfire.

Not entirely sure which option is best.

I noticed that there are quick-fit connectors on the market where there is special connector got installed between the engine and a petrol injector. The gas is being fed through this connector too. This is a very neat solution, but unfortunately, on this particular engine, injectors on the front and rear bank are not parallel to each other. Plus there is a fair bit of a problem with the petrol injector rail being pressed against the upper part of the inlet manifold.
Shame, so I need to choose from the 3 options above.

May 22nd, 2013, 23:04	#23
Volvo_Grip New Member Last Online: May 6th, 2015 20:14 Join Date: Nov 2008 Location: Sheffield	Options for injector & nozzle placement Hello gentlemen, I have been away for the best part of the month and did not have time to convert my S80 V8 yet. While I was away I was searching through the net and found this: http://www.bigastech.com/rootsgis/Sc...4S_LPG_ENG.pdf It does not seem to be neat and I, personally, don't like 25-35cm runners and then having further 20-25cm of convoluted manifold duct i.e nearly half a metre for a gas to pass from injector to cylinder with half of this 'journey' being in a premixed state. However, such arrangement makes conversion much easier without a need to take off petrol rail & the bottom part of the manifold. I guess, it would have been neater to put individual injectors on each or the ducts. Last weekend I took the upper part of the inlet manifold off just to see where would be the best places to drill the lower manifold. Not too much space here and there are a few alternatives. They are as follows: 1) Drill the wholes and install injectors directly between the lower and upper parts of the manifold. I completely agree with Dai that in such case one needs to go for extremely reliable LPG injectors. However, the space is tight there and the only way to make this option to work is by using 90 degree bent lpg hoses. Any attempt to bend a 12mm (6mm - i.d.) lpg pipe can collapse it. There are silicone hoses with 90 and 135 degree tight bends, but I have never used silicone hoses for lpg and will not do this unless I am completely sure that they are lpg-friendly. Any advice on their compatibility is greatly appreaciated? The upstream hoses need to be fed through the gap openings at the front(left) bank 2) Drill the holes in the lower part of the manifold and feed the lpg hoses through the gap openings at the front(left) bank. A couple of the injector rails need to be located outside the front bank and connected to the lpg hoses. The same problem as in (1): to keep the length of lpg hoses more or less equal one needs to use 90 degree hose bends so that the runners to the rear bank are not twice as long as the ones leading to the front bank. 3) Connect individual injectors to the ducts at the upper part of the inlet manifold as shown in the link above. The use of individual injectors will allow me to use 4-5 cm connecting hoses instead of 25-30cm thus reducing the length between the injectors and the inlet valves. Problem: a substantial part of the manifold will be filled with the premixed gas and there might be a risk of backfire. Not entirely sure which option is best. I noticed that there are quick-fit connectors on the market where there is special connector got installed between the engine and a petrol injector. The gas is being fed through this connector too. This is a very neat solution, but unfortunately, on this particular engine, injectors on the front and rear bank are not parallel to each other. Plus there is a fair bit of a problem with the petrol injector rail being pressed against the upper part of the inlet manifold. Shame, so I need to choose from the 3 options above.