LPG Camshaft and Mixer Selection
LPG Camshaft and Mixer Selection
(OP)
I have been discussing the idea of running wider lobe separation angles for LPG/Propane engines than you would on an equivalent Petrol/Gasoline engine with my colleagues and I am interested in hearing your ideas. If you agree that wider separation angles should be used to what extent do you think they should be widened?
Also does anybody know the minimum pressure difference required across Impco mixers, such as the 225 or 300a, in order for them to work correctly?
Also does anybody know the minimum pressure difference required across Impco mixers, such as the 225 or 300a, in order for them to work correctly?





RE: LPG Camshaft and Mixer Selection
RE: LPG Camshaft and Mixer Selection
RE: LPG Camshaft and Mixer Selection
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RE: LPG Camshaft and Mixer Selection
I understand what altering the lobe separation angle does, that was not my question, but thanks anyway.
So neither of you think that the possible improvements in cylinder filling when running wider lobe separation angles are important? It is beneficial when a system is under carbed, which, unless you want to increase port size, is to an extent what happens when running LPG.
As well as the above, running wider lobe separation makes engines less sensitive to slightly incorrect component selection, which is likely when building an LPG engine as information is limited and most engines are built using an understanding of petrol engines.
There is also the added benefit of improved idle quality and vacuum, which is important when using any non-injection based gas system (not a big deal with small cams).
I thought somebody may have studied the influence of varying the lobe separation in LPG engines as people have done with Methanol (which uses different values to petrol). I haven't done any such study, however, I have heard often from engine builders that LPG requires wider angles; unfortunately, they are unable to give me a reason why.
Can you help me with my other questions?
RE: LPG Camshaft and Mixer Selection
Many HD engine builders that work with gaseous fuels prefer a wider exhaust valve seat and face than standard, and others set the valve lash as loose as possible to provide the longest on-seat duration as practical.
Realize that these specially ground cams make up only a tiny fraction of the LPG or CNG powered vehicle market. In the vast majority of the vehicles, the standard camshaft works just fine, including two of my vehicles that ran well over 200,000 miles with no problems.
For any performance issues, my personal thoughts are that the traditional aftermarket cams work just fine, just be prepared for some exhaust valve service.
Franz
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RE: LPG Camshaft and Mixer Selection
RE: LPG Camshaft and Mixer Selection
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RE: LPG Camshaft and Mixer Selection
I think it is legitimate to post a link to a website here.
If that website listed your book, no problem.
I would also be interested to buy a copy
Regards
Pat
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