Originally Posted By: Dogan
Please correct me if im wrong, im trying to learn
Multi point injection modern engines spray gas on intake valves and provide coolant and lubrication (negliable or not)
MPFI washes the valves with the fuel mist to keep them clean.
Originally Posted By: Dogan
But old carburetor engines, jets send gas by venturi through manifold so no direct contact with valves and lack of Liquid fuel coolant and lubrication
The gasoline was suspended in the air flowing through the manifold and washes the valves in the same manner as the MPFI engines did.
Originally Posted By: Dogan
When my car is new, there is leaded fuel and still have mid of 90's
Lead in gas provide protection for valves but with unleaded,no
Lead provided some lubrication and protected against valve seat erosion as non-hardened seats were used. Modern valves are lubricated through the stem seal area (as were the old ones in days of yore, though perhaps not as well) but they now employ hardened seats that don't need the lead. Engines rebuilt to run on unleaded have the heads upgraded with hardened seats.
Originally Posted By: Dogan
I have 2 scenarios
-LPG or unleaded fuel wont harm my valves because no direct contact with valves
-both fuel wil harm my valves because lack of lead which provide protection my valves
And oil choice
Vr1 or Max life ?
If your engine doesn't have hardened seats, it is going to suffer seat erosion either way, whether you use gasoline or LPG. That is, unless you use gasoline with a lead substitute.