1158 wrote: ↑
Sun Jan 21, 2018 9:18 pm
What if the EGR was the way the "oil" was being pulled into the intake?
If the EGR pipe has two valves on either end to open and close it and a connection to the crankcase it would be an easy way to control when the vapors were making it into the intake.
Could be. It crossed my mind that EGR could have some interplay with the oil-air separator and/or crankcase ventilation. It's interesting to think about; there are many variables.
If EGR was developed, so too would have been the chemical composition of trace elements within the exhaust gas. This being a result of fuel composition and combustion properties.
Oil and/or oil vapor chemistry are also a suspected performance benefit.
Chemical reactions between exhaust gas, fuel, and oil, may be worth considering. Typically SI petrol exhaust is primarily composed of nitrogen, water vapor and CO2. Oxygen content may be higher given the high air:fuel ratio.
Could beneficial compounds be synthesized on the fly, which otherwise could not practically, or legally, be carried on-board the vehicle?
I've never seen anything resembling EGR pipework on the PUs, so it could be well obscured, or simply done in-cylinder via valve timing. For example, a portion of the exhaust could be made to backflow and partially fill the intake runner by opening one or both intake valves during the exhaust stroke. As long as in-cylinder pressure at that moment is greater than intake manifold pressure.
Furthermore: if the exhaust valves close early, and one or both intake valves open early (before TDC on the exhaust stroke), then the exhaust 'charge' would effectively be segregated into:
-exhaust bound for intake manifold backflow
-exhaust bound for the turbine/wastegate
The intake backflow portion would thus be the EGR. Fuel could be injected into this portion of the exhaust without waste because the exhaust valves would be closed; this is the portion bound for re-injestion, the 'EGR charge.' Injecting fuel into the EGR charge could promote fuel homogenization mimicking port injection, and allow for any beneficial exhaust-fuel chemical reactions to take place. Since fuel would be injected at the end of the exhaust stroke, there is provided a few more degrees of crankshaft rotation within which fuel injection moments can be spaced.
Given the a:f ratios which provide excess oxygen, along with turbo-assisted gas flows, there may be scope for playing around with valve timing, EGR, and early EVC/IVO specifically.