What did they do?

[maynard160]

From years of turning wrenches Im aware that alot of engine wear occurs during engine start. Mostly during that first cold start of the day. TCHs are constantly starting and stopping the engine while managing the Hybrid system. What, if anything, did Toyota do to help prevent engine wear from constant engine starting in the TCH?

The dealer said the atkinson cycle was the fix for this but I'm not buying it. Keeping the intake valves open longer shouldnt have anything to do with lubrication. Maybe check valves in the oil galleries to keep oil on the top end. Maybe special cylinder coatings. I'm just guessing but I'm sure something was done and I'm more curious that anything else.

Any ideas?

[thaharlequin]

I'm guessing it has to do with keeping everything lubed longer (kinda like a mechanical version of that lukas oil stuff?) as well as keeping everything near steady state in terms of engine temp. I've heard that starts on a warm engine aren't nearly as hard compared to cold starts because all the stuff in the engine has already undergone any changes due to thermal expansion and are all at ~ the point where wear is minimal. Iirc the prius won't use autostop at lights unless it's already warmed up.

[gideon1331]

The hybrid system spins the engine to 1000RPM before starting the engine, instead of having a starter spin the engine up to a very slow speed, and dumping on a lot of extra gas to, for all intents and purposes, kick-start the engine to a higher speed. This process is what causes most of the wear that comes from starting the engine. Since the hybrid system brings the engine up to a normal operating speed before starting it, there is little or no wear on the engine. It also saves the gas that is normally wasted during startup.

[maynard160]

Originally Posted by gideon1331

. Since the hybrid system brings the engine up to a normal operating speed before starting it, there is little or no wear on the engine.

Thanks for the reply. I guess I'm looking at this from the stand point of lubrication or more acurately, the lack of lubrication, until the oil pressure is built up enough to reach all engine components. When the engine is off, oil typically drains back into the oil pan. Weither spining the crankshaft slowly(conventional starter motor) or spining the crankshaft faster, as with the TCH, there is still that time it takes to get oil throughout the engine. Although I agree that spinning the engine faster will get oil pressure up quicker, my point was that the TCH is doing this a whole lot more than a conventional car. With your explanation, I'm trying to picture how ignition, at a faster engine RPM, will prevent engine wear(lack of lubrication) over many start cycles in a single period. I tried looking up component data for the 2AZ-FXE, but it looks like toyota isnt shareing much info on this engine just yet.

[Dave's]

I don't know anything about it but is it possible they have electric power running an oil pump before the engine restarts?

[maynard160]

They call that a Pre-Luber in the industry. That would be sweet but I doubt it. Once someone puts out an engine breakdown/drawing, I'll get to satisfy my curiousity.

Thanks for the input guys.