Originally Posted By: Blue_Angel
My friend, hold onto that Expedition of yours! Any vehicle that fires up at -30C and is instantly as free-reving and responsive as it is any other time/temperature is a special one indeed!
Oh, it wasn't instantly free-revving (throttle response was fine though), it felt sluggish, though I'm certain that the fact it had regular ATF in the pan (not synthetic) helped in making it feel sluggish. I can only imagine the viscosity of that fluid at -30C. And there's 17L of it there to heat up, LOL!
It just didn't feel or sound different than it did on any other cold start, that was my point
Driving it, yeah, you could tell there was some thick stuff in the drivetrain, but that should be expected at those temperatures. In warmer weather it feels the same hot or cold.
Originally Posted By: Blue_Angel
You bring up good points. My Vette has a HV Melling oil pump which may have something to do with it, though it's only 18% higher displacement. Also, the car has not been tuned to run with this cam, the tune that's in the car is a tune that was written for a stock LS6 with headers/intake (which was the case with my car before the cam went in).
My cam is far from radical, which is why it runs well without having an optimized tune. It's a Lingenfelter GT11, 215/231 duration, .631/.644 lift, 118 LSA. High lift, medium duration and wide lobe separation (118 LSA is the same as the stock LS6 cam).
Those two things may make the car a little more succeptible to oil drag related idle quality. An optimized tune could likely smooth the idle out a bit. Once it's up and running, though, it runs very well and I doubt a tune would do a whole lot for light load throttle transitions.
Yeah, I'd imagine if things are on the "edge" of what the ECM considers normal on a cold start, and you've added an 18% increase in oil displacement to that mix, that any little change might make an audible difference in what you hear on a cold start.
Did you do the HV pump when you did the cam? What was the logic behind the upgrade? Of course increasing oil volume is a key point here and one we shouldn't skim over. So while you are running a lighter oil than spec, you are also moving more of it (assuming we aren't on the relief), and that's important!
Originally Posted By: Blue_Angel
Are you absolutely sure there's no change at all, or just not enough that it becomes glaringly obvious? Both my Saturns and now my Cruze all have a noticeable increase in NVH at idle with the AC on. Our BMW and Vette don't, but they are larger six and eight cylinder engines. I would bet most Cruze 1.4T owners wouldn't "notice" the difference unless you pointed it out to them.
On the M5, absolutely nothing. but it is an 8 and you can't feel the engine in the car no matter what, it is incredibly well isolated. But you don't hear it kick on in that car either. Now, with respect to the 4-bangers, the Subie's 2.5L turbo-4 seems completely unphased by the cycling of the A/C
Same with the Focus, though you could observe the RPM briefly change and hear the audible click of the compressor, which is the same as it is with the Expedition. It is FAR more seamless on the M5 and Subie than it is on the Ford's IME.
Originally Posted By: Blue_Angel
Regarding fuel economy with and without AC, most people don't do "scientific-enough" testing to measure an accurate difference when using AC. They know it uses fuel, but their testimony as to exactly how much will rarely hold water.
Fair point! On the Subaru, the effect on fuel economy seems imperceptibly small, though I haven't done much tracking with it yet. On the Expedition, it works out to a solid .5Mpg at highway speed (can't tell in-town, as it is so bad on gas it doesn't matter). Over the same trip, instead of averaging 17Mpg for example, I'll average around 16.5. And that's repeatable. On a vehicle that is, based on my tracking of it, capable of a maximum of 18.5Mpg on a flat road, cruise set, with no wind (LOL!), anything that detracts from that, because it uses so much gas, is noticeable.
I haven't done enough tracking on the M5, and I like driving it with the windows down so I can hear it. So I can't really make a solid comment based on its consumption with/without the A/C. Though it would SEEM that gas mileage is a bit worse with it on.
Originally Posted By: Blue_Angel
Few things frustrate me more than seeing people discredit the Engineering that goes into producing a modern automobile. However, after working at the OEM level in automotive for several years (unfortunately not in Powertrain!) I understand that most things in a car are an assortment of compromises to cover most possible scenarios.
I do believe that if someone takes the time to properly educate themselves to the point where they understand what they're doing (which is rarely a simple task), some (not all) of those compromises can be safely tinkered with. AND, the tinkerer needs to fully understand that they are taking on the responsibility of their actions.
Running 0W-20 in an engine where 5W-30 is spec'd definitely falls into that category. My Vette has both oil pressure and temperature gauges/readouts so I am able to monitor the effects of the changes I'm making. In my case, my oil temperatures will never get high enough on the street to warrant a concern WRT oil viscosity. I also fully understand that extended high RPM use is out of the question without a very good oil temperature regulation system in place. That is another item on my ever growing list of things to do.
BINGO!! You are aware of what you are doing, even upgraded the oil pump! You've got the necessary gauges in place....etc. You are setup to run the experiment you are doing and it would seem we are on the exact same page here
