Originally Posted by MysticRob
Jeebus, you're such an experiment tease. Get on with it already.
Hahahaha! Indeed I am!
Morning run complete. Some notes:
1) I met a buddy for breakfast so I was not starting from stone cold but it was cold. Less than a 5 min/2 mile drive, 90 minutes before the data run. I also left my hood opened slightly to allow it to cool a little faster than normal while we ate.
2) Run started about 8:25am and it was about 65 degrees out. When I got to work (about 8:55am), it was about 62 degrees (I work on the coast, live inland so it gets cooler as I drive to work).
Here is the chart:
A) It ran slightly cooler than the 195 TStat runs but not much. It took about twice as long to reach 185 but I was starting at 130. I assume if I would have started at 75F it would have taken much longer than twice as long.
B) I noticed a pretty big disparity between my digital temp gauge (what the computer is being fed) and my stock dash temp gauge. This has never been the case; they have always, generally, matched. My EFI Temp sensor is in the front passenger side manifold bung (where the timing CTO used to be) and the Temp gauge sender is in the factory spot on the front driver side so I wonder if the coolant flow from one cylinder bank is different than the coolant flow from the other when there is no TStat.
C) Almost every time I stopped at a stop light, I noticed temp increases. My fan is computer controlled and only comes on when speed is below 25mph and at a certain temp (I don't remember for sure but I think it was about 205 on and 195 off).
D) My Air fuel ratios (measured as BLM on my laptop) ran richer, almost the entire time. I expected them to be richer when it was cold but it seemed a little more than expected, even when engine temps were 180+.
Engine did not overheat without a TStat.
It did run slightly warmer than normal on a few occasions but that was when only the fan was pulling air through the rad. Generally it ran a little cooler without the TStat. With the 195 TStat, it ran 197-205 while with no stat it's 195-200 with only 2 temp spikes. If the initial thought of "Coolant flows too fast through the radiator to shed it's heat" were true, I would think the times when I am sitting at a light at idle speed/fan on, would be the times when the coolant temp would drop the most since those are the periods when the coolant would be flowing through the radiator the slowest.
I will go home via 101 freeway tonight so we'll see if higher RPMs make a difference. It is supposed to be high 80's when I leave, too so that may also make a difference. I will also plan to run these runs one more time when my 180 degree TStat is installed next week and see if that really lowers my operating temp any. Since no-TStat is still operating at 195-200, I can't imagine a 180 degree is going to lower it much.
Full disclosure: I was totally gung-ho on this when it started. I am pretty nervous now! I really don't want to torch my engine! I am not worried it is going to create so much heat it will ruin a head gasket; more I don't know what the flow of coolant through the engine looks like without a TStat throttling it. For instance, is it just flowing into the block around cylinders #1 and #2, then up the head and out? How much coolant are #7 and #8 getting?