OVERKILL
$100 Site Donor 2021
So, replaced the impeller at the beginning of the season in the Supra, and it was in dire need, a couple of missing fins, some of the remnants of which were lodged in the inlet. I noticed water temp didn't get above 160 the entire season this year, whereas last year it ran at ~180, which I had assumed was normal.
Wrong.
Looked it up, the non-EFI PCM engines call for a 142F thermostat, the EFI ones call for a 160F stat, so it's bang-on and was actually running "hot" with the buggered up impeller, despite running cooler than a standard SEFI EEC-IV Ford, which it is. The cars had a 192F stat in them and a routine upgrade was to drop that down to a 180, which would still let it go into closed loop (wouldn't with a 160) but resulted in less timing being pulled.
So, I had mulled over the idea of putting in a 180F stat but figured I'd check the manual to confirm the 160 stock spec and I'm glad I did. This is from page 15 of the Service Manual:
So it sounds like it is expecting ~160F. I found this surprising, as this is a departure from the cars.
Now, I recall a study years back when I was looking at the thermostat temp thing with the Mustang and I recall that wear increased when engine temperature was kept below 180F (another reason to avoid the 160 stats) and performance was reduced when you got above 190, hence the 180 being the "sweet spot", a perfect balance of low wear rates and performance.
This seems to go right out the window with marine applications where temps are generally significantly lower and even the EFI engines are run "cold" when compared to their passenger car siblings of the same family.
Anybody got some insight into the logic behind this?
Wrong.
Looked it up, the non-EFI PCM engines call for a 142F thermostat, the EFI ones call for a 160F stat, so it's bang-on and was actually running "hot" with the buggered up impeller, despite running cooler than a standard SEFI EEC-IV Ford, which it is. The cars had a 192F stat in them and a routine upgrade was to drop that down to a 180, which would still let it go into closed loop (wouldn't with a 160) but resulted in less timing being pulled.
So, I had mulled over the idea of putting in a 180F stat but figured I'd check the manual to confirm the 160 stock spec and I'm glad I did. This is from page 15 of the Service Manual:
So it sounds like it is expecting ~160F. I found this surprising, as this is a departure from the cars.
Now, I recall a study years back when I was looking at the thermostat temp thing with the Mustang and I recall that wear increased when engine temperature was kept below 180F (another reason to avoid the 160 stats) and performance was reduced when you got above 190, hence the 180 being the "sweet spot", a perfect balance of low wear rates and performance.
This seems to go right out the window with marine applications where temps are generally significantly lower and even the EFI engines are run "cold" when compared to their passenger car siblings of the same family.
Anybody got some insight into the logic behind this?