Temperature questions

[Hipopinto]

Hey all I have a basic question but as usual I tend to over complicate things!

Where “should” the temperature on my 428 be on a hot humid Ohio summer day?

When the weather permits I drive my galaxie as often as I can to work and I have notice a few times that on the way home when it’s about 90-95 degrees out that the temperature gets close to 200

I also noticed that when that temperature is higher like that that the oil pressure at idle drops significantly (under 20 psi)

As soon as I start to move the vehicle the oil pressure climbs and at about 2000 rpm it’s holding a solid 40 psi

When the engine is colder it holds better pressure (25 ish at idle)

I run pennzoil 10w40 and a FL-1A filter

An old timer I know told me that FE engines run best at 160 degrees I have never had this thing that cool

This does not boil over just feels hot on those days

What is the opinion of the masses?

Thanks guys
Dave

 

[blykins]

I would like to see a little higher hot idle oil pressure, but the temperature does not scare me at all.   

The old timer would have made sure that he had continual condensation in his engine. 

[Hipopinto]

Ok

This is what I’m looking for

As for hot idle oil pressure how do I get it higher?

Should I change the oil type?

It does concern me as well

Thanks Brent I really appreciate your advice

Dave

[fryedaddy]

i dont know what rpm you are idling at but sometimes you can turn the idle up a little and it might increase the pressure a bit.

[blykins]

Ok

This is what I’m looking for

As for hot idle oil pressure how do I get it higher?

Should I change the oil type?

It does concern me as well

Thanks Brent I really appreciate your advice

Dave

Lots of variables here.  Yes, you can change the oil type if the bearing clearances will warrant it.   A 20W-50 would bring it up, but if the clearances are tight, probably not a good idea.  As mentioned above, you can try raising the idle rpm.  You could also try to eliminate any "leaks"....i.e. if there are no restrictors to the rockers, etc., you could add some. 

[Hipopinto]

Ok

I have erson roller rockers and Edelbrock heads

I think the heads are a little different then iron heads

I Know the rockers Are looser all around than factory units so it’s surely a “loss” there

Do edelbrock heads have restrictors built in?

Thanks
Dave

[jayb]

Edelbrock heads don't have restrictors built in.  The oil passage in the heads is a bit smaller than a stock head, but you can gain by restricting it down further.  I like to use a 0.070" restriction.  The hole in the Edelbrock heads is 3/16" in diameter, if I recall correctly.

The Erson rockers have needle bearings on the shafts, so they will leak more oil than a rocker with a standard type bushing.  So I think that restricting your oiling in the head is a really good idea, especially with those rockers.

As far as a 160 degree thermostat, I ran those for years back in the 80s and 90s with no issues.  However, that was before good radiators and electric fans were available, so in traffic that temperature would climb much higher, usually 190+.  I never saw an issue with condensation in the oil, maybe because of the higher temperature excursions.

My current summer daily driver has a set of my clear valve covers on it, and a 180 degree thermostat.  After sitting overnight, I can start it and sometimes will see the evidence of condensation in the clear valve covers, they fog up a little and you'll see some of that whitish foam in there.  Once it comes up to temperature, all that has disappeared.  It runs between 170 and 180 all the time, which should not be hot enough to evaporate all the water, but it does.  I think this has to do with areas of the cooling system that are actually hotter than what is recorded on the water temp gauge; after all, the water temp gauge is only measuring the coolant temp at a single point, so there may be local areas in the engine where the coolant is hotter, which helps with the condensation issue.

As far as maximum coolant temp goes, I wouldn't be too concerned until it goes over 220.  But in my experience when you see that temp, it's on it's way higher 

[plovett]

My opinion on coolant temperature:  160 is definitely too cool.  You will get condensation in the oil like Brent said.  I have tried it.

On the other hand lower coolant temp. does make more power.  That's why you'll often see dyno sheets with the water temp at 130 or 140 degrees.

200 is okay.  I personally like my coolant to be in the 180-190 degree range.  I think that is the sweet spot.  It'll evaporate the water out on a drive of moderate distance, but keeps your intake charge cooler for more power.

paulie

[plovett]

As far as a 160 degree thermostat, I ran those for years back in the 80s and 90s with no issues.  However, that was before good radiators and electric fans were available, so in traffic that temperature would climb much higher, usually 190+.  I never saw an issue with condensation in the oil, maybe because of the higher temperature excursions.

My current summer daily driver has a set of my clear valve covers on it, and a 180 degree thermostat.  After sitting overnight, I can start it and sometimes will see the evidence of condensation in the clear valve covers, they fog up a little and you'll see some of that whitish foam in there.  Once it comes up to temperature, all that has disappeared.  It runs between 170 and 180 all the time, which should not be hot enough to evaporate all the water, but it does.  I think this has to do with areas of the cooling system that are actually hotter than what is recorded on the water temp gauge; after all, the water temp gauge is only measuring the coolant temp at a single point, so there may be local areas in the engine where the coolant is hotter, which helps with the condensation issue.

As far as maximum coolant temp goes, I wouldn't be too concerned until it goes over 220.  But in my experience when you see that temp, it's on it's way higher 

I would say the length of the trip makes a difference too, Jay.  A 160 degree thermostat may be fine if your always driving a long distance.   And like you said, if the actual operating temp is above that anyway, then it is a moot point.

[Cyclone03]

My dumb only concerns me running temp is ambient plus About 100, unless it’s below 80 then it’s thermostat temp going down the road. So when I drive through Phoenix and it’s 107 , 210 On the gauge doesn’t bother me. I have only been in a high temp of 115, and yes I was running at 215.

[My427stang]

Oil temps burn off water, not coolant temps, and of course that's obvious and not saying anyone doesn't know that already, but it makes it very difficult to compare one setup to another.

That being said, warm day at 200 coolant temp sounds perfectly good to me if it stays in control.  I like to see 180-195 mostly to keep ahead of under hood fuel temps, but for the engine, 200 is fine, oil is likely running at 230-240, and conventional oil likes it there, it could be even higher with some synthetic.  That's cooking off water and other yuck just fine.

Keep in mind other science class experiments too though, lower the pressure (pull a vacuum) liquids boil off sooner. I would expect it to be the same here too if the engine can actually pull a vacuum, although unlikely without a vacuum pump.

One of the things that make the engine feel hot though is underhood evacuation and airflow exchange.  In many FE cars, like a shock tower Fairlane or Mustang, the air may be able to nicely exit in front of the engine, but from the shock towers back, you are relying on a low pressure under the car to pull air down, and it doesn't work well.  New cars do it too, and some modern cars will overheat without the factory air dam (spoiler).   

One thing I did in Virginia, but don't need in Nebraska because not much stop and go, is add an unsealed Boss 9 scoop and coat the headers. Heat escapes at the stoplight through the big Boss scoop, you can see it, and although I can't prove it, I think that it adds a little pressure to the top of the engine allowing air to flow down the back of the engine when moving with low pressure beneath.  It keeps the passenger compartment much cooler and all my vapor lock issues from 2005-ish when it was carbed, immediately went away.  The next step was going to be to add a Mach 1 style spoiler, but I didn't need to.

[blykins]

Yep, a little harder to get the oil temps up though when the water temp is so cool. 

[My427stang]

Yep, a little harder to get the oil temps up though when the water temp is so cool.

1/2 a fill with hard block and a small pan, no issue getting it hot.  9 quart pan and a SCJ cooler, different story.  We agree regardless.  I was just making a point that we need to focus on oil temp for burn off, and oil temp can be MUCH higher and should be.

Another thing that is equally important is bore wear/piston scuffing, etc, bores open when hot and pistons grow with heat at a different rate, if you are going to run it real cool water temps, likely should have a little more room for those pistons.

I did a quick search on the web for some data, although this chart doesn't at ALL give you enough to make a decision, it does give you a trend, especially if you zoom in above 160. Cold clearance, piston material, block material, ring tension and design, all matter... this was more of a trending effort than building for purpose.  I think you could of course build a motor to run happily at colder temps, but it would be slightly different.   That being said, you can see the trend of cold versus hot

[jayb]

Oil temps burn off water, not coolant temps, and of course that's obvious and not saying anyone doesn't know that already, but it makes it very difficult to compare one setup to another.

Ross, my experience has been that until the engine has been running for 15 minutes or so, the oil temp lags the water temp by a fair amount, maybe 20 degrees.  On my car with the clear valve covers, the condensation that may be present disappears about the time the coolant temperature hits 170, with the engine idling in the driveway.  The oil temperature is still lower than the coolant temperature, as read on the gauges, at that point.

My theory is that the hottest part of the engine is the combustion chamber, and the coolant is in direct contact with the opposite side of the chamber, so it picks up a lot of heat.  On the other side of the water jacket is the valvetrain area, so my guess is that the oil in that area is heated to about the same temperature as the coolant, despite what the oil temperature gauge (in the pan) may say.  Further, again despite what the coolant temperature gauge may say, the coolant in this area can be hotter than what is recorded on the gauge.  Seems like that heat could be radiated into the oil through the casting, and in a steady state condition that may be one reason why the oil temperature will go higher than the coolant temperature.

If you think about the circulation path of the coolant through the engine, coolant that goes all the way through the block to the back, up into the head, and then back forward to the intake will have the opportunity to pick up more heat than coolant that comes up through the block deck near the front of the engine, then into the head and the intake.  I'll be that if you could put a good temperature sensor at the rear of the cylinder head water jacket, it would read higher than one placed at the front of the head.

All this is just an explanation that makes sense to me, in light of the fact that the condensation all disappears while the engine is operating below water's boiling point (as read on the gauges).  Next time I start the car and idle it in the driveway, I'll have to try to observe where the condensation disappears first in the valve covers.  I'm betting it's going to be at the rear of the engine, because I think it's hotter back there. 

[blykins]

Oil temps burn off water, not coolant temps, and of course that's obvious and not saying anyone doesn't know that already, but it makes it very difficult to compare one setup to another.

Ross, my experience has been that until the engine has been running for 15 minutes or so, the oil temp lags the water temp by a fair amount, maybe 20 degrees. 

Same here.  You can watch it on the dyno.   As a matter of fact, if the oil temp catches up to the water temp in a relatively short amount of time, I get nervous and start looking for issues.  You can also control the oil temp on a dyno with the water temp.  If you set the water temp at around 160-170, even while breaking in a camshaft for 20 minutes, the oil temp will very rarely get above 190-200 degrees.