Is higher temp expected with CR/disp increase

[mike sampsel]

Added 98 mm pistons with 9.5 CR. So I guess I’m similar to the 84 or so Carrera engine. With 30/5 weight breakin and some spirited driving, I’m seeing temp gauge settle at the range in the photo.



Car runs warmer now, to be expected, right? I used to see (with 3.0 SC) the needle settle at 8:30 instead of 9:30, as shown.
Ambient temp about 75-80 degrees, fast acceleration for breakin.
I plan on adding the Carrera oil cooler and fan sometime, just wonder if the temp value increase is as expected.

[manbridge 74]

Yes

[Quicksilver]

Radiators in reality can be rated in horsepower because a pretty fixed percentage of energy in an Otto cycle motor goes out as waste heat. So a power increase will also increase the waste heat you have to get rid of.

Or as mentioned above: "Yes"

[911pcars]

I affirmatively agree with a Yes. The factory recognized 2.7 liters as the threshold for an external cooler. They attempted to resolve with their trombone "cooler", but thereafter relented with a real oil cooler (radiator).

Caveat: PAG knew earlier ('69) - the higher output S engines needed an external cooler and wisely included it. Some folks theorized that German engineers used their location as a reference point for operating conditions in the ROW. Thus, the delay until they realized US engines were succumbing due to emission-mandated measures and warmer operating conditions.

[mike sampsel]

Thanks gents, nice to get confirmation from folks with knowledge on the subject.

[Bill Verburg]

Don't confuse heat w/ temperature

While more heat will be added to the oil's thermal load there will only be a temperature rise to the extent that the capacity of the cooling is exceeded, If it's an SC w/ trombone cooler which is marginal w/ a 3.0 a high compression 3.2 would be expected to run hotter, All you need to do is update the cooler to late 3.2 Carrera radiator style and temps will fall right back to the level which the t-stats determine.

When there is an excess of cooling capacity you can watch the temp gauge go up & down w/ the closing and opening of the t-stat

[mike sampsel]

Originally Posted by Bill Verburg

Don't confuse heat w/ temperature

While more heat will be added to the oil's thermal load there will only be a temperature rise to the extent that the capacity of the cooling is exceeded, If it's an SC w/ trombone cooler which is marginal w/ a 3.0 a high compression 3.2 would be expected to run hotter, All you need to do is update the cooler to late 3.2 Carrera radiator style and temps will fall right back to the level which the t-stats determine.

When there is an excess of cooling capacity you can watch the temp gauge go up & down w/ the closing and opening of the t-stat

Yes, it all makes sense. The “Carrera style cooler and fan” is on my Christmas wish list.
Not sure what year for Christmas though . Good to discuss and have folks ease my anxiety of my first engine build.

[Reiver]

I have a 3.0 930-10 that has 9.8-1 compression and has had a top end done so possibly 10ish...I have that Carrera unit complete and it runs on normal days 185/190....even on hot Az days over 100 ambient it stays below 210 even running it hard....normal driving in that heat 195-205

[Bill Verburg]

Originally Posted by Reiver

I have a 3.0 930-10 that has 9.8-1 compression and has had a top end done so possibly 10ish...I have that Carrera unit complete and it runs on normal days 185/190....even on hot Az days over 100 ambient it stays below 210 even running it hard....normal driving in that heat 195-205

That's normal bothe t-stat's open at ~182-189F the temp rise curve normally looks like this



The first plateau is the engine t-stat and the second from the fender well t-stat w/ adequate cooling for the conditions the second plateau is it, w/ inadequate cooling you will see a rise that only stops when thermal equilibrium is attained

[GH85Carrera]

All forms of power generation produce heat. All of them. More power means more heat.

I saw some egghead did the calculations on the power packs that are in the Terminator, and each of the two (redundancy is needed) would make so much heat that the Terminator would melt unless he had a cooling system the size of a house.

[mike sampsel]

Hum ... I wonder where I can determine what this temperature is?

[jac1976]

[Reiver]

You look to be a 200 something...that gauge is very hard to read with the 200 to 240 so close together.
I have the numbered plate in mine and it is an extremely easy job done thru the back of the gauge...worth the trouble.

[911pcars]

Larger cylinders, combustion chambers and pistons provide more surface area to absorb combustion heat into the cooling system
Higher compression ratios produce higher volumetric efficiency and thus more energy and heat from the A/F mix.
More power increases friction between moving parts = more heat..... and more.

One might notice 3.6 and larger engine displacements often call for larger and/or multiple oil coolers. That is the trend that follows engine displacement.

Sherwood