Heat exchanger air flow, needed or not?

3rd_gear_Ted · 3rd_gear_Ted's Garage

I need to know the ramifications of capping off the air flow from the motor to the heat exchangers? Will the lack of airflow through them cause residual heat in the heat exchangers to be a problem with motor temp?

tcar · 09-12-2008, 02:05 PM

What year 911? Different for different years.

Probably OK. How are you doing it?

fireant911 · 09-12-2008, 02:52 PM

3rd_gear_Ted,
For what it is worth, I tried this procedure (capping off the fan flow to the heat exchangers) and saw the quickest climb as well as the highest oil temperatures I have ever seen in my 1981 SC. Normally, my oil temps are quite low (180°F-190°F)... but not on that day. Others have reported better results.

3rd_gear_Ted · 3rd_gear_Ted's Garage

My 1980 SC suffered the same fate @ the track, highest temps ever. Thats the reason I asked. It appears the heat exchangers act as big ass heaters without any air flow and the heat just rises. I wonder if the early style heater mod will help?

tcar · 09-12-2008, 06:45 PM

So it's an '80SC?

Backdating the heater (getting rid of the heater fan and extra hosework) will work well, if that's what you're talking about.

Danny_Ocean · 09-12-2008, 07:34 PM

Quote:

Originally Posted by tcar

So it's an '80SC?

Backdating the heater (getting rid of the heater fan and extra hosework) will work well, if that's what you're talking about.

I think he's talking about just capping them off, vs. back-dating.

I researched this same subject very early on in my Pelican membership and determined, after reading several posts, that it's not a good idea to leave the heat exchangers in place without airflow of some sort.

Headers or back-date.

don gilbert · don gilbert's Garage

danny is rite, i read several post ( i think from gunter or jww) saying that the exchangers must have flow through them to prevent heat build up in the bottom of the engine.

3rd_gear_Ted · 3rd_gear_Ted's Garage

Thanks folks, this information was a big help, solved my mystrey and made me realize (yet again) that every modification done to a 911 needs to be thought about from all aspects. To summarize; no air flow in the heat exchangers will allow most driving scenarios not to be impacted. Get the car on the track on a hot day and the oil temp in the front oil cooler will get to 220, but the oil filter will read 250+ due to the thermal heat load radiation from the heat exchangers!!! My laser temp device was a big help in the discovery process and it helped me get the data needed to share here. I'm going to backdate the heater system and see what happens.