327_TPI_77_Maro

iTrader: (8)

Hi guys, I set my fan on temp to 195 and fan off to 185 back when I started prom burning on my Stealth Rammed 1967 327. I know the factory fan on temps were way up there. I just started running a 180 stat. With a 160 stat in the winter time the car was barely running above 160 when moving. It would see 180s-190s absolute max under hard use, and would drop back into the 160s pretty quickly. I know this was way too cool to be running. I put the 180 stat in the other day and have not logged since. I probably should have put a 195 in for winter use but I didn't. I know it won't matter too much in the winter because the car will still be running on the cool side, but in warmer weather when the car stays at higher temps, is my 195 fan on temp fine, or would i be better off running a higher temp, like 210 ish? I know running a hotter engine means a more efficient engine (up to the point that lubrication and material properties start having problems with high temps), and that keeping an engine too cool can actually harm it, causing cylinder scuffing and carbon build up. The "slap a 160 stat in for more power" is not gaining anything in a street car, I know that for sure.

JPrevost

Designing a cooling system isn't that difficult. It's a lot easier when there is a fan controlled by some feedback system . With that being said, you pretty much can't screw it up. There was a thread about this a couple years ago that talked about when to turn on the 1 and 2 fans with the 730. I like turning on the primary fan just above the thermostat setting then turning it off at the thermostat "temp". Example of how I do it; 180stat. Primary fan on=186 off=180, secondary fan on=188 off=184. By doing this, I keep the secondary fan from turning on too frequently and it lives a nice long life. Same with the thermostat. They don't last forever! A cycle of opening and closing doesn't destroy them but if you do it often they don't last as long as they should. This is why I have the fans turn off before the stat closes. This keeps the stat from cycling to death so to speak. As for speeds. You can turn off the fans if you want but if the "off" temps are higher than the stat rated temp then they should never come back on if you've been cruising and getting good airflow to the radiator!
180 is my favorite stat for a "moderate to hot" engine which means one that makes ~1hp/ci or better. 195 for the daily drivers with <1hp/ci.
The other consideration is the type/style of the stat. The OEMs move slower so you should really keep the off temps higher than the stat rating to keep the actual coolant temps from swinging high and low. Taking a look at your datalogs will give you a good idea of how to tinker with the fans.

327_TPI_77_Maro

iTrader: (8)

Thanks. I'm just curious why the factory temps are so high. Obviously longevity was a concern. I only put a few thousand miles a year so I'm really not too concerned about fan/stat longevity. I only have one fan btw. It is a big big 18" single w/ shroud. It works quite well.

JPrevost

Emissions. Hot engine has a hot intake which helps vaporize fuel. That and the tolerances are closer resulting in better sealing. I don't think this is a reason but do you know how good your heater works when the engine is around 230 .

327_TPI_77_Maro

iTrader: (8)

So better vaporization, better sealing. Why is this not a reason for me to run on the slightly hot side (200-220)?

DENN_SHAH

iTrader: (1)

i have a 180 stat in my car, right now i have the temp on the primary set at 205 on 195 off, the secondary is set at 210 on & 200 off.

with those hot temps the factory runs, they aren't pushing the motor too hard performance wise & most have EGR.
i don't think you will gain much if any preformance by running at those hotter temps, or at least not enough to notice.
you also don't have much of a safety margin left when at the high temps the factory runs, it doesn't take long to go from 220~230 to 250 or higher.

JPrevost

Your engines coolant temp has a large influence on the temperature of the air filling the cylinders. Aluminum intake manifold coated on the underside with hot oil bolted to the heads which are hotter than the coolant temp... cool air = power. I doubt I have to tell you why that is .