C4SDayton

Is this recommended for any climate or mainly hotter areas? It is cool and cold for 5 months, warm for a few months and hot, 85+ for a few months. I am driving a good 5-6 miles or more now for my oil temp to register above 150 on my 18 mile 1 way commute. What say the experts? Does every 997.1 owner need this or just those in warmer climates?

Flat_Six_

RJ997.2

I was informed cars with the 3rd (center) radiator needed it.

STAR997

Sounds like I live in a similar climate (Georgia) to you. My Indy recommended I not do this. I just replaced the water pump and they told me the OEM allowed to engine oil to warm up quicker, which was better for the life of the engine.

Wayne Smith

There are two trains of thought here ...

1. Warm up engine quickly to prevent damage.

2. Warm up motor slowly to prevent damage.

I have always believed in 1, but have come to appreciate the arguments for 2. This can be a hot topic and I am sure others will chime in.

It is also my belief that a properly designed cooling system will work to keep engine temperature close to the thermostat value. Pam's AMG does this regardless of ambient temperature and loads. My F250 as well. Same for most of my other (non English) cars. My 997.2 can vary (oil temp) from 170 to 265F depending upon factors. I believe others will admit to this same problem.

Petza914

As everyone knows, Jake Raby, Charles Navarro, and I are in camp 2. The more gradual warm up from using the LTT is beneficial and the normal 180 degree thermostat is often not fully open until well beyond that, even though you can't see that on the gauge which is really an idiot light, disguised as a gauge and heavily buffered.

Appraiser

I went overboard with this a few summers ago; I did the LN engineering 160F LTT, Porsche third radiator kit, new water pump and coolant flush & water wetter because I had been tracking in heat (115F) and I felt uncomfortable relying on my car to get me home after the track day with the oil temps up to near 250F for multiple sessions. Never had an issue - just didn't feel comfortable with it. After I changed everything I'd be around 225F in the same heat tracking with a/c on. On the flip side regular driving it takes forever to get to 200F and won't go over unless I'm turning higher rpms for some time. So I think too much cooling could be an issue, too.

OP - I think with just the LTT you'll be fine if you're subscribing to the slow temp build up.

Wayne and Petza - what're your guys' thoughts on a smaller underdrive pulley and its effect on the water pump/circulating coolant and oil temps? More time for the coolant in the radiators could mean higher dwell heat sink. Alternatively, slower circulation speeds could allow for more engine heat soak.

C4SDayton

If I decide to go with the LTT camp, and my car has 28k miles, should I have it done soon or when I do a preventative WP replacement around 50-60k miles? I will look at the DIY instructions and see if I can handle it in my garage or not. I will be driving 10k year round.

shekmark

So, what is the gain here? Faster warm up in the winter, or just the opposite? I don't drive to work much when it's really cold in Jersey, because my office is only 1.5 miles away. I don't think it is healthy for my engine to do that drive and I often don't have time to take the long way. It takes a long time to warm up to 175 in winter.

rtl5009

Petza914

That's actually not correct. The warm up will be slower and more gradual. That's why the belief is that it helps prevent bore scoring by allowing the motor to come up to temperature more evenly. Once fully warmed up, the engine operating temperature is the same with either the LTT or regular thermostat.

Driving the car on 1.5 mile trips is not good for it with either thermostat.

rtl5009

Petza914

The LTT starts opening when the coolant temp reaches 160 which then opens the closed engine cooling system for the extra coolant in the reservoir (that's at ambient temperature) to then gradually start flowing though the motor. Now that you have a large supply of cold coolant mixing with the small warm coolant that was originally circulating in the closed loop system around the engine when the thermostat was closed it will take a while for all the coolant to come up to the same homogeneous temperature. The LTT isn't fully open until 180 degrees.

Now the regular thermostat doesn't start opening until 180 degrees and isn't fully open until 200 degrees, so with the regular thermostat the engine has warmed up further - to 180 - before the large reserve of coolant is introduced into the system. Because the LTT opened at 160 and the engine had to warm a much larger volume of coolant earlier, it takes the engine a longer time to get to the 180 temperature than it does with the regular thermostat where a much smaller volume of coolant circulating as the engine comes up to temperature.

Once either thermostat is fully open, it's open, and the engine is circulating the full volume of coolant through it.

Make sense?

Wayne Smith

The key here is that the thermostat doesn't snap open at a specific temp, but gradually allows more flow. A more gradual warm up allows the cylinders and the pistons to remain size matched, in theory. Thus less chance of boring.

The other school of thought is ... get the motor hot ASAP. I defer to others with more knowledge who, in the case of the 997.1 seem to have come to agreement on the LTT. This may not be the case with other cars.

Once the motor is up to operating temp either thermostat will remain fully open which is, IMHO, an indication of an inadequately designed cooling system (ideally the thermostat would regulate operating temp, but this is not the case on our cars). Thus I see operating oil temps vary from 170 to over 250 depending upon ambient and other conditions.

Vapor pressure (oil) increases with temperature and places more load on the AOS. This is of particular interest in the case of the 997.2 with DFI. Possible carbon build up on the valves is a concern, although there have been no reported problems on the 9A1 motor as yet.

Back to cooling design, Porsche continues to push the Flat 6. It is my opinion that they then compromise the cooling system to cut weight. A smaller turbocharged motor could fix this (allow for a bigger heavier cooling system). But would we enthusiasts accept that? This is only my opinion, but other cars I have owned regulate temperature for ideal operation. The 997.2 shows no indication of being able to regulate this.

Back on topic, the LTT seems to make sense.

rtl5009