Can someone explain to me the "lower temp thermostat"?

 the lower temperature thermostat gave me a lower starting temperature and therefore bought another 30 seconds or so of full throttle before I had to worry about boiling the engine.

I thumb's upped your post because im uhh.. not gonna thumbs up my own post you know? lol

 I know this part of his statement is mostly just peacocking, but I will say that this really rubs me the wrong way. If you don't seek to understand, then it is likely you will not understand. It doesn't make me trust what he says, it does the opposite. 

Im not a fan of the way that guy talks either, but I think i totally agree with him in the way that he meant, which i THINK is..   If you are measuring a bunch of stuff that's already failed and you see concrete undeniable patterns of wear/failure, nobody from Porsche is going to convince you/me that worn/tapered bores are justifiable to the actual end user under any circumstance. So if you build an engine that goes pear-shaped under fairly normal or expected use, I don't care what your justifications are either.  It makes sense to me.  Emissions, lenghtening OCI? Those are compliance and sales issues ie YOUR (oem's) issues, not car owner just wants a car with round bores and not have to give Jack Raby  five digits of money issues.  I mean if you shoot my dog because your friend said he'd give you $10, do i need to just respect that you're operating under a different incentive structure?

In reply to Vigo (Forum Supporter) :

If Porsche is making an engine that is failing, the best way to deal with their lack of action is to contact people who can make them fix it.  Which would be the EPA.  If the engine is not actually capable of meeting emissions as required, the EPA can make them do it.  Normally via recalls.

I know most enthusiasts think that the EPA is anti car- but they are not.  And there are a lot of enthusiasts that work there.  They can be used as a tool to make your investments actually meet their requirements.

Excellent discussion.

I have done it before for two reasons:

When I was young and new to cars and the internet was barely a thing yet I was advised to  by older, more experienced and more vocal car club members and bare bones websites. Some of those descriptors in that sentence could be in questioningly ironic quotation marks... the community as a whole advised it as a basic initial stage modification and the oem performance division sold the part at a reasonable price for racing applications. I guess I was a sheep in the heard trusting/hoping that we were all going in the correct direction?

Secondly was the described bandaid effect on a hot car that I kinda knew what I was doing with. Mostly I dealt with small, forced induction motors and in high specific output trim there is always a struggle with heat management. Multiple cooling modifications need to be employed. I have run 30 pounds of boost up 17% grades and greatly appreciated those precious extra seconds until a distracting warning light and a judgement call on when to shut it off.

I know we have all heard other myths, rumors and assumptions over the years but the technical discussion is a great addition. 

If Porsche is making an engine that is failing, the best way to deal with their lack of action is to contact people who can make them fix it.  Which would be the EPA.  If the engine is not actually capable of meeting emissions as required, the EPA can make them do it.  Normally via recalls.

I dont know if oval bores cause emissions failures but i doubt that is what Jack Raby is getting paid to fix. I'm just saying that if you are making a bunch of engines that are geometrically distorted before 100k miles, your list of excuses carries little weight. That's what i think was meant by 'not caring what Porsche thinks', and i think that's a reasonable stance

In reply to Vigo (Forum Supporter) :

If he sees direct evidence that lower coolant temp extends engine life, then that may be an argument for a lower temp stat. Which makes sense, because an engine should spend much of it's life hovering around the stat temp. BUT this is one place that a factory engineer is almost guaranteed to have more and better data than him. bore ovaling is also not the only way an engine wears. What other problems is he creating that the factory engineer knows about and he doesn't?

alfadriver (Forum Supporter) said:

In reply to AAZCD (Forum Supporter) :

It's interesting to see so many internet engineers second guess Porsche's.

I've said it before, I'll say it again- "common sense" is wrong sometimes.

And leave it at that.

Porsche's engineers can't simply use what's best all the time.  Engineering a car is a massive cluster of compromise, and I'm certain one of the big compromises they have to make is coolant temperature for the needs of emissions.  All the best engineering in the world means nothing if the car won't pass an EPA test.  If it's the choice between 5 fewer ponies vs selling zero cars and scrapping the investment, you use a 180 stat.

Robbie (Forum Supporter) said:

So I get the general idea. 160deg stat opens earlier than 180deg stat. But generally I put them with pod filters from pep boys - a solution to a problem that doesn't really exist, or at best a band-aid for not fixing the root cause.

But then Classic Motorsports goes and installs one in their Boxster S because their expert insists, and the main reasoning given is "florida". This shakes my understanding of thermostats to the core.

1. Did porsche really not consider that people would drive their Boxster S' in anger in Florida?

2. In my admittedly limited understanding, a lower temp thermostat would lower the temperature the engine coolant hangs around at. But a lower temp thermostat would not have any impact at all on the overall cooling systems ability to shed heat. So while the thermostat might lower your cruise temp, it would have no affect on maximum cooling ability, like on track in florida when you are actually generating maximum heat.

3. Hot oil generally flows better. So low temp thermostats I'd think can actually put your oil at the wrong temp, making it harder to flow to all the nooks and crannies and maybe costing you some HP in pumping losses?

So, is there real benefit to lower temp thermostats? 

(Let's not even get started on how a sub 70k mile porsche needs over $3k in parts alone and a clutch job with engine out labor before it is track ready, and that is not including the IMS stuff perviously done, yikes!)

Engines like to be hot.  Drivers want them to be cool.  The real answer is that the correct thermostat temp is best.  The correct temperature is based on hundreds of limitations by other things.  We use water-based coolants that have a limited range of heat capacity before they boil.  We therefore use gasket materials, oil formulations, and plastics under the hood that all work with those temperatures.

So, within a given engine/vehicle/cooling system design, there needs to be a proper coolant temperature.  If the engine block design puts the oil passages near the water jacket, it may do a more efficient job of stabliizing oil temps.  Too far away and it doesn't do enough.  Did the engineers use an oil cooler which would make the coolant temperature less of an issue for oil temp control?  All of these things work together.

A lower-temp stat (as you know) doesn't change the rate at which the cooling system can exchange heat, which is why it doesn't solve overheating issues.  It can, however mask them by simply giving you 5 more minutes before it does overheat

The engineers have their hands somewhat tied by the EPA.  They will be forced to choose a thermostat temperature which produces emissions within a range of acceptable numbers.  Otherwise, they can't sell the car.  So, internet engineers take to the web and start tinkering.  Sometimes their testing amounts to "I've been running a 160 stat for three years with no problems."  The benefit in some vehicles seems to be increased horsepower.  It's a pretty simple thing.  Less heat contained in the engine's coolant, metals, and surrounding things can cause a denser charge which the ECM then compensates with more fuel.  Kind of a no-brainer.  It also stands to reason that this is highly dependent on the engine.  A Chevy Vortec with a water passage in the aluminum intake might see bigger benefits than for instance a VW with a plastic intake and no water passage.  As long as the oil maintains proper temperatures to be healthy, often there are few drawbacks to a cooler stat.  There is the possibility of additional carbon buildup, catalyst health, or other issues, but usually not a big deal.

Many of us Impala SS/Caprice guys would do 160 stats.  The primary reason was power (we could often pick up 15+ hp), but the secondary reason was the reverse-flow cooling.  Instead of the stat keeping coolant in the engine until it reached temp, it kept it in the radiator.  Whereas a normal system waits until the coolant gets to 180 and then sends it to the radiator to cool down, in an LT1, it sucks in 180 degree water from the radiator and sends it to the engine to take on more heat.  It was never an overheating issue, and in fact the higher head coolant temps means that our HC emissions were usually really low... meaning more generous leeway for mods before we failed a sniffer.  There were guys in L.A. in the SS club making 500 hp with an LT1 and with careful tuning could pass the sniffer.

But the switch to a 160 stat for us was more like a 180 stat for anyone else because of our reverse flow cooling.

Back to the original thought.  You are correct about "temp hangs out at" and "ability to shed heat."  If we weren't shoehorned into things by the materials we use, I think we would have thermostat temps around 300 instead of 180.  We've all been so desensitized to the fact that 230 degrees is "overheating," but it isn't.  Cast iron doesn't melt until nearly 2000 degrees, aluminum around 1500.  Paper doesn't burn until 450, and some plastics can take 500 degrees.  For 100 years we have been shown cars that boiled over at 240 degrees and now they have a warped head.  The head didn't warp because it reached 240 degrees.  It warped because the coolant boiled and lost contact with the metal, and the metal in a few spots got to 700 degrees while other parts of it stayed 240 degrees.  It's not the temperature that warped it, it's the runaway heating of certain areas of the head that warped it.  The engine doesn't care if it's 200 degrees or 500 degrees.  There are thousands of explosions per minute inside there, each one at 2500 degrees.  All it cares about is that the heat out of the chamber is predictable and constant.  As soon as you get boiling, it can no longer count on that heat transfer and it's downhill from there.

The first time I drove with non-aqueous coolant was a really bizzare thing.  I had built a nice Caddy 500 to use in a tow pig.  I used Evans coolant.  I was towing a 10k lb RV from Phoenix to Flagstaff, which is 150 miles of non-stop uphill.  I-17 has water faucets beside the road every few miles, it's that abusive.  Foot to the floor, maintaining 60-65 mph, I watched the coolant gauge nearly peg at 290.  Oil temps did get to 240 for a bit.  Never a ping, never a problem, never a boil.  The one downside I didn't anticipate was transmission oil temps because I ran the fluid through the radiator before my cooler.  Live and learn.  But that is intended to demonstrate that if we weren't limited by the fluids and materials we use, coolant temperature is mostly immaterial.  I just imagine engineers leaping for joy now that they can spend more time on important things instead of struggling with HC emissions with 210 degree thermostats.  They could throw fuel at it, put a bigger EGR on it, and then go worry about things that matter.

I did some experimenting with my ZX2SR, a dd and tracked.    Didn't see much difference in performance.   Of course it's not a Porsche.

I ended using the 195 because of quicker wam up here in the great NE.

The "cold thermostat = power" history came about by mixing the two ideas that:

1. Cold intake air = more power (true)

2. Tricking ECUs of the day into thinking that the engine's cold, meant that they'd inject more fuel, thinking that the engine had just been started and was still in its warm-up phase. So the idea at the time was "more fuel = more power." Sort of true.

Combining the two somehow resulted in "cool thermostat = power", but time has moved on; manufactures have better intakes and smarter ECUs, so whatever benefit there was on those early-gen ECUs doesn't apply now, though cold air still does, which has nothing to do with the thermostat temperature.

Good morning. In response to Alfadriver:

I am not arguing your points, but want to be clear that the people that I quoted are not "internet engineers" second guessing Porsche.

I selected quotes from actual engineers who have been working with the particular engines that Robbie was asking about. I was trying to be helpful by passing on pertinent info to specifically answer his question. I did not intend to prove a point or show people that I was smarter than anyone.

I doubt that most people care to read it, but here's some clips of info on their backgrounds:

Wayne R. Dempsey:

Wayne Dempsey co-founded Pelican Parts in 1997 as a result of his own passion for Porsche. His first exposure to a 914 came though the father of one of his close friends. After driving the 914 around the hills of upstate New York, he decided he wanted one for himself! So upon his arrival in California, Wayne picked up his black 1974 914 Roadster before he had even found an apartment. He definitely knew his priorities! Originally from Long Island, Wayne spent 5 years in Boston where he received his undergraduate and master’s degree from MIT (Massachusetts Institute of Technology) in Mechanical Engineering. While at MIT, Wayne designed and implemented a fail-safe four point latching system for the gull-wing doors on the commuter car Aztec as part of MIT’s Solar Electric Vehicle Racing Team. He also single-handedly designed, constructed, programmed and tested a fully functioning PC-controlled assembly module for manufacturing connectors.

Charles Navarro:

Charles Navarro co-founded LN Engineering LLC while studying Computer Science at Northwestern University in 2002 along with his wife, Tammy Hellings, also a graduate of Northwestern with a degree in Chemical Engineering and MBA from Olivet Nazarene University. LN Engineering formed a niche business, previously non-existent for precision performance aftermarket engine components specifically targeted toward addressing known issues and improving upon original equipment engine components for Volkswagen and Porsche vehicles. LN Engineering is best known for its trademark Nickies air-cooled cylinders.

Originally focused solely on research and development on legacy air-cooled models LN Engineering continued to expand the business to include water-cooled Boxster, Cayman, and 911 models beginning with the M96 and later M97 engines utilized through 2008. Ever since then, providing products and solutions for these newer water-cooled engines has become an area of intense focus and development leading to the Nickies aluminum engine block sleeving process where failed blocks could be repaired rather than be replaced, while allowing for increased displacement as well as improved cooling and reliability. ….

Jake Raby:

In 1997, Jake Raby founded Raby Engine Development (RED) specializing in building,

modifying, and customizing performance engines and engine parts for Porsche

automobiles. In 2007, the Flat 6 Innovations division was created, specializing in the

modern, watercooled Porsche™ M96 “flat six” engine development. Having identified

many areas of weakness within the Porsche M96 engine; and noting that others were

not developing fixes for them, Flat 6 Innovations and LN Engineering coupled to

engineer components and processes to overcome the inherent deficiencies. Jake was

the first to install an IMS Retrofit bearing into a Porsche M96 engine and worked to

perfect the processes and tooling to make the IMS Retrofit a common practice today.

Jake’s most recent development, the IMS Guardian™ (premiered in the November,

2011 issue of Excellence Magazine,) is the first advanced monitoring system for

imminent engine failure. Coupled with their IMS RetroFit Kit, the first kit designed to

replace a faulty Intermediate Shaft (IMS) bearing, a relatively common cause of

catastrophic engine failure in the M96 engine, Jake pioneered solutions never before

available to keep these engines on the road. Jake has completed instructional engine

rebuild videos as well as offering the “M96 101 Engine Rebuild School, a 3 day

comprehensive, hands on engine assembly class with a focus on M96 engine

assembly and he is currently writing the book on M96 engine assembly. The Aircooled

Technology division of RED specializes in the Aircooled engine used most widely in

the Porsche™ 914, and a new division has been created to focus on Subaru EJ series

engines. Located in Cleveland, GA, Raby Engine Development, and their well

respected, certified RED Line products, are shipped and driven around the globe.

I do not know details about JFP in PA, but he does own a reputable Porsche shop, is a senior moderator on Renntech.org and has a reputation for providing simple, technically correct information to anyone who asks for help without getting into a 'pissing contest'. I remember reading somewhere that he came from an engineering background before owning the shop.

Vigo (Forum Supporter) said:

There aren't many high performance cars that can actually shed heat faster than they can make it. Pretty much any fast car, when you floor it you are starting a (fairly long) countdown to overheat or some side effect of it (like detonation). Starting that run at a lower temperature extends the timeline.  That's not the entire benefit, but the more powerful the car the bigger the effect that is, right up until your 160* thermostat turns into having full control of an electric pump water instead.

I ran a 180 degree thermostat (instead of the stock 195) and a Mishimoto radiator in my rallycross car for this reason.  It bought me a little extra time.  

I think Curtis confirmed something I suspected about the Impala SS - coolant temps always seem low on it, and now I know why.

In reply to AAZCD (Forum Supporter) :

The big issues I have with most aftermarket mod guys is that they are not the ones who have to sign off all of the required tests to sell a car.  Some are emissions related, others are durability requirements, and even others are for driveabilty.  Rarely do people actually understand what compromise they are re-defining when they make mods.  

It's not as if I put P on some kind of pedastool- IMS bearing is a blaring shorfall.  But I do know what the process is to sell a car from a development standpoint.

eastsideTim said:

Vigo (Forum Supporter) said:

There aren't many high performance cars that can actually shed heat faster than they can make it. Pretty much any fast car, when you floor it you are starting a (fairly long) countdown to overheat or some side effect of it (like detonation). Starting that run at a lower temperature extends the timeline.  That's not the entire benefit, but the more powerful the car the bigger the effect that is, right up until your 160* thermostat turns into having full control of an electric pump water instead.

I ran a 180 degree thermostat (instead of the stock 195) and a Mishimoto radiator in my rallycross car for this reason.  It bought me a little extra time.  

I think Curtis confirmed something I suspected about the Impala SS - coolant temps always seem low on it, and now I know why.

I forget if it currently has a 160 or a 180, but don't let that gauge fool you.  GM and Ford both like to do that little trick where the gauge reads lower than center to make drivers feel fuzzy about how well they keep cool.

IR thermometer on the stat neck will tell you which one is currently in there.

Edit... forgot.... did you hook up the wire to the gauge temp sensor?  I knocked it off long time ago and never put it back on.  Passenger side head just above the exhaust manifold.  I think it was a green wire.

Did you know, that running no 'stat can cause the engine to over heat ?

Race cars don't run a 'stat, just a restriction plate.   Temp is controlled by airflow.   

May not apply to all.

 This doesn't really apply to the thermostat question.

In reply to Robbie (Forum Supporter) :

Jaguars went from numbers to cold-normal-hot on the dial. 180 degrees was about the A on normal and so many people worried their car was overheating. They were convinced it needs to be at the N or O just commuting 

kb58 said:

The "cold thermostat = power" history came about by mixing the two ideas that:

1. Cold intake air = more power (true)

2. Tricking ECUs of the day into thinking that the engine's cold, meant that they'd inject more fuel, thinking that the engine had just been started and was still in its warm-up phase. So the idea at the time was "more fuel = more power." Sort of true.

Combining the two somehow resulted in "cool thermostat = power", but time has moved on; manufactures have better intakes and smarter ECUs, so whatever benefit there was on those early-gen ECUs doesn't apply now, though cold air still does, which has nothing to do with the thermostat temperature.

Given how many engines now have plastic intake manifolds (most/all) and port or direct injection (all), it doesn't make sense to apply "colder = better" theory that arose from carbureted engines with iron intake manifolds that also had coolant routed through them.

One thing that I found interesting was NASCAR engines running at 245F coolant temp, because it increases thermal efficiency, so they get more power from the airflow they are allowed to have...  They also used to run on the order of 19:1 compression on restrictor motors!

In reply to iceracer :

How does no stat cause an overheat?

In reply to Robbie (Forum Supporter) :

On my Honda, the thermostat is what directs coolant through the radiator. No thermostat the coolant bypasses the radiator and circles the block because that's the path of least resistance.

Toyman01 (Moderately Supportive Dude) said:

In reply to Robbie (Forum Supporter) :

On my Honda, the thermostat is what directs coolant through the radiator. No thermostat the coolant bypasses the radiator and circles the block because that's the path of least resistance.

Shocking that a wide radiator with big hoses have less resistance than the engine does.... or more correctly, not many consider that water path would be preferential....  

I think the lack of thermostat causing the coolant goes back to the engine is just the lack of blocking the bypass port the engine uses when the thermostat is closed. I would venture that some goes through the radiator and some back to the engine without hitting the radiator loop.

In reply to AAZCD (Forum Supporter) :

All three of those guys are respected in the Porsche community and probably would not steer anyone wrong, but they are also businessmen. Same can be said for my 30+ year Pcar mechanic friend. I respect all of them.

My friend knows how and where I drive my 987.1. He has told me not to worry about the IMS until I see metal on the drain plug as I actually drive the thing a lot rather than a bunch of non-op temp trips to get ice cream. He did tell me that the M97 cars still will need an IMS bearing as it is a wear item.

He also knows I am a huge fan of S CA canyons and will run them at 100*+, he has never said a thing about putting a lower temp tstat in my car. He has never mentioned screwing up the cyls either. Said Cayman never sees high water temps.

Just shy of 92k miles after this last cross country trip.

I am not being argumentative just showing a different opinion.

Off to change to a lower h2o thermostat in my 914s now that I am paranoid...

Robbie (Forum Supporter) said:

In reply to iceracer :

How does no stat cause an overheat?

It reduces pressure in the engine, allowing boiling around the exhaust ports.  The coolant may show okay temperature, but that is because it isn't transferring any heat away from the cylinder head because the hot areas are insulated from the coolant by a layer of steam.  Eventually it will get bad enough that the coolant will boil over.

Alternatively, in vertical-core radiators, the coolant restriction for the water pump stops being the thermostat and starts being the radiator, and the water pump will happily build enough pressure to blow off a lousy little 15psi cap, which is now on the high pressure side of the cooling system.

I've measured 45psi in normally operating stock engines.  A few years ago I had a weird combination of parts in a big block Ford that was building over 200-250psi in the block, blowing out core plugs and exploding heater hoses.  That one was fun to try to correct.

In reply to Pete. (l33t FS) :

Uh, I don't think the thermostat has any effect on the coolant system pressure....  That's more about the rad cap.  

Unless the T-stat is totally sealed- which I've never seen one that does not have a small bleeder hole.

alfadriver (Forum Supporter) said:

In reply to Pete. (l33t FS) :

Uh, I don't think the thermostat has any effect on the coolant system pressure....  That's more about the rad cap.  

Unless the T-stat is totally sealed- which I've never seen one that does not have a small bleeder hole.

BLOCK pressure, not radiator pressure.  The radiator is on the low pressure side of the cooling circuit.

A rule of thumb I have seen for racing engines is to size the water pump pulleys/restrictor orifice (racing engine = no thermostat) for 50psi pressure in the block.

I assume that suction side thermostats work at all because they are only ever employed on aluminum headed engines, and aluminum is a wonderful conductor of heat compared to iron.

What other problems is he creating that the factory engineer knows about and he doesn't?

Almost certainly problems that would bother a manufacturer and NOT an owner.   I base this only on the millions upon millions of examples of an untold variety of engine types running untold miles with lower-than-optimal coolant temp. There are WAY, WAY more engines surviving this horrible abuse than there are engineers to wring their hands over it.

There's no prize for putting engineers on a pedestal in this thread. Have you met people? People are people. Engineers are people. The stuff they get paid to do is more characterized by what they are getting PAID to do than by their titles, degrees, qualifications, credentials, etc etc etc.  If the goals they have to hit are different than what a car owner's goals for that design would be, tough E36 M3 for those owners! And also tough E36 M3 for the engineers if the owners don't put a lot of value on the compliance work those engineers had to do to hit goals the owners don't share. And tough E36 M3 if its Jack Raby who says it, or literally anyone else ever. Noone owes them anything.