Tested and Ready 70° and 75° Thermostat

[Bry5on]

Here’s a datalog driving uphill at 90-100*F with a stock relatively refreshed cooling system and AC on full blast. Coolant temp got up to 94C at steady state and coolant gauge registered just below the 3/4 dot. Hope this helps. https://datazap.me/u/bry5on/hot-uphi...oom=9655-26853

[HighOnLSB]

Okay sure. This is the primary reason why I added 75C for cold environment.

Not sure how cold it gets in Bahrain during those winter days but I will tell you
if its like in California during coldest winter time were I am still walking around with
shorts outside then this isn't cold enough....

Anyway, 75C is.

Regards,
Anri

Can you better define "cold environments"? In the PNW winter driving ambient temperatures are around 0-5C, but also summer track events are running during 30-35C days... Will the 70C thermostat be able to handle all of those conditions? Or is the 75C thermostat the more optimal option?

I tried to ask these questions in PM but have not heard back. Figure the information could be helpful to others as well.

[bigjae46]

Jae,

I specifically underlined that the Check
engine light will NOT turn on.

I just put 900 miles on the test car and out
of those 400 miles were on a 60F morning starts.

On 55C the check engine light will turn on..
one can turn it off from the ECU menu but
its cold for daily.

I have to ask Tomba and I hope he can
share some data at 70C if the OEM map is out
of Enrichment mode?


Regards,
Anri

Oh, I was thinking this was the 55c t-stat. Makes sense now. You're killing me with the celsius...lol

[Anri]

X2. How do we buy this?

Sent me PM with your name, shipping address, and
choice.

Also in the payment put a Note your Forum user name so I can
recognize who is who.

Thanks,
Anri

[discoelk]

X2. How do we buy this?

[ac427]

Hi Anri, I would like one of your thermostats.

Is 75⁰C only needed in very cold climates?

[Anri]

Thanks Anri. I wanted to go for the 75c because that should be good enough for the cooler weather too.

Okay sure. This is the primary reason why I added 75C for cold environment.

Not sure how cold it gets in Bahrain during those winter days but I will tell you
if its like in California during coldest winter time were I am still walking around with
shorts outside then this isn't cold enough....

Anyway, 75C is.

Regards,
Anri

[0-60motorsports]

Hi,

My suggestion is in such hot environment getting 75C is
waist of time. If its my choice I would go with 70C for sure.

I will sent you PM back.

Thanks,
Anri

Thanks Anri. I wanted to go for the 75c because that should be good enough for the cooler weather too.

[Anri]

Anri I need a 75c Tstat ASAP as temps have started to go up here in Bahrain and even at nights its like 90-110F!

Hi,

My suggestion is in such hot environment getting 75C is
waist of time. If its my choice I would go with 70C for sure.

I will sent you PM back.

Thanks,
Anri

[Anri]

Hi Anri I have to dig in to this, for sure the ECU checks if the normal operating temperature is reached in xx time.

Tom,

The 900miles test car I had it till yesterday.
I should have called you yesterday and have
you log in and get the data...I will be around
the car on Weekend if you are around?

Knowing how sensitive the ECU is on S54
after 900miles I don't have check engine light
and also not even passive code.

Edit: I will have ChapterM3 car for 70C t stat
upgrade and I will have you log in collect the data
from the 80C. After like an hour I will have the 70C
installed and I will have you log in again and get the
data. Meanwhile if you can dig those maps it will
be great.

Regards,
Anri

[Tomba]

I have to ask Tomba and I hope he can
share some data at 70C if the OEM map is out
of Enrichment mode?

Hi Anri I have to dig in to this, for sure the ECU checks if the normal operating temperature is reached in xx time. I would expect that parameter to be adjustable to prevent the error code from triggering or just disable it.

I suspect that lambda regulation kicks in after xx seconds of operation or once the front lambda probes exceed a certain voltage threshold. If started in -40°C environment it doesn’t take up to 70-80°C Coolant to enable lambda control. Enrichment tables are meant to add fuel during cold coolant temperatures to still target lambda 1. Currently only for short periods or really low temperatures a richer mixture is allowed. For an equal operating condition more fuel has to be injected on a cold engine as on a hot engine and the lambda value would still be equal once measured in the exhaust. From an OEM perspective you don’t want the lambda controller to adjust this, it has to be on target from the base.

In some engines the engine block and cylinderhead runs different temperatures by using double thermostats. On (current) BMW engines the (electric thermostat) temperature is controlled by load conditions (85 – 113°C). Full load will trigger to lowest to get maximum power from the engine. The highest are used in part load, ditching more heat will have less efficiency, the higher the better in terms of efficiency. New (BMW) engines have ditched the electric water pump and brought back the mechanical driven pump back. Engine developers used the mechanical driven pump for a reason, when increasing engine speed more horsepower is created (or better kiloWatts) and more heat loss. Once the pump rotates higher the massflow of medium is also higher (Q = massflow (m) * constant (Cp) * delta T(dt) ). Perfect as it is equal to power (Power = Torque * 2*Pi* engine speed in Hz).

On the test engines I have from OEM the coolant outlet temperature from the engine is controlled by the ECU. The coolant inlet temperature towards the engine needs to be controlled to ~70°C all time. I personally think that here the debate starts on the thermostats. If for some reason the radiator outlet / motor inlet temperature becomes too high the results is higher coolant temperatures than the thermostat is specified. From the M52 engine or maybe earlier BMW engines had a radiator outlet/motor inlet temperature sensor to control the auxiliary fan. Might not be present on S54 (I am not sure). It would be helpful to monitor this temperature in case the engine performs on higher temperatures than specified.

When fitting a lower opening thermostat I would suggest the complete delta of temperature is dropped and as a results prevents it from running on high temperatures. I would personally look for a root cause as I would suggest the radiator heat exchange might dropped by contamination (or blocked condenser) and or the water pump lost efficiency. There are probably more parameters to take care off.

I don’t know for people that currently experience issues if the environmental temperature has increased over time? As it is +25 years back the S54 was developed it might cause issues. Once no other options are possible to drop temperatures (increased waterpump flow, increased heat exchange from radiator, fans, etc) I would expect Anri’s thermostat to work as a (low cost) solution.

I believe on the S38 /E34 M5, different waterpump pulleys (smaller diameter to get more flow) were used in hot climate version. Also 1^st and 2^nd stage aux fan thermoswitch sensors were used to cool the engine better ways. I never seen thermostat difference.

I usually come by to a customer who is racing with a lot of S54 engines powered cars, currently even has the newest GT3/4 models as well. On none of these the thermostat opening temperature is changed, and no issues there. But our European temperatures might be relevant.

[Anri]

Might also throw codes in some cases - like on cold days.

Jae,

I specifically underlined that the Check
engine light will NOT turn on.

I just put 900 miles on the test car and out
of those 400 miles were on a 60F morning starts.

On 55C the check engine light will turn on..
one can turn it off from the ECU menu but
its cold for daily.

I have to ask Tomba and I hope he can
share some data at 70C if the OEM map is out
of Enrichment mode?


Regards,
Anri

[bigjae46]

Very interesting. What are the downsides for a dual-duty car? Additional wear on the street in some form from running colder?

I still have AC and my car definitely gets toasty on track despite having an all new OE cooling system. Can't remember numbers, but the gauge gets up against the red if I'm pushing in 90+ ambient temps depending on the track, though the manual says that's expected.

The only downside is your fuel economy will drop and the O2s might not last as long because it will run richer. Might also throw codes in some cases - like on cold days.

[0-60motorsports]

Anri I sent you a message on instagram. I need a 75c Tstat ASAP as temps have started to go up here in Bahrain and even at nights its like 90-110F!

In the mornings air temps are 125F around 10am onwards but road plus air temps might be around 135-140F. high humidity on most days too.

[EthanolTurbo]

I am more than happy to see more head gasket failures
coming to my shop between 5-6cyl...LOL

Regards,
Anri

This is exactly where mine failed LOL 😂