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bazhart
Approved Trader


Joined: 20 May 2009
Posts: 984
Location: Bolton Lancashire


PostPosted: Tue Dec 24, 2013 12:44 pm    Post subject: Low Temperature Thermostat Test Results Updated Reply with quote

It is several years since we last conducted the engine running temperature tests that resulted in the provision of the "low temperature thermostat" and we thought we should revisit the tests to be sure our advice provided since is still valid and to check several questions that readers have asked since about how to minimise the risk of bore scoring. Our original tests were carried out at this time of year and we know that in the Summer the temperatures are a little higher and the difference between std and our low temperature thermostat is slightly reduced by about 2 degrees.

In a standard 3.8 997 (with no Hartech machining mods to the coolant flow in the blocks i.e. as your standard car would be) but with 6 temperature sensors fitted to the engine and simply with first a standard and then a Hartech Low Temperature Thermostat we have just conducted back to back tests on the same day, routes and speeds etc and recorded temperatures driving, stationary, after ticking over for 2 and 5 minutes, switched off and on again after 5 and 30 minutes and at town and fast road speeds with the following results.

(1) Despite the temperatures recorded varying from 79 to 104 the dash board temperature gauge read 80 for every reading - confirming that the instrument in our test car has a buffer zone of about 25 degrees during which it does not change nor reflect what is going on in the engine or the coolant. This may lead to some who have fitted such a thermostat to question if it was doing its job! which it probably will be (and certainly will be if it is one of ours) .

(2) With the standard thermostat - on average the thrust side of bank 2 ran 5 degrees hotter than the thrust side of bank 1 @ 93 and 98 respectively. In contrast- with the Hartech thermostat - the difference was only 1.6 degrees @ 83.8 and 85.4 and this shows that the thrust side of bank 2 is now running cooler than the original thrust side of bank 1 (where we do not experience bore scoring failures).

(3) The oil temperature was on average 9.9 degrees cooler with the Hartech Thermostat (100 and 90.1).

(4) Whether driving slowly in traffic or fast on an open road the temperature differences between bank 1 and bank 2 were not significantly high (because at slow speeds there is little temperature generated anyway and at high speeds both the engine revs and air speed through the radiator are higher and overall cooling very efficient).

(5) The major difference was obvious when the car was either stopped but running on tickover for a few minutes or stopped for a few minutes with the engine switched off and started again. In both cases bank 2 thrust side increased temperatures much higher than bank 1 (because the contra-flow works on bank 1 and maintains a more even temperature gradient inside the engine whereas bank 2 exists with a higher temperature range that soaks out when the coolant flow reduces or is stopped) . On tickover or with the engine stopped - the oil around the piston in bank 1 and bank 2 would naturally gravitate to the bottom this would leave the piston in bank 2 thrust side (the top) with less oil on the thrust face for a restart and much hotter and thinner to resist the high torque loads possible driving off again - while bank 1 piston would be cooler and carry more oil on its thrust face (the bottom) for the re-start. This confirms our advice to drive off modestly after a period stopped at say lights or for a brief engine "off and on" stop before opening the engine up again. It also confirms that high speed driving at higher revs should not be a problem (as it has not been also in our race car engines).

(6) With both thermostats bank 2 cylinder head ran slightly cooler than bank 1 (96.7 to 98.1 std and 87.2 to 89.2 Hartech).

(7) The engine under test is fitted with pistons with yet another pair of different coatings and when it is stripped for the first time to check wear rates - we will modify the coolant flow to reproduce our usual rebuild changes and test out the results of those again too.

(Cool In general the fact that the thermostat is fitted on engine entry did not de-stabilise the temperatures but of course resulted in much higher internal running temperatures and thinner oil film strength than was the case when thermostats were fitted to the outlet. Assuming the same thermostat was fitted either before or after the cylinder block - the difference in internal cylinder temperatures would be about 8 or 10 degrees. The fact that the std thermostat is rated higher than those tradditionally used in more conventional engine coolant flow layouts would also mean that the internal engine temperatures std are probably in the region of 10 to 15 degrees hotter than they used to be (and all to assist the emission reductions required to export cars to major outlets).

Similarly with the more traditional layout the higher internal coolant temperatures were maintained the same as the engine usage was increased through faster more aggressive driving whereas with the thermostat on the inlet - as the engine is worked harder - so too does the internal temperature range increase.

I am not sure if it is an advantage to use a thicker oil if a lower temperature thermostat has been fitted (as the running temperature reductions will inevitably result in the same oil holding a higher viscosity) but personally - once any new parts have been run in - I still think an upgrade (as Wizard proclaims( is a benefit likely to extend the engines life).

It must be remembered that fitting a low temperature thermostat will not repair any existing wear rates that might have worn down the piston coasting somewhat already and therefore although running the engine at a cooler temperature may have avoided bore scoring all together if adopted when the car was new - with scored bores on bank 2 having occurred @ 9000 miles (but more usually about 30 to 60K) and as yet no evidence of scoring on bank 1 even up to 100K - it does seem that the temperature difference between the banks is what promotes early bank 2 failures and therefore although reducing those temperatures in bank 2 should extend piston life significantly, it is impossible to establish how worn they may already be at the time of fitting the low temperature thermostat and therefore being unable to predict how long the benefit will last for afterwards.

Although the low temperature thermostat is a low cost way of improving reliability - we are still working on hopefully even better solutions both for retro-fitting new designed parts to existing cars and during rebuilds. While fitting 6 Nikasil cylinders removes the problem all together - it is still expensive and so despite trying several different coatings unsuccessfully to date - we are still working on finding a reliable piston coating that may enable us to overbore scored cylinders that combined with changing the coolant and cylinder block temperatures - may eventually reduce rebuild costs with much improved long term reliability to "Nikasil" levels.

Finally I am not sure why there seems to be some form of competition to demonstrate where readers obtained their own lower temperature thermostats from and at what price - ours is just £35 + Vat and these test results only apply to our thermostat and do not necessarily apply to any others.


Have a great New Year - and "KEEP COOL"

Baz
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Maxie
Yas Marina


Joined: 11 Mar 2007
Posts: 8386
Location: London


PostPosted: Tue Dec 24, 2013 1:13 pm    Post subject: Reply with quote

Thanks Baz - very comprehensive report. I have a Wahler LTT fitted so I am wondering if my temps will be in the same ball park as the ones you have gotten with your replacement LTT also. The main difference to me has been an operating oil temp of 85C - as suggested by the dial in the dashboard - as opposed to 90C before LTT fitment at speeds below 4k rpm. Above 4k, my oil temp gauge reads 89C whereas prior to fitment it was 100C.

~ Maxie
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infrasilver
Fast & Furious
Fast & Furious


Joined: 04 Oct 2010
Posts: 8492
Location: East Midlands

2001 Porsche 996 Targa

PostPosted: Tue Dec 24, 2013 1:48 pm    Post subject: Reply with quote

I would be curious to see what my bores are like after running my Hartech LTT and additional 3rd Rad for about 2 years now (24k miles) and I got the rare chance to take a picture of my bores (5 and 6) when my engine was apart 14,000 miles ago.
Is it possible to get a picture from a borescope for comparison? That would be something really interesting to see.
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MisterCorn
Dijon


Joined: 08 Jan 2011
Posts: 7303
Location: Nottingham, England

2004 Porsche 996 Turbo

PostPosted: Tue Dec 24, 2013 2:05 pm    Post subject: Reply with quote

infrasilver wrote:
I would be curious to see what my bores are like after running my Hartech LTT and additional 3rd Rad for about 2 years now (24k miles) and I got the rare chance to take a picture of my bores (5 and 6) when my engine was apart 14,000 miles ago.
Is it possible to get a picture from a borescope for comparison? That would be something really interesting to see.


I have access to a borescope which you are welcome to use when you are in Nottingham. I can't get it until 6th January though. It doesn't do photos but does have a video output so no doubt you could get a grab from it somehow.

MC
 
  
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elliot_holder
Nürburgring


Joined: 15 Nov 2010
Posts: 400
Location: Guildford


PostPosted: Tue Dec 24, 2013 2:42 pm    Post subject: Write up Reply with quote

Thanks Baz - Very thorough write-up.

So glad I fitted the low temp thermostat and 3rd Rad to mine, given how much they cost and the benefits / piece of mind it's a no-brainier. Smile
 
  
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K9Md
Silverstone


Joined: 01 Jun 2013
Posts: 115
Location: Essex


PostPosted: Tue Dec 24, 2013 3:57 pm    Post subject: Reply with quote

Thanks Baz, very reassuring seeing those figures after having your LTT fitted a few months ago. thumbsup

Do you have any recommendations regarding an additional 3rd rad in conjunction with the LTT (such as 'DO IT!', or 'only if you track her'), and are you planning any similar tests with the additional 3rd rad?

Have a great Xmas!
 
  
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Stokepotter
Montreal


Joined: 21 Sep 2012
Posts: 623
Location: Stoke-on-Trent


PostPosted: Tue Dec 24, 2013 4:12 pm    Post subject: Reply with quote

Cheers Baz, good feedback, how do I go about ordering one?
Your site quotes £42 as opposed to the £35 you mention above, also, is it the same LTT for the 996?
 
  
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elliot_holder
Nürburgring


Joined: 15 Nov 2010
Posts: 400
Location: Guildford


PostPosted: Tue Dec 24, 2013 4:47 pm    Post subject: Reply with quote

Stokepotter wrote:
Cheers Baz, good feedback, how do I go about ordering one?
Your site quotes £42 as opposed to the £35 you mention above, also, is it the same LTT for the 996?


£42 is the correct price, it's £35 + VAT
 
  
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infrasilver
Fast & Furious
Fast & Furious


Joined: 04 Oct 2010
Posts: 8492
Location: East Midlands

2001 Porsche 996 Targa

PostPosted: Tue Dec 24, 2013 5:00 pm    Post subject: Reply with quote

MisterCorn wrote:
infrasilver wrote:
I would be curious to see what my bores are like after running my Hartech LTT and additional 3rd Rad for about 2 years now (24k miles) and I got the rare chance to take a picture of my bores (5 and 6) when my engine was apart 14,000 miles ago.
Is it possible to get a picture from a borescope for comparison? That would be something really interesting to see.


I have access to a borescope which you are welcome to use when you are in Nottingham. I can't get it until 6th January though. It doesn't do photos but does have a video output so no doubt you could get a grab from it somehow.

MC


Cheers MC, you'll have to nip over one day in the New Year and we can have a look if you fancy it. Thumb
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DynoMike
Albert Park


Joined: 25 May 2012
Posts: 1575
Location: The Cotswolds

2003 Porsche 996 Turbo

PostPosted: Tue Dec 24, 2013 5:10 pm    Post subject: Reply with quote

That is an excellent post Baz.

Of most interest to me is the nigh-on equalisation of the thrust side temps, along with a 10% drop in oil temperature. Good things to keep an engine running happier for longer.

I'm slightly bothered by your findings on actual temps vs displayed temp; that is very sloppy on Porsche's part. I suppose they just want 'happy' customers who do not ring the dealer network every five seconds complaining of a fluctuating temp gauge.

Keep up the good work Thumb
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Stokepotter
Montreal


Joined: 21 Sep 2012
Posts: 623
Location: Stoke-on-Trent


PostPosted: Tue Dec 24, 2013 5:47 pm    Post subject: Reply with quote

elliot_holder wrote:
Stokepotter wrote:
Cheers Baz, good feedback, how do I go about ordering one?
Your site quotes £42 as opposed to the £35 you mention above, also, is it the same LTT for the 996?


£42 is the correct price, it's £35 + VAT


The web site quotes £42 plus vat, it's one or the other!
 
  
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bazhart
Approved Trader


Joined: 20 May 2009
Posts: 984
Location: Bolton Lancashire


PostPosted: Wed Dec 25, 2013 12:04 pm    Post subject: Reply with quote

I will check after Xmas but the price is £35+ Vat - £42 - not back at work though until 6th Jan.

I seem to remember from some summer testing that once the temperatures exceed 110 the dash board gauge reads OK again - or at least suddenly jumps up.

I have not found a third radiator necessary yet when you have a low temp thermostat - but perhaps in very hot climates it may be advisable?

Still more testing needed on lots of ideas and improvements - it is quite a task for such a small business - but we need to know what is going on to find solutions and Porsche seem to have abandoned interest.

We also need to be thinking about availability of some replacement parts as cars get older and spares prices will probably rise - much development work going on here right now with several new bits and pieces - but long term testing takes time before products can be on general released.

Baz
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GT4
Nordschleife
Nordschleife


Joined: 08 Nov 2008
Posts: 30174
Location: Hertfordshire and Hampshire


PostPosted: Wed Dec 25, 2013 12:18 pm    Post subject: Reply with quote

By definition, the centre rad is only beneficial once the thermostat is fully opened.

Of course the flip side of the LTT is that it is fully opened at lowers temps than the standard thermostat.

It isn't even really a case of whether you track or other heavy load (which would be a no brainer), but if your intention is to use the sports car for what it was designed for!

Fit a centre rad.

It's the best VFM bargain from Porsche as the full OEM kit from OPC is just £120!

DIY fitting instructions in 997 FAQs
 
  
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infrasilver
Fast & Furious
Fast & Furious


Joined: 04 Oct 2010
Posts: 8492
Location: East Midlands

2001 Porsche 996 Targa

PostPosted: Wed Dec 25, 2013 12:23 pm    Post subject: Reply with quote

bazhart wrote:
I will check after Xmas but the price is £35+ Vat - £42 - not back at work though until 6th Jan.

I seem to remember from some summer testing that once the temperatures exceed 110 the dash board gauge reads OK again - or at least suddenly jumps up.

I have not found a third radiator necessary yet when you have a low temp thermostat - but perhaps in very hot climates it may be advisable?

Still more testing needed on lots of ideas and improvements - it is quite a task for such a small business - but we need to know what is going on to find solutions and Porsche seem to have abandoned interest.

We also need to be thinking about availability of some replacement parts as cars get older and spares prices will probably rise - much development work going on here right now with several new bits and pieces - but long term testing takes time before products can be on general released.

Baz


I think mine was £80+ but that when you'd first had them for sale, it made sound reading what you had said before and I didn't want to wait for a definitive result from your findings so just jumped in like a lot of people that have read your comments on the LTT.

I know there is not any proof for the benefit of the 3rd rad addition (I do use it on track occasionally) but I was thinking ahead for road use and if the coolant capacity is increased and the coolant is cooler between the rads when the engine does get very hot it cools down quicker as there is more cool coolant available and would also take longer to get to its critical hot status.

Mine ran cooler when I changed to the LTT and then a few more degrees cooler when I added the 3rd rad, so for me this is a plus point. Fuel consumption probably is higher and power may be increased slightly at certain temps but the 3rd rad has got to help IMO.
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GT4
Nordschleife
Nordschleife


Joined: 08 Nov 2008
Posts: 30174
Location: Hertfordshire and Hampshire


PostPosted: Wed Dec 25, 2013 12:37 pm    Post subject: Reply with quote

The only proof you really need for the third centre rad is where Porsche fit it to the 911: X51, the GT3 and even the Tip.

Any time the car needs more help dissipating heat.

The Turbo (and C4S/Anni) also features 30% more radiator surface area.


If you are driving Miss Daisy, then don't.

If you ever push you car towards the envelope, make provisions to move that envelope further.

And as I said, fitting the LTT means the new safer, lower temp/higher flow regime ends earlier than standard (ie it reverts to standard full flow at a lower temp than standard thermostat continues to open).

That does not mean the LTT is bad, just that the compromise of being cooler/safer is only over a smaller or net lower range than the standard thermostat operates at. Although the entire range it does operate over is a a higher flow rate, it hits max flow earlier.

So if you wish the LTT benefits to continue into the higher regime (which is still part if the expected normal usage envelope, as that is where the standard thermostat still operates), then you need to extract more heat.

ie a third rad.

LTT vs STD:

 
  
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Stokepotter
Montreal


Joined: 21 Sep 2012
Posts: 623
Location: Stoke-on-Trent


PostPosted: Wed Dec 25, 2013 3:24 pm    Post subject: Reply with quote

Cheers Baz. I will give you a call after the holidays and order one.
 
  
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Paza3
Nürburgring


Joined: 17 Jun 2012
Posts: 466
Location: Cotswold


PostPosted: Thu Dec 26, 2013 8:56 am    Post subject: Reply with quote

Me too , think I have seen enough evidence now

Anyone have the product code for the 3rd rad kit for OPC?
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987.1 3.4 S Cayman - Blue
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GT4
Nordschleife
Nordschleife


Joined: 08 Nov 2008
Posts: 30174
Location: Hertfordshire and Hampshire


PostPosted: Thu Dec 26, 2013 9:06 am    Post subject: Reply with quote

Or complete fitting instructions Question

997 X51 rad:
http://911uk.com/viewtopic.php?t=86467

997 LTT:
http://911uk.com/viewtopic.php?t=83808

996 LTT:
http://911uk.com/viewtopic.php?t=65932


You could even fit grills while you're there, but I'll leave you to check out the relevant 996/997 FAQs sub-forum rather than list it all here!
 
  
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stokie1
Spa-Francorchamps


Joined: 23 Feb 2010
Posts: 290
Location: Staffs


PostPosted: Thu Dec 26, 2013 12:47 pm    Post subject: Reply with quote

Hi guys - I think I know the answer but will these thermostats invalidate extended warranty
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DucatiGary
Spa-Francorchamps


Joined: 28 Dec 2012
Posts: 276



PostPosted: Thu Dec 26, 2013 3:48 pm    Post subject: Reply with quote

I put the deep Sump Oil Pan kit on mine also to compliment the third rad and the LTT, more oil + cooling fins = better for your 911 Very Happy

http://www.design911.co.uk/fu/prod127610/Deep-Sump-Track-Oil-Pan-Kit-Porsche-996---997---Boxster-986---Boxster-987---Cayman-987C/

it has a warning about clearance on their website but I have never had a issue and I live in carrot country where most of the roads are deemed "Off Road"
 
  
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