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GT4
Nordschleife
Nordschleife


Joined: 08 Nov 2008
Posts: 30178
Location: Hertfordshire and Hampshire


PostPosted: Sat Aug 20, 2011 6:37 pm    Post subject: Reply with quote

Now I have bedded the tstat in (read stopped driving it with Miss Daisy Grin ), I concur with infrasilver that the temp guage seems to sit just left of the analogue tick mark for 80oC.

Anyway, having done a 60 mile round trip yesterday and the coolant level not changing, I guess all my airlocks are (probably) all out.

So now all is well, what did I do next?

Sat in in my garage running the engine to boiling point (not quite, that's why the system is full of coolant concentrate too).

Hope you lot are grateful!

Quote:
Outside 18/21 oC - garage 17.5oC at rads START/END
15oC at coolant sensor

45k miles
97 RON Super Unleaded
Mobil 1 0w40

PIN DOWN/BYPASS OFF
AC OFF
STATIC AIR FLOW - ex X51 advantages
HEAT OFF

START TEMP 15oC O sec


From 74oC the LTT starts diverging from the STD.

Between STD 87 and 93 the LTT is 6 or 7oC lower.

Once LTT hits 93/94oC coincidence occurs again all the way north now.
 
  
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PeterS
Fuji


Joined: 01 Nov 2009
Posts: 9283
Location: Solihull

2003 Porsche 996 Carrera 2

PostPosted: Sun Aug 21, 2011 11:02 am    Post subject: Reply with quote

So on those figures it looks like this is a mod worth doing, so long as you have enough rads to keep it there.

I don't particularly want to go to the hassle of fitting the middle rad.

Thanks.
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GT4
Nordschleife
Nordschleife


Joined: 08 Nov 2008
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PostPosted: Sun Aug 21, 2011 11:58 am    Post subject: Reply with quote

As long as your car runs at between 74 and 93oC (which I appreciate cars will go beyond this in high load/low cooling scenarios), then your car will benefit.

As "90" is the nominal operating temp this mod will benefit everyone (except the from-factory cold-running 997.2 DFI and GT1 blocks)

Note: this was a static test, the fact I have three rads makes no difference (as there was no airflow, not even vehicle fans).

You make a valid point though, a triple rad will allow my car to run cooler for longer though, but that was true before the mod too (ie at any tstat opening, whether STD or LTT, including when fully open), the X51 centre rad will allow a higher rate of coolling (that is what it and GT3 install are for).

ie during racing the heat extraction via the centre rad approaches 25% over stock.

However, that was not the point of this mod, nor the experiment. To reiterate, all airflow was stopped (so this test is compatible with a simple double rad install).

The charts are just to compare the initial opening and fully open characteristics of the two thermostats.

There are two basic factors to the cooling system:

1) coolant flow (controlled by thermostat)
2) radiator surface area (defined by how big and how many, C4S and Anniversarys get the larer Turbo rads, which is why their X51 does NOT need the centre rad)
 
  
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GT4
Nordschleife
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Location: Hertfordshire and Hampshire


PostPosted: Sun Aug 21, 2011 12:32 pm    Post subject: Reply with quote

In fact, from the point of view of how much the thermostats open, the number or rads or outside temp or engine load are red herrings.

Although the x-axis is measured in minutes it is in fact almost equivalent to just thermal units (Joules) - ie the engine was run at idle and one minute in any part of the chart represents the same amount of fuel converted to heat, and therefore, excluding the negligible passive heat loss from the block, the aggregate temperature rise.

If you drove around with an ice block attached to the rads (ie Artic circle testing) or an oven strapped to the front (ie driving in Dubai), it would make no difference to the characteristics of the tstats and hence of the charts (except to make it longer or shorter to reach any particular temperature).

If you converted either chart from the Arctic or Dubai back into actual accumulated thermal units (Joules), then they would be identical.

The STD tstat will always start to open at 88oC and the LTT will always start to open at 71oC.
 
  
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GT4
Nordschleife
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PostPosted: Sun Aug 21, 2011 1:13 pm    Post subject: Reply with quote

Excuse the "bouncy" camera phone picture, but here is my analogue display (as infrasilver drew).

I think I know why it was on the other side of the tick mark (as per my "photoshop"), of course straight after fitting the LTT I had the bleed Pin-Up in bypass mode, so that would have suppressed the temp too.
 
  
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GT4
Nordschleife
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PostPosted: Sun Aug 21, 2011 1:29 pm    Post subject: Reply with quote

Having done some relative viscosity calculations, I am running the equivalent of 0w47 @ 87/93oC.

I guess this is getting towards the Holy Grail of

1) Ultra thin "fast" oil at start-up - to run all the oil actuated sytems:

Hydraulic tappets (for valve control from the cams)
Variocam (all models - eg 996 3.4/3.6) hydraulic chain tensioners (for valve timing control, must be in equilibrium to balance IMS)
VariocamPlus (later models - eg 996 3.6) hydraulic cam lobe actuation (for valve range control)

and of course lubricate all the components at cold start-up as soon as possible.

2) Thicker oil at operating temp to protect all the lubrication surfaces (ie prevent bore scoring etc) and help to "seal" the pistons when they have expanded to thermal equilibrium at operating temp.
 
  
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Daniel
Donnington
Donnington


Joined: 02 Feb 2005
Posts: 11866
Location: Not where I want to be!

2000 Porsche 996 GT3 Mk1

PostPosted: Sun Aug 21, 2011 1:54 pm    Post subject: Reply with quote

Will the part fit a GT3?

My car goes in for her service in Oct, I may get the OPC to fit a Hartech special. ?


Good write up too.. Thumb
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GT4
Nordschleife
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Posts: 30178
Location: Hertfordshire and Hampshire


PostPosted: Sun Aug 21, 2011 2:03 pm    Post subject: Reply with quote

Stop being greedy, Cup cars get the option of a 130oF thermostat!

However, the road-going OEM parts (190oF thermostat insert) are identical, so I don't see why not.

Of course your block and cooling chambers is a quite different design (ie already better), plus you have the third rad from the off.

As far as bore scoring goes, GT3 Nikasils are far superior (harder) than the "cooking" (no pun) Carrera Lokasils too.

You may have a slightly different optimum method for bleeding too.
 
  
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Daniel
Donnington
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2000 Porsche 996 GT3 Mk1

PostPosted: Sun Aug 21, 2011 2:57 pm    Post subject: Reply with quote

Calling Baz Smile
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*Current - GT3 996.1 Clubsport (Manthey K400)

EX VR993 - C4
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SVC4S
Trainee


Joined: 27 Jun 2008
Posts: 71



PostPosted: Sat Aug 27, 2011 2:03 pm    Post subject: Reply with quote

Fitted my LTT yesterday to my 6C4S and needle stays at the tick mark, even after a good run.

Thanks to GT4 for an excellent write up Thumb

Recommended mod!
 
  
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GT4
Nordschleife
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Location: Hertfordshire and Hampshire


PostPosted: Sat Aug 27, 2011 5:49 pm    Post subject: Reply with quote

Thumb
 
  
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GT4
Nordschleife
Nordschleife


Joined: 08 Nov 2008
Posts: 30178
Location: Hertfordshire and Hampshire


PostPosted: Wed Aug 31, 2011 10:42 pm    Post subject: Reply with quote

In another thread grandadg90 wrote:
GT4 great write up. Here is my question.

In the write up, when you bled the system with the bleed valve open, revving the engine to 4k for one minute did you place the coolant cap back on or did you keep it off. Not clear in your write up.


The engine was run with the header tank cap off and bleed valve up for the (still inclined) 4k airlock bleed.

For all the driving around only the bleed valve was open (ie I put the header tank cap back on!)
 
  
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steve r
Monza


Joined: 26 Sep 2011
Posts: 215



PostPosted: Sat Oct 22, 2011 5:17 pm    Post subject: Reply with quote

Thanks for putting this guide together, I fitted a low temp thermostat to my car today.

One of the 3 bolts holding the metal pipe to the engine was reluctant to come out to start with and had me a little worried but a good spray with WD40 helped. The top bolt on the housing is a little difficult to get to, used a cranked spanner for that one.

Pic of old vs new taken during test fit, I cleaned up the housing fully before refit:



Last edited by steve r on Sun Oct 23, 2011 5:42 pm; edited 1 time in total
 
  
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wizard993
Donnington
Donnington


Joined: 23 Jan 2008
Posts: 11982


1966 Singer Gazelle

PostPosted: Sat Oct 22, 2011 6:38 pm    Post subject: Reply with quote

I'd never run a 996, or in my case a 997(done) without this mod Thumb

I have long had the view that heat management(or lack of) contributes to engine failures on 996/997.

The reason they run hotter as standard is to meet the reduced emission level demands that the eurocrats forced onto Porsche, with regards to the 996/7.

You will see a slight increase in the emission levels come MOT time but they should still be well within the legal requirements. Thumb

I think for the GT and Turbo cars they stuck one finger up to the eurocrats Floor
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GT4
Nordschleife
Nordschleife


Joined: 08 Nov 2008
Posts: 30178
Location: Hertfordshire and Hampshire


PostPosted: Thu Nov 17, 2011 5:49 pm    Post subject: Reply with quote

FYI - this is the spec for OEM coolant (made by Elf for Porsche):

http://911uk.com/download.php?id=22997
 
  
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davidarose
Monza


Joined: 25 Jul 2007
Posts: 243
Location: Southwater, West Sussex


PostPosted: Thu Feb 16, 2012 3:16 am    Post subject: Reply with quote

I did mine yesterday morning, what a faff a couple of those bolts were! Great write up as always GT4!

In my rush to see where the temp. gauge would settle I drove straight over my chocks though... Embarassed Embarassed Embarassed
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GT4
Nordschleife
Nordschleife


Joined: 08 Nov 2008
Posts: 30178
Location: Hertfordshire and Hampshire


PostPosted: Thu Feb 16, 2012 8:46 am    Post subject: Reply with quote

Yeah, the top one or two are certainly a pain.

Definitely need the small extension universal joint sockets.

Report back when the temp has settled (you will probably need to monitor the coolant level for a few days unil it is definitely "burped" and all the air is out)

Thumb
 
  
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davidarose
Monza


Joined: 25 Jul 2007
Posts: 243
Location: Southwater, West Sussex


PostPosted: Thu Feb 23, 2012 3:00 pm    Post subject: Reply with quote

So the coolant level appears to be steady now (added about a litre in all). Couple of before and after pics:

Before:



After:



Does anybody want to hazard a guess at what amount (% perhaps?) of extra protection ive provided my delicate bores?
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MY2004 Midnight Blue 996.2 Carrera Aerokit Hartech'd + Mercedes GLE 350d
Previous: BMW X5 M 40d, Megane RS 265 cup, C63 AMG, Seal Grey 996 C4S, Lapis blue 986 Boxster S
 
  
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infrasilver
Fast & Furious
Fast & Furious


Joined: 04 Oct 2010
Posts: 8312
Location: East Midlands

2001 Porsche 996 Targa

PostPosted: Thu Feb 23, 2012 3:11 pm    Post subject: Reply with quote

davidarose wrote:
So the coolant level appears to be steady now (added about a litre in all). Couple of before and after pics:

Before:



After:



Does anybody want to hazard a guess at what amount (% perhaps?) of extra protection ive provided my delicate bores?


That was about the same as my temp gauge was showing before and after. I think you've given the engine another 2 days of life. Grin
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GT4
Nordschleife
Nordschleife


Joined: 08 Nov 2008
Posts: 30178
Location: Hertfordshire and Hampshire


PostPosted: Thu Feb 23, 2012 5:23 pm    Post subject: Reply with quote

Now try it in summer.
 
  
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