Let the tinkering begin...

[Greg Roles]

Oh dear god you got them... where and how much

Fleabay from the Phillipines actually, about $70 delivered from memory. They are big suckers, and sounds like a normal horn on roids.

[Greg Roles]

I guess it depends on how much that reduction in heat is worth to you. At most lights you would only be there for 2-3 minutes ? If your coolant temp goes up your main radiator fans would come on automatically. Does your aircon fan come on all the time when the aircon is switched on ?

If you did install one it would be preferable to only have it running when you are stationary or at very low road speeds (once you are moving natural air flow will do the job for you without wearing out the motor or consuming electricity).

Eliminating extra (unwanted) heat is more of an issue if you are chasing that last small percentage of performance or economy in hot weather.

If you wanted some hard data to support your decision maybe you could design some testing procedures to see what is happening temp wise, and what affects that has. I'm thinking of things like :

Intially get a digital thermometer with multiple probes and monitor temps at different parts of the cooling system over a 10 minute idling period, then try putting a small 240V electric fan on and see what reductions you get.

Then if you want to see what affect heat has on power do a couple of dyno runs (WITHOUT intake temp correction), the second one after your engine has been stopped for half an hour or so (to cool down), then let it idle for 5 minutes before starting (but I think the main radiator fan will come on anyway after a while of idling in hot weather).

This way you will have empirical evidence of what actually happens, rather than working off a "sounds like a good idea in theory". I'll always back well designed empirical evidence over a good theory anytime, as if they disagree then it is usually a problem with our understanding (ie the theory).

Plus, will any benefit be outweighed by the additional weight ? We all know you love to follow the dictum of Colin Chapman (of Lotus fame) "Don't add power, add lightness ! "

Let us know how it goes.

Mr scientist huh? Well I have a nice 4 probe digital thermo about to go in for some base line tests.....and also now I'm actually starting to learn how to use my Vag com, I have a TON of data at my disposal. Lots of measuring coming up!

[Greg Roles]

No dumb questions here, (only smart@ss answers sometimes).

If you have an intercooler it is placed somewhere after the turbo outlet, but before the inlet manifold. In VWs it usually looks like another radiator type thing in front of the engine, only with large air pipes in and out, not smaller fluid pipes.

If you want more info, I'm sure a search of this forum or wikipedia will show you many pictures and diagrams.

Post 24 in this thread. It's between the black air con radiator, and the "normal" radiator.

[gregozedobe]

Mr scientist huh? Well I have a nice 4 probe digital thermo about to go in for some base line tests.....and also now I'm actually starting to learn how to use my Vag com, I have a TON of data at my disposal. Lots of measuring coming up!

Sounds good, and I don't think you'll be the type who needs to worry about "paralysis by analysis" (too much information confusing things leading to an inability to make a decision)

If you want more info, I'm sure a search of this forum or wikipedia will show you many pictures and diagrams.

{Page 3} Post 24 in this thread. It's between the black air con radiator, and the "normal" radiator.

See, didn't have to go too far at all

[Greg Roles]

You know me, drill first, ask questions later....

On that my oil is sitting at 180 deg F on cruising, climbing to 200 F if I'm up it at the sump. A much better location, I can see real time heat buildup and drop in the oil. That's 82 - 93 deg C in new speak.

I had planned to monitor real coolant temps with one of my digital therm channels, but I can get real time Vag com readings, so I'll do some monitoring in the traffic once I get my head around it properly.

I'm loving the acceleration data!! 7.5 and 15.7 at 118kph thus far...

[gregozedobe]

On that my oil is sitting at 180 deg F on cruising, climbing to 200 F if I'm up it at the sump. A much better location, I can see real time heat buildup and drop in the oil. That's 82 - 93 deg C in new speak.

That seems like pretty good oil temps. It may go a bit higher still if you go up a long, steepish uphill climb, as that will get the turbo working harder for longer.

I believe a hard working turbo puts a fair bit of heat into both the coolant AND the oil on water cooled turbo diesels. I certainly notice the heater kicking in much better on my TDI when I go up hills on frosty Canberra mornings and nights (and I look forward to some cooler weather again after our curent heat wave ends). The heater can then actually cool down again as you go down a long downhill if the engine isn't fully warmed up yet (very thermodynamically efficient these modern TDIs).

Speaking of cool weather, when we do finally get some, I'd be very interested in how much longer it takes to warm your engine oil up after the coolant has reached 90C ie how long does it take for a TDI engine to reach proper operating temperature in both coolant AND engine oil ? A lot of people think that once the coolant has warmed up you can then flog your engine, but in cold weather I suspect it may be quite some time after that before your oil is properly warmed up as well.

[Greg Roles]

You're spot on greggo, I've noticed it takes about 10 minutes of regular traffic for the oil to both show some temp rise, and to drop in viscosity. Normal oil operating pressure is 20-60 psi on my gauge, and at revs when it's cold it's showing up to 100. I am suprised that the oil is running "around" engine coolant temps, in the sump at least. I'm sure once it goes through the turbo it's a different story! At least VW had the good sense to run the oil through the cooler, then direct to turbo, then back to engine. I'm still nutting out the best way to boost that cooling, either by increasing the water cooling component of the oil cooler ( small effect ) or by actually cooling the oil or the pipe on the way to the turbo. I am reluctant to increase the volume between the cooler and the turbo, so that the turbo bearings still get oil on startup in the shortest possible time. All in the aim of countering future boost increases.

I've no qualitative data as yet, but as a rough guide it takes about twice as long for the oil to show some heat rise as it does for the coolant to show operating temps. It's the main reason I installed an oil temp gauge, as on my old ford GT I used to wait for the oil to heat up before flogging it in any way, and the TDI is no different, even if it is a tractor!

I'll be monitoring it over the coming weeks and will see if I can expand on that.

[Greg Roles]

Well I can confirm that on the drive it, when I checked at traffic lights, that the water temp guage showed normal 90 degree operation from 83 to 92 degrees according to Vag com. It didn't rise much above 92 at any point of sitting idle.

The oil temps took longer to rise, and I'd say that with a quiet drive in the oil wasn't showing temps for a good 5kms. Water was up, according to the VW gauge in half the time.

Oil sat at around 82 degrees once at temp, which corresponds to my 180 F reading on the aftermarket gauge.

No boosting on the way in, and would be kinda hard to drive it so AND look at laptop Vag readings. Wil have to enroll my girlie, bet she'll be thrilled!

[gldgti]

good to hear some hard data coming out of all of this cog - nice work.

i have no temp guages apart from the in dash coolant temp in my mk3 as yet - i use the oil pressure readings as my temperature reading too - just by looking for the telltale drop in viscosity as it warms up.

I have to say that after hearing your temps though, i'm very interested to put some guages in my car.

my coolant temp guage reads a cool 75 deg on the cruise, and will idle up to 90-95 sitting still in traffic.... UNLESS the a/c is on, in which case the dual fans come on behind the radiator and cools it right back down to about 79deg.... this got me thinking about hte heat soak in traffic thing - probably best just to switch on the a/c and let the radiator fans pull ait through hte intercooler for you.

still no EGT readings???

[Greg Roles]

Haven't hooked up the probe for my aftermarket EGT gauge as yet, need to weld in a port or splice the stock one, but I've no doubt I'll be able to track it on vag com via the stock probe. I can get several temps at once, and I just need to use my digital probes to confirm what each one is.

Don't worry, my propane and tune plan means EGT's are critical to monitor.