Cylinder Head Temp

[Vee Dub Nut]

What kind of head temps are you running on your turbo'ed VW's? Trying to get a feel for what is normal. I just installed a gauge on my car because I felt that the new engine is running a little warmer than the old engine, but want to know what is good/bad.

[Vee Dub Nut]

Also.. will an engine that is breaking in show higher temps than a motor thats been fully run in? (like the engine being tight still and higher friction?)

I made a quick run after putting the gauge in (VDO CHT), and it would cruise between 350-375, and go up to 400 when on some load. Ambients were not terribly high today, but it was KILLER humid this afternoon.

[Vee Dub Nut]

Another piece of data to chew on.. I pulled the sensor and did the boiling water check. i also checked a few other landmarks on the gauge as the water temp rose. Here is how it stacked out:

VDO-----Water Temp (from thermometer)
150 ----- 116
200 ----- 162
240ish --- 208 (max temp I saw in the water)

So it looks like its reading about 35-40ish degrees high? If so, that means my head temps are looking more normal.

[MinamiKotaro]

On a hot day, mine will peg the gauge in Tuner Studio at 311 degrees, as high as it will go. I'd say my real head temp is around 350.

Most of the time, it's around 260-280.

[miniman82]

Only gauge I have is a speedo, so I couldn't tell ya.

[Stripped66]

Another piece of data to chew on.. I pulled the sensor and did the boiling water check. i also checked a few other landmarks on the gauge as the water temp rose. Here is how it stacked out:

VDO-----Water Temp (from thermometer)
150 ----- 116
200 ----- 162
240ish --- 208 (max temp I saw in the water)

So it looks like its reading about 35-40ish degrees high? If so, that means my head temps are looking more normal.

The VDO CHT gauge is not temperature compensated and you need to account for the ambient temperature to calculate the true CHT. IIRC, the VDO gauge is calibrated around 70 degrees F, so if the temperature outside (more appropriate, if the temperature under the dash) is 70 F, then the CHT is as it reads on the gauge. As the ambient temperature increases, the reading on the gauge decreases; i.e. if it was 100 F outside, your VDO gauge would read 30 F low, you would need to add 30 F to the gauge readout to determine your true CHT; if the ambient temps are colder than 70 F, then the gauge reads high, and you need to subtract the difference from the gauge readout.

Given that your VDO read 30 F too high for boiling water, and you probably were not in a room that was 40 F, I'd suspect your gauge is not accurate. I also would not make any blanket correction factor based on the water test. Personally, I'd return it and buy a better instrument, unless all that you want is a needle that goes up when the engine load goes up, and goes down after the engine load goes down.

[Vee Dub Nut]

I understand that the VDO gauge is not temp compensated, but that doesn't make it completely useless in my mind. All I'm trying to do is establish what is "normal" for my engine. This gauge will tell me that IMO.

I've established that my gauge is off with the water test. The ambients when I did this, and when I drove the car yesterday were the same, so I know what my engine was actually doing yesterday.

Now all I'm looking for is know what other people consider is "normal"

[seabeebuggy]

350 to 375 for mine. It has seen 400 to 425. I try to not go over 380.

[Vee Dub Nut]

We'll I got some more updates on this..

Decided to ditch the VDO gauge. I'm in the market for a Dakota Digital gauge now.

In the mean time, I enlisted some help from the guys at work and we instrumented up a sparkplug with a K type thermocouple right above the sealing washer (spot welded it to the plug body). I'll post some pics of one tomorrow to show what we did. This should give the temp seen at the plug head interface like the under plug washers do. (I do fuels and lubes research on diesel engines as my day job, and we are VERY used to instrumenting engines that run on dynos. Got some guys that I work with that routinely weld TINY thermocouples to jet engine nozzles for testing) Anyways, I installed that this weekend and did some driving around monitoring the temps with a 120V monitor plugged into my DC/AC inverter.

I basically saw run temps from about 345-375, with the higher ranges seen when I've got my foot in it running 80mph on roads with some moderate elevation changes. Generally I back off quite a bit when I'm slabbing it down the highway. Take the foot out of it and coast down to a stop the temp drops down in the 340's. Most of the time it sits around 355-360. From what I've read, this seems about normal. I've seen a few N/A folks quote lower temps, but most of the turbo guys seem to be in this range from what I've found. I figure 400 is my drop dead point, if I see that I'll pull over.

All in all I think I'm where I need to be. Of course lower would be better, but I'm not in a bad spot considering the engine config and me being in South Texas. I'm going to be replacing me copper manifold gaskets soon (don't buy the empi ones, they are super thin compared to the ones CB sells), and I plan to wrap the header with wrap which should also cut down on the heat buildup in the engine bay. I get a lot of heat up from the breast plate area since its cut up so much for the turbo housing.

Just FYI for the next person searching this kind of info

[MarioVelotta]

Thanks for the great documentation! You do a great job at it.

[Vee Dub Nut]

Thanks for the great documentation! You do a great job at it.

LOL.. one of these days I'll get some install instructions to you

[Stripped66]

We'll I got some more updates on this..

Decided to ditch the VDO gauge. I'm in the market for a Dakota Digital gauge now.

May I suggest MGL Avionics TC-1?
http://www.mglavionics.com/html/infinity.html#TC-1

The costs up front are a little more expensive, especially with paying for 3 additional thermocouples, but having CHT of all 4 cylinders is a dream for tuning (or a nightmare if you're obsessive/compulsive). I'm running this gauge in my car and it's been very helpful for directing modifications to my 911-style shroud in an attempt to equalize temps across all 4 cylinders. It can also help with annoying diagnostics...when I recently fouled a plug, I just looked at the gauge and knew exactly which cylinder wasn't firing

In the mean time, I enlisted some help from the guys at work and we instrumented up a sparkplug with a K type thermocouple right above the sealing washer (spot welded it to the plug body). I'll post some pics of one tomorrow to show what we did. This should give the temp seen at the plug head interface like the under plug washers do. (I do fuels and lubes research on diesel engines as my day job, and we are VERY used to instrumenting engines that run on dynos. Got some guys that I work with that routinely weld TINY thermocouples to jet engine nozzles for testing) Anyways, I installed that this weekend and did some driving around monitoring the temps with a 120V monitor plugged into my DC/AC inverter.

I basically saw run temps from about 345-375, with the higher ranges seen when I've got my foot in it running 80mph on roads with some moderate elevation changes. Generally I back off quite a bit when I'm slabbing it down the highway. Take the foot out of it and coast down to a stop the temp drops down in the 340's. Most of the time it sits around 355-360. From what I've read, this seems about normal. I've seen a few N/A folks quote lower temps, but most of the turbo guys seem to be in this range from what I've found. I figure 400 is my drop dead point, if I see that I'll pull over.

I see about the same temps on cylinder 3 with my 911-style shroud. Cylinders 1 and 2 run around the lower end of that range on the freeway (about 340), and cylinder 4 is the hottest at 375 to 390+. My drive up to Cooker's VWs last thursday (180 miles on the freeway round-trip, some decent hills) briefly pushed 425 degrees through cylinder 4 during some of the climbs. Fortunately, no decrease in valve lash to suspect the seats had sunk in, but that doesn't mean they still won't fall out I do agree with being cautious at the 400 degree mark.

[Vee Dub Nut]

We'll I got some more updates on this..

Decided to ditch the VDO gauge. I'm in the market for a Dakota Digital gauge now.

May I suggest MGL Avionics TC-1?
http://www.mglavionics.com/html/infinity.html#TC-1

The costs up front are a little more expensive, especially with paying for 3 additional thermocouples, but having CHT of all 4 cylinders is a dream for tuning (or a nightmare if you're obsessive/compulsive). I'm running this gauge in my car and it's been very helpful for directing modifications to my 911-style shroud in an attempt to equalize temps across all 4 cylinders. It can also help with annoying diagnostics...when I recently fouled a plug, I just looked at the gauge and knew exactly which cylinder wasn't firing

Thanks for the link. I'll look into them. I can make my own thermocouples, so that is not an issue for me. A gauge that will read out more than one would be nice, although I'm starting to relate to the statement in bold. At one point I didn't have ANY gauges in the car (pre turbo and efi), and ignorance was bliss

In the mean time, I enlisted some help from the guys at work and we instrumented up a sparkplug with a K type thermocouple right above the sealing washer (spot welded it to the plug body). I'll post some pics of one tomorrow to show what we did. This should give the temp seen at the plug head interface like the under plug washers do. (I do fuels and lubes research on diesel engines as my day job, and we are VERY used to instrumenting engines that run on dynos. Got some guys that I work with that routinely weld TINY thermocouples to jet engine nozzles for testing) Anyways, I installed that this weekend and did some driving around monitoring the temps with a 120V monitor plugged into my DC/AC inverter.

I basically saw run temps from about 345-375, with the higher ranges seen when I've got my foot in it running 80mph on roads with some moderate elevation changes. Generally I back off quite a bit when I'm slabbing it down the highway. Take the foot out of it and coast down to a stop the temp drops down in the 340's. Most of the time it sits around 355-360. From what I've read, this seems about normal. I've seen a few N/A folks quote lower temps, but most of the turbo guys seem to be in this range from what I've found. I figure 400 is my drop dead point, if I see that I'll pull over.

I see about the same temps on cylinder 3 with my 911-style shroud. Cylinders 1 and 2 run around the lower end of that range on the freeway (about 340), and cylinder 4 is the hottest at 375 to 390+. My drive up to Cooker's VWs last thursday (180 miles on the freeway round-trip, some decent hills) briefly pushed 425 degrees through cylinder 4 during some of the climbs. Fortunately, no decrease in valve lash to suspect the seats had sunk in, but that doesn't mean they still won't fall out I do agree with being cautious at the 400 degree mark.

Cool.. glad to know that I'm on target with my temps. Thanks for sharing your data.

[MarioVelotta]

Maybe I should swap my egt for a cht sensor for a bit, just to check my situation

[64bug]

Probably a good idea mario. A laser temp gun can be useful too, but not like you can use one while on boost...