www.tdiclub.com

Economy - Longevity - Performance
The #1 Source of TDI Information on the Web!
Forums TDIFAQ Articles Links Meets
Orders TDI Club Cards TDIFest 2014 Gone, but not forgotten VAG-Com List Unit Conversions TDIClub Chat Thank You



Go Back   TDIClub Forums > VW TDI Discussion Areas > TDI Fuel Economy

TDI Fuel Economy Discussions about increasing the fuel economy of your TDI engine. Non TDI related postings will be moved or removed.

Reply
 
Thread Tools
Old April 8th, 2012, 19:03   #571
shoebear
Veteran Member
 
Join Date: Aug 2002
Location: Colorado Springs, CO
Default

Hey there, flatlanders!

My daily commute tops out at 7343' elevation at the end of a medium length steep grade at 75mph speed limit. Furthermore, I can be at 14,110' (the top of Pikes Peak) within an hour of leaving my house (or less, depending on traffic and road conditions). At my house (6300') water boils at 201*, which means I have less coolant temperature margin than most.

Even if you don't live and drive in high elevation, you may want to vacation here sometime, and you have to plan for the extremes. So it seems to me that a 205* t-stat would risk coolant boil at high elevations unless you were using waterless Evans. Any thoughts?

If I did ever convert to Evans, a quick trip up Pikes Peak with a loose radiator cap seems like a fast way to purge leftover water. Water boils at 186* at the top.

I just picked up a Stant Superstat 45379 like GreenENG has (p36, post #528). Even though that's a 195* t-stat, he reports running at 205*. When I get it installed, I'll post my results back here for comparison. When I left to get it, I hadn't seen GreenENG's post yet -- otherwise, I might have just gotten the regular Stant because of my high-elevation concerns. BTW, the regular Stant would have been $8, the SuperStat was $10. According to the Stant website, the Superstat regulates temp more evenly with fewer and narrower temp swings compared to a regular t-stat.
__________________
1998 Jetta TDI: Luk clutch, K04/K03 hybrid turbo, Bosio DLC1019 nozzles balanced & set to stage 1, Kerma chip, braided turbo oil feed line, Frost Heater
2005 New Beetle GLS TDI: Kerma "Dog Collar" CAC hose repair, Frost Heater

Last edited by shoebear; April 9th, 2012 at 17:51.
shoebear is offline   Reply With Quote
Old April 9th, 2012, 18:55   #572
shoebear
Veteran Member
 
Join Date: Aug 2002
Location: Colorado Springs, CO
Default

The Stant Superstat 45379 is in, and a few non-freeway miles got the temp up to 202*F (briefly) on my ScanGauge. I'll be commuting tomorrow, so we'll see where it stabilizes on the freeway.

From what I can tell HERE and HERE, G12 at 50/50 at sea level with a 15psi coolant cap boils at about 265*F. The air pressure at the top of Pikes Peak is about 8psi, or 6psi below sea level. At 3*F / psi, that would lower the boiling point by 6 x 3 = 18*F to 265 - 18 = 247*F.

I can think of three reasons to leave some margin between the max temperature reported by the temp sensor and the actual boiling point of the coolant.
  • I suspect there are hotspots within the cooling system, and I wouldn't want any part of the coolant to get above boiling.
  • In case the coolant cap was a little weak and didn't hold a full 15 psi.
  • I'm sure cavitation becomes more likely as the coolant approaches the boiling point.
I have no idea how much wiggle room to leave, but I'll make a WAG at 25*F. So on Pikes Peak, I want my max coolant temp to be 247*F - 25 = 222*F, which should be within the operating range of the Stant Superstat 4537.

If 25*F margin isn't enough, it sounds like VW permits up to a 70/30 mix of G12, which would raise the boiling point by 13*F.

Comments?

I'll report back tomorrow evening after my commute.
__________________
1998 Jetta TDI: Luk clutch, K04/K03 hybrid turbo, Bosio DLC1019 nozzles balanced & set to stage 1, Kerma chip, braided turbo oil feed line, Frost Heater
2005 New Beetle GLS TDI: Kerma "Dog Collar" CAC hose repair, Frost Heater

Last edited by shoebear; April 9th, 2012 at 19:03.
shoebear is offline   Reply With Quote
Old April 10th, 2012, 00:24   #573
SD26
Veteran Member
 
SD26's Avatar
 
Join Date: Jan 2010
Location: WI
Fuel Economy: Almost 51MPG
Default

Quote:
Originally Posted by josh8loop View Post
SD26,

When you assembled your "Hybrid" T-stat, did you notice when you pressed the rear section on that it seemed a bit loose like you could have changed it's position by hand pressure alone? I'm wondering if the inconsistancy of temperature regulation is from the rear bypass disc changing it's position once in service. Remember when the T-stat increases temperature it's length is modulated according to engine temperature. At certain temperatures the rear section is pressed up against the round hole in the block, and if it's not pressed on tightly it may cause it to shorten some changing it's temp regulating characteristics.
No looseness at all. And I was wondering if that was what was happening when I had very inconsistent temperatures on the first thermostat that I assembled.

So, I did a second one from completely different parts.

But I do have a concern on the disc itself. Seems that in my removal of that "back" section of the thermostat, the "shaft" that the disc is mounted and retained to gets a little deformed from my removal processes. Thus, my disc doesn't remain as parallel to the block as an unmodified one. What seems to happen is that my support for the removal leaves something to be desired, and the area that is turned down to keep the disc on is deformed enough to make a difference. I'd like to figure out a way where something could be inserted into that area to pull it off the thermostat rather than doing it from the outside where it can deform that disc area. Haven't given it a ton of thought as of yet, but there's certainly a way to do it.
__________________
Dave
1998 Jetta TDI "Jerry" - 5sp,ventectomy
2002 Jetta TDI "Matt" - 5sp,
2003 Jetta TDI Wagon - totalled
SD26 is offline   Reply With Quote
Old April 10th, 2012, 00:35   #574
SD26
Veteran Member
 
SD26's Avatar
 
Join Date: Jan 2010
Location: WI
Fuel Economy: Almost 51MPG
Default

Quote:
Originally Posted by shoebear View Post
  • I suspect there are hotspots within the cooling system, and I wouldn't want any part of the coolant to get above boiling.
  • In case the coolant cap was a little weak and didn't hold a full 15 psi.
  • I'm sure cavitation becomes more likely as the coolant approaches the boiling point.
I have no idea how much wiggle room to leave, but I'll make a WAG at 25*F. So on Pikes Peak, I want my max coolant temp to be 247*F - 25 = 222*F, which should be within the operating range of the Stant Superstat 4537.

If 25*F margin isn't enough, it sounds like VW permits up to a 70/30 mix of G12, which would raise the boiling point by 13*F.

Comments?
Well, aren't you answering your own questions?

For sometime, I always found that Evans was easy to default to. Why? Well, first, the boiling point of 375*F. That should be more than enough for you. Next, that's at zero PSI, so, if you have a problem with your cap, you still have a 375*F boiling point. With that, cavitation is pretty much eliminated. Yeah, I suppose that one could get it, but you're probably reaching a point of huge destruction for that...or it might be representative of the heat in the egr...

Next, water... It is the enemy. If it's in your oil, your fuel, or anything else, you'll get rust, corrosion, or other oxidization. Same thing goes for coolant. If you can eliminate water there too, there are minor things like better life on hoses over the long term. At least that is my experience.
__________________
Dave
1998 Jetta TDI "Jerry" - 5sp,ventectomy
2002 Jetta TDI "Matt" - 5sp,
2003 Jetta TDI Wagon - totalled
SD26 is offline   Reply With Quote
Old April 10th, 2012, 05:25   #575
dieselfuel
Veteran Member
 
Join Date: Dec 2008
Location: ohio
Default

Shoebear,

Just cut to the chase and use the Evans HDTC. As a bonus, it will not corrode your cooling system (the heatercore is a real, no pun intended, bear to replace).

Running Evans and very satisfied,

df
__________________
2003 Jetta TDI 200,000 mi. Horrible fuel milage? Check your thermostat: http://forums.tdiclub.com/showpost.p...49&postcount=7
dieselfuel is offline   Reply With Quote
Old April 10th, 2012, 18:40   #576
shoebear
Veteran Member
 
Join Date: Aug 2002
Location: Colorado Springs, CO
Default

OK, here are the temp results for the Stant Superstat 45379, as reported by my ScanGauge --

Once up to full temp on the freeway, the coolant hovered between 197-200*F. After a hill climb or acceleration, a few times it got up to 202*F, but quickly dropped back down. This isn't quite what you folks are looking for -- but it's a great improvement for me. I had been running 177*F, but recently dropped to about 171*F -- so 197*F is +26*f.

It also gives me a bit more margin between operating temp and boiling, which makes me feel better.

I will probably go to Evans at some point; I agree that it's superior. But G12 is one of the best water-based coolants, and so I'm not it a great hurry. If it ain't broke...
__________________
1998 Jetta TDI: Luk clutch, K04/K03 hybrid turbo, Bosio DLC1019 nozzles balanced & set to stage 1, Kerma chip, braided turbo oil feed line, Frost Heater
2005 New Beetle GLS TDI: Kerma "Dog Collar" CAC hose repair, Frost Heater

Last edited by shoebear; April 10th, 2012 at 19:10.
shoebear is offline   Reply With Quote
Old April 11th, 2012, 19:07   #577
aellen
Member
 
Join Date: Aug 2009
Location: Grand Rapids, Mi
TDI(s): jetta 06
Fuel Economy: 46-47
Default high temps

I just did Josh's 205 mod, and got my readings up to 106.3 C on my vcds. Not sure about that and I am not liking it. So I put my old one back that regularly gave me a 99.6C reading with the heater OFF. I'll keep that one in use. I think a 223F reading is too high, and not worth the risk,.....
aellen is offline   Reply With Quote
Old April 12th, 2012, 05:06   #578
dieselfuel
Veteran Member
 
Join Date: Dec 2008
Location: ohio
Default

223 is fine if you're running Evans HDTC. Otherwise, yes, it's too hot, imo.
__________________
2003 Jetta TDI 200,000 mi. Horrible fuel milage? Check your thermostat: http://forums.tdiclub.com/showpost.p...49&postcount=7
dieselfuel is offline   Reply With Quote
Old April 13th, 2012, 20:34   #579
josh8loop
Veteran Member
 
josh8loop's Avatar
 
Join Date: Sep 2009
Location: Vero Beach, Fl.
Fuel Economy: 45 MPG City with the previous 01M, 5-speed 60+ MPG City. Always searching for ways to make it better!!
Default

Quote:
Originally Posted by aellen View Post
I just did Josh's 205 mod, and got my readings up to 106.3 C on my vcds. Not sure about that and I am not liking it. So I put my old one back that regularly gave me a 99.6C reading with the heater OFF. I'll keep that one in use. I think a 223F reading is too high, and not worth the risk,.....


If you are able to, it would benefit the group for you to remove the rear bypass section of the "Hybrid" and press it on so it's a little longer than before by about .030". This may reduce the temperatures you are seeing in theory at least.
__________________
2002 VW Jetta TDI 5-speed(completed 01M-5-speed swap at 155K miles) 60+ MPG City.
Experimenting with the "Hybrid" 205 Deg F T-stat:
http://forums.tdiclub.com/showthread.php?t=306799&page=4
Now have Nokian Entyre Low RR tires!
josh8loop is offline   Reply With Quote
Old May 28th, 2012, 23:11   #580
SD26
Veteran Member
 
SD26's Avatar
 
Join Date: Jan 2010
Location: WI
Fuel Economy: Almost 51MPG
Default

Managed to run a couple tanks through the wagon. Remember that I had a 205, but my temperature results were a little goofy. I removed the 205 hybrid build by myself and installed a 198F Wahler tstat in my 2003 wagon.

On the trip south, I had the massive 18" wheels on, and they just kill my MPG, so I found a set of Avus 15's. Threw those on, and things got better.

My last two tanks were about 56 and 57MPG. Pretty happy with that. No shutting off the engine going down hill or anything. My daily commute is about 27 miles one way, and I don't get on the interstate at all.

Would like to grab 60MPG. Would like to put in a hybrid yet too. I think I mess up the bypass disc during the removal.
__________________
Dave
1998 Jetta TDI "Jerry" - 5sp,ventectomy
2002 Jetta TDI "Matt" - 5sp,
2003 Jetta TDI Wagon - totalled
SD26 is offline   Reply With Quote
Old June 7th, 2012, 13:23   #581
Tom W.
Veteran Member
 
Tom W.'s Avatar
 
Join Date: Dec 2005
Location: Raleigh, NC
Fuel Economy: Getta 49MPG IDI 60MPG Passat 34mpg
Default

I've been running w Evan's since 1996. Good stuff. It takes a looong time to get the water out.
Also, your coolent level sensor may no longer work- The sensor in my 86 IDI depends on the electrical conductivity of normal coolent to tell if the level is low. Evans doesn't conduct electricity(this is a good thing for engine longevity) so my coolent sensor always thinks I have no coolent. One solution is to bend the 2 probes of the coolent level sensor so that they are within about 1/16 of an inch from each other (normally they are about 1 inch apart).
I normally block off part of the radiator on the 86 w cardboard in the winter, to get my engine temps up to "Normal".
I forgot to take the cardboard out one spring, and that summer I was averaging over 65MPG (I normally average 52MPG)
I've left the cardboard in place ever since...................
Hmm, wify has some mini blinds she's not using...................
__________________
Chemically cleaning your turbo: http://forums.tdiclub.com/showpost.p...8&postcount=48

canadiangrizzly's Diagnosing limp mode: http://forums.tdiclub.com/showthread.php?t=179589

GoFaster on loss of power:
http://forums.tdiclub.com/showthread.php?t=75959

Last edited by Tom W.; June 7th, 2012 at 13:30.
Tom W. is offline   Reply With Quote
Old June 8th, 2012, 14:38   #582
nicklockard
Torque Dorque
 
nicklockard's Avatar
 
Join Date: Aug 2004
Location: Tucson, AZ
Fuel Economy: Tdi avg 48.6mpg. BMW avg 10 CPM and practically NO MAINTENANCE!
Default

I had PM'd Josh about this idea a while back:

As many know, thermostats are wear items. The bimetal springs slowly fail toward more open. Eventually, they all fail to full-open, all the time. In my experience using ScangaugeII device to track temperatures, most OEM t-stats last about 3-4 seasons before they begin to exhibit this failure. Aftermarket ones like NAPA branded usually perform worse out of the box and degrade in the same time frame.

16 months after installation, a 90C t-stat will open sooner and your engine warmup times will roughly double. That is lost fuel economy and more engine wear.

So when I was talking to Josh about this idea, he pointed me to this discussion on the Jeep forums.

So, rather than replacing t-stats every 4 seasons (minor PITA), I think adding a secondary, in-line, in-hose thermostat like this at the entry to the radiator will keep warm-up times consistently short. Even as the main t-stat begins to open sooner and cooler, the distance to the other in-line, in-hose t-stat will mean that it sees cooler temps (the hose itself radiates some heat), and will thus help regulate engine temperatures better.

There is a downside: if your car needs maximum, full-flow cooling, then adding another flow restrictor won't help. On the other hand, if your has over-sized cooling system and struggles to warm, like the Tdi engine family, this could improve FE and reduce engine wear by reducing warmup times.

I'm going to buy one for my car and report later.
__________________
EnviroFit..Edmund's TCO..NIST applet..Slow Fueling Warning..What tire psi?[..ROAD LOAD CALCULATOR, or: how much power does it take to...?/Do I need nitrogen in my tires?
.
Knowledge is knowing a tomato is a fruit. Wisdom is not putting it in a fruit salad.
nicklockard is offline   Reply With Quote
Old June 8th, 2012, 16:39   #583
josh8loop
Veteran Member
 
josh8loop's Avatar
 
Join Date: Sep 2009
Location: Vero Beach, Fl.
Fuel Economy: 45 MPG City with the previous 01M, 5-speed 60+ MPG City. Always searching for ways to make it better!!
Default

Quote:
Originally Posted by nicklockard View Post
I had PM'd Josh about this idea a while back:

As many know, thermostats are wear items. The bimetal springs slowly fail toward more open. Eventually, they all fail to full-open, all the time. In my experience using ScangaugeII device to track temperatures, most OEM t-stats last about 3-4 seasons before they begin to exhibit this failure. Aftermarket ones like NAPA branded usually perform worse out of the box and degrade in the same time frame.

16 months after installation, a 90C t-stat will open sooner and your engine warmup times will roughly double. That is lost fuel economy and more engine wear.

So when I was talking to Josh about this idea, he pointed me to this discussion on the Jeep forums.

So, rather than replacing t-stats every 4 seasons (minor PITA), I think adding a secondary, in-line, in-hose thermostat like this at the entry to the radiator will keep warm-up times consistently short. Even as the main t-stat begins to open sooner and cooler, the distance to the other in-line, in-hose t-stat will mean that it sees cooler temps (the hose itself radiates some heat), and will thus help regulate engine temperatures better.

There is a downside: if your car needs maximum, full-flow cooling, then adding another flow restrictor won't help. On the other hand, if your has over-sized cooling system and struggles to warm, like the Tdi engine family, this could improve FE and reduce engine wear by reducing warmup times.

I'm going to buy one for my car and report later.

Nick,

This will be a really neat experiment. Are you planning on installing it directly after the plastic water distribution fiting? This might be a good location since the added T-stat wax pellet section must get coolant flow in order to sense the coolant temperature as you know. The plastic water distribution fitting on the upper radiator hose has a small hose that runs back to the engine and establishes a small coolant flow through this miniature loop at all times-this flow loop is also approximately the highest point in the circulating coolant flow path, and is responsible for shuttling air that is in the coolant system directly to the reservoir. If your added T-stats wax pellet section was in the flow path of this miniature coolant flow loop it would be seeing the outlet coolant temperatures. Where were you thinking of installing it?
__________________
2002 VW Jetta TDI 5-speed(completed 01M-5-speed swap at 155K miles) 60+ MPG City.
Experimenting with the "Hybrid" 205 Deg F T-stat:
http://forums.tdiclub.com/showthread.php?t=306799&page=4
Now have Nokian Entyre Low RR tires!

Last edited by josh8loop; June 8th, 2012 at 16:44.
josh8loop is offline   Reply With Quote
Old June 8th, 2012, 16:55   #584
josh8loop
Veteran Member
 
josh8loop's Avatar
 
Join Date: Sep 2009
Location: Vero Beach, Fl.
Fuel Economy: 45 MPG City with the previous 01M, 5-speed 60+ MPG City. Always searching for ways to make it better!!
Default

One of the guys on the Jeep forum used this thermostat:

http://imageshack.us/photo/my-images/21/1013026.jpg/


Federated (MotoRad) 237-192


I would go with this type of setup as long as the outside diameter of the T-stat will fit into the inside diameter of your top radiator hose. You would also want to find one with a suitable temperature range for your liking. If you went with this type of T-stat you would want to place it before the plastic water distribution fitting.


..
__________________
2002 VW Jetta TDI 5-speed(completed 01M-5-speed swap at 155K miles) 60+ MPG City.
Experimenting with the "Hybrid" 205 Deg F T-stat:
http://forums.tdiclub.com/showthread.php?t=306799&page=4
Now have Nokian Entyre Low RR tires!
josh8loop is offline   Reply With Quote
Old June 8th, 2012, 17:15   #585
josh8loop
Veteran Member
 
josh8loop's Avatar
 
Join Date: Sep 2009
Location: Vero Beach, Fl.
Fuel Economy: 45 MPG City with the previous 01M, 5-speed 60+ MPG City. Always searching for ways to make it better!!
Default

Thinking this dual thermostat thing through a little bit further brings an interesting possibility with bad consequences. What if the original thermostat in the vehicle opens up fully(which closes the internal engine bypass loop) and requests coolant flow through the radiator only to receive none since the added thermostat is not yet open? In this scenario coolant flow would all but completely stop until the added T-stat allowed coolant to flow through it.
__________________
2002 VW Jetta TDI 5-speed(completed 01M-5-speed swap at 155K miles) 60+ MPG City.
Experimenting with the "Hybrid" 205 Deg F T-stat:
http://forums.tdiclub.com/showthread.php?t=306799&page=4
Now have Nokian Entyre Low RR tires!
josh8loop is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
higher boost = higher blowby.... now a solution oldpoopie TDI Power Enhancements 113 January 7th, 2009 06:13
Higher the price = Higher the MPGs Joe333x TDI Fuel Economy 2 March 13th, 2008 18:02
36 mpg's on 2002 5 speed / tracking mpg's days-like-this TDI Fuel Economy 23 July 21st, 2002 01:04
Higher Altitude = Higher Boost? :confused: Stealth TDI TDI Power Enhancements 4 July 10th, 2001 09:42
Higher Profile Tire for Higher Gear Ratio? VelvetFoot TDI Power Enhancements 7 June 14th, 2001 22:00


All times are GMT -7. The time now is 10:20.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright - TDIClub Online LTD - 2014
Contact Us | Privacy Statement | Forum Rules | Disclaimer
TDIClub Online Ltd (TDIClub.com) is not affiliated with the VWoA or VWAG and is supported by contributions from viewers like you.
1996 - 2013, All Rights Reserved
Page generated in 0.20010 seconds with 12 queries
[Output: 149.89 Kb. compressed to 127.36 Kb. by saving 22.54 Kb. (15.04%)]