Fuel Cooler...

TDIMAXIMA

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Jul 5, 2004
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MARKHAM, ONTARIO, CANADA
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2004 4motion Passat 5 speed 1.8t
You said TDIfly had a 2 line cooler. Looks more then 2 lines. My biggest concern is how to you mount a line cooler? I dont see any holes or brackets.

Paul.
 

oldstreetracer

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May 31, 2006
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Holland, MI
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2013 Passat SE

FlyTDI Guy

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PNW
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'01 Jetta GLS
Here's the rather long story... The OEM Automatic fuel cooler is certainly an option for those with manual tranny's. I was a little taken back by the value/price. Plan B was to order a fuel cooler from Jegs (or was is Summit)
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http://www.jegs.com
http://www.summitracing.com
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It was much more reasonable in cost so I ordered it. The maker is Flex-a-lite and the model is 4130. Upon arrival, it looked like this...
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Kinda small I thought. A short while later, I was at an auto parts store for other items and there sat a row of transmission coolers (also by Flex-a-Lite) ranging from small to huge. Essentially, they were exactly the same thing as I had already bought but... MUCH larger. To add insult to injury, they were at the same or less price than I had paid for the original. Convinced, I went for big (probably too big) and got their model #4116, 6 pass as seen here...
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http://www.flex-a-lite.com/auto/html/translife-coolers.html
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Hookup was pretty straight forward. After removing the front cover, IC shroud, and bumper, I routed the hoses up to the fuel filter area...
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I did have to cut a notch in the plastic radiator housing in order to make room for the hoses...
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Satisfied with the routing, I tightened things up with some zip ties...
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Here I re-installed the IC shroud, hoses clear fine...
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The cooler I mounted center of the radiator, I could have offset it but I figured I'd leave the hoses long in case I want to move it up later (FMIC). The cooler comes with mounting hardware amounting to some plastic base pads with long center 'spikes' that are intended to poke through the radiator fins from the engine side. Once poked through both the radiator and cooler fins, you put on a ratcheting zip-tie like cap over the notched 'spike' to clamp the works together. I opted to just wire it tight over the face of the radiator. Not that elegant but easily removeable and non-destructive. I didn't feel like buggering the radiator fins only to find I hit a coil behind and have to try again. I double clamped each hose to make sure things stayed leak-free.
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Another view showing the fancy 'wire' technology trapping both the cooler and hose tight to the radiator face...
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Here I've got the bumper re-installed and... this is why you can easily go with the 4 pass cooler instead of the 6. Two passes are buried behind the bumper anyways. I'm sure they get some flow but, 6 is probably overkill anyways.
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Hookup on top was pretty straight forward... I feed the cooler from the out side of the thermal 'T' on top of the fuel filter. I used a male to male barbed connector to connect between the tank return line and the output side of the cooler shown just below the red wire (another story, lift pump).
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All things considered, this was an easy mod and only took a couple hours. Much of the time was spent just mapping out how to go about it. As the cooler is post-IP pump, the fuel is at its hottest before it returns to the tank. As the best a cooler can do is return the fuel to ambient temps, the largest temperature differential exists at this point rather than attempting to cool the already diluted fuel coming from the tank. This may not be the most elegant solution but for around $30 plus hose, coupler and a couple clamps, it certainly is affordable and, I believe, effective.
 
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BleachedBora

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Oct 16, 2003
Location
Gresham, Oregon
TDI
'81 DMC-12, '15 GL350 CDI 275 hp/448 tq - '81 Caddy ALH, '05 E320 CDI 250hp/450 tq
Nice writeup! Add another thing to my mod list for the summer :). Maybe for once I'll do it myself.... *ponders* (You reading this Oldpoopie and Jetpuf? ;))
Cheers,
-BB
 

Gothmolly

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Joined
Feb 3, 2005
Location
Providence, RI
TDI
2002 Golf
I'm considering this, however, on a hot day, where the cooler is supposed to prevent the fuel from heating up too badly, since the cooler is 'breathing' road temperature (100+ F) air, doesn't it end up a fuel heater?
 

TDIMAXIMA

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MARKHAM, ONTARIO, CANADA
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2004 4motion Passat 5 speed 1.8t
Most of my driving is highway. FMIC, fuel cooler, all work with the moving air. I had my air charge down to 25C cruising home. outside temp was 21.
 

Gothmolly

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Location
Providence, RI
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2002 Golf
TDIMAXIMA said:
Most of my driving is highway. FMIC, fuel cooler, all work with the moving air. I had my air charge down to 25C cruising home. outside temp was 21.
Right, and when it hits 35 degrees out, and the road air temp is 45, I'm thinking that this loses some of its usefulness. Moving 45 degree air is still 45 degree air, unless you're going to put a mister on it.
 

FlyTDI Guy

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PNW
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'01 Jetta GLS
Does a fuel cooler work? I guess you have to consider the alternative, no cooler at all. If you're dealing with road and air temps around 100º F (like you assert), you also have to assume your tank fuel is going to be close to that as well (minus any IP heating). Add in the heat added by your IP compressing the fuel to +300 bar and what do you have? There are mods posted here that fool the ECU into thinking your fuel is cooler than it really is. Personally, I would much rather actually cool it. Much the same as intercoolers, the best they can do is get you closer to ambient temperature. If ambient temps are high, the amount of change is relative. I personally don't have any logs of fuel temps under extreme conditions. Other threads here claim it can be as high as 80º-90ºC. Even if ambient temps are 100ºF, there's quite a bit of headroom there and potential benefit from a fuel cooler.
 

mojogoes

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england
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mk3 tdi golf
Fly......go for a run with $5 of fuel in the tank and then go for one with half a tank and see what if any difference in power there is......or after you've given the car a bit of a lick! ....see if the power falls off...having no fuel cooler.
 

FlyTDI Guy

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'01 Jetta GLS
All of this, 100%, is based on the premise that hot fuel causes retarded timing which, in turn, equals reduced performance. I've never been able to produce, log or feel this phenomenon. That leaves all this in the realm of hypothetical and placebo... Here's run #2 of WOT romps (pre-cooler install) in an effort to produce it. Fuel does get hotter but timing stays stable. Go figure...



Fuel never got hot enough to make a difference. This was a cooler 60ºF evening so... maybe I need to reproduce the test @ +80º ambient.

Just so everyone knows, I did this in anticipation of an 11mm pump install. I did both a lift pump and fuel cooler, neither of which I can say made any tangible difference in power to this point. Maybe when I get the 11mm fuel cooker installed, this mod will earn its keep. Maybe...
 

tongsli

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Baltimore, MD
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2000 Jetta TDI, 2004, Jetta Wagon TDI PD
The PD's and VE's fuel coolers are all located on the return line going back to the fuel tank.
 

SuperJ

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Apr 11, 2006
Location
Waterloo, ON
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2006 Jetta TDI
Like someone already said. The cooler should be positioned where there is the larger differential between fluid and air temps. This will give you the greatest BTU/hr capacity.

Anyone know if Mk5's come with a fuel cooler?

It seems to me the car is weaker feeling after driving it for an hour and a half than it is just after warmup. Could be in my head though.:confused:

Fly TDI guy... could you post a log of your timing versus fuel temps sampled over the course of a 1 hour plus drive? In a single WOT throttle run the higher temps are probably due to the injection pump heating up. (is the temp sensor on VE engines pre or post pump. The may not be sustained for long enough to produce a timing retard, but this is pure speculation. Maybe the ECU compensats for steady state higher temp conditions that are sustained over time.
 

mojogoes

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england
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mk3 tdi golf
SuperJ said:
Like someone already said. The cooler should be positioned where there is the larger differential between fluid and air temps. This will give you the greatest BTU/hr capacity.

Anyone know if Mk5's come with a fuel cooler?

It seems to me the car is weaker feeling after driving it for an hour and a half than it is just after warmup. Could be in my head though.:confused:

Fly TDI guy... could you post a log of your timing versus fuel temps sampled over the course of a 1 hour plus drive? In a single WOT throttle run the higher temps are probably due to the injection pump heating up. (is the temp sensor on VE engines pre or post pump. The may not be sustained for long enough to produce a timing retard, but this is pure speculation. Maybe the ECU compensats for steady state higher temp conditions that are sustained over time.
The temp sensor on ve motors is in the top of the f-pump......and with it setup on the feel line to the pump , when my car is low on fuel it seems to have as much power as if it were a full or half plus tank or even a little bit more powerfull.......but that may be all in my head or from my new found power.
 

mojogoes

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england
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mk3 tdi golf
Most likely because the steering wheel is on the wrong side...:D

:D :D :D !
 
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FlyTDI Guy

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Nov 3, 2001
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PNW
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'01 Jetta GLS
SuperJ said:
Like someone already said. The cooler should be positioned where there is the larger differential between fluid and air temps. This will give you the greatest BTU/hr capacity.

Anyone know if Mk5's come with a fuel cooler?

It seems to me the car is weaker feeling after driving it for an hour and a half than it is just after warmup. Could be in my head though.:confused:

Fly TDI guy... could you post a log of your timing versus fuel temps sampled over the course of a 1 hour plus drive? In a single WOT throttle run the higher temps are probably due to the injection pump heating up. (is the temp sensor on VE engines pre or post pump. The may not be sustained for long enough to produce a timing retard, but this is pure speculation. Maybe the ECU compensats for steady state higher temp conditions that are sustained over time.
I don't have a long duration, hot weather log but... I'll do one on the next hot day we encounter. In another thread, I suggested to prove (or disprove) the timing retard thing that someone get out on a blistering 100º day in the desert (Arizona?) set the cruise for 85 mph and run for as long as possible. In this duration, have a double pole switch set up to kick in the resistor mod KERMA has developed which fools the ECU into thinking fuel temps and IAT are like 30ºC cooler than they really are. One would think that you'd see a jump in timing as well. This would be a hot fuel/air cruising scenario vs my WOT/maximum advance scenario.

The ability to simply meet requested timing advance under various conditions means nothing in that the ECU could be requesting less advance based on temps. Doing a sudden switch-over might reveal something. The scenario that KERMA cites is switching over to 200º SVO/WVO from D2 at ambient temp. As most of us don't run SVO and heating our D2 or Bxx mix to 90ºC seems to be extreme, the benefits of this mod are kind of elusive and hard to record/demonstrate. Those doing the resistor mod, aka FAT or KERMA mod seem to be reporting everything from better mileage to nothing to less mileage to CEL's to "now my car won't run". Some of those are simply due to incorrect wiring. Regardless, results seem all over the map. As I've already installed my cooler, I've lost my baseline ability. Maybe someone with an Auto (11mm pump) can log his fuel temps over a period of time on a hot day to get a feel for just how bad a problem this truly is. There really isn't much data to support the problem, much less the solution.
 

darkscout

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May 28, 2006
Location
Michigan
TDI
2003 Golf
I've been considering doing this on my Mk3 AHU.

Right now I have Sprint 520s w/RC2. In the future I'm looking at PP520s and an RC2/RC3 or Alligator chip.

I'm not looking at breaking any dyno records. Just a bit better running during these summer months, especially on long trips. I can't imagine multiple thousands of PSI + 90* weather + AC & Loaded engine makes fuel too cool.

Would I notice any benefit from something like this? I was in autozone the other day and they have transmission coolers for pretty cheap, 24$. Just looking for something to avoid heat soak.
 

MAXRPM

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May 7, 2008
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US
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00 Jetta and 99.5 Golf, 2015 Passat TDI,BMW 2
Reviving this thread,, any updates about this mod? is it working OK so far?
 

mojogoes

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May 1, 2003
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england
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mk3 tdi golf
If you don't just make sure your tank is no less than half empty.......which will keep the fuel at near the best temp's.
 

FlyTDI Guy

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PNW
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'01 Jetta GLS
Well, here it is almost a year later and... My fuel cooler is working perfectly. One of my concerns was if it would become a negative influence during cold weather. Even when the temps were in the teens (ºF) for days, my car ran without any apparent negative effects. It doesn't get much colder than that around here so I can't speak for those in Canada, etc.

As far as hot weather performance, total advance is really limited by physical properties of the VE pump and all I can say is, I've never seen my car deliver any less than that when romping on it. In a Rally scenario where you are in a sustained, high performance situation, hot fuel could indeed be a negative. Timing aside, for a given volume of fuel, hotter will be less dense. Like air, colder is better. This mod may not produce any tangible power but it sure couldn't hurt from a mass standpoint. Now as for combustion properties of hot vs cold fuel, I really can't speak to that. Maybe someone more schooled in the physics of this can contribute something. I do know this, hotter fuel will ignite sooner, or more accurately, the differential between ambient and combustion temps will be less. As the ALH has limited ability to monitor when actual combustion occurs, timing is guessed and set by conditions via a table/map in the ECU. Cooler fuel (as this is part of the timing calculation) should increase your headroom when running under extreme/hot conditions. Long story short, it couldn't hurt. Done for cheap, I consider it good insurance.
 

mojogoes

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england
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mk3 tdi golf
I've said this before and many others too that actually saying colder fuel is more dense is correct but the aim here isn't to make the fuel any cooler so the density is increased but to keep the fuel at or around the optimum temperature...........and for people who were drag racing and who were concerned about weight were putting a bare minimum amount of fuel.

It was at this point that the fuel in the tank was getting supper heated especially if you were using an 11mm or larger with the higher pressures involved ......some people then said that the fuel temp sensor would report these high temps too the ecu and then in turn would pull timing and / or reduce the amount of fuel injected.........so more about "keeping the power you've paid for" than increasing it.


Just to add its been reported that in some extreme cases up to 10 to 20hp can be lost when there was no fuel cooler used and a low level of fuel in the tank and the car seamed to be a little flat which i to experienced.
 
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DbLog

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Jun 30, 2006
Location
Royal Oak, MI
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2011 335d
Mine is only a 2 pass but gets the job done. Can't feel the car getting slower at the end of 25min sessions anymore. If I were to do it again, I'd go for a 4 pass.

 

ak47tdi

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Nov 16, 2005
Location
Delaware
TDI
99, white,2 door golf and 98, white, Jetta
I have a Kerma widget instead of the stock thermostatic tee. Wondering if i should go back to the stock tee before a mod like this?

I always wondered weather i was doing more harm than good when i go to the track with a 1/4 tank or less.
 

TornadoRed

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Saint Paul (ex-San Diego)
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2003 Golf GL 5-spd, red; 2003 Golf GLS 5-spd, indigo blue; 2003 Jetta TDI wagon, Candy White
Does anyone have any hot-weather before-and-after fuel economy data with a fuel cooler?
 

mojogoes

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england
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mk3 tdi golf
TornadoRed said:
Does anyone have any hot-weather before-and-after fuel economy data with a fuel cooler?
This mod is not about economy its about not loosing any of the power you have paid for from having to high fuel temperatures.
 

darkscout

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May 28, 2006
Location
Michigan
TDI
2003 Golf
mojogoes said:
This mod is not about economy its about not loosing any of the power you have paid for from having to high fuel temperatures.
And they say you invented the language.
 

mojogoes

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Joined
May 1, 2003
Location
england
TDI
mk3 tdi golf
You understood what i was saying/meant............and that was all you could come up with some $hit about my spelling..............you disappoint me you really do!!


And there are plenty of you you too......which is a real pain in the $$
 
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