Air/Water Intercooler - page 1 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• Air/Water Intercooler by vanbcguy on 13 Jan, 2009 17:40
• I'm seriously considering installing an air/water intercooler... Main reason is I really don't want to hack a bunch of holes in my car, and I REALLY don't want to weaken/remove any of my bumper structure...
  
  I poked around a bit and found these kits:
  
  Air/Water Intercooler Kit
  
  Now I don't know about you but it seems a LOT simpler to route some water hoses around rather than a great big 2" air pipe, not to mention it should be easier to both get it cool and keep it cool... Heat soak should be practically non-existent...
  
  I was looking at the radiator supplied in the kit, and while I think I can find some creative places to mount it I started thinking about other options.  My car doesn't have AC, so that got me thinking about using an AC condenser mounted in the stock location.  The stock condenser for my car looks like it has reasonably sized tubing, I KNOW it will fit behind the bumper without any trouble and it's designed to handle more heat than I'd be seeing from my turbo...  The biggest potential problem I can see would be corrosion... Am I nuts?
• #1 by zagarus on 13 Jan, 2009 21:58
• ive been looking at the same kits and considered the AC condenser as well. I say go for it.
• #2 by Limey on 13 Jan, 2009 23:50
• I've been pondering the same kit for my MK3
• #3 by gldgti on 14 Jan, 2009 02:33
• air/water is OK - but keep in mind that the more thermal mass your intercooler system has, the longer it will take you to get rid of the heat you suck out of the inlet air.
  
  the high heat capacity of water (or coolant) could therefore cause problems for you if you are running lots of boost and do long hauls up hills etc - you may not be able to cool the whole system quickly enough at high loads - hence you end up with a "heat soaked" system. this is why air/water intercooler steups are most often used on drag car setups (high thermal mass and short duration runs) or pretol vehicles that typically only boost a small percentage of the actual driving time.
  
  i can appreciate not wanting to to cut up the bumper, but if you're careful and savvy, theres no reason you can't end up with a good result....
  
  http://www.vwwatercooled.org.au/newforum/upload/showthread.php?t=24787
• #4 by dillenger1 on 14 Jan, 2009 03:03
• youll still have to route charge pipe?
• #5 by TedV on 14 Jan, 2009 09:08
• Quote from: "dillenger1"

  youll still have to route charge pipe?

  
  
  yes, but charge pipe for an air/water is much shorter.  My air/water IC is right over my transmision.  Pipe runs from the turbo, length of the cam cover, into the IC, out the IC to the intake manifold pipe, kneck turned around 180 degrees.  I use a oil cooler as my IC water radiator infront of the radiator fan side of the engine radiator and a Bosch pump from a Ford Lightning.  My reservoir is behind my pass seat.  Mostly cruising the K24 or T3 is not making much boost, so IC water stays cool.  My aim is autocrossing and it works very good for that.
• #6 by vanbcguy on 14 Jan, 2009 09:22
• My belief as to why dragsters run air/water was more that they sit on the tarmac baking for a long time before they actually get going.  An air/air intercooler with no airflow over it (stationary vehicle) just sits there getting hot and won't provide any benefit until enough air has flowed over it to cool it down.  An air/water intercooler on the other hand can continue to have active cooling while the vehicle is stationary.  For drag applications you can go one better and use a large water reservoir with ice in it and get way lower temps than you ever could with an air/air intercooler.
  
  If the radiator for an air/water intercooler is too small then yes, the system can be heat soaked.  If you put a tiny rad in a poor position with poor airflow then I can easily see it having trouble rejecting all the heat from the system.  I'm sure there's some math out there somewhere to properly calculate the rad surface area versus ambient temperature versus desired intake temperature drop...  Actually my "gut" feeling is that the small rad included in the kit in the link may well suffer from exactly that...
  
  Most of my driving is in the city, which means a lot of stop and go cycles, and all the 'go' cycles will be right after sitting stopped at a light for a while.  Since an air/water system will continue cooling itself down after I come to a stop I'm thinking it should actually work better for my circumstances than an air/air intercooler would.
  
  I think that Mk III FMIC setup looks great and I'm happy to see some extra metal added to the bumper support to try and make up for the material that was removed.  To me though it's part of the safety system for the vehicle... I'd never drive around with half a seat belt, so I don't feel right driving around with half a bumper.  I figure VW put the absolute minimum amount of materials in there that would meet the crash test requirements when the vehicle was made, so it would stand to reason that removing some of it must reduce the car's crash rating. My Mk III only scored 3/5 for head on crashes in the first place, I don't have air bags, and I live in a city that can probably boast the worst drivers in North America!
• #7 by TedV on 14 Jan, 2009 09:34
• air/air IC will also become heat soaked.  You do not want to touch the stock cooler or lines on my 98 TDi after some spirited driving unless you like to get a burn.  3 back to back runs at autocross and you can feel the power drop in it, no such drop with the 1.6TD air/water setup.  
  
  I read Corky Bells book, Maximum Boost years ago before an ABA 2.0 16V turbo build, and the Spearco notes in the Turbonetics catalog on air/water setups.
  
  If only I was allowed to put ice in my cooler before autocrossing..  :cry:  :x
• #8 by TedV on 14 Jan, 2009 09:38
• oh, about corrosion, I use antifreeze in the IC water so I don't have to worry about that and frozen lines in the winter with Redline Water wetter.
  
  I would be tempted to try their kit.  it looks close to what I assembled a few years ago except my pump is better quality.
• #9 by zagarus on 14 Jan, 2009 14:02
• I was going over in my mind last night about the radiator size that comes with the small kit from the top link.  10x12x2 is a fairly small rad. Should only cover about 1/4 of the stock mk2 radiator.  So it would make sense that for more cooling using a bigger rad for the air/water would be a logical choice, so im going to go ahead and try an AC rad.  Cars with AC had no problem cooling the actual cooling radiator with an AC rad in front so there should be no problem using it for an air/water cooler
• #10 by vanbcguy on 14 Jan, 2009 15:05
• Quote

  I was going over in my mind last night about the radiator size that comes with the small kit from the top link. 10x12x2 is a fairly small rad. Should only cover about 1/4 of the stock mk2 radiator. So it would make sense that for more cooling using a bigger rad for the air/water would be a logical choice, so im going to go ahead and try an AC rad. Cars with AC had no problem cooling the actual cooling radiator with an AC rad in front so there should be no problem using it for an air/water cooler

  
  
  Sweet!  
  
  I'm probably going to have to wait a month or two before I can order anything, but I think the air/water setup is really going to be the best way to go.  And I think using the AC condenser as a radiator is going to provide the most trouble-free installation - if possible I'd always prefer to use stock-type parts rather than having to fit something else in place.  But I should be able to find a condenser at the junkyard provided I can find a Mk III at all...
  
  For people that have an air/water setup going already, what did you use for a pump?  The kit pump looks kind of cheap, and they actually say on the site that they consider it to be the "weak link" in their product...  I see a bunch of references to a Bosch pump but it costs as much as the intercooler itself!
• #11 by zagarus on 14 Jan, 2009 15:54
• does a VR6 auxilary pump sound like something? im pretty sure the setup that first got me interested in air/water used some sort of VR6 aux pump.  I could be mistaken though.
• #12 by dillenger1 on 14 Jan, 2009 16:16
• You dont need performance in stop n go traffic.
• #13 by vanbcguy on 14 Jan, 2009 16:59
• Well we don't have any actual "freeways" in Vancouver whatsoever... I care a heck of a lot more about my 0-60 km/h time than I do about 0-100 km/h!
  
  In 15 km from home to work I go through 28 traffic lights (I just counted on Google Maps)... No, I don't need a 'performance' car which is why I drive a diesel Jetta instead of something more "acceleration" oriented.  But I sure as heck like to have a car that can get out of its own way!  In an ideal world those lights would all be green the whole way here and I'd barely be in to boost at all...
  
  Right now when my turbo is COLD I can stomp on it and get no smoke whatsoever.  Do a couple hard acceleration runs in a row though and I start getting more smoke and loosing performance because the turbo / intake is heat soaked.  So one would ask, with a turbo diesel what is the correct way to correct this condition?
  
  My goal is to get an IDI that performs close to as well as a newer TDI, without really spending much cash.  I figure adding an intercooler is reasonably inexpensive (I can probably pull it off for less than $300), should have a "noticeable" improvement on the performance of the car and won't do anything to the vehicle that will make it hard to sell later on provided I'm not cutting anything up.
• #14 by vanbcguy on 14 Jan, 2009 17:03
• Quote from: "zagarus"

  does a VR6 auxilary pump sound like something? im pretty sure the setup that first got me interested in air/water used some sort of VR6 aux pump.  I could be mistaken though.

  
  
  I found some pictures of one online, it looks about right... I know of a few VR6 Pasat's in a yard not too far from here... Might be a good source for one of those cheap!