1.7l 16v TDIm? - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• 1.7l 16v TDIm? by burn_your_money on 03 Nov, 2006 16:27
• Just a crazy idea I had while at work...
  
  Would it be possible to take a gas 16V head, have it shaved down to diesel compression ratios and have the spark plug hole enlarged for TDI injectors?
  
  Then the plan would be to bolt it onto a 1.6 hydro block. I'd use headstuds due to the shorter head. The block would have to be bored out to accept 1.9 TDI pisons. Unless it would be better to start with a 1.9 IDI block?
  
  I'd imagine custom cams would be needed to avoid valve vs piston confrontations.
  
  I was planning on either not running glow plugs or having them in the intake manifold (unless this causes a concern for fires)
  
  I'm not sure how the timing belt would work
  
  Does any of this seem feasable? I chose the 16V head since the spark plug is in the center of the cylinder head.
  
  
• #1 by 935racer on 03 Nov, 2006 16:53
• Quote from: burn_your_money

  Just a crazy idea I had while at work...
  
  Would it be possible to take a gas 16V head, have it shaved down to diesel compression ratios and have the spark plug hole enlarged for TDI injectors?
  
  Then the plan would be to bolt it onto a 1.6 hydro block. I'd use headstuds due to the shorter head. The block would have to be bored out to accept 1.9 TDI pisons. Unless it would be better to start with a 1.9 IDI block?
  
  I'd imagine custom cams would be needed to avoid valve vs piston confrontations.
  
  I was planning on either not running glow plugs or having them in the intake manifold (unless this causes a concern for fires)
  
  I'm not sure how the timing belt would work
  
  Does any of this seem feasable? I chose the 16V head since the spark plug is in the center of the cylinder head.
  
  

  
  
  No it won't work, theres too many reasons for me to get all the way into it but you first major issues here is the valve angle vs. pistons.  The second major issue is the combustion chamber in the 16v head vs. the combustion chamber in the DI piston vs. compression ratio. Trust me I have looked long and hard into the 16v head to make it work for both IDI and DI diesel applications, and I wasn't be cost effecient or practical either.
• #2 by burn_your_money on 03 Nov, 2006 17:11
• Thanks. I figured as much, just don't know enough about the 16V head to know if it would work and if it would what would be required.
• #3 by rabbid79 on 03 Nov, 2006 17:30
• I liked someone's idea on here a while ago about converting a VR6 to diesel.  Has anyone put any more thought into that?
  
  935racer, I wish you would elaborate.  I'd like to know what kind of issues there would be.
• #4 by 935racer on 03 Nov, 2006 18:23
• I already stated the major issues here, there are plenty of other ones that go with what I already said, but its pretty self explanitory.
• #5 by jtanguay on 03 Nov, 2006 21:07
• well you could probably get a vr6 to diesel... but why? the motor would run very poorly, and probably have a lifespan of... a day at the drag strip lol...
  
  over in russia they had trucks that would start on gasoline, and then be ran on diesel... so it can be done, but sticking with diesel components is the best way to go.  There's a reason we have 23:1 compression ratio (us Canadians know that reason best hehehe)
• #6 by rabbid79 on 04 Nov, 2006 01:04
• Why?  Why convert a VR6 to diesel?  The question is why not.  Are we to the point now that the 1.6 is really the best we can do?  We can't convert 16 valve engines to diesel?  We can't bore and stroke 1.6s to 1.9s?  We can't connect this piston to that rod, and install it in this block?  I'm sorry, but it seems that lately there's been too much of a CAN'T DO attitude around here.  I'm not saying that the members of this forum don't know what they're talking about, but has anyone actually tried to put a 16V head on a diesel?  Has anyone actually tried to convert a VR6 to diesel?  I think the people on this forum deserve to know why these ideas won't work.
   
  What do you mean the engine would only last 1 day?  Why would it run poorly?  If you're going to give answers like that, I think you ought to explain yourself.  VR6s are amoung the toughest engines out there.  Could it really be much more than custom pistons, machining the head to accept injectors where the spark plugs are, and mounting a 6-cylinder VE pump?  No prechambers, no glow plugs.  Did you know that cast-iron turbo manifolds are readily available for the VR6?  Can you imagine what kind of power (and sound) a 2.8 or 3.2 liter 4-valve per cylinder turbo-charged VR6 diesel would make?  That's why.
• #7 by lord_verminaard on 04 Nov, 2006 05:52
• If you are gonna go 16v, toss the gasser 16v junk head in the trash and try to convert a 16v PD head over to using a VE pump.  You're already miles ahead of the game at that point.  I thought Simon (TDIRS) was trying to do just that same thing to have a full mechanical PD engine, but have no idea where he ended up with the project.  
  
  As the VR idea, I thought I heard that VW's original idea for the VR was to have a diesel version, hence the flat cylinder head.  Trust me, if I had the time and money laying around, I WOULD try it.  But alas, I am trying to figure out what bills to pay so I can still eat this month.  
  
  Brendan
  84 Scirocco 8v
  00 Camaro L36 M49
• #8 by burn_your_money on 04 Nov, 2006 06:52
• If you want a 6 cylinder diesel enigne just take one from a volvo. They are made by VW and are essencially a VW engine with 2 extra cylinders.
  
  Does anyone have any links to this 16V diesel head?
• #9 by QuickTD on 04 Nov, 2006 07:32
• There are a few fundamentel differences between engines designed for diesel operation and those designed for gas. The most major difference is the combustion pressure. A diesel operates at more than twice the combustion pressure of a gas engine, the parts must be considerably stronger in the diesel. The strengthened parts include the block, which has heavier cylinder walls and thicker crank main bearing webs, the head which has smaller valves, more material between the valve seats, more material around the head bolt holes and larger head bolts and the rods which have larger pin bores and heavier construction. VW (nor any other manufacturer that I can think of) has never used the same block for both a gas and a diesel engine. The VW diesel has similar dimensions to the gasser, allowing it to be machined on the same transfer lines/machining centers, but it has never been the same casting.
  
    A diesel engine operating at stock power levels generates loads on the components similar to that of a very highly tuned gasoline engine. Loads generated within a highly tuned diesel go far beyond that of a the most highly tuned gasser. Rods bend, heads and blocks distort and blow gaskets. If you've been here for a while you've probably seen some of the problems that arise.      
  
  

  Quote

   We can't bore and stroke 1.6s to 1.9s?

  
  
  No, the 1.9 crank won't swing inside the 1.6 block, the stroke is too long and the crank throws hit the sides of the crankcase. You would need to cut holes to accomodate the crank throws, but it would be hard to keep oil in it....
  
  

  Quote

  We can't connect this piston to that rod, and install it in this block?

  
  
  Sometimes you just can't, the proper length rod with the proper pin hole diameter just isn't available. The relationship between the rod, the pin boss height in the piston, the pin bore size and the crank stroke must come together to enable a swap. The pin holes can be bored but the pin diameter difference between a gas and diesel rod is too large. There isn't sufficient material in the pin hole boss to allow boring to accept the diesel pin and the gas pin lacks sufficient strength.  
  
   

  Quote

  but has anyone actually tried to put a 16V head on a diesel? Has anyone actually tried to convert a VR6 to diesel? I think the people on this forum deserve to know why these ideas won't work.

  
  
  No one has tried to put a 16v head on a diesel because anyone with the skills to do it knows that it cannot be made to work. The 16v head has large combustion chambers that would lower the compression too much, the engine wouldn't start. It also has insufficient strength in the valve bridges, around the spark plug (injector?) hole and the deck portion is too open to deal with the pressures of diesel combustion. It would be a cracked up mess in minutes.  
  
  

  Quote

  What do you mean the engine would only last 1 day? Why would it run poorly? If you're going to give answers like that, I think you ought to explain yourself. VR6s are amoung the toughest engines out there. Could it really be much more than custom pistons, machining the head to accept injectors where the spark plugs are, and mounting a 6-cylinder VE pump? No prechambers, no glow plugs. Did you know that cast-iron turbo manifolds are readily available for the VR6? Can you imagine what kind of power (and sound) a 2.8 or 3.2 liter 4-valve per cylinder turbo-charged VR6 diesel would make? That's why

  
  
  The VR6 is not a good candidate for diesel coversion. There are no pistons available with the proper combustion "bowl" for direct injection use, custom pistons would have to be manufactured. Custom rods with a larger pin bore would also be required to insure longevity. A custom block would be needed with heavier cylinder liners, a heavier deck surface and larger head bolt holes to prevent bore distortion from the higher combustion pressure. The head would need to be a full custom casting to provide sufficient strength between the valve seats and around the injector hole. A pump drive would have to be somehow rigged off the front of the engine, the VR6 timing chains are at the rear and aren't heavy enough to provide the 5-10hp required to drive the pump. The turbo part is a snap, no need to even mention it.
• #10 by bert on 04 Nov, 2006 10:50
• Personally,i think the site and the people are ace  :wink:  if i didnt find this site my mk1 diesel golf would have stayed n/a. Thanks to all the technical help (explaining what an aneroid pin is) etc,i now have a golf TD which flies and im really happy with it.
  Thanks guys
  Bert
• #11 by jtanguay on 04 Nov, 2006 11:28
• didn't gm convert some of their gas engines to diesel back in the 80's?  they werent turbo, and thats probably why they lasted around 100'000km.
  
  if you managed to get a vr6 to diesel, just by adding a turbo to it, you're going to melt/break a bunch of components like pistons & valves.
  
  vw had to introduce a better/stronger alloy for the pistons and rings, increase the strength of the crank, use stronger alloy for the head, and valves, and add piston oil cooling jets to add a turbo to an already strong diesel engine.  
  
  If you were an engineer, and had lots of time on your hands, oh and money, you could probably get a 16v system working on a 1.6 or 1.9.  but why not just use the PD 16v head as mentioned above?
• #12 by RabbitGTDguy on 04 Nov, 2006 12:22
• My dad had one of those mid-80's GM diesel spoofs...
  
  1985 Chevy Caprice Station Wagon.... with a "converted" Oldsmobile gas V-8....
  
  In its span it had something like two sets of cylinder heads done on it...a pump and I can't even remember what else... I think this motor was deemed a boat anchor wasn't it?
  
  Joe
• #13 by lord_verminaard on 05 Nov, 2006 07:22
• Quote from: RabbitGTDguy

  My dad had one of those mid-80's GM diesel spoofs...
  
  1985 Chevy Caprice Station Wagon.... with a "converted" Oldsmobile gas V-8....
  
  In its span it had something like two sets of cylinder heads done on it...a pump and I can't even remember what else... I think this motor was deemed a boat anchor wasn't it?
  
  Joe

  
  
  They were dimensionally very similar, but different castings.  (popular for the hot rod guys to use a diesel block in their build ups) The main problem with them was the fuel system and a poorly designed water separator.  They were something like 22.5:1 compression, and with the poor filtration system, water would get in the pump and basically throw the whole injection cycle out of whack- which usually lead to the head gaskets blowing out.  The water separator was actually so bad that sometimes they would even hydro-lock.   :shock: I've known a couple that have run for 300k+ miles- usually with modified water separators and regular service intervals.   My dad had one in a Cadillac, it was a pretty sweet machine and he drove it all over the country for years.
  
  Brendan
  84 Scirocco 8v
  00 Camaro L36 M49