can a 1.6T bottom end marry to a 1.5 top end? - page 1 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• can a 1.6T bottom end marry to a 1.5 top end? by NintendoKD on 14 Oct, 2009 22:31
• found a bottom end/rotating assy. for cheap and as opposed to building a 1.5 "weak block" build it up from a 1.6 TD block and rotating assy.using the top end from the 1.5....... same? Like lego blocks?  Also the crank is damaged in the TD rotating assy. can I use the perfectly good one from the 1.5 and swap it into the 1.6 bottom end?  I checked the FAQ's and did, in fact, use the search feature.
  
  thanks folks,
  
  Kevin
• #1 by rabbitman on 14 Oct, 2009 22:36
• I think you'll get a very high compression ratio. Lotsa talk been done about that.......
• #2 by RabbitJockey on 15 Oct, 2009 04:31
• yuo can use the 1.5 pistons rods and crank if you want, but you'll need to notch to the pistons for the oil squirters, and a 1.5 head won't work with out modifications
• #3 by maxfax on 15 Oct, 2009 05:11
• The 1.5 head still uses 11mm head bolts, so you'll either have to drill out the head bolt holes in the head as the TD block (as well as anything 82ish and up) uses 12mm head bolts.... You'll also need a reducer in the front center oil drain such as this http://www.vwdieselparts.com/1.5-1.6.htm and a 1.5 head gasket, which once again will need the head bolt holes reamed to fit the 12mm bolts..
  
  THe compression will jump from 23:1 to about 26:1 IIRC..  I've been running a similar combo for a few years now in NA form with no problems..  If you're thinking turbo the story may be different...
  
  If you have an un cracked 1.5 block your better option would be to use that with a set of head studs as that pretty much fixes the weak block problem... 
• #4 by clarkrep on 15 Oct, 2009 06:54
• I think the 1.5 crankshaft has smaller rod journals than the 1.6td and also a shorter stroke. Can someone confirm that?
• #5 by maxfax on 15 Oct, 2009 07:15
• Yes the rod journels are smaller and the stroke is shorter on a 1.5..    The difference?
  
  1.5 Rod Journal/Stroke = 45.96mm/80.00mm
  1.6 Rod Journal/Stroke = 47.76mm/86.40mm
• #6 by Rabbit on Roids on 15 Oct, 2009 12:01
• ok, now im asking you this.
  why would you want to put such a weak head on a notably tougher block than a 1.5? it just makes no sense. its not going to work right. the compression ratio will be way too high to be any benefit.
• #7 by Turbinepowered on 15 Oct, 2009 15:17
• Quote from: maxfax on 15 Oct, 2009 07:15

  Yes the rod journels are smaller and the stroke is shorter on a 1.5..    The difference?
  
  1.5 Rod Journal/Stroke = 45.96mm/80.00mm
  1.6 Rod Journal/Stroke = 47.76mm/86.40mm
  

  
  Are the early 11mm 1.6 rod journals the same size as the 1.5s?
  
  I went browsing through the Diesel section of my Dasher Bentley (which covers 1.5s until '80, and then 1.6 in '81) and it only lists one table for crank main and rod journal sizes.
  
  Any chance someone has measurements for 1.6TD and 1.5 rods?
• #8 by maxfax on 15 Oct, 2009 22:17
• Quote from: Rabbit on Roids on 15 Oct, 2009 12:01

  the compression ratio will be way too high to be any benefit.
  

  
  It should start pretty darned easy...      The engine in my daily beater is a conglonmeration of spare parts I had around..   1.5 block and head with 1.6 rods crank and pistons.. I really haven't noticed any down falls, but no gains either.. Other than the easy starting...
  Had I not been cheap and thrown studs at the thing it would actually work quite dandy... (Yeah I know.. Now you know why I harp about studs so much)
  
  Turbinepowered,
  
  The 1.6's are the same rod journels across the board, both early and late..   Just the 1.5's got the smaller ones..  About the only difference between the early and late 1.6 rotating assembly is the crank nose...
  
  Are you just looking for the ID's of the rod at the crank and wrist pin??  If no one else has them I can measure a couple rods..   The 1.6 both N/A and TD should be the same on both ends..   The 1.5 of course will be smaller at the crank, and IIRC the wrist pin is smaller too...
• #9 by clarkrep on 16 Oct, 2009 08:37
• Maybe this will help, thanks MJF for the link. http://www.kotinet.com/matti.farm/img01.jpg
• #10 by Rabbit on Roids on 16 Oct, 2009 08:47
• idk what the hell it says, but there is differences. over a milimeter. i just wish i knew what parts they were talking about on that german tech article. and you are going about it all wrong Kevin. take a 1.5 rotating assy, balance it, notch the pistons, then throw it in a 1.6 block, or even better yet, a turbo block. and put a 1.6 or 1.9 head on it. then you would have one tough, high revving, piston squirter equipped 1.5. i really dont see the benefits of your engine you want to build. you cant even bolt it right together. my combination bolts together. yours would require drilling the head at very least.
• #11 by Turbinepowered on 16 Oct, 2009 13:32
• Quote from: maxfax on 15 Oct, 2009 22:17

  The 1.6's are the same rod journels across the board, both early and late..   Just the 1.5's got the smaller ones..  About the only difference between the early and late 1.6 rotating assembly is the crank nose...
  
  Are you just looking for the ID's of the rod at the crank and wrist pin??  If no one else has them I can measure a couple rods..   The 1.6 both N/A and TD should be the same on both ends..   The 1.5 of course will be smaller at the crank, and IIRC the wrist pin is smaller too...
  

  
  Actually I meant the rod lengths. I'm assembling a high compression ethanol burner (she shall see very little gasoline ) out of an early 11mm headbolt diesel block and crank with 1500 gasser pistons. Trying to work out the proper set of rods to give me a bit of diesel-esque piston protrusion.
  
  I just picked up a buret clamp to go with the buret I bought for use with biodiesel titration (then promptly lost, only recently refound) so I'll be measuring the chamber volumes on the 1.6 gasser head I have to determine how much I need to get to shaving. I'll do the piston dishes, too.
  
  Small valves for air velocity (Probably just going to leave them stock, honestly) and throw a small daily-driver type turbo to put me at right around 90-100hp for passing and merging, and we'll then start tuning for economy in my daily driver.
• #12 by NintendoKD on 22 Oct, 2009 22:31
• So the short answer is .... a resounding NO!??? um........ so now what? my best bet is to rebuild the block I have and go n/a with ARP studs? or should I go with the 1.6 bottom end and keep the 1.5 head? better compression is good right??? plus, I have a recently acquired audi 5000 intake mani for better flow, If I am doing the 1.6 bottom end conv. I will need solid answers and how to's etc. instead of wishy washy stuff like which snout to use, which rotating assy to use, do I have to modify the head? etc.  sorry for all of the questions folks but if this is going to be unique I want it to be done right or not at all.  I would prefer to compile a list of all of the parts to use for this build to make thing a great deal easier.
  
  Thanks,
  
  Kevin
• #13 by maxfax on 22 Oct, 2009 23:07
• I think it was all already said earlier in this post, scroll up and read...   If you want it done best, build a 1.6 with a 1.6 head using an 82 or newer engine...  Next down the line would be to have your 1.5 block checked, if it is good, rebuild it with arp head studs..  The same could be said about an early (1981) 1.6 with 11mm head bolts... 
  
  
  Mixing and matching a 1.5 head on a 1.6 bottom end has been done in many forms.. As mentioned earlier starting may be easier, but otherwise no gains to be had, possibly more downfalls due to the increased compression..   As mentioned earlier, a turbo on this getup would most likely be very bad...
• #14 by NintendoKD on 23 Oct, 2009 06:05
• I think, that I will just rebuild my 1.5 with ARP head studs