1.5/1.6 Hybrid

[Zukiman87]

So I ended up buying 2 1.5s thinking they were 1.6s. Ya had a brain fart! But apparently it might not be a bad thing. I've heard of the hybrid but can't find too much info. Sounds fairly simple to stuff the guts into a 1.6 block. Has anyone built a complete one?

[maxfax]

It's pretty straight forward..   Slap the 1.5 crank rods and pistons in the 1.6 block...  However if your block has been or needs bored oversized 1.5 pistons are made of "unobtanium"... You will need to use the 1.6 head and your compression will be slightly lower than a normal 1.6.. IIRC 21:1 instead of 22:1..  Not necessarily a bad thing except for possibly harder starting...

[R.O.R-2.0]

and if you put a 1.5 rotating assy in a turbo block, do not forget your piston notches for the squirters. 1.5 engines never had squirters, so never needed notched pistons..

[Zukiman87]

I have a 1.6 td piston that I can use to measure the notches. What kind of turbo and boost do you think I can run with the block studded and the steel headgasket?I'd like to have a turbo with not too much lag.

[R.O.R-2.0]

i ran a VNT17 on my 1.5 engine. stock head bolts, block, and HG.. it finally cracked the block at around 40 psi..

my vnt spools up nice n low.. but i dunno if you can get away with running one in a sammi.. might hit the frame rail.

[Zukiman87]

Would it be inefficient to put a 1.5 head on the 1.6 block?

[rabbitman]

Would it be inefficient to put a 1.5 head on the 1.6 block?

Extra high compression ratio.

[RustyCaddy]

i think the compression ratio for a 1.5 on a 1.6 short block is like 25.3 to 1 verses 23.5 to 1 for a regular 1.6 l (or something like that); so like 7% higher compression. 

Mine starts really easy but the mpg is still pretty low for 10,000 on the rebuild, something like 36mi/gal; read that would be a downside to the setup along with decreased durability.  it seems to run a little hotter to.

[Zukiman87]

Just wondering because I have a mint 1.5 head. Didn't really want to have to try and find a mint 1.6 or 1.9 head.

[RabbitJockey]

stock 1.5d is 23.5 stock 1.6d is 23

[8v-of-fury]

The added .5 of compression ratio won't harm anything. Port out that Minty 1.5 head, it will perform just fine.

[maxfax]

Using the 1.5 internals in a 1.6 block with a 1.5 head will not change the compression as it will still be a 1.5.. However a 1.5 head with 1.6 internals will bump the compression as mentioned..   The issues will be the size difference of the front center oil return and if you're using a 12mm block the head bolt sizes...

Check this out for head swapping details: http://www.vwdiesel.net/forum/index.php?topic=21952.0

[RustyCaddy]

Thanks for fixing the mistakes i had with the numbers...it looks like the compression is almost 10% higher for a 1.5 over a 1.6 than for a matched 1.6 head and short block

it will be interesting to see how quickly a k14 turbo with low boost will blow up my engine

[maxfax]

it will be interesting to see how quickly a k14 turbo with low boost will blow up my engine

The head gasket will be the fuse I'd guess..  Are you running with head studs?

I have 1.6 internals with a 1.5 block and head (don't ask, long story).. Managed to get about 150K miles out of it till (surprise surprise) the block cracked, then I ran it about another 50K (more story).. ..     The mileage indeed was indeed a tad low..  Peak was about 47mpg with darned good behavior.. Average was usually around 36-40 pending on weather and the driving habits for that week...  But darn did it start good..

[Zukiman87]

Thans for the help guys. As soon as I round up a good block I'll start a build thread on it. Only other decision now is what turbo to run!