The ultimate 1.5TD

[saurkraut]

really? 1.9 rods with shaved 1.6 pistons on them? think it will work? im so tired of looking for 1.5 os pistons, and i really dont want to sleeve my block back to stock. but i dont want to use an 11mm block either. and i have a dead MF block laying around just waiting to get all slutted up..

Yah, thats what I'm currently contemplating.  I foreget what the actual numbers are.  Best of my recolection is .063" off the top of the pistons, and something to reduce the 26mm holes in the 1.9TD rods to accept the 24mm wrist pins.  Its the best of all worlds: short stroke, long rods, TD pistons, oil jets.

see, thats what i wanted, the short stroke and long rods to turn some mad rpms. but i also liked the oil jets in my MF block. i also want to run a 1.9 head. and some crazy single turbo, or a nice set of compounds  :twisted:

I've putzed with compression ratio figuring:

The 1.6 head on a 1.5 block yields a CR of: 21.37:1

The 1.9 head on a 1.5 block yields a CR of: 17.68:1

The 1.9 head on a 1.6 block yeilds a CR of: 19.01:1

I wonder if the 1.9 head would have the ignition problems that some folks are experiencing when they put a 3 notch in a 1.6/1.9 head combo.  I gues there is only one way to find out....

Rod stuff:

1.6TD rods, center to center, are 136

1.9TD rods, center to center, are 144

Difference: 8mm

1.6 stroke is 86.4

1.5 stroke is 80.0

Difference: 6.4mm

Rod Difference: 8mm
Stroke Difference 6.4

Amount the 1.6TD piston need to be shaved: 1.6mm (.063")

[Rabbit on Roids]

im 100% against running a 1.5 block. i wont do it. not for my next build. only reason i used another 1.5 block this time was because it was free. i blew my first 1.5 block to bits with a stock fuel system and almost 40 psi boost. the head gasket even survived better than the block. the gasket blew because the deck of the block got so messed up. i ran over 30 psi to that gasket more than a few times.. and it was just a stock crap fiber gasket.

and why the lower compression? is it that the AAZ head has bigger swirl chambers? i know its not the combustion chamber size, as that is in the piston.

[saurkraut]

My appologies.  When I say 1.5 block for the purposes of this discussion, I mean a 1.6TD block with a 1.5 crank and 1.9 rods and shaved 1.6Td pistons.  The swept volume will be the same as a stock 1.5 block.

Yes, the swirl chambers get progressively bigger as the displacement was increased.  The smallest are in the 1.5 head, the biggest swirl chambers are in the 1.9 head.

Here's a dandy table the Roger Brown put togather:

http://www.4crawler.com/Diesel/index.shtml#EngineSpecs

If the proper thickness head gasket is used, and with the material removed from the top of the 1.6td pistons, the 1.9 head might work.  I need to measure the depth of the pockets in the 1.6td pistons.  It might be necessary to cut them deeper befor machining the top of the piston as they may dissapear.

[drrtybyl]

Would you need to shave the 1.6 deck significantly to use the original 1.5 rods with modded 1.5 pistons?
I've slowly accumulated enough parts to build a second bottom end using the above-described combo.

[Rabbit on Roids]

Would you need to shave the 1.6 deck significantly to use the original 1.5 rods with modded 1.5 pistons?
I've slowly accumulated enough parts to build a second bottom end using the above-described combo.

put a 1.5 crank, 1.5 rods, and 1.5 pistons in a 1.6 block. everything fits as it is. no need to modify the 1.5 pistons.. only 1.6 pistons. then you have the beauty of a short stroke 1.5 with the beefy 1.6 block and head. or you could throw a 1.9 head on it..

[saurkraut]

Is there a difference in the pin offset between the 1.6 or 1.9 pistons?

Yes, its in the bently manual.  Something like 1.1xmm

[saurkraut]

Would you need to shave the 1.6 deck significantly to use the original 1.5 rods with modded 1.5 pistons?
I've slowly accumulated enough parts to build a second bottom end using the above-described combo.

put a 1.5 crank, 1.5 rods, and 1.5 pistons in a 1.6 block. everything fits as it is. no need to modify the 1.5 pistons.. only 1.6 pistons. then you have the beauty of a short stroke 1.5 with the beefy 1.6 block and head. or you could throw a 1.9 head on it..

But as we all know, fresh 1.5 oversized pistons are very rare.  And the oil jet notches in the 1.6 pistons have reinforcing around them.  So if you notch the unavailable oversized 1.5 pistons for the oil jets, they may crack.

Its unfortunate that the pin hight is lower than the 1.5 piston, as it takes away from the long rod advantages, and makes it imposible to use 1.6 pistons.

[saurkraut]

Well, if the pin bore is offset differently, then you would want to take that difference into consideration with regard to how much the pistons need to be shaved.

Yup.  I should have 1.9td rods soon.  I have and extra 1.5 crank.  I'll figure out how to rebush the rods to the 24mm pins.  I have a fresh first over size TD block and pistons standing by.  I'll assemble it and measure stuff.  It will be essentially de-stroking a 1.6TD.  the only 1.5 part will be the crank.

[Jettagli16v]

Sorry to threadjack, but my buddy has a couple NOS 1.5 Brazilian Metal Leve piston sets w/ rings. He has std, .5 and 1.0 over.
PM me if I can help!
-Brad

[drrtybyl]

Makes you wonder why VW didn't just leave the original dimensions for the crank, piston and stroke alone when beefing up the block?..

[Rabbit on Roids]

Makes you wonder why VW didn't just leave the original dimensions for the crank, piston and stroke alone when beefing up the block?..

They had already changed the bore and stroke to make the 1.6 before updating the block.

i thought the 1.5 and 1.6 had the exact same bore size, just less stroke?

[Rabbit on Roids]

Would you need to shave the 1.6 deck significantly to use the original 1.5 rods with modded 1.5 pistons?
I've slowly accumulated enough parts to build a second bottom end using the above-described combo.

put a 1.5 crank, 1.5 rods, and 1.5 pistons in a 1.6 block. everything fits as it is. no need to modify the 1.5 pistons.. only 1.6 pistons. then you have the beauty of a short stroke 1.5 with the beefy 1.6 block and head. or you could throw a 1.9 head on it..

But as we all know, fresh 1.5 oversized pistons are very rare.  And the oil jet notches in the 1.6 pistons have reinforcing around them.  So if you notch the unavailable oversized 1.5 pistons for the oil jets, they may crack.

Its unfortunate that the pin hight is lower than the 1.5 piston, as it takes away from the long rod advantages, and makes it imposible to use 1.6 pistons.

why cant you notch the pistons for the jets? i know of some machine shops that ive spoke with that use 1.6 n/a pistons and just notch them for turbo motors. i seriously think we could notch them and not worry about it. there isnt much load or stress down by the piston skirt. thats where they file off material when balancing them.. so why cant we take a little more off and have ourselves a notch? i think i would take the chance of notching some 1.5 pistons.

[MJF]

Doesn´t 1,5 crank have smaller con rod journals than 1,6/1,9?

[Rabbit on Roids]

Doesn´t 1,5 crank have smaller con rod journals than 1,6/1,9?

no, all the journals are 50.6mm according to someones bently manual. im pretty sure i got those measurements from sauerkraut. so basically, all IDI diesels, and i know atleast the first TDi's had rods that were interchangeable with AAZ rods. so they must be 50.6mm also.

[drrtybyl]

why cant you notch the pistons for the jets? i know of some machine shops that ive spoke with that use 1.6 n/a pistons and just notch them for turbo motors. i seriously think we could notch them and not worry about it. there isnt much load or stress down by the piston skirt. thats where they file off material when balancing them.. so why cant we take a little more off and have ourselves a notch? i think i would take the chance of notching some 1.5 pistons.

I agree --  the material is relatively soft, and it's not like you'd need to remove that much metal to clear the jets.