Converting a 9a gasser shortblock to diesel???

[Jetmugg]

Thanks for the link, RJ. 

Based on the dimensions that I have found, the compression height of the Ford 1.8TD pistons is 45.65mm.  To work in a 9A block, I think that would require a custom set of "shorty" rods, regardless of which crankshaft is used (86.4mm stroke or 92.8mm stroke).


Not impossible, but not regularly available, either.


Using the ABA block, it appears to be plausible.

[Karel87]

Why not to use 144mm AAZ or TDI rods? When using 92.8 stroke crank, pinstons would be placed only 1,35 mm lower compared to AAZ. That depth can be easily milled off from the block deck. Been there done that! Maximum depth, what I have seen was 9mm . It was 1,6TD block used to make small displacement gasser racing engine.

[Jetmugg]

Perhaps I'm missing something in the dimensions, but I don't think so.


The 9a block is 220mm from c/l of crankshaft to the top of the deck.

With 92.8mm stroke, 144mm rods, and 45.65mm compression height of the Ford 1.8 piston, that shows me.....



(92.8/2) + 144 + 45.65 = 236mm, which would put the top of the piston 16mm up past the top of the block.

[theman53]

You are missing the point. If you go with all the custom stuff it would probably be less expensive to go full on aaz with a bore job to get to 2.0. The 16v pistons are flat top not notched like the ones RoR was talking about. If you get a cheap decent condition 9a bottom throw your head on and run it before and see if it works out. If it does then get the forged pistons that crsmp5 is talking about for 600 and let it rip.
Otherwise I think aaz will be cheaper than the 9a hybrid ford piston thing that might or might work.

[Karel87]

my mistake! I thought that 9A had also 236mm height block like ABA.

[RabbitJockey]

http://www.vwdiesel.net/forum/index.php?topic=12486.20;

http://www.vwdiesel.net/forum/index.php?topic=15610.0;

[Jetmugg]

You are missing the point. If you go with all the custom stuff it would probably be less expensive to go full on aaz with a bore job to get to 2.0. The 16v pistons are flat top not notched like the ones RoR was talking about. If you get a cheap decent condition 9a bottom throw your head on and run it before and see if it works out. If it does then get the forged pistons that crsmp5 is talking about for 600 and let it rip.
Otherwise I think aaz will be cheaper than the 9a hybrid ford piston thing that might or might work.

I get it - the only real way to make the 9a deal cost-effective is to run it basically as-is and see what happens.   I was just checking around to see if there was some combination of oddball parts that might also work.  As you said before, it will run - but how well and for how long.

On a somewhat related note, for next year, I'd like to up the ante on my AAZ head.  I'll send you a PM about the cylinder head guy you used in Ohio.

Steve.

I think I have enough parts to assemble a complete AAZ head, in addition to the one that's already on my 1.5L, with the exception of 1 hydraulic lifter.

[Jetmugg]

RJ - that 2.4 piston, 1.6 block stuff is pretty creative.

Those Chevy rods with Honda journals are some pretty trick goodies, too.  I'd like to find a set of those in my Halloween trick or treat basket.

Steve

[theman53]

You could use your aaz head on the 2.0 deal and get a built 1.6 head for your 1.5 engine. I have a stock cam and at full lift my head is flowing right at 150cfm. Alcaid has an aaz head with a custom cam that ultimately flows more, but at the stock lift my head is flowing 10 cfm more than his. The 1.6 head my machinist and I think have a better port design than the 1.9 aaz. Also IIRC the biggest valves you can put into the aaz are 38mm and my 1.6 head has the 40mm.

[MJF]

Honda journal rods are tried. Too small big end for diesel piston pin, exploded one engine.

[Jetmugg]

Honda journal rods are tried. Too small big end for diesel piston pin, exploded one engine.

Too small on big end, or too small on small end?

[MJF]

Oh, sorry. Too small small end. This is what happened.

[Jetmugg]

Thank you for the clarification.  That photo is an ugly sight.   Any ideas about what the details of that build were?

I figured that the big end was probably OK, due to the fact that they are used in NASCAR type applications, very high RPMs, Chevy sized journals.

The large diameter of many diesel piston wrist pins is certainly a challenge.  Our VW's seem to be on the small side of what's used in common practice for small diesel engines.  The small Ford and Opel diesels are in the range of 26-27mm for the wrist pins.

[R.O.R-2.0]

1.8 is not flat top... has a V milled into it and makes a weak spot...

they make forged 9a pistons.... $$$$ yes.. but if it pulls good #s on the stock ones... why not then invest? pre testing fun...

it is cheap experiment.. 9a value very little vs a aaz bottom end.. hell cheaper then worn out 1.6 diesel ones...

i think will last a few thousand... i think 5-30 with stock 11mm tty headbolts and 30psi... im going to try to greanade mine with nos/propain mix though before that... i want to see what is the weak part..

11mm block WILL NOT take 30psi @ 20:1 compression

PCP will be WAY too high, and you will blow the head off/crack the block..

ive done it before! and i used a diesel block to start with!!

the forged gasser pistons will still not have the toughness of a stock diesel piston...

STAINLESS RINGLAND INSERTS!!!

[Jetmugg]

Probably not stainless steel, but more likely a Ni-Resist cast iron

On another point, does anyone know the volume contained in an AAZ prechamber, with a glow plug and injector installed?  Trying to do some calculations.