Converting a 9a gasser shortblock to diesel???

[theman53]

I used to, it is in the FAQ somewhere. IIRC the volumes were like 1.5 was 18cc and the 1.6 N/A was 18.9cc and the 1.6TD was 18cc and the 1.9aaz was 19.9cc. They varied little between them. I will do some FAQ searching as I think that is where it was and I know it was discussed on here.

I had a friend in ohio with a turbo VR6, 11mm head bolts and it took lots of boost, like 20psi or something. He drove it for almost 50,000 miles and sold it. I have another friend with a 1.8  8v GTI, runs a 12.57 in the 1/4 mile, stock head bolts 19psi from a 18t turbo and a 50hp nitrous shot on top of that. He has raced it for at least 15 years with different power setups. The 11mm bolts and block will hold, just not a 1.6 or 1.5 diesel block, they just seem not to hold up as well as the others.

[theman53]

http://www.vwdiesel.net/forum/index.php?topic=12633.0

so I was way off...you will have to look into exactly what they are saying as some used different methods to measure them.

[Jetmugg]

Hmm, I tried to determine the volume through dead reckoning calculations and some minor assumptions.  I came up with about 20cc's for the AAZ pre-cup volume.

I'm messing around with different pistons that might work in a 9a block, calculating C.R.'s.

I'm actually thinking that the 9a flat-top pistons would give a little bit too much C.R., based on the 92.5mm stroke.

Steve.

[Jetmugg]

Sorry, 92.8 stroke.

[theman53]

I could tell you what I did to mine, but that would be in PM's

[CRSMP5]

 why i keep commin back to the idea of a new head shim..

a aba metal gasket = min thickness as any thinner pistons would hit the head..

then you have a 1 notch aaz one... a nice new piece of steel or copper in a new thickness = win... zip the silly rivitsd off that hold the gasket and shim together and your set.. this is what they did with the turbo vr6 project headgasket... to drop compression..

http://www.cometic.com/  is a place that makes speciality headgaskets and shims... 9a, aba listed there... different thicknesses for turbo apps and such... when me and mr no hair were discussing vr6t stuff.. he hooked me up with this place.. $$$$ yes... but you have a machine shop to do same thing... make new shim...

what happens if you double up the aba shim?

11mm headbolts.. if arp studs used are not a issue.. only a 1.5/1.6 thats been KNOWN overheated to blow a head gasket is weak.. if it cracks the head from heat.. the 11mm block 95% of time cracked... when you goto torque it... supposedly arp studs thread further in then 11mm head bolts...

9a.. i doubt was hot.. not a issue... unlike the mid-lay 80s.. 1.5/1.6 11block histories are gone.. and i knew what it took to see them crack then.. now.. who knows if it been hot.. unless your like me runing ssame 11mm block since 90... and knew its history from previous owner at that..

also if you mill in the micky mouse ears on top of the flat pistons you loose cc too.. so calculate that..

[Jetmugg]

I'm  currently keeping my eyes open for a scorching-hot deal on a set of forged flat-tops, "just in case".

[R.O.R-2.0]

I'm  currently keeping my eyes open for a scorching-hot deal on a set of forged flat-tops, "just in case".

the money you will have to dump into a 9A, will probably be MORE in the end, than just starting out with a slightly more expensive 1.9 bottom end...

Forged slugs are $$$, and not designed for 25:1 compression..

i still think diesel pistons would be tougher/more durable than forged gasser slugs..

[Jetmugg]

The diesel slugs would almost certainly be more durable.  They are engineered to last hundreds of thousands of miles.  This deal will not be about durability.

I already have the 9a short block, and I'm not into it for much $$$.  It was an abandoned project, has stock sized but honed bores, ARP main studs, ARP rod bolts (re-sized rods), and a polished crank.  All new bearings, ring set, and gaskets were part of the deal.

A set of STD sized forged flat-tops, a little time on the Bridgeport, and I'm in the game.

This thing can be a total time bomb and still be a success.  If I can get it to last at least 6 miles, 2 of which must be over 129 mph, then I'm a happy camper.  I don't want to blow it up on the first pass, but if it lets go on the last pass, that's totally OK.

The goal is to put it in the SCTA record books.

[R.O.R-2.0]

The diesel slugs would almost certainly be more durable.  They are engineered to last hundreds of thousands of miles.  This deal will not be about durability.

I already have the 9a short block, and I'm not into it for much $$$.  It was an abandoned project, has stock sized but honed bores, ARP main studs, ARP rod bolts (re-sized rods), and a polished crank.  All new bearings, ring set, and gaskets were part of the deal.

A set of STD sized forged flat-tops, a little time on the Bridgeport, and I'm in the game.

This thing can be a total time bomb and still be a success.  If I can get it to last at least 6 miles, 2 of which must be over 129 mph, then I'm a happy camper.  I don't want to blow it up on the first pass, but if it lets go on the last pass, that's totally OK.

The goal is to put it in the SCTA record books.

Let us know how it runs..

i WANT you to prove me wrong.. but you will need the important parts of an AAZ (head) anyways, so why not go all the way?

that ARP hardware will fit in a diesel bottom end, fwiw..

[CRSMP5]

he has  head.... he has a150+hp at the wheels 1.5 td.....

he wants to run his 1.5 class and the up to 2.0 class... the shorty block here lets his turbo oil lines, exhaust and all swap right over... with just a bottom end swap...

if he is pulling as much hp/torque as he has pulled on his 1.5  id expect 2.0 bottom end will be well over 200... for no more then playing with bottom end...

p.s. down in classified some ad i saw aaz bottom end for 400... in cali... id snatch it up too... just as it not dipped in gold price most are..

[Jetmugg]

Yeah, I have 2 AAZ heads right now. One built with plenty of Techtonics goodies and a Giles cam. The other is bare now, but should get a nice off-season porting before being built up.

[Jetmugg]

Just a little update - I sent JE pistons an email to see whether they could provide a set of forged flat-tops (PN #302339), without any valve reliefs.  I figured that would be a good starting point.  I'll let everyone know what they say.

Steve.

[R.O.R-2.0]

Just a little update - I sent JE pistons an email to see whether they could provide a set of forged flat-tops (PN #302339), without any valve reliefs.  I figured that would be a good starting point.  I'll let everyone know what they say.

Steve.

its gonna be way easier to source a 1.9 bottom end, than to pay out close to a grand for custom pistons..

[CRSMP5]

those valve releifs are less dished then the micky mouse ears if they were milled in.. why i do not worry bout them....