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November 29, 2008, 02:43:49 pm

voodoo

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« on: November 29, 2008, 02:43:49 pm »
there is no substitute for a real 1.9 tdi

reinventing the wheel with inferior parts is a bad idea

influencing others to waste time money or effort on a bad idea would be wrong for me to do so I removed the post.



Reply #1November 29, 2008, 03:11:07 pm

Vincent Waldon

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« Reply #1 on: November 29, 2008, 03:11:07 pm »
Interesting idea.

Probably the very first thing to do is a bit of math:  will you be able to get in the neighbourhood of 20:1 compression with that configuration ?  Diesels have a very long stroke and the pistons actually protrude above the block deck at TDC, all part of getting to 20:1.

Some bigger mechanical plumbing issues to look into:

- does the ABA block have holes in the right place to mount the IP bracket
- will the standard diesel IM shaft fit the ABA block (diesel IM pulley runs on the back of the timing belt and so the gear that drives the oil pump is cut in the opposite direction)

The above are deal-breakers... and perhaps others will think of more.

There's some design things to think thru as well:

- the TDI pistons have a very specific cut-out for proper combustion
- dunno if ABA pistons/rods/crank/mains would stand a 20:1 pounding for long

Definitely an interesting idea... looking forward to what others come up with here.
Vince

Edmonton, Alberta, Canada
2001 silver TDI Jetta Malone Stage 1.5 , 2001 blue TDI Jetta SBIII 216s Malone Stage 3, 1970 Bay Window bus

Gone but not forgotten: 1969/1971 Beetles, 1969/1974 Westies, 1979 Rabbit, 1986 TD Jetta, 1992 gas Jetta, 1994 TD Jetta

Reply #2November 29, 2008, 04:15:57 pm

voodoo

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« Reply #2 on: November 29, 2008, 04:15:57 pm »
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Reply #3November 29, 2008, 06:28:15 pm

Tintin

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« Reply #3 on: November 29, 2008, 06:28:15 pm »
I dont think the bloc, piston and rod last long.

Have you really look at a Diesel piston compare to gaz?

Reply #4November 29, 2008, 06:33:26 pm

Vincent Waldon

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« Reply #4 on: November 29, 2008, 06:33:26 pm »
Quote from: "voodoo"

because the 1.5L diesel is mostly a converted gas engine with different pistons and head and 23:1 compression, same 11mm head bolts and if that works then I cant see why a more modern engine would not work as well.


There's a great paper floating around from the originial dudes that worked on the VW diesel design that speaks to the  considerations made as they worked this... I'll see if I can dig up a working link.

The block looks the same because they wanted to reuse some of the bulk casting molds and some other gasser parts (oil pan, etc) but there are many many differences as well.

In any event, everything else is moot if you can't get somewhere around 20:1 compression... I'd recommend you start with the math and see if you can get it to work.
Vince

Edmonton, Alberta, Canada
2001 silver TDI Jetta Malone Stage 1.5 , 2001 blue TDI Jetta SBIII 216s Malone Stage 3, 1970 Bay Window bus

Gone but not forgotten: 1969/1971 Beetles, 1969/1974 Westies, 1979 Rabbit, 1986 TD Jetta, 1992 gas Jetta, 1994 TD Jetta

Reply #5November 30, 2008, 12:03:23 am

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« Reply #5 on: November 30, 2008, 12:03:23 am »
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Reply #6November 30, 2008, 01:56:25 pm

VW_Commuter

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« Reply #6 on: November 30, 2008, 01:56:25 pm »
Here are some of the 'issues' that I can come up with off the top of my head for this project:

1.  Diesel EGTs can reach 1200+ F for sustained periods of time, are the ABA pistons capable of living in those conditions?

2.  Would the thrust that is developed during the power stroke be too much for the con rods, crankshaft, bearing webs?

3.  Since the CR of the ABA is around 10:1 and TDI's run around 19:1, can the ABA block withstand a doubling of the cylinder pressure?

These are just a few things I came up with quickly.
Greg

'06 Golf TDI traded in for a '12 Jeep Rubicon (the Phatbox is available)
'91 Jetta TD, a work in progress (I'll do a build thread when I start in earnest)
'65 Notchback, a project not yet started

Reply #7December 01, 2008, 12:01:03 am

Vincent Waldon

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« Reply #7 on: December 01, 2008, 12:01:03 am »
In case Search leads someone here some day... here's a thread with the original SAE design paper that explains lots of what the original designers of the VW diesel thought thru:

http://www.vwdiesel.net/phpBB/viewtopic.php?t=17187
Vince

Edmonton, Alberta, Canada
2001 silver TDI Jetta Malone Stage 1.5 , 2001 blue TDI Jetta SBIII 216s Malone Stage 3, 1970 Bay Window bus

Gone but not forgotten: 1969/1971 Beetles, 1969/1974 Westies, 1979 Rabbit, 1986 TD Jetta, 1992 gas Jetta, 1994 TD Jetta

Reply #8December 01, 2008, 12:30:46 am

jimfoo

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« Reply #8 on: December 01, 2008, 12:30:46 am »
Don't forget the 11mm head bolts were barely acceptable for a 1.5. I predict major HG leaks. The TDI pistons are developed for swirl. You will get crap burn with gas pistons.
Jim
1966 Land-Rover 88" with 1.9 1Z which has been transformed to an M-TDI
TFO35 mechanically controlled VNT, IC , and 2.5" exhaust.
Driven daily

Reply #9December 01, 2008, 12:58:35 am

cyrus #1

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« Reply #9 on: December 01, 2008, 12:58:35 am »
Thanks Vince, I just read that SAE paper through!

What size head bolts do TDI's use?  The SAE paper stated that the swirl chamber design distributes combustion pressure much more evenly than DI.
Cody

2002 Jetta TDI
2000 Jetta TDI - R.I.P.
1990 Jetta 8v-Eventually to be 1.6TD

Reply #10December 01, 2008, 03:47:24 am

jtanguay

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« Reply #10 on: December 01, 2008, 03:47:24 am »
TDI's use 12mm

that paper is cool! explains how the governor works as well as many others!!! thanks!


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Reply #11December 01, 2008, 01:08:50 pm

voodoo

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« Reply #11 on: December 01, 2008, 01:08:50 pm »
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Reply #12December 01, 2008, 01:21:24 pm

zukgod1

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« Reply #12 on: December 01, 2008, 01:21:24 pm »
I wonder if you could do an over bore and install TDI pistons in your block?

I cant remember what the TDI bore is but I think it's close to the ABA.
dan

99 Golf TDI (now CNG powered) , 82 TD Caddy

Reply #13December 01, 2008, 09:08:29 pm

jtanguay

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« Reply #13 on: December 01, 2008, 09:08:29 pm »
Quote from: "voodoo"
which is stronger ARP 11mm head studs or  OEM grade 10.9 12mm diesel stretch bolts?

the last febi brand set of 12mm bolts I bought came from taiwan

are the people who bought ARP 11mm head studs complaining about constant head gasket failures after the installation of ARP studs?

the end goal for this is a 50 hp no turbo diesel with 17:1 compression and any engine with a  TDI head.


you could try buying some prothe TDI pistons to help keep the cost down, but thats the only way i see this working...

i personally think you will have better luck trying to get the 1.6TDI idea of his working.  

i could somehow see the injector burning a hole into the ABA pistons over time...


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Reply #14December 02, 2008, 02:56:03 pm

voodoo

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« Reply #14 on: December 02, 2008, 02:56:03 pm »
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