I know there's several threads (and one really big one) on the subject
of 20/20 conversion. However, 98% of that only centers around pre MK4 motors.
One of the biggest difference MK4 motors DO NOT require plugging
any oil drain holes in the 20v head (among other differences).

I'd like to consolidate the MK4 conversion info into this thread.
This swap should be alot easier and shouldn't have all the extra
details associated with older motor conversions confusing others researching this conversion.

I'll post later with any MK4 specific info from the big 20v thread and all the info I have on this subject.

BIG THREAD - 20V Hybrid - How To

Thanks,
Rey

edit: Let me start off with this:

The biggest problem that we have to get past which will convince 99%
of you just starting research NOT to go through with it is this....
you CAN NOT use the stock 2.0L pistons as they are. The stock pistons
will NOT clear the middle intake valve on the
20v head (at least not with safe tolerance). You have 2 choices:

1) modify the stock pistons by machining a notch relief to clear the valve

2) buy custom pistons

I won't get into reasons for going with either now, BUT either choice REQUIRES
removing the pistons from the block. This also involves at least prep honing
the cylinders and new pistons rings that you need to properly gap.

Modified by elRey at 2:09 PM 2-13-2006

'90 Black Jetta GL
MK4 2.0L turbo AZG/02J 5spd swap w/ VR6 spindles/LCA/complete rear beam and disc brakes/5lug/TT front brakes & TT 11" rear brakes/ & 16" MK4 steelies

1.8t Swap FAQ

Use a regular 1.8t timing belt.

Using a stock 1.8t headgasket you get ~7.8:1 compression. Using an AEB headgasket you get ~8.5:1 compression.

The stock pistons must be notched to clear the 5th valve.

If you retrofit the 2.0 CPS to the 20v head it can be run off 2.0 engine management and coil w/ longer spark plug wires. Just build a custom intake pipe w/ maf and custom exhaust manifold.

... internally don't bother with the stock pistons and rods. The stock pistons are extremely weak. The stock rods are the same as the 1.8t in strength. Replace them. Talk to Rodney @ JRC about internals he has done all the match and done these pistons for a 20/20 many times.

http://www.jrcmotorsports.com/

Is there a tooth count difference b/w the 1.8T and 2.0 belt?

Quote, originally posted by 2kjettaguy »

Using a stock 1.8t headgasket you get ~7.8:1 compression. Using an AEB headgasket you get ~8.5:1 compression.

Would using a 1.8 head gasket require boring it out for the larger cyc bore?

Why not use a 2.0 gasket? cr? 3 oil passage holes need to be added to the gasket... easier than boring cyc clearance tho

Quote, originally posted by 2kjettaguy »

The stock pistons must be notched to clear the 5th valve.

Quote, originally posted by bobqzzi »

Intake valve diameter 26.95mm Center valve 15 degrees*

Quote, originally posted by 2kjettaguy »

If you retrofit the 2.0 CPS to the 20v head it can be run off 2.0 engine management and coil w/ longer spark plug wires.

Can the 2.0 management not run the 1.8T CPS? Just splice correct connector?

What about injectors? Can the 2.0 management run the 1.8T injectors?
Or can the 2.0 injectors be used w/ the 1.8T intake mani and rail?

Thanks for the great info.
Rey

'90 Black Jetta GL
MK4 2.0L turbo AZG/02J 5spd swap w/ VR6 spindles/LCA/complete rear beam and disc brakes/5lug/TT front brakes & TT 11" rear brakes/ & 16" MK4 steelies

The real crux here is engine management. There are little to no 'chip' options for the AEG/AZG/AVH 2.0. There's nothing for a 20/20. Your only option for boost sofware is ATP (sucks) or EIP (uses Boost FPR). Still neither will be perfect. EIP can do custom software for you but you'll need to leave the car with them for a while. For $1500 you might as well go standalone.

Evan

Sorry. I had it in my mind due to my personal project timeline, that if 2.0 management would even be considered, it would be for a NA application (a temp situation/phase for me). Like one step in the complete conversion ending with a 20v head and turbo.

I wasn't even thinking 20/20 turbo'ed management yet.

Rey

Modified by elRey at 2:02 PM 2-11-2006

'90 Black Jetta GL
MK4 2.0L turbo AZG/02J 5spd swap w/ VR6 spindles/LCA/complete rear beam and disc brakes/5lug/TT front brakes & TT 11" rear brakes/ & 16" MK4 steelies

What about the NS SC chip, if I recall correctly you ran in in a 2.0T engine

Or what about the stock 1.8T AEB software?, it was driver by cable.

Modified by randallhb at 7:53 PM 2-12-2006

Knowledge and experience after that turbo project tells me that software was nowhere near correct for what I was doing.

1.8t software won't work if you're doing this to a 2.0. If you're doing this to a 1.8t then yes, it will.

Evan

So, what software Eurospec uses for those engines.

I don't believe they offer any software for their engines. They just give you the hardware and leave you to fend for yourself on the software side.

'90 Black Jetta GL
MK4 2.0L turbo AZG/02J 5spd swap w/ VR6 spindles/LCA/complete rear beam and disc brakes/5lug/TT front brakes & TT 11" rear brakes/ & 16" MK4 steelies

All the following sourced from: BIG THREAD - 20V Hybrid - How To

-------------------------------------------------------

Quote, originally posted by Wizard-of-OD »

Well same principal applies if you dont want to spend money on pistons.Your CR IS going to drop from 10:1 to 8.5:1 when you place the 20V on the AEG bottom end. I wouldnt bother buying an "OEM" exhaust manifold when there are tons of decent fabricators all over vortex that can build you a decent extractor for less than what you would pay if you were to import an OEM unit.Talk to Silly SOHC for all your fabrication needs.

'90 Black Jetta GL
MK4 2.0L turbo AZG/02J 5spd swap w/ VR6 spindles/LCA/complete rear beam and disc brakes/5lug/TT front brakes & TT 11" rear brakes/ & 16" MK4 steelies

Here are some parts that will need to be replaced with 1.8t specific
parts beyond head & mani's (assuming end product will be 20v with stock turbo):
- oil filter bracket (OR find different source for turbo oil feed)
- coolant pipe on from of block (needed to clear turbo inlet pipe)
- remove or relocate sec. air pump (1.8T hoses/bracket)
- most of the coolant lines
- all of the vac lines
- coolant supply hole drilled into back of block for turbo (OR find different source)
- oil pan w/ oil return connection (or modify 2.0 pan)
- downpipe

Modified by elRey at 9:28 AM 7-4-2006

'90 Black Jetta GL
MK4 2.0L turbo AZG/02J 5spd swap w/ VR6 spindles/LCA/complete rear beam and disc brakes/5lug/TT front brakes & TT 11" rear brakes/ & 16" MK4 steelies

OKOKOK

So I have a decked (.01") AEG block and I was wondering if this was going to make it practically impossible to modify the pistons so much in order to clear the valves on the 20v head?

Modified by twicepardoned at 12:16 PM 7-4-2006

I hear what you need is aeg headgasket (although 1.8t will work and make even lower CR) and you can use aeg timing belt. You WILL need pistons, that is something everyone here can agree on. Stock AEG ECU MIGHT make the head WORK, but it won't make it work WELL.

So engine management's the biggest obstacle as of now.

Anyone selling/fabricating rods/pistons for this project? AND can we organise a group buy?

Modified by Kougaiji at 3:13 PM 7-4-2006

"cheap radar detectors are like using a box of condoms knowing that one of the condoms has a hole (but not which one), it may save you a few times but eventually you will get screwed over."

"cheap radar detectors are like using a box of condoms knowing that one of the condoms has a hole (but not which one), it may save you a few times but eventually you will get screwed over."

'90 Black Jetta GL
MK4 2.0L turbo AZG/02J 5spd swap w/ VR6 spindles/LCA/complete rear beam and disc brakes/5lug/TT front brakes & TT 11" rear brakes/ & 16" MK4 steelies

Other than that, I think you may have a good point and maybe just doing a bit of custom work on the pistons wouldn't be so bad after all!

NEVER MIND>>... I'm an even bigger idiot because I just followed your link and discovered what squish quench is.... *stupid, stupid, stupid*

Modified by twicepardoned at 8:07 AM 7-5-2006

Very insightful article... I certainly will NOT be using a thicker gasket. I am 100% convinced that it will be much more beneficial to do minor modification to the pistons (or simply buy ones for this application).

Thanks Elrey!!!!!

Also what abought the accesories like the intake and exhaust... I assume you have to use 1.8T's equipment as well????

That's a positive on all counts.

"cheap radar detectors are like using a box of condoms knowing that one of the condoms has a hole (but not which one), it may save you a few times but eventually you will get screwed over."

I think this means I will really be taking my time putting this project together. LOL

Granted I don't think I want to put a 20v and a turbo setup on a stock 2.0 block... because sooner than later I imagine I'd find myself ticked when I blew the bottom end out.

You're safe with AT LEAT 19 psi, most likely more.

"cheap radar detectors are like using a box of condoms knowing that one of the condoms has a hole (but not which one), it may save you a few times but eventually you will get screwed over."

Don't worry about your bottom end too much right now unless you start heading closer to the 300hp range.

"cheap radar detectors are like using a box of condoms knowing that one of the condoms has a hole (but not which one), it may save you a few times but eventually you will get screwed over."

"cheap radar detectors are like using a box of condoms knowing that one of the condoms has a hole (but not which one), it may save you a few times but eventually you will get screwed over."

For simplicity, best from a jetta/gti or audi tt 180.

8v manifolds WILL NOT bolt up to a 20v head.

If you intend to go N/A or aftermarket turbo, you'll more than likely need
a custom exhaust mani.

cheapest turbo route is to go all stock 1.8T stuff used. Will not get you much power, but cheap.

cheapest NA route is to use stock 1.8T stuff and have a custom connecting pipe fab'ed from 1.8T exhaust mani to your stock downpipe. Not the best for power, but I said cheapest.

With any of these options, you'll still need to modify your stock pistons to get the 20v head on.

We haven't even discussed wiring issues or software.

But focus on the modifying/custom pistons obstacle. If you can't swallow that, don't think about this swap any longer.

Rey

'90 Black Jetta GL
MK4 2.0L turbo AZG/02J 5spd swap w/ VR6 spindles/LCA/complete rear beam and disc brakes/5lug/TT front brakes & TT 11" rear brakes/ & 16" MK4 steelies

The only thing that sounds difficult to me is finding a donor car to use. Because I am not going to garage my car for months and swap a piece at a time. When I do it I'm doing it all at one time.

I'll probably take a week of vacation time from work and smash it out with 2 or 3 friends in a week and couple days.

In fact I just has a friend in KC who was hit in the side in his Passat. It was the turbo also. But unfortunately instead of buying it back from the insurance company he sold it to them!!! So I'm currently chasin g that wreck down and trying to buy it from the insurance co.

I just wish I would have known before he signed it off. I think they paid like $500 or something small like that.

'90 Black Jetta GL
MK4 2.0L turbo AZG/02J 5spd swap w/ VR6 spindles/LCA/complete rear beam and disc brakes/5lug/TT front brakes & TT 11" rear brakes/ & 16" MK4 steelies

But at the same time I won't even begin the process until I can put together the full set piece by piece in my garage or I get a parts car.

A parts car is most reasonable because I need a 5 spd also. So basically I know it'll be awhile before I can start so I'm continuing to pursue my 8v setup.

"cheap radar detectors are like using a box of condoms knowing that one of the condoms has a hole (but not which one), it may save you a few times but eventually you will get screwed over."