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View Full Version : Swapping a 16V Into an 8V Jetta with Digifant FI


Mr_Diesel
08-02-2005, 05:25 AM
Hey all... I was removing the diesel engine from my coupe to go over some things.

1. Tranny mount was bad... Engine moved almost freely.
2. Clutch was slipping pretty badly
3. CV Joints were toast
4. Tranny was making noise... Needed to swap in one of my spare trannys.

I took out the engine and replaced the tranny mount. I took the tranny off, installed a used clutch disc from the collection of parts that has about 50% of it's life left. Installed a different transmission.

To put a long story short, I decided the engine was old and tired. The diesel has well over 450,000 miles on it, and it just wasnt worth my time to be messing with anymore.

A ENGINE SWAP WAS NECESSARY!!! I have a spare 16V sitting in my garage, and I figured what the hell. The coupe is GETTING A 16V!!!

I am going to try to best document this swap in this post... If you think I may have missed something let me know and I will add it to the list.

While pondering the installation of this engine it occured to me that the 16V uses CIS injection... This is a commodity that my 91 Jetta (originally equipped with an 8V engine) did not have. Thinking about the best ways to do this. I could either install the entire CIS system, which would be a PITA, or I could modify the 16V to run on Digifant electronic injection. Since the coupe already had a Digifant ECU, and I already have tons of Digifant sensors and other parts, it was the most viable way to do this.

I chose Digifant injection.

Most of you are probably asking me why the hell I am going digifant... Lots of people call it Digifart... While this is true with digifant II, this is not true with digifant I. The G60 corrado uses Digifant I. There are several differences in the G60 Digifant I, and the Digifant I that was installed in my 91 Jetta. Due to stricter emission controls in California, Volkswagen offered Digifant I in their later model MkII's. Instead of using batch fire fuel injectors, the fuel injectors each have their own circuit, and they each fire individually, this helped VW reduce emissions a bit. More precise fuel injection.

Digifant I california, also had a check engine light, and more advanced electronic diagnostics. My coupe had a freaking SMOG pump, and an EGR system! I'll have to take pictures of this thing... It's amazing... Anyway, my Jetta had two cat coverters. None of this crap will be used in the 16V swap. Before the diesel swap, I removed the 8V engine with the EGR and smog controls. I removed both cats for the purpose of the diesel. I tucked away all the wires for the digifant I, because I was too dang lazy to remove the ecu and wires (thank the maker for this one... now I don't have to reinstall it).

Basically, I am going to modify the 16V engine to make the ECU think it's still an 8V. This will include the following.

1. First and foremost. An EFI fuel rail. You can't use the 8V fuel rail, because there is not enough room under the 16V manifold for the rail. Instead, we need a custom fuel rail. These can be purchased from http://www.eurospeed.ca or http://www.bahnbrenner.com . Eurospeeds rail is much much cheaper, and you can bolt up your 8V factory fuel pressure regulator to the rail. I paid 147 US dollars for my eurospeed rail, whereas BB's rail was over 190 dollars with the "optional" fuel pressure regulator adapter. Not a good deal. I've heard good things about the eurospeed rail, so I chose this one.

2. You will need a lot of stuff from the 8V setup. Make sure you keep the maf sensor, you'll need this for the swap. KEEP EVERYTHING until the swap is done.

3. The water temp sensors, knock sensor, oil pressure senders on the 16V engine can be used. They are compatible with the 8V injection system. You will need to source a throttle body from a G60 corrado engine, or a passat 16V engine (WITH AUTOMATIC TRANSMISSION). These two throttle bodies have the throttle position sensors you will need for your conversion. Either will work fine. The manual tranny 16V passats will NOT work for this. The hal sensor inside the 16V distributor is plug and play I am told. No need to swap this out. The ISV (idle stabilization valve) is plug and play. The 16V ISV will work with the digifant system. The MAF sensor is necessesary for Digifant's operation. Use your 8V maf sensor, it will work just fine.

4. Leave the fuel system in tact. The 8V fuel pumps will work just fine. I am going to use 1.8L 8V fuel injectors for this application. Ideally you could get high flow injectors (30lb mabey?) from bahn brenner, but I don't think it will be necessary unless running a turbo or something.

5. Make sure you get the 16V exhaust manifold with the engine you obtain for the swap. The 8V exhaust manifold WILL NOT FIT on the 16V head. Plus, the 8V manifold is restrictive anyway.. the 4-2-1 manifold is great... these come on 100% of 16V engines.

6. THE CIS 16V OXYGEN SENSOR WILL NOT WORK WITH YOUR DIGIFANT SYSTEM!!! Make sure to harvest the oxygen sensor from your 8V system. It will fit just fine in the oxygen sensor hole on the 16V manifold.

7. Make sure you plug off the cold start valve on the 16V manifold. It is not needed for EFI. It's usually blue, located on the right side of the manifold. There will have been a fuel line running to it.


This is all I can think of at the moment... I havent yet finished the swap, but I have done many many hours of research. Remember what we are doing, basically is making the ECU think the 8V is attatched. We modify the fuel rail, and adapt all the connections to accomodate the sensors on the 16V.

Now we come to the biggest question... What about a turbo? Doesnt Digifant suck for a turbo? The answer is yes and no. Digifant II sucks for a turbo. Period. Worst ECU EVER for forced induction. But here I am working with Digifant I. I am luck enough to have a california Jetta with a variation of the G60 ECU. The california jetta's ECU will gladly accept chips designed for the G60 ECU. Parts list for turbo digifant I:

1. Bigger air sensor. BMW used a VERY similar air sensor on their older cars. These had a much larger pathway for the air to travel, and require very little modification to work with digifant I. (i'll make a post about it when I come to this point)

2. More Fuel! High pressure fuel pump. 3.5 or 4.0 bar fuel pressure regulator. 30 or 40lb injectors. (and of course, a chip. ECU software to control this new fueling method) All of these things are availible online on various parts websites. Bahn Brenner has all of this stuff... So does Eurospeed.com

3. Lower compression. This is where the bid decision comes in. Different pistons to lower compression? Nah... EIPtuning.com has cylinder head spacers that help lower the compression. In my opinion, ideal compression would be in the neighborhood of 8:1 to 8.5:1. If you choose not to lower compression, I wouldnt go any higher than 5 or 6 psi with the stock 16V engine.

That's pretty much it. Remember, I started out with a Digifant I ECU... Most of you will have Digifant II... I think digifant II will work fine with the 16V if you don't plan on running a turbo, but digifant I or standalone like megasquirt is necessary.



That's the end of the post for now... I'll see if I can get some pictures tommorrow. I"ll let you guys know if I run into any more issues.[/b]

twig
08-02-2005, 07:58 AM
too bad that it won't be diesel anymore, "MR. 16v Digifant F1" just doesn't have the same ring to it

Gotturbo
08-02-2005, 11:31 AM
5. Make sure you get the 16V exhaust manifold with the engine you obtain for the swap. The 8V exhaust manifold WILL NOT FIT on the 16V head. Plus, the 8V manifold is restrictive anyway.. the 4-2-1 manifold is great... these come on 100% of 16V engines.

Yea cody! Good thing I still have my parts car!!!

MKIIVR6
08-02-2005, 09:13 PM
That cool Cody. The trans am just was not the same as the coupe. :lol:

Mr_Diesel
08-03-2005, 01:34 AM
That cool Cody. The trans am just was not the same as the coupe. :lol:

Yeah... I miss the trans though... Ohh well...


I installed the engine today. Got it all mounted up. The exhaust manifold is on, but not hooked up to my cat yet. None of the electronics are hooked up yet... I was too greasy and tired to finish that up.

The transmission mount was hell. For some reason, the MkII transmission mount is always a bizitch to hook up... But I got it in there right this time. Tomorrow me and Sam (gotturbo) are going to the junkyard. I need to get a throttle body from the automatic passat. A misc 16V coolant hose. A fuel resivior/fuel pump housing off a digifant jetta and then all I need is the fuel rail to come in the mail, and i'm golden.

Pictures to come.

TisforTurbo
08-03-2005, 04:05 AM
sounds pretty sweet, when do you think the fuel rail will get in? in time for the mt nebo cruise?

damn, why am I on here at 3:10 in the morning??

Mr_Diesel
08-03-2005, 04:18 AM
sounds pretty sweet, when do you think the fuel rail will get in? in time for the mt nebo cruise?

damn, why am I on here at 3:10 in the morning??

It's 3:21a.m. right now... Just working the graveyard shift right now... LOL... We are one in the same.

The cruise is what I am aiming for... I ordered the rail a couple days ago from canada... So it should be a week atleast... In the mean time I get it all done and ready except for the fuel rail.

Mr_Diesel
08-06-2005, 05:27 PM
Hey all... I was up till about 4:00 a.m. last night working on the "Coupe De Gras". I got lots done.

Here is an overall picture of the swap... Taken a lot of time and planning getting it to this stage.
http://www.dubnetworks.net/images/16vcoupe/IMG_1269.jpg


Here is a picture of the intake I rigged up... Since I am doing digifant I, and 16V, I needed to rig up a combination of the 2 intake pipes. I cut off about 4 inches of the old 16V intake pipe, and about 2 inches of the 8V intake pipe to make a rubber sleeve to connect the 16V pipe to the air sensor. A hack saw and about 10 minutes. Don't forget the hose clamps (like I did :evil: )
http://www.dubnetworks.net/images/16vcoupe/IMG_1270.jpg


A side shot of the engine. You can see the yellow throttle body in this picture and in the last picture. This throttle body is off a 16V passat (automatic tranny). It has a throttle position sensor on it, like the 8V engine. I got this from the junkyard, where the engine was painted yellow (barf!).
http://www.dubnetworks.net/images/16vcoupe/IMG_1271.jpg


Here are some goodies I got from the junkyard while I was there. A digifant fuel resivior with a bosch fuel pump inside. I got this out of an automatic 1.8L 8V jetta with 58,000 miles on it!!! A 250 dollar bosch pump for 10 dollars at the local wrecker. (SCORE!!!)
http://www.dubnetworks.net/images/16vcoupe/IMG_1272.jpg


Here is another goody I got at the junkyard. The infamous digifant VAM air sensor. Since the car only had 58k, I figured I might as well pick this up while I am at it... Paid 20 bucks. List price for this is usually around 200 bucks as well. Yet another score.
http://www.dubnetworks.net/images/16vcoupe/IMG_1273.jpg


Hose clamps and hoses. Big hose is for the ISV (which I have yet to rig up) and the crankcase ventilation (which I have yet to rig up. But they must go on the intake hose before the throttle body and after the maf... Sooooo I dunno how I am going to do it, but we'll see.).
http://www.dubnetworks.net/images/16vcoupe/IMG_1274.jpg
http://www.dubnetworks.net/images/16vcoupe/IMG_1275.jpg


The old 1.6L diesel engine with 480,000 miles on it... It's life as a car engine is over, but I am going to buy harbour freight's 30kw alternator and make another volkswagen generator.
http://www.dubnetworks.net/images/16vcoupe/IMG_1276.jpg


Dead 16V block, and the old retired manifolds from the diesel setup.
http://www.dubnetworks.net/images/16vcoupe/IMG_1277.jpg


Single/Individual Injector Fire Circuit Harness for Digifant I
http://www.dubnetworks.net/images/16vcoupe/IMG_1278.jpg

GoodDayForADrive
08-09-2005, 09:13 AM
Wow, interesting setup. This is gonna be sweet to see how it all works out :lol:

Mr_Diesel
08-14-2005, 01:27 AM
I got the sucker back on all 4 wheels... It's been sitting on jackstands for months. I cleaned all the volkswagen parts and the rats nest of wires out of the trunk so I can work on the fuel pump wiring.

I fixed the fuel pump system under the car (since I had straight piped everything for the diesel). Only things left to do:

1. Waiting for my fuel rail.
2. Weld some 3 inch pipe after my cat all the way back to a hallowed muffler.
3. Run wires to my new fuel pumps
4. Install the WHITE fenders and take off the blue fenders.
5. Find a good white hood in the junkyard.
6. Reinstall front and rear bumper covers.
7. Reinstall the radiator.

Everything except the fuel rail should get done next weekend, so all I'll need is the rail.

GoodDayForADrive
08-14-2005, 05:44 PM
I wish I actually knew stuff about cars... lol

Gotturbo
08-14-2005, 06:01 PM
That coupe in the JY that I was gunna get the visor out of was white... The hood might be good on it.

Mr_Diesel
08-14-2005, 07:32 PM
That coupe in the JY that I was gunna get the visor out of was white... The hood might be good on it.

You talking about that one that is sitting on it's side? lol

SteveXs2
08-15-2005, 12:36 AM
Damn man, this is gonna be a sick car. 3 inch pipe from the cat back? Fun :D

I'm looking at piecing together a fatter exhaust myself, I just need some money coming in to get the pieces (like $8 each at Canadian Tire) and a decent muffler.

What else do you have planned for this car?

Mr_Diesel
08-15-2005, 08:26 AM
Damn man, this is gonna be a sick car. 3 inch pipe from the cat back? Fun :D

I'm looking at piecing together a fatter exhaust myself, I just need some money coming in to get the pieces (like $8 each at Canadian Tire) and a decent muffler.

What else do you have planned for this car?

Well... this is the way I see it.... There is a fat pipe coming of each port on the exhaust manifold... Those 4 form 2 big ones, and those 2 form one huge one... about 2 1/2 inches wide, actually... The inlet on the cat is about 2 1/2 inch. So I am going to take a hack saw and make the outlet on the cat about 3 inches... Then I will take my mig welder and weld a nice piece of 3 inch on there... This will go all the way back to my muffler which will rest in the position of the resonator (under the back seat)... Then I am going to run 2 3/4 or 3 inch pipe from the hallowed out muffler over the rear axle and out the back... It's going to have a really deeeep rumble at low rpm, and probably sound like a weedwacker at high rpm.

got_turbo
08-15-2005, 11:55 AM
Yea the one thats on its side.

streetdblo
01-01-2007, 10:57 PM
man dude, that car is coming along very very nicely.... any idea where i could get me a 16v ora 2.0 mk3 engine? going for lots and lots of power out of my 89. and get some more pics up... i want to see the finished car. not to many ppl do stuff with these old jettas any more