The Project Pad

Folks, this appears to be the best forum for posting these types of swaps. So, here it goes.

I have a great condition 1987 Audi 4000CS Quattro. Engine is great, but slow. The stars recently aligned and I was able to pick up a cheap 1990 Audi 200 with a 20vt engine. Because my day job won't afford me with enough time to do the swap myself, I hired a local Audi master mechanic who owned the same Audi 4000 and has worked for Audi since the 80's. He is very familiar with both vehicles and is up to the task.

I am sure I will have questions and need some advice. I would love to hear from others that have done a similar swap in the past or currently drive a 4000 with the 10tv engine.

IMG_2302 by TrailAgent, on Flickr

IMG_0006 by TrailAgent, on Flickr

IMG_0005 by TrailAgent, on Flickr

First question. Does anyone have any opinion (or real world experience) on which transmission and rear differential to use - the existing 4k 016 transmission (4.11:1 final) or the 200 (3.889:1 final)?

If I go with the 200 drivetrain, I lose the locking center differential. Is losing the center locking differential worth it?

The 10tv engine has a 2Bennet boost chip installed already, so the engine will be will be putting out more power than a stock 10tv.

I am more interested in spirited city driving than overall top speed.

Nice to see a 20vt swap pop up.

I kept the stock 4kq drivetrain when I did mine and I didnt regret it. I prefer the center/rear locker, but thats just me.

Welcome!!!

definitely use the 4kq driveline. Short gears are fun and locking diffs are awesome.

I think you'll find that the short gears will be annoying when you have all the extra grunt of the 20vt.So 200 gearing would be better... But you'd have to swap the rear diff for a 3.89:1 diff as well. And the only one out there (that should fit) is the urq's.

So, what some do instead is change only the short 5th gear on the 4kq transmission.

Another option is the 200 20V transmission. It's 4.11:1 and has longer gears, but no locker.

TrailAgent wrote:I am more interested in spirited city driving than overall top speed.

given this statement, i cant see bothering to swap out the trans and loose the locker being worth it to gain taller gears.

I really liked my 20vt with the 4kq trans. Made it feel really quick. To each his own, either way the car will be fun!

Thanks for the feedback! Glad to hear that staying with the 4kq transmission is a viable option.

I'll look into the 5th gear swap.

From a time and cost standpoint, my choices are limited to either using the existing 4kq transmission or the 200 transmission and 200 differential. In other words, I don't want to spend a lot of time and money sourcing transmissions and differentials unless I have to. If the 200 differential won't fit the 4000, then that means I will need to stick with the existing 4kq drive train this go around. If it becomes unbearable, I can change it out another day.

Forget the 200 drivetrain and put the 20vt in. Like others said add the tall 5th gear. You'll like the short gears and you'll have this project done a month ahead of time

Second question:

Does anyone have advice on fitting the 20v air box and intake boot into the 4000? There seems to be two routes. One is to cut a hole in the fender wall. The second is to find a URQ "igloo". I suspect that finding an igloo will be difficult.

Does anyone have a source for purchasing the URQ igloo, or is there an alternative solution, such as using the intake boot from a BMW such as the following? Or, is the most practical solution simply to cut the fender wall?

https://www.fcpeuro.com/products/bmw-en ... aQoddk4Psw

Thanks!

Disregard the old and nasty engine bay. This was my old car. I just used the stock 4kq airbox (you can use the Urq one), 5ktq fuel dizzy, Urq airbox inlet (igloo), and the factory Urq hoses from the igloo to turbo inlet. If you are feeling really saucy get a Urq downpipe as it bolts up to the rest of the exhaust.

You CAN cut the fender, but it really depends on how clean you want things. The 5ktq injector lines are longer, but there are ways to route/tidy them up.

Looks tidy! I guess the question is where can I find a Urq airbox inlet (igloo). So far, I have not found any for sale.

I think Angry taco had one fs a while ago.

Sent from my SAMSUNG-SM-G870A using Tapatalk

According to his listing, its sold.

Taco sold his, and the 2 that were on eBay are also no longer listed. You might try looking through audifans.com, there were some on there as well.

DE80q wrote:Taco sold his, and the 2 that were on eBay are also no longer listed. You might try looking through audifans.com, there were some on there as well.

lol, I had sold him one of those

On Facebook William Foster has one for sale. I think there was another person on the 'Small Chassis Audi' page also looking to sell theirs.

FWIW, I'm throwing a 3.89 trans and urq rear dif in mine with the 2.5L 1Ovt stroker I'm building.


Looking forward to seeing how this goes. I ran 13.6s consistently with mine on a factory k24 and CIS

Mechanic has taken everything out of the 200 and has started to assess what needs to be accomplished for the swap. It turns out that my 4KQ differential lockers do not work and the 4KQ transmission could use some work. So, we will be using the 200 transmission and rear differential. Apparently, the 1990 rear differential should fit the 4KQ, whereas the 1991 200 rear differential does not. Worse case, I will need to find a 5000Q rear differential.

Does anyone know for sure if the 1990 Audi 200 differential will or will not fit the 4000?

the 5000/type 44 rear diffs aren't the same, nor will they bolt into a Type 85 car. Anything is possible, but the 200 rear diff is considerably longer than the 4000 rear diff, so you'll need a different drive shaft (shorter) to make it work.

You'd be better suited to find a 200 20vt trans as mentioned above... or fix the lockers on the 4000.

Do they not work b/c of the vacuum system/bad actuators? That's what normally keeps them from working, not an internal transmission issue.

That's right. I'm getting my transmissions mixed up. My mechanic didn't completely diagnose the lockers, but saw a lot of rust on parts, so it may be the actuators.

It takes a little work, but actuators can be fixed... Plenty of people have done that. I decided to go full torsen personally (200 20vt trans and swapped in the V8 torsen guts into my 4000 rear diff), as I didn't have a need for the lockers, despite them working/functioning fine.

I have some time before I need to make a decision on the transmission. The engine won't be ready for a few weeks. I think my options are as follows:

- Stick with the stock 4K transmission and differential. Swap the 5th gear and worry about the lockers later.
- Use the 200 transmission and find a URQ differential with 3.89 ratio ('83 URQ differential)
- find a 200 20V transmission and keep the 4kq differential.

why dont you just run the trans and diff that are in it as is and see how you like it? I never thought my 20vt 4kq needed a taller 5th, you might, you might not.

Likely the diff locks are not working because of vac leaks. The system is not too hard to diagnose and repair. used parts should be available.

dana wrote:why dont you just run the trans and diff that are in it as is and see how you like it? I never thought my 20vt 4kq needed a taller 5th, you might, you might not.

Likely the diff locks are not working because of vac leaks. The system is not too hard to diagnose and repair. used parts should be available.

Thanks for being the voice of reason. It is much appreciated.

As stated above, just stick with the 4kq trans and rear dif.

Too much trouble will go into fitting the t44 rear dif