swapping the 2.8 12 valve to the 2.8 30 valve

Posted: Mon Sep 15, 2014 9:36 am

My 2.8 12 valve from an 80 is fitted in a mid engine car that I built, (pictures in a previous topic). I have problems with the current engine and am considering fitting the 2.8 30 valve from an A4. Does anyone know if the block and engine mounts are the same and if the wiring will be compatible?

Camped on the site Joined: May 10, 2013 Posts: 228

I believe that I've seen someone here with a 30v engine in a Audi Cabriolet, I can't remember who it was but I'm sure he'll have your answer. Smile

Posted: Tue Sep 16, 2014 9:45 am

Would be handy if he does see the post. I have been trawling through topics again as you do and found out that the block is the same so the engine and gearbox mounts are not a problem. Just need to know about the wiring now. I can't see it being that different but electrics are not my strongest subject!

Site Moderator Joined: Jan 31, 2003 Posts: 9144

Fast28 - best send him a PM

Posted: Tue Sep 16, 2014 1:42 pm

Wiring is mostly the same with the following exceptions, (off the top of my head)
Throttle with built in ISV
Camshaft adjusters for VVT
2x Cam position sensors
Coil pack

If it helps, I am breaking a C4 A6 30v so will have a full loom and ECU available, the engine is also available but a bit tired

Posted: Tue Sep 16, 2014 4:23 pm

Thanks, that's helpful. A pity the engine is tired. I really want to drop one in that doesn't need work except the usual belts etc.

Newbie Joined: Feb 11, 2012 Posts: 14

The 30v will go in but is slightly wider, down pipes will need to be fabricated etc

The 30v is a great engine, decated with good exhaust ot will push out well over 200bhp.

Posted: Thu Sep 18, 2014 6:01 pm

Oh right. I had read in a previous thread that it uses the same block as the 12 valve so I assumed that the dimensions would be the same. If you have seen my car from a previous thread you will see space is at a premium. Is it wider at the top or bottom? Down pipes have already been fabricated for the 12 valve so does it use different manifolds? Also would my existing gearbox fit?

Needs to get out more Joined: Jan 07, 2014 Posts: 107

It would ofcourse be wider at the top due to the twin cam shafts on each bank and the exhaust manifold will be different, it could easily be 3 inch's wider each side. What about adding a super charger to the 12V you'd end up with about the same power output and it would fit nicely in the V.

Camped on the site Joined: May 10, 2013 Posts: 228

Well what kind of car is it going in? A series 4 Audi 80 Coupe?

Posted: Fri Sep 19, 2014 1:07 pm

That about does it then without major modifications. Don't really want to go down a super charger route as the cost I believe is too high for the gain. The only reason for considering the 30 valve is because I haven't been able to sort out issues with the 12 valve and thought the 30 valve would be a better option. I am sick of handing out money to people who say they can fix it!! If it was a tractor I would have no problem getting things sorted in Lincolnshire!

Appreciate your help guys but it looks like I will just go for another 12 valve.

If you want to see the car I posted a few pictures 12 Nov 2010 headed - Need Help With Audi 80 2.8L V6.

Posted: Fri Sep 19, 2014 7:47 pm

What are the issues with the current motor?

Posted: Sat Sep 20, 2014 10:27 am

There are two problems I have lived with since fitting the engine.
1- If I coast up to a junction etc in a high gear, when I dip the clutch at the last moment it won't hold a the revs and cuts out. Starts again no problem. Doesn't do it if I use the gears to come down.
2- At tick over if I throttle quickly it gasps before picking up. It just doesn't respond as it should.
The only way I have improved both slightly is to fit a small resistor between the temp sensor and ECU to make the engine think it is slightly cooler than it actually is. This makes me think that the ECU is not receiving the correct fuel message at low RPM although I am told everything checks out okay!
I have developed two more problems that are more difficult to explain, they really need listening to.
3- When returning to the car after a run and starting it up sometimes a strange moaning sound comes from the engine. By increasing the revs it will get to a slightly higher pitch and stop. This is the only time you hear it, never from cold. It is almost like oil is leaking through something or it is struggling to get somewhere.
4- The engine has also developed a strange whirring noise like a worn bearing. I am convinced it is from the front (the engine is mid mounted so it is just behind my head). I ran the engine without the belt on the alternator and power steering pump to discount them. The cam belt has been changed along with the water pump and idler. I have tried listening with a stick on various parts and have found the noise is more prominent when on the remote filter housing!
This makes me think it could be the oil pump but getting one for this engine is practically impossible. It would have to come direct from Germany at £542 plus vat plus carriage!! Hence the reason for me thinking it would just be far easier to fit another lump in!
I have had different people look at it but I am not shelling out any more!

Needs to get out more Joined: Jan 07, 2014 Posts: 107

I see
1. could be your idle control valve, they get stuck you can remove and clean with carb cleaner.
2, could be throttle position sensor, but are you also using the right fuel found mine has to run on 98 octane or l get hesitiation
3 ???.
4. if you have a oil presure gauge it shoulf read 5bar all day long and only drop to at least 1,5bar at hot idle.

Posted: Mon Sep 22, 2014 12:52 pm

Thanks for input.
Idle control valve has been done.
Throttle position sensor has been checked and I am told all is okay. 98 Octane makes no difference.
I haven't an oil pressure gauge in the car but I could get one and slave it in temporarily. I'll get on with that one.
Any more input would be appreciated

Needs to get out more Joined: Jan 07, 2014 Posts: 107

ok, only other thing could be an air leakage somewhere?

Posted: Mon Sep 22, 2014 2:32 pm

Yes, also done. All the obvious things have been checked. I think the answer is probably staring me in the face but but it is just hitting on it. I am still up for any more input before I get a good 80 or A4 runner though as one of you guys may come up with it.

Needs to get out more Joined: Jan 07, 2014 Posts: 107

what about the timing?, have you checked that, l know you are supposed to lock the crank and the cam shafts when you change the belt,then take the camshaft pulleys off the put the belt on tighten it up then tighten the cam shaft bolt to lock everything inplace. I know l didn't do that because l did the cambelt change in my hotel carpark in germany lol!

Posted: Mon Sep 22, 2014 6:22 pm

Yes I see where you are coming from but the belt was done before dropping the engine into the car and again in June this year by different people. Unlikely to be the problem!
Ordered an oil pressure tester off ebay today so will check that as soon as I get it.

Posted: Mon Sep 22, 2014 8:54 pm

I'd be inclined towards an air leak too, my old 12v used to suffer similar symptoms when going on throttle, turned out the plastic intake pipe had a hose missing so was allowing unmetered air in.
It might be worth removing the throttle and PCV system and giving the whole lot a good clean out and rechecking/replacing hoses where required. I find the rubber hoses can deteriorate underneath the braiding so less likely to be seen.

Other than that, might the fuel system be at fault if you have to fool the ECU into delivering more fuel to get round the idle issue?
Faulty pressure regulator or blockage in the system, or possibly the injectors could benefit a clean.
It might be worth getting the fuel rail off and testing the injectors for flow rate and pattern, a reasonably quick and easy job on these engines.

Posted: Tue Sep 23, 2014 4:03 pm

Yes I hear what you say but checking for air leaks was the first thing I did and it has been checked over and over again because that is just what the fault sounds like. All the other points have been checked as well over the last four years!
Clutch release bearing started to squeal today. That was new when the car was built and has only lasted 22,000 miles.
Extremely jacked off. Sad