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Discussion Starter · #1 ·
Anybody done it? By my calculations a 20v head on an NG or NF block will yeald about an 8.xx:1 CR which would be perfect for turboing. I would think this would be a pretty common conversion, right? Any thoughts on what kind of fueling/timing syustems would work with this? Sounds like it could be a pretty fuss-free way to do a turbo conversion. Especially if you use a 20v head and the turbo off a 5000 TD which as in integral wastegate so you wouldn't have to use a bent control arm or relocate the battery. It would be pretty much bolt on from what I can tell. Thoughts?
 

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Re: Turboing an NG or NF engine... (MFZERO)

sounds alot easier than finding a 3B, thats for sure. for fueling, that 034efi system could probably be used, to forego CIS completely.
would the timing belt attach properly?
(and the NG is from the 10v 80/90, and NF is 100, right?)
 

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Re: Turboing an NG or NF engine... (delta v)

The timing belt attaches correctly if you use the crank pulley and oil pump from the 20v. Some of the NG ones will work, but some won't and if you have a 20v motor lying around its easy to scavenge parts.
The NG is found in the 87.5 Coupe GT, 88-92 80/90 quattro, and 89-91 100, DESPITE what ETKA says. This is a little discrepancy where the motor is identical to an NG, the trunk label says NG but apparently the block says NF.
The REAL NF is found in 87-88 5000 and 5000 quattro. The bottom ends are identical, all the differences are in the head, intake manifold, and fuel management.
If you plan on using a 20v head for anything, the thought of using CIS is immediately discarded. It is A)a step in the wrong direction and B)exceedingly difficult as all 20vs are originally equipped with EFI.
At the very least, I would run Megasquirt and Spark on it. No factory system will be able to handle its duties well on such a hybrid motor. Maybe Motronic from the 20vt, but thats a very expensive system, and just a chip costs more than MS&S. $150 for MS&S, $200 for laptop off ebay - fully tunable and programmable fuel and timing (distributor-based) for $350.
And because it will undoubtably come up...
YES 034EFI IS BETTER...but in my opinion, the power differences you will notice between the two will be minor enough that the $1000 you saved on your ECU can easily be put into something like a nice GT-series turbo or a tube header, or something.
So there!
Oh and the NA pistons aren't that strong. I would be hesitant to push any more than 300hp on the 10v NA bottom end. Take a 10v NA apart, then take a 10v turbo apart and you'll see what I mean.
 

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Re: Turboing an NG or NF engine... (billzcat1)

Forgot a couple things!
The turbo from a 5000 turbo diesel sucks. A lot. Don't use it. The nature of a diesel motor requires a small turbine and compressor that are efficient at low rpm and spool very quickly. This then limits top end significantly. I would not trust one to produce more than 200hp. And on a 20v, it would be a serious bottleneck and the motor would be a choked-up torque monster.
Also, wastegate placement on a 20vt exhaust manifold does not require a bent tie rod like in the 10v. The WG is right in the middle of the manifold and is actually somewhat effective in releasing excess exhaust gas. The 10v manifolds are terrible. So in other words, ditch the crazy 5000TD idea, as it does not apply to a 20v whatsoever. Use a K24, or a K26, or have Innovative build you what they call "RS2 Plus" for cheaper than the RS2 turbo. Stock manifold is good to around 300hp (about the same as a 10v bottom end), RS2 manifold well into the 400bhp mark.
 

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Discussion Starter · #6 ·
Re: Turboing an NG or NF engine... (billzcat1)

Humm...so my idea isn't that crazy?
OK, so which 20v head is going to be better? There are 3 to chhose from, 2 from 20VTs and one from the NA 20V. MS&S, that the system where I have to build the ECU board, right? No way could I do that. I have no need for a 300 hp monster...I'm looking for an easy way to get to 200-250...
 

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Re: Turboing an NG or NF engine... (duandcc)

Your idea is not crazy at all. In fact I myself want to build one just like this someday and I spent the last few years learning Audi stuff just to do this swap.
You can have someone build you the MS&S - a friend of mine in college is always looking for side work and he has an MS&S on his quantum syncro wagon (MC swapped of course). He's putting out incredible 1/4 mile times on stock boost.
If all you need is 200-250hp, you can use Motronic and not even chip it.
Pick whichever head is in the best condition. At these power levels, the advantages the 20vt heads provide will not be realized. There's a rebuilt and ported 7A head on audifans right now for $400 which is a steal. All 20vs have sodium-filled exhaust valves, but the 20vt have a few more water passages for knock resistance.
Also, matching the head to your management is important. 3B management won't run on an AAN head because there is no distributor. MS&S (which I strongly advocate) will run on 7A and 3B heads. 034EFI will run on anything (Stage IIc)


Modified by billzcat1 at 2:44 PM 4/16/2004
 

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Re: Turboing an NG or NF engine... (duandcc)

Quote, originally posted by duandcc »
I have no need for a 300 hp monster...I'm looking for an easy way to get to 200-250...

If that's the case, why build a hybrid at all? I mean other than the "different from everyone else" factor you can make the kind of hp you seek from a chipped MC motor (mine's making 220hp at the crank). Seems like it'd be less work (probably less $$$ too).
J.
 

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Re: Turboing an NG or NF engine... (billzcat1)

would using parts that were stock on a 80/90 (NG and 7A) make things like air conditioning, ect easier? (im assuming 7A head would be easier to source than either 20vt head)
soooo.....a preliminary parts list for somthing like this would include:
20v head
NG/NF bottom end
what about intake and exhaust manifolds? would a 3B or AAN exhaust manifold bolt up to a 7A head?
and im guessing forged pistons would be in order (as per billzcat1), since turbo and NA have different bores--or would bottom end and piston strength be in the same ballpark?
 

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Re: Turboing an NG or NF engine... (delta v)

Ahhh ok now there's some confusion.
There are 2 ways to build a 20vt without starting with one.
The cheapest and easiest way is to use a low miles NF/NG block (or one that simply has consistent compression test results) and just drop a 20v head on it.
If you are going to the trouble and expense of forged pistons, it doesn't matter what block you start with as long as it was made after 1985. These blocks have slightly different oil passages and will adapt to the 20v head perfectly. Doesn't have to be a 10v block, you can drop pistons into a 7A block too. By the time you do this, you have to have the honed, and probably bored to boot. Might as well polish the crank, new rod and main bearings, and whaddaya know? Its a full rebuild and you are all of a sudden in $2000 for a built bottom end. Granted it will be very strong and ready for anything.
Bore has nothing to do with it. All that affects is displacement and to a smaller degree, compression ratio. Either motor has plenty thick walls in each cylinder whether it was 82.5mm or 81mm bore. The reason the NF/NG is preferred is that it has a larger dish in the piston that when mated to a 20v head will produce a low 8:1 range compression ratio.
Yes, all the turbo manifolds bolt right up to the 7A head. They all use the same castings, but the turbo versions have about twice as many exhaust studs holding the manifold on. Plus the AAN has the distributor hole blocked off.
One problem with accessories is that you are adding an extra one on the passenger side. There's a turbo there and the A/C compressor might interfere. Use the bracketry from an NF 5000 or MC to put the alternator there instead and put the PS and AC on the driver's side. Might be a tight fit. I haven't been there, done that but thats what I have read on the various lists. And it certainly makes sense from looking at numerous 10vts in the junkyard.
 
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