Hi Everybody,

My name is Martijn, i live in Holland and drive a '93 polo coupe.

At the moment, i have a 3f engine in parts, which has to be rebuild and be put in my polo.

But i actually found out a few things, one is that i can combine the 3f head with another under block (don't know the correct English term)

The easiest seems to be to switch the 3f underblock with a 1.4 abd block, you will get a few extra bhp and especially the torque gets better.

And the one i like to make, is an ABU underblock combined with a 3f head.

I know, these two combined will make your cr go to around 1:15.

Does anybody know the length of a 3f conrod? if they are shorter than the ones of a abu engine, maybe i can use 3f conrods in stead, to bring the cr down as well.

Are there things i need to be aware of?

Do i use the crankshaft of the ABD/ABU?

Help and tips wanted please.

Well I have some info for you:

ABU conrods are 144mm centre to centre, I believe the 3F conrods are 122mm, same as the G40. Quick google and I found this:

http://www.engine-dynamics.com/ForgedConne...orgedRodSet.asp

To build an ABU/3F hybrid you would need to have some custom pistons made as the ABU is 76.5mm bore and gudgeon pin is 17mm while the 3F is 75mm bore with a 20mm gudgeon pin.

You may be better of retaining the ABU cylinder head but fitting double valve springs from the 3F and getting the 3F intake manifold adapted to fit.

The ABU cylinder block is taller than the 3F/ABD to accomodate the extra long stroke of the 1.6. The ABD/3F block is the same but the ABD has a shorter piston/conrod assembly than the 3F. I do not know the measurements for the ABD except that the gudgeon pin size is 17mm

So, from a practical point of view, it is best to get an ABD under block.

Makes other parts ,i still want to put on, a lot easier to put on.

If the ABU block is bigger, then it would be a pain in the a##, to get a 4-2-1 manifold to fit there.

Than the set-up would become: ABD underblock with a modified 3f head, 264 newman cam and the g40 exhaust willl prob be replaced by a 2" system.

Would there be a need to upgrade my injectors? I now have the standard 3f injectors.

Combined with the the bit of extra cc's it should have some torque but some bhp as well to play with

I've got mixed feelings about the injector size. I've got some 180cc ones from the original audi 4.2L V8, these are larger than 3F injectors but smaller than G40 - I tried G40 injectors but I thought they were too big. I haven't tried the audi ones yet.

part number for the audi injectors is 0280150424 (bosch) , 077133551F (vw)

And in what kind of engine you have those injectors??

I am afraid, because of the different cam and modified head and the exhaust and chip i have planned, it will go lean @ higher rpm.

Info of my engine specs is here:

http://www.clubpolo.co.uk/forum/index.php?showtopic=44726

I would say that without a proper remap of the ECU to compensate for the increased cc, and the improvements to the cylinder head. The 3F injectors are not going to provide enough fuel. But I don't think that the 3F injectors are too small for the job. Using larger injectors is just cheaper than having the ECU reprogrammed.

Are there some other thingies i have to take in account?

I can just use the ABD crankshaft, conrods, pistons etc

Do you mean that you wish to fit the ABD crankshaft, pistons and connecting rods into a 3F block? I remember someone wanted to do this about 10 years ago, to preserve the original engine number in the car. But it isn't straightforward, I believe that the ABD (and 1W) block has more room inside to fit the wider crankshaft, so machining of the 3F block is required to make the ABD (and 1W) crankshaft fit.

No,

I want to have a ABD underblock combined with a 3f cilinder head.

"underblock" as you put it is the engine block, or "lump" above this is the cylinder head

so you want an abd block with a 3f head... go to a motorfactors/car spares place and ask nicely if you can trace round both the 3f and the abu head gasgets... cut them out and lay one ontop of another trying to line the stud holes up (unless of course you have both of these lying about) check the oilways/waterways ether match up or are close to matching..

There is no need to do that on this occasion because I can tell you right now that fitting an abd 'underblock' to a 3F head is as straightforward as fitting a 3F underblock to a 3F head. For all intents and puropses the external dimensions and gasket mating faces are the same.

The abu also has the same pattern for the mating face but combustion chamber design differences prevent a straightforward hybrid of the abu/3f

I want to have a ABD underblock combined with a 3f cilinder head.

Then please go right ahead and make this happen - it is as easy as 1-2-3 :)

Here are some other minor considerations that you might be interested in.

What you should also know is that the ABD cylinder head is the same as the 3F - The aluminium casting I mean. The ABD and 3F valvetrains are assembled using different parts but all these parts are interchangeable. All you need to 'upgrade' an ABD cylinder head to 3F specification is some inner valve springs and the camshaft.

There are some minor differences between early and late 3F engines

Early 3F engines use 8mm valve stems (up to 1992)

Late 3F engines use 7mm valve stems (1992 onwards)

This is also the case for the ABD engines but I think more ABD engines use 7mm valve stems. There may be some small advantage in performance with 7mm valve stems

Early 3F engines use a 108 tooth sqaure profile cambelt up to engine number 3F008500 approximately

Late 3F engines and all ABD engines use a 128 tooth round profile cambelt.

Conversion between one and the other is as simple as changing the pulleys and the water pump.

I hope you understand what I'm saying. I know there is a bit of a language barrier here.

The abu also has the same pattern for the mating face but combustion chamber design differences prevent a straightforward hybrid of the abu/3f

So in the ideal world the ABD head is better than?

If i get it right, all the bobs and bits that go on the 3f engine can be transferred to the abd engine?

The valves that are in the 3f head are the same size as the ABD ones?

I maybe can get a abd lump, bu it has no valves and camshaft (shouldn't be a problem: a 264 Newman shaft is waiting and i have the 8 valves of the 3f head)

It is not that i think i will get a massive hp gain, but it is a more plug and play job than putting in a ABU and for future "gain more hp" it is a better basis than the 3f engine.

Edited 26 January, 201313 yr by martijnt

The valves on the ABD/3F have the same head diameter (36mm inlet and 29mm exhaust) but, as i described above: Some valves have 7mm stems and some have 8mm stems depending on year. It is possible to convert from one to the other by replacing the valve guides with the appropriate ones for the valves you are using.

Personally, I would use the 3F head as you've already got it ready for a rebuild I assume? Then get the abd block. Bolt everything up and away you go!

I'm all for the improvements for the ABD over the 3F. I have done two ABD engine conversions and I'm contemplating a third for my daily.

The valves on the ABD/3F have the same head diameter (36mm inlet and 29mm exhaust) but, as i described above: Some valves have 7mm stems and some have 8mm stems depending on year. It is possible to convert from one to the other by replacing the valve guides with the appropriate ones for the valves you are using.

Personally, I would use the 3F head as you've already got it ready for a rebuild I assume? Then get the abd block. Bolt everything up and away you go!

I'm all for the improvements for the ABD over the 3F. I have done two ABD engine conversions and I'm contemplating a third for my daily.

Well, to be honest: i am a bit in doubt.

Basicly: i have an 3f engine, but it has damage to the head.

I may be able to buy another 3f engine for 60 € (around 51/52 pound), take the head en sell the rest on for the same amount (3f cams are pricy)

But there is also the option to buy a ABD engine for roughly the same amount, fully rebuilt lump, but cam, valves etc are missing.

I happen to have valves and also the double valve springs lying ready for a 3f/abd head, (6 out of 8 are already cleaned and polished)

Also have a few new parts ready for the 3f and extra bonus would be if i can just mount them to the ABD lump.

Must be interesting to see how the ABD lump will function with al the 3f electronics on it.

The gas pump of an 3f engine pumps @ 3 bar, do you happen to know at what pressure the ABD normally gets it's fuel?

I thought it was (like almost all the old polos 86c) somewhere around 1.5 bar?

As standard the ABD runs bosch mono-motronic fuel injection and the fuel pump is rated at 1.2 bar.

Both my ABD engines ran on Digifant fuel injection from the 3F. First one was 93 bhp with 3F cam. Second one is approximatey 100bhp using a schleppebel head and schrick 280 cam

Based on that damage you might as well purchase the ABD engine with cylinder head and rebuild that. The valves can be put in, you'll just need to re-lap the seats and fit new valve guides.

Both my ABD engines ran on Digifant fuel injection from the 3F. First one was 93 bhp with 3F cam. Second one is approximatey 100bhp using a schleppebel head and schrick 280 cam

Whoah

Let me get this straight: you take out the 3f engine, replace it with the ABD, put everything (3f) back on (cam, injection, the lot) and you end up with around 90/95 ish on the wheels? WTF.

What was the rest of your set up? (Gearbox??)

Both my ABD engines ran on Digifant fuel injection from the 3F. First one was 93 bhp with 3F cam. Second one is approximatey 100bhp using a schleppebel head and schrick 280 cam

Whoah

Let me get this straight: you take out the 3f engine, replace it with the ABD, put everything (3f) back on (cam, injection, the lot) and you end up with around 90/95 ish on the wheels? WTF.

What was the rest of your set up? (Gearbox??)

That power will be at the engine flywheel not the wheels :-)

Oke, you are right about that.

But so is the 75 hp of a 3f

But i think if i buy the abd engine,raise the cr a bit, combine it with a 264 camshaft, a head that will have some work done, 3f mpi, nice 4-2-1 manifold, free flow exhaust it will go a bit better than the aav with 3f exhaust and cam i now have

Edited 27 January, 201313 yr by martijnt

Yes 90-95 at the flywheel!

Ok, there has been a little update for now.

I have recently bought the ABD lump, it is completely rebuild, apart from new pistons.

All gaskets, bearings en piston rings are new, got a set of headbolts and a headgasket with the lump to.

In June , a friend of mine with a nice big shed, will help me for a week, to make the transplant to another polo.

Set up will be:

lowered 60/40 with 185/55/14 tyres and hopefully volvo 240 brakes with 4 pistons and disks of an ibiza GTi (256mm if i am not mistaking)

I want to fit a ppp frame

with some g40 arms with pu bushings.

Planning on having an g40 rear axle, which has been blasted, painted black, new pu bushings etc and some kind of rear stabiliser.

Engine:

1.4 abd with slightly raised CR, 264 cam, 3 bar fuel pump to raise fuel pressure, 3f MPI and ecu, it will breathe through a g40 exhaust system (48 mm dia instead of the 42 mm of an aav system)

The rev limiter of the ABD will be raised to 6250 because of the 3f ecu.

I guess it should be heaps of fun to drive

Edited 10 March, 201313 yr by martijnt

the discs need to be rover 216 gti discs 262mm not 256mm to go with them calipers

thats the same setup il be running

What size wheels are you running?

And isn't the stopping power going to be so much, that you constantly lock up?

i like a bit of a bite on my brakes(eyeballs touching the windscreen) , but i still need to have a good feeling of control, because i don't have abs.

Edited 10 March, 201313 yr by martijnt

I don't have abs either and il be running 15" wheels

The reason you use the rover discs is for the offset of them

As from what I garhered the VW range of discs have the wrong offset to match the Volvo calipers

Il be running a bias pedal box with mine and

I doubt you will lock up with bigger brakes that would be the opposite of what happens

And also don't forget you will need to upgrade to a bigger m/c for the extra fluid needed for the brakes

Mmm, i am driving with 14's, wonder if it'll fit

What kind of m/c are you looking at?