Building a 1500cc block using ABD?

[Tommo]

I have seen this done with the 1W diesel block, just with oversize custom pistons.

Now from what I gather the ABD is a very similar block/crank to the 1W, still 75mm bore like most stuff, but with a longer stroke, but it dosent have the piston cooling jets. I also gather that the gudgeon pins are a different size to the polo engines, so fitting G40 pistons etc is difficult. Hence the custom pistons.

So my question is does this conversion require the same pistons as it does with the 1W block? Makes life easyer if I could order them from a company that has done a set before.


Cheers

Tommo

[sinister polo]

someone on here was selling a set of forged pistons to work with a 1.5 diesel crank a while ago,
i think he said there were only 2 sets in exsistance!

[Nick_S]

1W is a 1398cc and ABD is 1391cc standard, therefore 1W crank produces a longer stroke. Gudgeon pins are only thicker on the diesel.

Not sure if you could produce a 1.4 G40 using an ABD crank though?

[polo classic]

I do not think the other 1,4L cranks are as strong as the 1W cranks

[Tommo]

I would guess that the 1W crank is super tough because its a diesel, so has to be. But thats not to say that the ABD crank isnt strong enough to handle a fair bit of power. After all, I gather that a G40 crank is nothing special, and people seem to run plenty of power on that.

So, if the gudgeon pins are the same dia, what stops you fitting G40 pistons to an ABD to have a 1400 G40? Perhaps the deck height etc is all wrong.

Either way when Ive got some cash I will be buying an ABD, and then I shall know. If I have to I will just machine the pistons to lower the CR. Then see if the bottom end disintigrates. But I cant see it myself, if a 3 bearing non counterweighted mini crank can rev to 7k with 180bhp with no problems then im sure VW's finest will have no bother.

[Yoof]

Why would VW make a 55bhp diesel crank doing a max of 4000rpm stronger than one destined for a 113bhp 6800rpm 1.3 ?

Also does anyone know the flow of the oil jets in a 1W and the calculated drop in oil pressures effect on say... a lader or turbo?

Or if indeed the blocks are actually stronger...

And has anyone made decent power on one yet?

[hayesey]

And has anyone made decent power on one yet?

that's the million dollar question isn't it! The only one I've seen at a rolling road day made 165bhp which is unimpressive to say the least, although he only had 8psi boost for some reason.

[polo classic]

I seem to remember that Tony Lo mentioned that the normal 1,4 cranks where cast while 1W is forged, or if it was different materials

[Tommo]

Why would VW make a 55bhp diesel crank doing a max of 4000rpm stronger than one destined for a 113bhp 6800rpm 1.3 ?

Because the compression ratio in the diesel would be in excess of 20:1, that crank is going to take a massive pounding all its life. Im guessing thats why they increased the size of the gudgeon pins as well, obviously they were a weak point.

I can believe that the 1W has a forged crank. Are the 1.3 cranks forged? I will have a look tomorrow.

As for the blocks, the strength of them is fairly irrelavant. These little VW engines have pretty massive main caps anyway, dosent look like much chance of stretch.

In a week or so I should be finding out how much boost you can run on a standard 9.5:1 1.3 engine. See how long it takes to det its way through a piston or two. Im not worried, plenty of spares.

[Dan]

What are the Conrods like on ABD ?

What sort of management and air flow/mass measuring are you employing there ?

[lance]

forged crank wouldnt be smart. if they where gonna uprate one it would be steel.

[Tommo]

What are the Conrods like on ABD ?

What sort of management and air flow/mass measuring are you employing there ?

Haha, Im old skool baby! Ask your dad what a carburettor is.

Yeah ive got an R5 GT Turbo carb on there at the min. Mainly because its cheap and easy. In the future when everything else is going well it will either get a system built with VEMS or just bodge everythnig on off probably an S13 200SX.

At the moment the timing is ridgid as well, so no good for economy, but awesome for boost!

Its just a bit of a play about really. It isnt costing much to do and it is somthing to do. I thought about a G40 conversion but I like playing with stuff and I dont have £600.

[Yoof]

I realise the compression ratio is higher, the G40 crank still has to deal with a larger amount of energy transfer in a shorter space of time 

Hence, why make a diesel crank stronger?

VW didn't forge them, you can see casting marks!

[Dan]

I'm aware of carburettors thanks 

Rather than a spray of fuel going in with EFi, it's a big shower of fuel. Not exactly accurate, neither is fixed timing. I see it as a step back in efficiency from standard equipment on a Mk3 Polo. Fair enough your trying to make a turbo work, but why not do a good job in the first place ? You say that you don't have £600 or whatever to spend on G40 stuff, but if you might end up spending more than that on replacing broken parts and rebuilding things.

[Tommo]

I'm aware of carburettors thanks 

Rather than a spray of fuel going in with EFi, it's a big shower of fuel. Not exactly accurate, neither is fixed timing. I see it as a step back in efficiency from standard equipment on a Mk3 Polo. Fair enough your trying to make a turbo work, but why not do a good job in the first place ? You say that you don't have £600 or whatever to spend on G40 stuff, but if you might end up spending more than that on replacing broken parts and rebuilding things.

I must admit I almost take offence at that comment, and I hope I didnt cause offence with the 'ask your dad' jest.

Carburettors are fine on turbo cars as long as you pay attention, I have a wideband AFR setup so getting the carb to deliver the correct amount of fuel should be relatively straight forward. Bear in mind that people have run 240bhp on these carbs.

The fixed timing is also a cheap and easy solution, which compromises only efficiency.


The digifant system in my eyes is in no way ideal either, and I cant map it myself. Plus I know relatively little about it.

But please rest assured, I am probably less likely to melt an engine running fixed timing and a carb than I would be with the digifant system, simply becuase I can tune what I have now at the side of the road.

What can I say, I enjoy messing with stuff. EFI wouldnt quite be the same for me unless I made it myself.

To give you an idea though, My carb was £30, Cosworth IC was £20, Turbo was nothing, (although the turbine housing and turbine wheel I have fitted cost me £30), I have made my manifold for the cost of the bends (£20). The car cost me £340.