ABF and KR/AAL 16V differences. 360Kb Pics

[Slowboat]

For those who are wondering what's the difference between the 2L 16V ABF and our local 2L 16V AAL.
Here's some basic info with pictures.

Rods length:
AAL - 144mm
ABF - 159mm (Good for high revving, less stress on the rods)

Block Length:
AAL - 220mm (Has forged crank, no 60-2 tooth wheel)
ABF - 236mm (Has forged crank, has 60-2 tooth wheel)

Head:
There's some believe that the ABF flows better than AAL WHICH is not true. Both head and it's port sizes are the same. The VW part number for the both heads are the same.
However there is a slight differences in the valves. For example the valve guide in the ABF is shorter (35mm) than the AAL (38mm).

Fuelling:
AAL - K-Jet (Mechanical)
ABF - Electronic injectors (Computer Control. Can be remapped)

Ignition:
AAL - Computer Control (Can be remapped)
ABF - Computer Control (Can be remapped)

Inlet Manifold:
AAL - 50mm. The design not so great. Got "dents" in manifold.
ABF - 50mm. The design is great. Got no "dents" so air flow is smooth.

Cams:
The cams specs that I've came across are basically the same spec as the AAL. There are small differences depending area(country) the engine was realeased. But nothing higher duration, that I came across, as the 1.8L 16V.

So what makes the ABF motor better than our local AAL?
It's the Manifold design and it's running on full EFI. VW has actually detuned the ABF to 150BHP. Once properly tuned the ABF motor can make 165-168BHP. The reason why VW has detuned it, is that the VR6, during those times, were making 174BHP. Not a good marketing ploy for the 2.8L VR6, when a 2L 4Cly making close to 170BHP.

Here's some pictures:
K-Jet motor (AAL)



ABF Motor



ABF Motor again



ABF Motor with top inlet manifold



ABF Motor with top inlet manifold again



AAL and ABF lower inlet manifold (Top is K-Jet and bottom is ABF)



ABF lower inlet manifold
Notice there is no "dents".



K-Jet(AAL) lower inlet manifold
Notice the big "dent". Not good for air flow.



AAL and ABF upper inlet manifold (Left is the K-Jet and right is ABF)



AAL and ABF upper inlet manifold from the bottom(Left is the K-Jet and right is ABF)

[GtiTuned]

My exact notion that the heads are almost the same is right, i think that its the inlet manifold and cams that make the difference between the old and the newer 16v..

A nice experiment will be to fit the inlet maniold unit with tb,tps and injectors from an abf onto a kr 16v.. wonder what the diff will be??? Why i choose the 1.8 is that the kr revs real well in the stock form... i know its a pointless exercise as the abf should be stronger but the ques is by how much??

Those who hav the 1.8 kr can fit the abf inlet and the gains should be good instead of buying the complete abf motor..

I think vw got it right with the air flow design , injector spray on the abf.

I see that overseas many guys are using the abf motors and fittting kjet to it, and playing around with the inlet manifolds..with huge gains. In my experience, i think inlet manifld design and tuning plays a big role on the 16v.

Then thers another using the diesel crnk on an abf and no prob with the bearings as the longblock and long conrod helps not to cause any problems..

[roger]

Plz help me out here. If I understand correctly, I change the intake om my AAL 2L 16V and fit Mr. Turbo it should be close to the power of the ABF?

Rog!

[GtiTuned]

It will prob be close to the abf but not rev as well cos of the rod ratio, thats why i said 1.816v. The abf and 1.816v have a similar rod ratio. With the 1.8 the torque will be down definately... but again by how much???

In my opinion, i think the 1.816v was better than the 2.016v bubble in stock form.

Now heres the real problem, where can u get an inlet manifld and cams from an abf??, since the engines are so rare the bits will be even harder to get.

[jsk]

Slowboat,

Is the positioning of the injectors the same for the two different engines?
If so, where can you get a ABF intake without buying the complete motor?

[Mk1-fan]

I'll be selling all the extra stuff from my abf engine, once it is up and running. That will hopefully be within the next month. I'll post it in the for-sale section.

[bigman]

Guys ii am wondering about something , how can the rod ratio be better with a longer rod ? surely it is the opposite as the rod is longer , therefore it builds up more velocity and heat because it has to travel further on each stroke ? bike engines and ultra performance motors are all short stroke , which means less piston speed per revolution ..... or am i missing something ?

also this whole abf thing is questionable on a n/a car as once you start krapping on the motor a lot of the abf "advantages" fall away . also for n/a short stroke is def better is it not ? i have a golf + mag with a 16v shootout , 90% of the guys used 9A motors as there basis and many made 200hp or close to that on kjet !!!!!! with the help of k-star fuelling . the times they ran 0-160kmh would thump almost any stock hatch out there whether turbo or not !!

[LittleG]

Guys ii am wondering about something , how can the rod ratio be better with a longer rod ? surely it is the opposite as the rod is longer , therefore it builds up more velocity and heat because it has to travel further on each stroke ? bike engines and ultra performance motors are all short stroke , which means less piston speed per revolution ..... or am i missing something ?

Nope Stroke IE distance traveled by piston rod etc is determined by the crank not the rods, the shorter the crank the shorter the stroke. You could have a 3m long rod on a 92.7mm crank and the stroke would still be 92.7mm. The angle on the rods decreases though as the rod gets longer per revolution.

[Life-GP]

Rod to stroke ratio is a simple ratio. If the rod is 5.7" and the stroke of the crank is 3.48" you have a 1.6379 rod to stroke ratio. In theory the higher this ratio the more power it makes. The reasoning behind this longer rod is more power comes from a couple of aspects.

1. Is that if you go back to basics of a simple machine the pistons, crank and rods are basically a compound lever. The up and down movement of the piston translates into rotational motion of the crank.
In an engine a longer rod can make more rotational TQ from the same piston force because it's a longer lever!

2. Due to the angles involved a longer rod is less angular than a shorter one and side wall loading is less. What this means is that the piston is pushed more up and down the bore than to the side of the block thus reducing friction and increasing HP.

Raising the piston pin height changes the rod angle noticeably. You will also notice that the piston top doesn't change. Many people believe that longer rods make an engine a stroker but this is simply not so. The only thing that can change displacement in an engine is the bore or the stroke.


3. The pistons speeds change with rod length. The piston has more dwell at TDC and BDC. The slower it gets at TDC the more pressure builds up at the ignition point. The piston also accelerates away from TDC and BDC quicker making the intake compression and exhaust strokes more turbulent thus making more power.

[Slowboat]

Slowboat,

Is the positioning of the injectors the same for the two different engines?
If so, where can you get a ABF intake without buying the complete motor?

Yep, the injectors are in the same place.

[Slowboat]

Raising the piston pin height changes the rod angle noticeably. You will also notice that the piston top doesn't change. Many people believe that longer rods make an engine a stroker but this is simply not so. The only thing that can change displacement in an engine is the bore or the stroke.

Raising the piston pin height on the piston does not change the crank to rod angle at all. But lengthing the overall rod length will. (Not sure if you were trying to say this).

3. The pistons speeds change with rod length. The piston has more dwell at TDC and BDC. The slower it gets at TDC the more pressure builds up at the ignition point. The piston also accelerates away from TDC and BDC quicker making the intake compression and exhaust strokes more turbulent thus making more power.

The piston travels slower or hangs there longer at TDC and BDC. It does not build up more pressure. It holds the pressure at longer times than the short rod. By holding the pressure at longer times you have better combustion and from that a bit more power. Also you can run less timing.
But there's a draw back on the long rods. Since the pistons travels slower to and from the TDC (also for BDC) the airflow will be slower so the air filling cylinder won't be so much as the short rods at low rpm. So the manifold selection, port sizes and cams becomes an important factor.

So the Long Block is good for medium to high rpm revving engine. If you drive like a granny stick to the short block .

[BillyBob]

I still regard this as one of the most informative technical threads - covering an often-discussed & queried subject...

I vote for Sticky!

[Kaktus]

I still regard this as one of the most informative technical threads - covering an often-discussed & queried subject...

I vote for Sticky!

+1

[Jetta2]

Stickified

[audioworx3]

hey guy i've been doing some research, was wondering about this, the main differences are the rod length and intake right?

On my 16v i used the long block sub, with 16v pistons in order to correct the cr the block needed a little skimming, but otherwise everything seems to fit!
I would like to see how much the long block 16v makes with aal intake and with abf intake! I noticed the abf intake is also longer! Is the throat diameter the same as the aal? i think its 50mm or 51mm! If the abf intake is longer it should affect the torque curve not so?

[Uitenhage.com]

Awesome, fantastic, gob smackingly good thread

Does anyone have the standard quoted killerwhales and torque outputs at rpm for the various 16v motors, 2l and 1.8? TIA

[Spiderman]

What's the bore and stroke of each motor? If the rods on the ABF are longer then it shouldn't rev as high as the AAL, but i don't know the strokes of each motor...

Otherwise this is an interesting topic

[Slowboat]

The bore and stroke are the same on both motors.
Bore = 82,5mm Stroke = 92,8mm

[Slick3349]

Very interesting thread!

I Have both a 2.0l long block and a 1.8l block. Currently my car has the long block with a 16v head and a modified 20v inlet manifold for turbo use.

I am rebuilding my design as I am having issues with the turbo behind the head and want to make an ex manifold that allows the turbo to sit above the gearbox so that I can get more directed airflow over the turbo for cooling purposes.

Now this thread is making me wonder weather or not I should change to the short block.

hmmmm....