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6 Cylinder Engine Info 


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 Post subject: 6 Cylinder Engine Info
Posted: Mon Sep 29, 2014 6:28 am 
Getting Side Ways
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Joined: 22nd Jun 2011

All info dug up and copied from a cached deleted post of tickford_6 for everyone to use. Pics are uploaded to a paid account on imgur and will not be deleted.

First, Rods and Pistons

EF Forged TRW rod on the left, XF (late forged) on right (I know the crossflow engine isn't SOHC, but the SOHC engine is an evolution of the crossflow).


The XF one 'looks' good in the photo. It is how ever lighter the EF rod, the XF rod is lacking metal in the beam and has a lot of weight in the balancing pads compared the EF rod.

The quality of machining is also very poor on the XF rod.

There is a lot of talk about the last of the cross flows and the first of the OHC engine being produced side by side. There has also been reports of some of the early 3.9 engine being fitted with rods that have F 250 on the side, denoting the rods as being a crossflow rod. The late XF rod is a better rod then the early 250 rods, and may be a result of ford tooling up to start production of the OHC engine.

XF vs EF - XF on right EF on left.

EF vs BA (lpg) - EF on right BA on left.

AU I & II con rods have been replaced by the later AU ones (series III) and must be replaced in a set.
AU2 6200 A AU/BA/BF/FG standard, LPG up to 30/11/2002 $74.50
BA 6200 C BA/BF/FG LPG 01/12/2002 onwards $66.80
BA 6200 A BA/BF Turbo up to 30/04/2006 $72.20
BG 6200 A BF/FG Turbo from 01/05/2006 $59.80

Have an XF, an EF and an AU1 rod on the bench.
The XF rod weighs in at 594grams.
The EF rod weighs in at 641grams.
The AU1 rod weighs in at 634grams.
The AU1 rod is longer and is skinnier in the beam.
I also have a set of SPOOL XR6T H-beam rods which all weigh in at 644grams.
Spool claim their XR6T I-beam rod is 550grams.

AU1 left, EF centre, XF right.

Section of the three rods, XF left, EF centre, AU1 right.

XF piston 509grams.
EF piston 442grams.
AU1 piston 376grams.

The Mahle motorsport BA forged piston in 0.5mm over size is only 351grams.
The gudgeon pins for the EF and the AU where the same weight at 131grams.
The gudgeon pin supplied with the Mahle pistons is 112 grams.

If you take off the wasted metal in the balancing pad at the small end of the XF rod to make it the same shape and size of the EF and AU1 rods, the weight comes down to 587grams.

It becomes very obvious why even the very last of the crossflow engines have such a low red line; with the light rod that is lacking metal in the beam combined with such a heavy piston.

There is about 15 grams of useless metal in the beam and small end of the EF rod. Combine that with a quality light weight gudgeon pin of about 100grams and you'll have about the strongest rod you'll get using factory gear.

IMO the AU rod is waste of time.

In saying that, with the cost of spool rods you're wasting your time in trying to get every last bit out of the factory rods.

They have a nice light weight I-beam rod that would be perfect for a revvy N/A engine and do H-beam rods in both AU and EF length.

The EF length will also fit the crossflow engine.

Aux shaft and Aux shaft oiling.

There seems to be a lot of people suffering failure of the Aux shaft, when stripped for repair they are reporting excessive wear on the large bearing journal in the block.

Below is the journal from a good running engine with no problems.

The next photo shows the path the oil take through the block to reach that journal.
Oil is delivered to the front main bearing journal from there it is transferred through a slot in the bearing shell to a passage leading to the Aux shaft journal.

In this photo you can see the slot in the bearing and the very obstructed oil passage down to the Aux shaft. The opening into the passage is only 2mm.

This is an EF block, the engine had a blown head gasket and sat for a while, which pitted one of the bores.
You'll see the Aux shaft oil feed has the same offset as the AU block.

In this photo you can see where the passages run through the block.


Here are some photos of the same VCT head I posted before, but these ones are nice and clean and all casting and machining marks are visible.


On the above photo I have marked in green the seat its self the narrowest point of the throat in red and in blue is the bottom of the third angle cut. You could call these seat a 4 angle seat, as there is one cut on the chamber side of the seat, then we have the seat its self we then have 2 more cut on the port side.

The ID of the red part is 32.60mm the ID of the blue line is approx 34.40mm.
the throat can easily and safely be taken out to 34.40mm and you will see an improvement in flow when this is blended into the port.

On the intake seat you can see the same cuts.

In this case the red line is 40.60mm (there is a step at the transition from seat to port, the port at the same line is 40.38mm).
The blue line is 41.25mm.
The applies here, the throat can be opened and blended. Given the width id the cut i'm talking about, the throat can be opened out to 42.25mm and then blended to the port. This will give the same width as the same cut on the exhaust port.

94AB intake port next to AU VCT intake port.


As promised the exhaust of an AU VCT head.
It has been cut through the center line of the port opening, not through the valve guide.
The port is offset from the valve, cutting through the valve guide was going to loose to much detail.
I'm going to take this stuff to work and bead blast all of it. the carbon makes it hard to see.


94AB vs. AUVCT exhaust port.

EFXR6 valve spring next to AU valve spring.

Pre AU intake valve next to AU intake valve.
EF valve weighs 104grams AU valve weighs 94grams

And an EF BBM runner.




EL Ghia

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