Ive blown the head gasket in my EL falcon and after a bit of research it sounds like dropping an AU engine in is the way to go, theres heaps of info out there about whats required to do the swap but what I cant find any info on is what makes the AU engine superior to the EL engine?

Is the power delivery smoother? does it feel beefier all round? Is it more durable?

Basically, when I finish the swap and drive it around the block the first time am I gonna have a huge smile on my face going holy f**k thats awesome or am I gonna go meh that was alrite??

The car will rev smoother, and be better on fuel. Same power and torque from both engines. You will probably feel a power increase if your EL engine is tired.

You will need to have the sump modified to fit into the EL K Frame.

AU engine is smoother and more refined, stronger bottom end.

Things required to fit AU engine to EF/EL (updated 15/02/14)

1) Sump needs to be modified to fit K-Frame, you can cut and weld the K-Frame but that is up to you, will need engineering after being cut. You cannot use an EF/EL sump as the sump is totally different to AU. There is are cases of the E series sump being used but filler plates or large quantities of sealant wre used, not recommended. Also you loose the advantage of the cross bolting of the AU sump when using the E series sump, one of the major strength points of using the AU Block.

2) You need to use AU/BF alternator or you will need to modify the block and drill and tap mount points to mount the EF/EL alternator.
If you use an AU I alternator you will need to change the plug for the alternator to one from an AUI as these are different from the Mitsubishi alternators.
Note: The AUII & III and BA alternators have the same plug as EF/EL.

3) Remove the Oil Drive Block where the Dizzy (EL) or cam sensor (EF) goes and remove the gear from the shaft and fit to your Dizzy (EL) or Cam Sensor (EF). This will then mean that the gears are matching and you should have no issue’s, there have been issues with dizzy’s failing when this has not been done. Some modding will be required to use the existing mount point, extra notch in the clamp plate or grind the tab off the Cam sensor.
Note:Do not try and drill hole in existing EF position on AU block, you will drill through the block.

4) You will need to use an EF/EL thermostat housing as these have your temp sensor and AU housings do not. You could use the EB type if you wish as this has an extra fitting for an additional sensor is required at a later date.

5) You will need to use the EF/EL BBM as the upper section is different to the AU. Also use the EF/EL throttle body as some of the plugs are different to the AU.

6) Use the EF/EL wiring loom.

7) You will need to tap the block on an AUII/III Block with an M12 1.5 tap if using the EF/EL Knock sensor. AUI is already tapped with the correct thread for the EF/EL Knock Sensor. If using the AU sensor you will need to modify the plug.

8) a) You will need to cut the EF/EL AC pump mount spacers down to 30mm to suit the AU block as well as shortening the bolts by 10mmm if using the AU alternator to suit the standard serpentine belt.
b) If using the EF/EL alternator with modified mounts you will not need to cut down the mounts and be able to use the standard Serpentine belt.
c) Alternatively you can use the AU alternator , standard AC spacers and a Serpentine belt from an XH (Slightly longer).

9) Use the EF/EL power steering pump. This is a direct bolt up. The AU pump hose connection is different to the EF/EL.

10) You do not need to change the Harmonic balancer for either EL (Dizzy) or EF Coil Pack.

11) If fitting to EF you will need to use your original Coil Pack or an AUI coil pack as these are different to AUII & III. (different plug) You can use an AUII/III coil but the plug with need to be changed as well as different leads.

12) You can use the AU head or fit you EF/EL head, that is up to you.

Thanks for your in-depth reply mate, I really appreciate it.

But to be blunt, is it worth the work?? If output figures are so similiar, im not so convinced?

Is the AU engine any more responsive to mods? Ie. Cam, exhaust, CAI etc

Really depends what you're doing. There isn't much noticeable difference if you get a decent EL engine. People use AU engines when going for high output turbo power or for the sake of that minor increase in smoothness and reliability. But in your case it's probably just easier to stick to an EL motor.

One thing to note though is getting another E series engine may lead to yet another head gasket failure in the near future, bringing you back to square one.

I would honestly go with the AU engine if you have enough motivation and some extra cash for the mods required.

R u saying AU's are impervious to head gasket failure?

Im a fitter by trade so doing the swap isnt a drama and can get the welding done for free, its just can I and should I be bothered?

Au engine, looked after, you wont see another headgasket problem again,..

Eseries engine.. basically a ticking timebomb, awaiting your love
ifs its never had a headgasket change anyway.
if its been recently changed she'll be good for another 300k,
provided the knob that done it, did it properly ... you never know these days..

The problem with the E-series head gaskets blowing was solved in the AU by changing from a composite gasket to a multi-layer steel (MLS) gasket. The (AU) MLS gasket is the recommended replacement for a blown E-series gasket; lots of people have done it, and it works great. The MLS gasket is as reliable in an E-series as it is in an AU. It also gives a slight increase in compression because it's thinner, so a fraction more power.

The AU engine is much smoother than the EF/EL, but it's probably not worth the trouble swapping just for that. I would get a decent used or reco EL short block, use an AU head gasket, get your existing head skimmed for compression (if you haven't already), get the cam reground (prob about $150), cheap headers and cat-back sports exhaust, and TI Performance Stage 2 chip ($189). For not much money or hassle, you would have a fun and reliable daily driver.

au head + au head gasket

make sure u use ALL the parts of the AU head ie cam and rockers etc

EL hybrid