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Compression Ratios in EB2/ED - EF/EL Heads. 

 

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 Post subject: Compression Ratios in EB2/ED - EF/EL Heads.
Posted: Sun Jan 30, 2005 5:02 pm 
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Okay, Just working on a motor at the moment for a mate ... EB2 4.0 (head work)

Now, keeping the motor pretty standard ... But I know the compression ratios are different in the EB2/ED to the EF/EL

Now, I know that the EB2/ED had a compression ratio standard of 8.8:1
And the EF/EL had a 9.0:1 ..

What im asking, is, if that the difference is JUST in the heads, or did the block help it out too? .

Or was the EF/EL had just shaved a little more? Or becuase of the differenent combustom chamber in them? ... .. different gaskets? etc? .

What im trying to find out was, where did the extra .2:1 compression come from!

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Posted: Sun Jan 30, 2005 6:35 pm 
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EB/ED pistons are dished, EF/EL aren't, so that's gonna change it.
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Posted: Sun Jan 30, 2005 11:27 pm 
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Okay, so thats the only difference in them? . I knew the ef/el are flat top, thought that would make a difference . but yeah, just wondering if it was anything to do with the head ..
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Posted: Mon Jan 31, 2005 6:45 pm 
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Okay, What about the T heads? ... from understanding too, they have a smaller comsbustion camber, making more compression .. because the EB2/ED XR6's had a 9:0:1 compression too .

Hmm .. just wondering where it all fits in ...
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Posted: Tue Feb 01, 2005 1:58 pm 
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EF/L is 9.3:1, EF/L XR6 is 9.35:1.
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Posted: Tue Feb 01, 2005 3:04 pm 
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but the EL has smaller combustion chambers..

 

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Posted: Tue Feb 01, 2005 3:08 pm 
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Dont forget head gasket thickness will affect compression ratio as well.

 

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Posted: Tue Feb 01, 2005 3:48 pm 
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Dellboy999 wrote:
Dont forget head gasket thickness will affect compression ratio as well.


also how many times the head has been machined.

 

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Posted: Tue Feb 01, 2005 6:47 pm 
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the EF's do have subtle dished pistons to help with the squish area. I cleaned the carbon out of these when my head was off. Im sure that head gaskets were different thicknesses between the models

 

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Posted: Wed Feb 02, 2005 12:23 am 
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I’ll tell you one thing the EF head fits and runs nicely on the EB II block. I’m running one myself. It’s only had a little work, the cam tunnel got re-surfaced, slight port and polish, etc, but it goes hard and hasn’t had any problems ever since I put it on. From what I understand the EF and early EL heads used a different combustion chamber design, larger ports and runners. I always believed that although the pistons where changed from the EF onwards, the only real difference they made was to allow for more rigidity and strength and that they did not affect compression at all, but the raised compression was a result of the different heads combustion chamber design. A warning to you though if you are thinking of fitting an EF/EL head – I was told when doing the change over originally that later model EL heads (some of them anyway) where released using the small port head design of the AU. Probably better to go for an EF, or better yet an EF XR6 which has 2mm larger exhaust valves. A few head rebuilders also told me that apparently the EF Fairmont Ghia had a partial tickford head that included these larger valves, but I don’t know if this is fact or rumour.

As for the head gasket I’ve used one out of an EF head kit, and I’ve had no problems with it. Just make sure you get a set of AU head bolts for it; but you will need to grind around the head of the bolt as it is too large and will interfere with the stilts for the rocker gear. Only need to take a little off. Don’t know what they retail for as I only paid cost through a mate who works for Ford servicing.
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Posted: Wed Feb 02, 2005 4:39 am 
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Yeah, just playing with the idea of different heads on motors, I've got a motor im redoing at the moment, and its a EB2 block, I've got two heads for it, an EB2/ED head and a EF Just wondering it was the compression ratio in the heads that made the difference ..

I only use AU head bolts in my motors, and AU headgaskets ... bolts cost me $2 each ..
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Posted: Thu Feb 03, 2005 2:12 pm 
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Hi,

I have come in a little late to the thread ... but ....

Firstly, why 'AU' head bolts?

Secondly, EA 3.2 cylinder heads have a higher compression ratio ..... put some XR6 valves in perhaps .... just a thought?



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Posted: Thu Feb 03, 2005 3:02 pm 
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If you want compression, just take 50thou off the head and 30-40thou off the deck... then you'll end up with almost 12:1 compression like my wagon.

AU Head bolts? I think their the same. The EF/EL head gasket issues are more due to incorrect torque specifications in the workshop manuals. Try doubling their figures!!

 

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Posted: Sat Feb 05, 2005 12:49 am 
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Ok, despite what some try to say there is a difference with AU head bolts. I have a few mates who work for Ford as mechanics and they only replace E series head bolts with those of the AU due to differences in the bolt (Don’t know exactly what anymore, ill ask them next time I see em) but they recon they generally don’t get them back for the same problem once replaced with AU bolts. I mean hell if that’s what they are taught to do at Ford why the hell would you bother doing anything different?

Secondly you do not want to take an EA head, especially an EA 3.2 litre head! Why would you even want to do this? First of all I’m not even sure if the water jackets would align with an EA 3.2 litre, secondly they flow like crap in comparison to stock EBII or EF/EL heads, thirdly the intake runners are smaller, and by fitting one you are actually making your engine a 3.2 litre as the difference between these engines was primarily in the head. Oh, and that’s if you can fit it with valve clearances as well?

Yes you need to make sure you torque the bolts down correctly and then you need further tighten them down by 90 degrees.
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Posted: Sat Feb 05, 2005 2:02 am 
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Defective wrote:

...Secondly you do not want to take an EA head, especially an EA 3.2 litre head! Why would you even want to do this? First of all I’m not even sure if the water jackets would align with an EA 3.2 litre, secondly they flow like crap in comparison to stock EBII or EF/EL heads, thirdly the intake runners are smaller, and by fitting one you are actually making your engine a 3.2 litre as the difference between these engines was primarily in the head. Oh, and that’s if you can fit it with valve clearances as well?



Hang on, its to my understanding that engine volume is taken from the total stroke of the piston, from TDC to the lowest movement point... that is where you get your cc/litres, any volume in the head above TDC is disregarded (although you need to know the volume to figure out compression ratio)... anyway, fitting a different head wouldn't effect your engine volume. I think I remember reading somewhere that the engine volume of the 3.9 engines was made by increasing the stroke, hence why 3.2 piston heads can be used in the 3.9's...

But I have no idea about water jacket matching, but a head gasket would confirm it... even then I dont think there is any difference between a 3.2lt to a 3.9lt CFI or MPFI head gasket.

The only one I'd be a bit iffy on would be valve clearances... I'm sure there is data somewhere on all of this...

But from looking at the data in a Gregorys manual... there is no difference between an 3.2-3.9 litre engine apart from the stroke, and injection method.

 

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