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Ohh dear, it seems i have an eta!!!
Posted: Tue Oct 04, 2005 11:26 pm
by slimey
ok, so i have an e30 323i that at some time had an engine change. during the last week i have been pulling the car down for a recon, stamped on the bottom end was 2.7, i got a little excited until i found stamped on the head the letters ETA!!! as most of you can understand i was most disappointed and felt a litte dirty, any way my questions are this, what the hell is the difference between a 2.5e head and a 2.5i one? is there anyway that i can turn an eta engine into a true 2.7 litre tarmac burner? or should a dump it and cry into the empty engine bay where the engine once sat?
Cheers guys
Posted: Tue Oct 04, 2005 11:28 pm
by dsio
I think its that i heads are hemispherical, and eta heads are flat. Which is why they dont mix that well from time to time.
Posted: Tue Oct 04, 2005 11:31 pm
by dazleeds
i have a 323i breaker lovely engine
welcome to the zone matey
Posted: Tue Oct 04, 2005 11:31 pm
by Ziggy
is there anyway that i can turn an eta engine into a true 2.7 litre tarmac burner?
Basically, yes you can!
It's not just a case of sticking a 325i head on though... Just do a
search on here & you'll find out all you need to know
& welcome to the zone!
Posted: Tue Oct 04, 2005 11:33 pm
by dsio
From bmwe30.net:
People always ask and talk about putting an 'i' cylinder head on an 'e' block to improve performance. You would think this makes sense because the 'i' and 'e' are both M20s and the parts are interchangeable. This would work out great if it wasn't for one thing; the 'i' and 'e' combustion chambers are completely different.
On the 'i' chamber (head) you have a large, high volume, dome design. This works well on an 'i' block because an 'i' has pop up pistons. When the raised dome piston reaches top dead center (TDC) it fills the dome chamber and results in a compression ratio around 8.8:1. Think of it as two puzzle pieces. The piston fits the shape of the chamber to make a match.
Then there's the 'e' head. The 'e' chamber is a flat chamber and the pistons are also flat (the 'i' design is superior) so when they are at TDC you get solid compression, and a ratio that is actually higher than an 'i' at around 9:1.
So here's the problem with swapping... The 'i' chamber needs a pop up piston in order for it to get the compression ratio it needs to make good power, and the 'e' pistons aren't of that design. When you put the 'i' head on top of a stock 'e' bottom end you are LOWERING the compression ratio, lowering equals bad, lowering equals less power. By doing this the ratio becomes LESS than the 'i' stock ratio of 8.8:1, I believe it's something like 8.4:1.
Now hopefully this clears that up.. if there are further questions email me. So what does yield more power? I'll be posting another article soon with different methods of building up M20s. 'e' and 'i'.
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Posted: Tue Oct 04, 2005 11:40 pm
by LOOPYLEE1965
cant give you any advice but welcome all the same m8
Posted: Wed Oct 05, 2005 12:21 am
by Brianmoooore
Ziggy wrote:is there anyway that i can turn an eta engine into a true 2.7 litre tarmac burner?
Basically, yes you can!
It's not just a case of sticking a 325i head on though... Just do a
search on here & you'll find out all you need to know
& welcome to the zone!
You can make quite a usefull (and reliable) engine just by sticking a 320 head on it though.
Posted: Wed Oct 05, 2005 1:02 am
by MONSPORT42
As well as the different combustion chamber shape, you also have bigger valves and double springs and better cam profile on the 325 head.
Posted: Wed Oct 05, 2005 8:43 am
by Geeman
Easy solution... stick a 320i head on in place of the eta head...
Posted: Wed Oct 05, 2005 9:15 am
by E30BeemerLad
or better still Cabrio327i has a 320 head which he has had machined and put the larger 325i valves in, should make for quite a lively 2.7.He was going to put it on his cab which was already a 2.7 but he has sold it.
Think he said he wanted Ԛ£150 for the head, think it needs the valve seats cutting in and some minor machining to finish the job off. PM him if you or anyone else going the 2.7 route is interested.