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84 ETA M20 block, 92 E30 head compatible?

E28 technical advice asked and given! Troubleshooting, modifications and more.
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vai2iant

84 ETA M20 block, 92 E30 head compatible?

Post by vai2iant »

I searched M20 head swaps and I know ETA and Super-ETA are completely different. My car is stamped 10/84. I found a parts E30 1992 locally, and was wondering if there is anyway I can use the head from that motor and if it has anything to do with electrical.
TSMacNeil
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Post by TSMacNeil »

Bimmerguy2002
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Location: Lodi, California

Post by Bimmerguy2002 »

yes but there is moar tings need done
vai2iant

Post by vai2iant »

Ahh i get it now, new crank and pistons ouch! I'll just stick to a 84 325i head swap =] Thanks guys!

"If you are starting with a eta equipped car, this will require an upgrade to Motronic 1.1/1.3 from a 325i in order to get the desired revs and fuel/spark mapping. This will require the use of the entire engine harness, ECM, front crank pulley with crank sensor and bracket, all the sensors (including AFM), injectors (Etas built before September 1987 with the older Motronic system use low-impedance injectors, wereas the 325i computer must use high-impedance injectors) , also 325i plug wires and the EVAP purge solenoid. An instrument cluster with the 7000 rpm tachometer and a small wiring modification to make the tach work will also be necessary. Owners of Etas made before December 1986 will need to widen the hole where the engine wiring harness goes into the car. Owners of older Etas that have a rectangular plug joining the engine harness to the fuse box instead of a round one will have to change to the later model fuse box or splice all the wires and make a custom connection."

Now is that a MUST, if i do find a 84 eta i head just to get it running? and slowly replace computer, harness, crank pulley, etc.
Bimmerguy2002
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Location: Lodi, California

Post by Bimmerguy2002 »

no no

eta no need dat much work, top only, and harness. Maek more HP.
TSMacNeil
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Post by TSMacNeil »

"Ahh i get it now, new crank and pistons ouch! I'll just stick to a 84 325i head swap..."

Nope. The "super eta" has a more robust bottom end, and the required Mot 1.1/1.3 management....it also has the 885 head already. The article indicates that all you really need to do with your "standard eta" is change out the "200" head with a complete "885" head (325i)..(cam, etc). That means you also need the intake manifold, throttlebody, ECU ,harness and related ignition components for the swap....nothing in the bottom-end whatsoever.
turbodan
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Post by turbodan »

V1cut wrote:Nope. The "super eta" has a more robust bottom end, and the required Mot 1.1/1.3 management....it also has the 885 head already. The article indicates that all you really need to do with your "standard eta" is change out the "200" head with a complete "885" head (325i)..(cam, etc). That means you also need the intake manifold, throttlebody, ECU ,harness and related ignition components for the swap....nothing in the bottom-end whatsoever.
The super eta has the same bottom end as the 82-87 eta with different pistons.
TSMacNeil
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Post by TSMacNeil »

turbodan wrote:
V1cut wrote:Nope. The "super eta" has a more robust bottom end, and the required Mot 1.1/1.3 management....it also has the 885 head already. The article indicates that all you really need to do with your "standard eta" is change out the "200" head with a complete "885" head (325i)..(cam, etc). That means you also need the intake manifold, throttlebody, ECU ,harness and related ignition components for the swap....nothing in the bottom-end whatsoever.
The super eta has the same bottom end as the 82-87 eta with different pistons.
Can you be more specific about the super pistons? What change was made for the 885 head? (I really don't know) I thought there was a major rod/piston change in the super....I realize they're both strokers, but is the super rod beefier? Thats what I thought anyhow.
Bimmerguy2002
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Post by Bimmerguy2002 »

pistons are just different, thats it really, the entire head is different, ports, combustion chamber, and other stuff.
TSMacNeil
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Post by TSMacNeil »

gotcha...thanks.

(and to think, I've been wrong all this time...shocking! :shock: )

the 10 parts we were discussing, was the head part of that?

Since mine is a super, I have the correct head/valve combo already...needs cam/springs, etc though...

I cant find the old thread.

Im a dickhead...found it.

325i air flow meter
325i intake bellows (brand new)
325i throttle position switch
325i fuel pressure regulator
325i vacuum line and check valve
325i throttle body
325i intake manifold (hot tanked)
325i camshaft
325i inner valve springs
325i 173 ECU
Last edited by TSMacNeil on Mar 25, 2010 1:31 PM, edited 2 times in total.
turbodan
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Post by turbodan »

V1cut wrote:Can you be more specific about the super pistons? What change was made for the 885 head? (I really don't know) I thought there was a major rod/piston change in the super....I realize they're both strokers, but is the super rod beefier? Thats what I thought anyhow.
The crank and rods are the same for all etas. The super eta pistons have a different crown and updated rings.
TSMacNeil
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Location: Phoenix, Arizona

Post by TSMacNeil »

turbodan wrote:
V1cut wrote:Can you be more specific about the super pistons? What change was made for the 885 head? (I really don't know) I thought there was a major rod/piston change in the super....I realize they're both strokers, but is the super rod beefier? Thats what I thought anyhow.
The crank and rods are the same for all etas. The super eta pistons have a different crown and updated rings.
Thanks brutha....never knew exactly what was different down there.
shagrath
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Post by shagrath »

V1cut wrote:gotcha...thanks.

(and to think, I've been wrong all this time...shocking! :shock: )

the 10 parts we were discussing, was the head part of that?

Since mine is a super, I have the correct head/valve combo already...needs cam/springs, etc though...

I cant find the old thread.

Im a dickhead...found it.

325i air flow meter
325i intake bellows (brand new)
325i throttle position switch
325i fuel pressure regulator
325i vacuum line and check valve
325i throttle body
325i intake manifold (hot tanked)
325i camshaft
325i inner valve springs
325i 173 ECU
You can also source these from an early e34 m20 525i. Remember for ease of install use a Super eta wire harness, unless you like hacking into stock harnesses.
TSMacNeil
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Joined: Jan 22, 2009 5:37 PM
Location: Phoenix, Arizona

Post by TSMacNeil »

shagrath wrote:
V1cut wrote:gotcha...thanks.

(and to think, I've been wrong all this time...shocking! :shock: )

the 10 parts we were discussing, was the head part of that?

Since mine is a super, I have the correct head/valve combo already...needs cam/springs, etc though...

I cant find the old thread.

Im a dickhead...found it.

325i air flow meter
325i intake bellows (brand new)
325i throttle position switch
325i fuel pressure regulator
325i vacuum line and check valve
325i throttle body
325i intake manifold (hot tanked)
325i camshaft
325i inner valve springs
325i 173 ECU
You can also source these from an early e34 m20 525i. Remember for ease of install use a Super eta wire harness, unless you like hacking into stock harnesses.
Yessir,

I the OP has a standard 84 eta...mines an 88, so no problemo.
Xenocide
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Joined: Jun 08, 2008 4:29 PM
Location: Atlanta, GA

Post by Xenocide »

turbodan wrote:The super eta pistons have a different crown and updated rings.
And a slightly higher compression height, which is why the super eta has an 8.5:1 compression ratio whereas with the 885 head (with the i cam and springs) on eta pistons you'll be making an 8.35:1. The general consensus over at e30tech (as far as I've seen) is that an ordinary stock eta with an 885 head will make 130~140 HP and a little less torque than stock due to the better flow and lower compression ratio. This is a great build for a turbo setup, but not so good otherwise.

I wouldn't waste the cash unless you were going to replace the pistons or go FI, and certainly don't waste the cash if it's the (e).

more info
AFAIK all that info is good. The whole site has proven to be very useful.
turbodan
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Joined: Jan 09, 2007 10:19 PM

Post by turbodan »

The crown design is the significant difference. The standard eta pistons are flat with a plain dish, the super eta pistons are domed with an offset dish. They have a more effective quench area than the standard eta chambers. An 885 head on a standard eta block will be less resistant to detonation than it would be with the correct pistons, which quite possibly negates any benefit to the slightly lower CR. There is a lot more to the combustion chamber than just the compression ratio.

The head swap isn't the most labor intensive part of the job. Thats a bolt on operation. If you have a super eta harness its not too bad, but its a bitch wiring in the e30 harness. The injection swap makes the whole thing work. If you dont want to do that as well you're better off running the eta top end.
vai2iant

Post by vai2iant »

V1cut wrote:gotcha...thanks.

(and to think, I've been wrong all this time...shocking! :shock: )

the 10 parts we were discussing, was the head part of that?

Since mine is a super, I have the correct head/valve combo already...needs cam/springs, etc though...

I cant find the old thread.

Im a dickhead...found it.

325i air flow meter
325i intake bellows (brand new)
325i throttle position switch
325i fuel pressure regulator
325i vacuum line and check valve
325i throttle body
325i intake manifold (hot tanked)
325i camshaft
325i inner valve springs
325i 173 ECU
Wow I need that huh? I plan on boosting it anyway.
Xenocide
Posts: 3370
Joined: Jun 08, 2008 4:29 PM
Location: Atlanta, GA

Post by Xenocide »

turbodan wrote:The crown design is the significant difference. The standard eta pistons are flat with a plain dish, the super eta pistons are domed with an offset dish. They have a more effective quench area than the standard eta chambers. An 885 head on a standard eta block will be less resistant to detonation than it would be with the correct pistons, which quite possibly negates any benefit to the slightly lower CR.
I always wondered about that, thanks for clearing that up dan.
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