Can I Use m20b25 cam and springs in m20b27 head?

[derrith]

Hi guys, I've got a 1985 528e with an m20b27. I'm looking for a mild performance increase and have been looking at installing a 325i head and leaving the stock bottom end. I've read that it's possible to install an e21 323i head and gain a nice horsepower increase without losing compression. However, here in the states m20b23 heads are hard to come by and not worth seeking out. I know that my eta uses the 200 head casting while the b25 uses a 731 head casting. Is it possible to swap the cam and valve springs to my eta head to create a 323i style 200 head? Thanks for your advice.

[Madhatter]

the b25 uses an 885 casting, its a little different than the 731 casting which is a later model 323i head.

Valve springs yes, but you need to have the head modified by drilling the remaining cam bearings to lubricate the 323i camshaft. Unfortunately, eta's only use 4 cam bearings in the head, the rest are there but they arent drilled as the cam doesnt use it. All other cams use 7 bearings, so you can run them without lubrication otherwise it will sieze the cam. A machine shop should be able to do the work for you with minimal problems though.

[derrith]

So all I need to do is drill the remaining camshaft bearings and I can use the b25's more aggressive camshaft and valve springs? I realize I won't gain the full benefit with the 200 head's smaller valves but I'm more interested in making my eta a little faster and raising the rev limit to make it more fun to drive.

[kenika65]

Putting an i cam in an eta head will not raise your r3vlimit in your case, it will only raise your power ban and acceleration.

Then your fuel and air will be off with out a chip.

Read this thread about 1.1/1.3 Motronic Up-Grade it will help you raise your revlimit and hp/tq with your eta.

Be sure to click all the links.

http://www.r3vlimited.com/board/showthread.php?t=100939

Then let me know what you think.

Do you have any pictures of your 85 528e

[derrith]

Putting an i cam in an eta head will not raise your r3vlimit in your case, it will only raise your power ban and acceleration.

Then your fuel and air will be off with out a chip.

Read this thread about 1.1/1.3 Motronic Up-Grade it will help you raise your revlimit and hp/tq with your eta.

Be sure to click all the links.

http://www.r3vlimited.com/board/showthread.php?t=100939

Then let me know what you think.

Do you have any pictures of your 85 528e

Oh, I'm totally aware I must make the motronic 1.1/1.3 upgrade and swap in a custom chip or the 173 ecu. I have the harness out of an e28 super eta ready to go in but most of the guys on mye28.com are more knowledgeable about the m30 than the intricacies of the m20, which is why I asked this question here at r3v.

You can see some pictures of my car here(It's the black one).

From further research I think it's in my best interests to locate a 731 head if possible. Sticking with the 200 head will limit my intake at higher revs, leaving my car more out of breath than it already is. With the 731 head I'll be able to use the larger intake and throttle body from a 325i.

I appreciate everybody's feedback.

[StereoInstaller1]

Can you get the motor or at least pistons/head from the E28SETA?

[derrith]

Can you get the motor or at least pistons/head from the E28SETA?

I could, I just don't have the expertise or the facilities to pull my engine. I'd like to do what I can with my eta bottom end. It's in good shape, leaks no oil, averages 160-165psi across all cylinders, so I don't want to pull it. I'd rather see what I can do with the block that's in there since I see that as a little more interesting challenge and the road less travelled.

[kenika65]

Just so you know you can bolt on everything from an i car on to your eta block and head, you can even leave the head stock and it will run like a charm, This is what I did.

I have my stock 1986 2.7 eta block and head(never been taken off).

Then I took everything off of my 89i parts car and put it on my 86es.

i intake,tb,injectors,fpr,

all i sensors, harness, 173ecu

i exhaust,

all i pulleys(toothed crank pulley for crank shaft positioning sensor) water pump pulley.

She fired right up and has more torque then an i car and the rev limit is now 6300

since then I have installed i double valve springs, but kept the eta camshaft. ( i put double valve springs because the if the stock eta valve springs were to fail then valve and piston damage would occur)

The reason I left the eta head on is because it has 9.0:1 compression and has perfect compression across the board and I enjoy the high torque and great economy.

If I needed to replace the head or gasket then I would install an i head or get my eta head drilled for an i cam.

[derrith]

Since then I have installed i double valve springs, but kept the eta camshaft. ( i put double valve springs because the if the stock eta valve springs were to fail then valve and piston damage would occur)

The reason I left the eta head on is because it has 9.0:1 compression and has perfect compression across the board and I enjoy the high torque and great economy.

If I needed to replace the head or gasket then I would install an i head or get my eta head drilled for an i cam.

I'm curious why you left the eta cam installed, it was my understanding that the eta cam doesn't deliver much useable power further north than 5300 rpm or so. What has been your experience in the last 1000 rpm before redline?

Thanks again for everybody's input.

[danzo]

Kenika why do you say the rev limit is 6300? Shouldn't it be ~6800 with the 173 computer? Is this the limit of the eta cam?

I have an '84e w/ebay chip that pulls very strongly to the 5500 limit. With a 3.73lsd it is a very different car than when it left the factory. I plan to slap on an i head/intake in a month or so, then go to carburation when my car becomes emissions exempt in Texas in 7 months.

So does anyone know where to get a carb intake manifold?

- Danny

[kenika65]

I'm curious why you left the eta cam installed, it was my understanding that the eta cam doesn't deliver much useable power further north than 5300 rpm or so. What has been your experience in the last 1000 rpm before redline?

Thanks again for everybody's input.

*I meant 6800rpm factory i r3vlimit.

I left the eta cam installed because I have no reason to take the head off, if I was to install the I cam then I would have to drill cam bearing holes in the head.

The eta cam with 1.3M and all i parts performs wonderful especially after 5300 That is when the torque is at it highest.

I enjoy the eta cam for its economy and high torque output. If and when you put an i cam in, your torque and hp will move up the power ban meaning you will have to rev higher to get the same torque I have at a lower rpm.

[Madhatter]

there is no way it keeps building torque after 5300rpm. Thats very high for a motor, especially for a camshaft in a motor that made peak torque below 4000rpm.