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E30 (1982 - 1993)
God's Chariot. The E30 was produced primarily from 1982 through 1991. The cabriolet was the one exception which was produced through 1993.

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  #1  
Old 03-08-2013, 08:05 AM
Chaunceton Chaunceton is offline
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To Port or not to Port?

My head gasket is compromised and the head will soon be sent to machine shop for cleaning and inspecting. While it's there, should I have it ported and polished? It's a 1989 325i, standard M20 engine, close to 300k miles. In the long run I'd like to turn this into a track/street car. Are there substantial hp/torque gains from porting the M20? I ported a 66 Mustang and it made noticeable difference, but is the M20 already built to perform really well?
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  #2  
Old 03-08-2013, 10:16 AM
markseven markseven is offline
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Quote:
Originally Posted by Chaunceton View Post
My head gasket is compromised and the head will soon be sent to machine shop for cleaning and inspecting. While it's there, should I have it ported and polished? It's a 1989 325i, standard M20 engine, close to 300k miles. In the long run I'd like to turn this into a track/street car. Are there substantial hp/torque gains from porting the M20? I ported a 66 Mustang and it made noticeable difference, but is the M20 already built to perform really well?
BMW was very good at developing and manufacturing heads that flowed well right off the dealer lot. The old cast iron and first gen aluminum units do benefit from P&P, however that is not the case with the M20. A CAI and headers combined with a TMS chip will give a decent bang for your buck though.
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  #3  
Old 03-08-2013, 11:53 AM
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_Ethrty-Andy_ _Ethrty-Andy_ is offline
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to reiterate, yes, there are gains. but your money is better spent elsewhere on this engine.
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  #4  
Old 03-08-2013, 12:46 PM
Chaunceton Chaunceton is offline
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Awesome that's exactly what I wanted to know. While I have the head off, any performance boosters I should be aware of?
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  #5  
Old 03-11-2013, 02:20 AM
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Nick323 Nick323 is offline
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I beg to differ
A M20 head can be made better by porting, matching and in certain cases putting in bigger valves.
BUT I would not ask my local machine shop to attempt this, but rather somebody who specialises in that.

If we do heads, we also rebuild them, pressure test the lot & therefore the porting is but a small part of the overall cost.
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Old 03-11-2013, 06:53 AM
markseven markseven is offline
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Originally Posted by Nick323 View Post
I beg to differ
A M20 head can be made better by porting, matching and in certain cases putting in bigger valves.
BUT I would not ask my local machine shop to attempt this, but rather somebody who specialises in that.

If we do heads, we also rebuild them, pressure test the lot & therefore the porting is but a small part of the overall cost.
For that matter a Porsche GT3's heads can be made better as well. Consider the OP's situation...
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Old 03-11-2013, 07:31 AM
markseven markseven is offline
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Quote:
Originally Posted by Nick323 View Post
I beg to differ
A M20 head can be made better by porting, matching and in certain cases putting in bigger valves.
BUT I would not ask my local machine shop to attempt this, but rather somebody who specialises in that.

If we do heads, we also rebuild them, pressure test the lot & therefore the porting is but a small part of the overall cost.
Nick, I know you know your stuff BTW.
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Old 03-12-2013, 01:29 AM
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Nick323 Nick323 is offline
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Thumbs up I would port if it includes a recon

I did consider the OP situation
he has a head that needs an Overhaul

In his case I would ask his local & respected machine shop what they would ask for the job & also somebody who does porting
The guys who do the porting should also include the OH, as that is normally part of the job

How often don't I get guys coming to me after they had their tops reconditioned & ask for the porting
I would have to do the valves again in anycase, as well as the guides, seats etc as the machineshop is never going to do what I do to them.
I would have to check the sealing surface for straightness and if my client wants a warrantee I would PT the tops after my work for checking.
a Lot of duplication here, but for one to get a better result

I just hope to enlighten the OP so he does not bite his arse afterward
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  #9  
Old 03-12-2013, 06:46 AM
Chaunceton Chaunceton is offline
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Quote:
Originally Posted by Nick323 View Post
I did consider the OP situation
he has a head that needs an Overhaul

In his case I would ask his local & respected machine shop what they would ask for the job & also somebody who does porting
The guys who do the porting should also include the OH, as that is normally part of the job

How often don't I get guys coming to me after they had their tops reconditioned & ask for the porting
I would have to do the valves again in anycase, as well as the guides, seats etc as the machineshop is never going to do what I do to them.
I would have to check the sealing surface for straightness and if my client wants a warrantee I would PT the tops after my work for checking.
a Lot of duplication here, but for one to get a better result

I just hope to enlighten the OP so he does not bite his arse afterward
It's a shame you don't live in Utah and I can't just bring my head to your shop. The head will be sent to the machine shop, but I won't be getting it ported. I think my money is best spent elsewhere on this one. For instance maybe a higher performance camshaft. Any thoughts in that department?
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  #10  
Old 04-03-2013, 02:19 AM
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Nick323 Nick323 is offline
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Maybe you should have a look at www.nicksracing.com for my thoughts on this
The camshaft is the brain of your motor, so it is to be replaced last in order to augment the other modifications.
i.e. If you flow your head with bigger valves= overall more power with a considerably higher gain at high RPM
I normaly build headers for torque.
I strap the stock car to my dyno for a run before I do the mods and then when 'm finished. Let's say I see a considerable increase in torque at low RPM, then I will grind the cam to take away some of this torque and make more top end power.
My engine is not built round the cam, but the cam is built to suit the power I want !
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  #11  
Old 04-03-2013, 05:59 AM
Chaunceton Chaunceton is offline
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Quote:
Originally Posted by Nick323 View Post
Maybe you should have a look at www.nicksracing.com for my thoughts on this
The camshaft is the brain of your motor, so it is to be replaced last in order to augment the other modifications.
i.e. If you flow your head with bigger valves= overall more power with a considerably higher gain at high RPM
I normaly build headers for torque.
I strap the stock car to my dyno for a run before I do the mods and then when 'm finished. Let's say I see a considerable increase in torque at low RPM, then I will grind the cam to take away some of this torque and make more top end power.
My engine is not built round the cam, but the cam is built to suit the power I want !
Awesome man, great information. Eventually I'll probably need a more aggressive cam anyway if I plan to turbo it.
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  #12  
Old 04-03-2013, 07:48 AM
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Nick323 Nick323 is offline
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Your Turbo blows enough air through the motor
You would want a different cam to a normally aspirated unit, if you wish to change at all.
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