porting my head

[custom e30]

im going to fix a bend valve in my m20b25 2.5L head, i also want to port both the exhaust and intake side as well as the intake its self, im going to buy the ebay metal templates so i know the correct amount to take out,

whats im wanna know is,
1. is it worth the trouble, will i notice a difference?

2. will i need to throw bigger injectors and a regulator in?

[custom e30]

anybody?

[Adrian_Visser]

Maybe you should figure out why your engine won't turn over before you think about porting your head. That said are you thinking of actually fully porting or just gasket matching? A proper port job isn't as simple as holding a template up and shaving out metal. You have to precisely match the volume in each port to the others. One way is to fill the ports with water and measure what they hold. The valves have to be installed and must seal properly for this. Without installing larger valves you aren't going to see much improvement imo.

[custom e30]

http://cgi.ebay.com/ebaymotors/BMW-E30-M20-cylinder-head-PORTING-MATCHING-templates_W0QQcmdZViewItemQQhashZitem2558b47be3QQitemZ160402013155QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

this is what i planned to buy and used. what you think?

[StereoInstaller1]

OK, like Adrian said, gasket matching is fine, which is all that kit is for.

That isn't porting. Porting means an actual reshaping of the valve pocket, which you are not even remotely qualified to do.

A little gasket matching is great. Fun and easy, plus you get bragging rights.

[StereoInstaller1]

Oh yeah, here is a quote taken from that ad:

It is is a matter of precision

[digger]

Maybe you should figure out why your engine won't turn over before you think about porting your head. That said are you thinking of actually fully porting or just gasket matching? A proper port job isn't as simple as holding a template up and shaving out metal. You have to precisely match the volume in each port to the others. One way is to fill the ports with water and measure what they hold. The valves have to be installed and must seal properly for this. Without installing larger valves you aren't going to see much improvement imo.

whats the volume of the port got to do with anything when the intake runner is an extension of the port and therefore affects it, you'd want to account for this?

[E30QC]

i'll answer,
the the intake runner is dry up until it meets the head, what i mean is the gas is not injected in the mix yet in the intake. >So the port of the head must be ultra aero-efficient, and must also be standard displacements across the cylinders to not create a lower pressure zone.
The porting of all heads must be done using a flowbench, something that measures the aero-dynamics of the port in question, >both intake and exhaust ports may be "ported" and polished.
unfortunately, as you own a bmw, it sucks that you may take great discomfort in knowing that engineers did spend a ridiculous amount of time creating an' efficient head for your stock application, and that its' already quite good at displacing the proper amount of air to the proper amount of fuel your injection system decides to send into your stock motor. A shame.. really.. the loss of those precious few millimeter in between gasket and metal could of unleashed 1 gazzilion horsepower. good luck with all that nos man, you have enough nos to blow yourself up

[StereoInstaller1]

Note I said "fun" and "easy" along with "bragging rights".

You will not gain anything. No added HP or torque, nor better economy...just bragging rights.

[custom e30]

i was looking and the intake side is already huge so i think ill leave that alone and just port the exhaust side to match the headers.

[StereoInstaller1]

i was looking and the intake side is already huge so i think ill leave that alone and just port the exhaust side to match the headers.

Yeah, I am sure BMW just screwed up and left it small.

Its not like there was a team of highly qualified engineers that designed this thing. I am sure you and a die grinder can do better.

[nando]

you don't want to gasket match the exhaust, you want them 1-2mm smaller. Otherwise you can suffer from reversion.

there's definitely a lot of room for improvement on both sides of the head, but you aren't really going to benefit from simply making them bigger. There's even been discussions on the "other" site about adding material to the roof of the intake side since they're so huge.

the best thing you can do is clean up the bowl (there's an obvious casting ridge around the valve stem), work the exhaust (smooth/polish) and soften the short side radius of the intake (the difficulty of this is high though). Do not polish the intake ports. You can also polish the combustion chamber and remove sharp edges that could create hot spots and lead to pinging.

Other options are to completely smooth off the valve guides on the exhaust side and reshape the entry of the intake, but these are much more advanced.

the best money you could spend would be on a good 3 or 5 angle valve grind, and maybe having the valves back cut. +1mm valves aren't really much benefit, they can be but you'd want to be overbored as well.

of course none of this is really going to matter if you have a stock cam, stock exhaust, stock bottom end and a stock computer.. I'd just drop it off at a shop, have it rebuilt and slap it back on. fresh valves and seals are going to matter way more than a back yard port job.

[xLegendOZWest]

Yeah, I am sure BMW just screwed up and left it small.

Its not like there was a team of highly qualified engineers that designed this thing. I am sure you and a die grinder can do better.

+1 we didnt have the best engineers in the world design precision engines so they could be hacked at by anyone with a die grinder. if you really want this done. take it to a shop that has a flow bench, and have a professional do it.

[ikkitousen]

Greatest thread EVAR! No. Really.

Stereo Installer = GOD!

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DAMN HAVENT LAUGHED THIS HARD IN MONTHS!!!

[custom e30]

i ported myself and now a shop has the head, i got a call about a hour ago and said the valve replacement is done and tested the head where i ported, everything looks good and is equal