Port matching the intake manifold.

[Jordan]

Couple weeks ago I decided I wanted to do this after cleaning my intake manifold, and taking a look at the runners.

Just before they meet the gasket there are 2 steps that no doubt reduce air flow. Of more concern however, is how small the runners themselfs are. They are significantly smaller then the intake gasket!

Since my head was ported, and the port is the same size as the gasket, I see no reason why the intake manifold should be so small on the other side!

I used a OEM gasket to mark all the mating surfaces, so I knew how much material I had to remove. From there I used a rotory rasp on my dremel to smooth the casting texture, and to remove the stepping. After that I used the same tool to flair the edges out. Once everything was fairly flat I used cartrige sanding rolls to gain a flat smooth surface. Then I used my finger and rolled up 150grit paper to futher smooth. Once I had it as smooth as I could get it I switched a abrasive buff onto the dremel and buffed the runner with the aid of WD-40. Again I switched out the bit, to a polishing head, and gave it a final biff/polish. End result is a stepless, clean, smooth, polsihed surface that flairs into the gasket to meet the head.

I have 4 of the 6 runners done, and I plan to finish it up tomorrow.

pics:

[Jon325i]

Man....is there ever a noticable difference. Just the visiual itself is significant. I'm certain things will flow better than before once you've finished it.

Those dremel's are kick-ass :up:

Jon

[rs4pro3]

Looking good. I need to do My I intake manifold soon so it port matches my I head. But I might be running the mulit throttle intake so who knows.

[schnitzer teil-jäger]

READ ME,

http://www.metricmechanic.com/pg18.htm

[shadowracer]

...Too bad the only real way to make any real power gains is to extrude hone the entire intake since port matching alone will not make much, if any difference. Why you ask? If you take and port the opening of the intake alone, the rest of the intake is still the same size, so you don't gain anything, (example) if you have a 2" pipe that is 3' long, and stretch half to 2.5", it will still only be able to flow the same amount of volume the 2" side will allow it to flow.
I will admit though, it really looks nice!!! :up:
Your best bet for more power is to either extrude hone the entire intake, which is pretty pricey, or go with the multi- throttle body intake, which is pricey too. ;)

[Jordan]

...Too bad the only real way to make any real power gains is to extrude hone the entire intake since port matching alone will not make much, if any difference. Why you ask? If you take and port the opening of the intake alone, the rest of the intake is still the same size, so you don't gain anything, (example) if you have a 2" pipe that is 3' long, and stretch half to 2.5", it will still only be able to flow the same amount of volume the 2" side will allow it to flow.
I will admit though, it really looks nice!!! :up:
Your best bet for more power is to either extrude hone the entire intake, which is pretty pricey, or go with the multi- throttle body intake, which is pricey too. ;)

\

Yeah, I guess I'll have to be happy with my "fake" power gains then. The point he is that air speed charge is increased by deceasing turbulence.

"why you ask?" I didn't ask for you to quote me a bunch of information that I already knew, that overlooks more important principles.

Extrune honing is a waste of money on any m20 other then a 3.0

schnitzer: yup, read that years ago :)

[Jordan]

...Too bad the only real way to make any real power gains is to extrude hone the entire intake since port matching alone will not make much, if any difference. Why you ask? If you take and port the opening of the intake alone, the rest of the intake is still the same size, so you don't gain anything, (example) if you have a 2" pipe that is 3' long, and stretch half to 2.5", it will still only be able to flow the same amount of volume the 2" side will allow it to flow.
I will admit though, it really looks nice!!! :up:
Your best bet for more power is to either extrude hone the entire intake, which is pretty pricey, or go with the multi- throttle body intake, which is pricey too. ;)

Yeah, I guess I'll have to be happy with my "fake" power gains then. The point he is that air velocity is increased by deceasing turbulence.

"why you ask?" I didn't ask for you to quote me a bunch of information that I already knew, that overlooks more important principles.

Extrune honing is a waste of money on any m20 other then a 3.0

schnitzer: yup, read that years ago :)

[modifiede30]

There are some real myths to extrude honing. The biggest is that it aids air flow. If you read the metrix mechanics site, it makes several valid points about some turbulance being necessary for better flow.

There is another reason that the intake runners are not as smooth as you'd get from extrude honing. This doesn't mean that smooth isn't good, but everything I've read indicates that getting them too smooth interferes with air fuel mixture, and that the rough surface creates a subtle turbulance that is meant to better mix the fuel and air prior to its entry into the cylinders.

Jordon, I notice you flared the edges instead of just taking everything down as far in as possible - so that there is no transition between the head and intake. Won't this dip in the transition disrupt flow?

[rwh11385]

quality work there..... they look beautiful :D , too bad no one will see them :roll:

oh well, sweet work

[Jordan]

I notice you flared the edges instead of just taking everything down as far in as possible - so that there is no transition between the head and intake.

I would have perfered to do it like that. However... the cast aluminum used on this manifold is rather soft, and it clogs cartrige sanding rolls, and rasps quite quickly. removing that much material would be murder.

granted it doesnt allow the maximum transition, but its vastly better then how the manifold started.

[modifiede30]

I bought a porting kit for mine. It came with about 30 different sanding rolls, and a 4" and 6" lenght drill attachment for getting deep into the head and intake. I'll let you know how things turn out.

[SickE30]

I have a certain respect for a man that makes his BMW muscular.

[shadowracer]

Well, I seem to have annoyed someone, sorry that was not my intention. I was simply stating a small point. "In my opinion", just porting the cyl. head side of the intake on the m20 intake seems like a waste of time since the rest of the intake is still unchanged, which is why I used the "pipe" example. As for the statement of "fake" power gains, I never said there would be none, I said not much if any. Yes some velocity may be gained, but is it worth the time, and trouble of doing it? Honestly, I don't know with an m20. Doing a complete job on the intake with extrude honing seems more practical since there would be a much smoother airflow charge going thru it, and then meeting the fuel at the cyl. head opening.
I do know that porting a cyl. head is a better idea, and if you have that done, then all the power to you!
..... What do I know about once building a 670hp race engine? :roll: Oh yea, it wasn't a BMW engine!
Like I said before I don't know what gains would be made with the M20, but if some are made thats good!
Good luck!! and again sorry to have annoyed you.

[AndrewBird]

Rather then using a sanding drum to take it down, you should have used a cylindrical cutting bit like this one (only bigger, this on is for a Dremel and is used for smaller applications).

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXC557&P=7

They chew through aluminum like it was butter.

Andrew[/url]

[Jordan]

Rather then using a sanding drum to take it down, you should have used a cylindrical cutting bit like this one (only bigger, this on is for a Dremel and is used for smaller applications).

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXC557&P=7

They chew through aluminum like it was butter.

Andrew[/url]

Thats a rotoray rasp... I did use one, as said above the cast aluminum used on the manifold is soft, and loads bits up quickly. IE it metls into the groves, and you have to clean the bit out every 20-30 seconds.