I have seen some talk about porting polishing and exude honing e36 heads and intake manifolds. It seems odd to me though, I would love to know why you would exude hone (or if you even could) a molded, perfectly smooth PLASTIC intake manifold.
Port matching? I dont see how you could given that the intake manifold has 6 individual gaskets and is once again a precision hi temperater thermoplastic or composite of some sort. I know how to do it on a a big old american V-8 as those manifolds are big metal castings of questionable finish quality and precision. But a very smooth (yes had my fingers in one this weekend ) extremly well finished intake manifold? I can see doing a three angle valve job, i can even see head work on the exhaust side, and perhasps even a camshaft swap, (assuming you happen to have that nifty little three thousand dollar tool for removing the camshafts lest you break them..). but i cant see porting, polisahing and gasket matching on this motor. (maybe some of the folks are familiar with american iron and thought these techniques would be applicable?
I want to port the sh*t out of my head, and stuff some bigger valves in. I've seen some al intakes manifolds around for about a $1K. I'm not sure if it would be worth it to port/polish it though, probably flows enough out of the box.
Kevin is right. Porting or extrude hone is a waste of money. BMW's manifolds already flow quite well. Don't forget once you upgrade the manifolds it's almost useless unless you port out the intake ports and your heads. You'll also need more aggressive cams to suck in more air inorder to make use of those upgrades.
When you get into headwork it doesn't stop at one thing, you have to make sure everything matches, think big $$$$.
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I got an email back from a company this morning, see reply below....
"We do, though most gains are achieved with valve seat, valve, and
combustion chamber work. We clean up the ports but greatly enlarging or reshaping them isn't necessary. Most often we use special valves which have a reduced stem diameter at the head to improve flow even more.
Labor to do the mild porting and a complete performance valve job is
$1100 isn't bad for a port and performance valve job. I asked about flow numbers and if they had any dyno numbers. A 15% increase in flow should be good for 10% increase in hp and torque. I think when paired with an aggressive set of cams, the combo would make decent numbers.
I got another email from the guy this afternoon. He said they build their engines to produce 300+hp. I asked for the details on what needs to be done to reach this power level. I'll let everyone kno when I hear back from him tomorrow.
Are the narrower stemmed valves something they use in their race cars or something? I'm sure they're strong, I'd just be nervous about putting them in a head I don't plan on rebuilding again, like they would with their race cars.
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I'd rather spend the cash on individual direct throttle body induction conversion.
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