Not with a 292, no, I wouldn't worry either.
You can clean up the most obvious problems and
port- match it yourself and be 98% of the way there for 0%
of the money!

The M10 head's pretty good...

t
_________________
I have a car disease. There is no cure.
I'm not even managing the symptoms very well...

WH wrote:

In a short answer "NO". Flowing the stock head will not gain you that much extra HP over just installing the 292 cam, maybe another 5 hp if you have a flow bench (you do don't you????). If not and you just start grinding away you may well ruin the flow characteristics of the head, as remember bigger is not always better. Every engine has a different shape for internal passages and what makes the best hp for that particular engine. BMW heads are well designed stock, heavily moddifying them is not necessary as they flow well from the factory. You could clean up the internal castings if they're super rough but otherwise leave it alone. if anything add a header and free flow exhaust to your mix and you'll be better off. The MSD won't add HP BTW unless you're stock bosch distributor or ignition is worn or tired. Go get a good book on engine modifications, I own several but my favorite is "Tuning the A series engine" by David Vizard. A good read for any motor nut even if it is about British engines, not German. Many of the principles are the same, just you don't need to do as much to a BMW engine as a A series to make high HP. WH

WH, as usual, your advice is quite sound. I have read vizard's primer as well as many other treatises on the subject. And yet, there seems someone routinely trying a new twist on the subject and inviting more argument on the subject.

I have actually watched heads and piston combinations tested on flow benches and dynomometers and still heard conclusions that defy logic. Laminar flow be damned a few old timers have said and these same old timers had Nascar races under their belts. Anti reversionary grinds are supposed to be good and then there are those who claim dimpling and ridging (see metric mechanic's site) are the only way to go. I think I recall seeing a lengthy discussion on this very topic in the archives. Justin, try searching them more often and you will find many of your questions answered. This is not exactly on point, but I think JimK has lectured on this subject. http://www.bmw2002faq.com/component/option,com_forum/Itemid,57/page,viewtopic/t,293119/

For what its worth, we took the 121 head and unshrouded the valve stems to promote airflow. After the modification, according to the dyno, we lost .5 hp. So, I pretty much agree with your opinion. On the other hand, I had a friend who modified the prop on his outboard motor and had a manufacture buy the modification, so go figure. I would discourage most experimentation, but you never know.

As an aside, I read your post regarding "U" ad "V" grooved electrodes on spark plugs and agree with you there too. However, I noticed that Bosch Super Plus plugs now sport the same "V" groove, so I have to assume there is some value to this, although it may just be more hype and hope than real help.

Cylinder Head Porting - Head Porting Basics
Get more power out of your cylinder heads by following five easy rules

By David Vizard
photographer: David Vizard, Johnny Hunkins: http://www.popularhotrodding.com/tech/0610phr_cylinder_head_porting/index.html

In my opinion a 45DCOE with a 292 and stock valve sizing and non-ported head is too much carb for that motor.......I think you could make more power with a 38/38....

just thinking out loud.....
_________________
68' 1602
98' ///M3 Sedan

88' ///M3 Sold *
06' ///M3 Competition Pkg Sold *

http://www.bmw1602.com/

I was at my machinist's the other day, and he had an old sidevalve block sitting
in the bench. The ports looked like an accident, as in, HOW does air get through
THAT mess. I pointed at it, and said 'You know, that's where the idea of porting started,
and while the manufacturers mostly fixed their problems, the hotrodders never learned!'
He's a hotrodder. He laughed, and said, 'Yeah, there are a lot of heads that really don't need
much. In fact, things like yours, it's pretty easy to make it worse. That's why your cylinder head is only
a couple hundred to port, where that thing would take days. And I'd probably
hit water if I didn't do my research.'

or something along those lines...

t
_________________
I have a car disease. There is no cure.
I'm not even managing the symptoms very well...