flowing, porting
 

anyone looked at the oem intake and exhaust to see if any benefit to doing any flow work on them? how well do they match up with the intake and exhaust ports on the heads?

Hello Radium,

You may want to check out the website of Len Hoffman as he specializes on this type of work: https://newsite.hamheads.com/porsche/

It has pretty interesting pictures, you will enjoy the reading :-)

thanks - some potential inthe heads, hey? i was wondering more if there is any need to work the intake or exhaust manifolds where they mate with the heads.

you're talking about what I've always called "port-matching". I have never seen a motor that was machined or cast so precisely that it couldn't benefit from a little work that way. But I'm sure the Porsche Purists will tell us that these motors were all hand-ported / matched before they were assembled on a shaker-table...... ::eye-roll:: :p

If you don't have experience with port-matching yet, (you probably do? but just in case) one of the first rules I use when looking at doing the match work is that adding material is just as important as removing it, in most cases. Here's why: if you simply scribe the ports to each other, and then grind to the scribe-line, as most beginners do, what you'll inevitably end-up with is a "bulge" at the port, where you've made it bigger than the rest of the runner, on either side of it. This can be HORRIBLE for velocity. And depending on your cam duration / overlap numbers, it can cause some real rough-running issues under certain part-throttle conditions, where that bulge "absorbs" a pulse. Much better to blend those ports together by adding here, removing there, until your ports are the same shape and match perfectly.
If you check the best porting-work, you'll find the use of epoxies is very common.

Home | JPrecision Is local to me and has done work on one of my KTMs,( custom porting, valves, and squish/planing), friends buells, and Hondas. Not Porsche specific but have it on good authority that he does Ferrari heads...
May be worth a call to inquire.

100% agree!

Even something as simple as re-working the valve seats (5 or 7 angle) can provide an increase (small but measurable) over stock (3-angle).

The exhaust manifolds can use some smoothing, there was extra thick welds on mine at the entrance that seemed to be the biggest restriction, plus it's really fun to grind without getting shavings in the cats! ;)