huskeric

As I move forward with my stroker build, I will need to get a valve job for my R3 heads. I suspect they will need guides and milling to true the surface.

Anyone have this done recently? What am I looking to spend (of course, realize there are many factors) for a basic valve job and then addition of new guides?

Also, I may also consider some reasonable porting work to allow the 6.5L to breath.

any help would be appreciated.

rick

1989 S4 928 Stone Gray
1989 944 (952) Turbo S Stone Gray
2005 Corvette Lemans Blue
2002 BMW 32i medium blue
2005 Landrover Freelander
2011 Harley Softal Heritage Classic Silver

huskeric

anyone?

17prospective buyer

3-4K to do it right? That's my best guess. Porting adds alot of money onto a basic valve job, clean up and shaving the head. Especially if it's done right with a flow bench and everything is taken into consideration.

Kevin in Atlanta

If you are not replacing the valve guides you can do the work yourself. You can limit the shop's contribution to replacing the guides and planing the head, assuming it needs it. I have done a couple of these on 32 valve heads. The tools to remove the valves can be rented for free, the valve grinding compound is readily available as are the tools to lathe the surfaces. It's a good upper body workout. There are folks on this list that have the Porsche tool for removing and installing the cams, too.

IcemanG17

lots of places "can" do it.......but only one is the best...... Doc Brown at Precision Motorwerks in Anaheim CA..... He builds more strokers than anyone and they last the longest too....

Rob Edwards

This is one of those things where experience trumps everything- Greg will be the first to tell you that he learns something on every set of heads- Not sure which century Greg started porting 928 heads, but Hebert's 2012 stroker heads incrementally out-flow my 2010 stroker heads, and there were several sets of ported heads between mine and Dan's. It is a black fricking art, mitigated only by having a calibrated flow bench so he can iteratively see what works (and what doesn't).

IIRC Greg's baseline porting charge is $3K, for whatever that's worth. Every set of heads' cost is going to vary a little depending whether they're pitted, have been re-surfaced before, etc.


EDIT: Huskeric, tell us more about your 6.5L engine- who built it? No such thing as too much stroker discussion here.

terry gt

Just had my 32v heads done . 968 intake valves / 968 seats / valve guides / cleaned/ new oil-frost plugs / multi angle grind/ surfaced/ valve height set/ valve springs seat preasure/ head volume cc / ported int and ex / checked on a flow bench / linsey racing valve springs / valve seals/ new valve retainer clips / new LIZARD cams / refinished lifters/ the heads were mint R2 cost 1200. the machine work cost 2800. + valves / guides/ seals/plugs ect . springs 550. cams 1800. So add it up !

BisimotoSales

Greetings Rick,
I would be more than happy to assist you with a price quotation for proper performance head porting services, machine work and supporting valvetrain components to suite your needs. I just PM'd you to request additional information. Thanks.

- Julio A.

GregBBRD

Get an idependant base flow bench reading before you start....and insist on one when you are done.....before you pay the bill. Independant is important.

Air flow through these heads is like dyno results....frequently amplified. No one ever wants to think that they just spent a pile of money and actually lost air flow....

I've flowed "Devek" heads, I've flowed "Threshie" heads, and I've flowed a dozens of sets of "other" heads.

I've never seen a set of heads, with 968 valves installed, that flow better than the stock heads....unless they were done here. And I'm not saying that I want to do it....I'm just saying that it took me 400 hours, on the flow bench, to figure it out. The majority of these heads flow at least 10% less air. than the stock heads. And the ones that do flow more....they have such a huge port that they velocity is terrible....so the low end "torque", which is what these engines are the best at, is way down.

A good "introduction" to what it takes to make a 968 intake valve flow air is to go look at a 968 port. You can fit the volume of both the stock 928 intake and exhaust port into the 968 intake port....they are huge!

I've got a set of "super trick" heads with "super trick" oversize titanium valves that have been ported by "the best guy around". The only thing that is "super trick" is the amount of money that was spent on them. The intake port flows 14% less air than stock and the exhaust port flows 6% less. I've been staring at them for over 3 years and have no clue on what to do to make them work. They are really expensive junk.

huskeric

thanks for all the input -
now, gotta save the $$...

BC

Cubic inches or boost is the way to get more power, and some detail work to the ports, as well as the intake.

And, my personal, but unsupported opinion is that the LH system is holding many back.

17prospective buyer

Who is it holding back? Strokers and high boost supercharged crowd maybe.

Jim Devine

Head development is an art. Greg is giving good advise as he has probably done more of them than anyone else. Development come from hours of trying things.
I knew a guy that worked at Chaparral on the Trans Am Cameros. At that time Chevy/G.M. used Chaparral for their "unoffical" factory race team.
He told me that Chevy sent down a whole pallet of head castings so they could try anything. Instructions were- we don't care if you ruin most of them, sooner or later you'll find something.
If it meant grinding into a water passage- no problem, just epoxy it for flow test purposes.
When they finally got the heads the way they wanted them- they shipped them back to Chevy & they re did the casting core to allow for enough material. Took hours & hours & lots of scrap heads before they got it.
Someone that only does a set every once in a while is at a big disadvantage.

Don Carter

I can tell you that in Houston, a set of 1R heads were rebuilt by a local shop that has been around forever, and does a lot of Porsche work, for just over $700. New valve guides, 3 angle grind, not sure about milling. No performance work, just a standard rebuild. I have these rebuilt heads for sale for $900 and they were NOT blasted when cleaned (inside joke).

I'm not sure I buy all the mystery around a standard head rebuild. 4 valve aluminum heads are supper common these days, and most machine shops have rebuilt many 1000's of them. Maybe there's something special I'm not aware of, and happy to hear that I'm totally wrong and it does take a specialist to rebuild them.

Rob Edwards

Agreed that there isn't any real mystery about a standard head rebuild, best practices for any head rebuild apply to 928 heads too (though I'd wager there are some devil-in-the-928-details that are key to best-outcomes....). The mystery is in modifying ports.