Carl Fausett

Sterling - None of Threshie's stuff will make it to the dyno. It was a disconnected inventory of many parts that did not work together at all. Some really weird stuff. Still, individual pieces were interesting and at least I got back into the black on my investment into his inventory.

As to your heads - I wouldn't think it likely that they CNC'd them. The programming, fixturing, and setup charges are high enough (greater than $3000) that they do not lend themselves to doing just one set of heads. It only made economic sense to me providing I can sell this as a service to reclaim the large up-front investment. So, if I had to guess and they just did your heads and dont do 928 heads for a living, I wouldn't think they would use a CNC process.

Tuomo - This program is only for the 87-95 heads fitted with the larger 39.5mm intakes. I dont think there is much point in porting the heads and leaving the valves small - so the two kind of go together naturally. And the 85-86 heads ovatte in the opposite direction and would require their own separate program.

Sterling -

Carl Fausett

Tuomo - I just realized I did not answer your camshaft question.

The "best" camshaft grind is the one that most closely suits the application. As there are many application variables, there is not a single best camshaft.

The variables include: the driver and his/her preferences, the final drive ratio of the vehicle including rear wheel diameter, the power band the customer requests, and the intended uses (street/sport, Autocross, or Road Racing, for example.

So, when we hear the owner wants a certain use, has a certain transmission and tire size, and wants the power to come in between a certain range - we help him select a camshaft for that. That is the "best" cam for him.

RicerSchnitzzle

Great work as always! Any chance of a modified 16V head in the future? Let me know if you need a test mule.

Carl Fausett

Sterling - your comments are VERY inflammatory. We have a long history of testing our products (sometimes for years) before they go to market. In this case, we flow benched our results and showed the photographs of the machining in process.

There is no way that Threshie and I are used the same machinist - why would Threshie travel to Wisconsin? Ridiculous. Not to mention the difference in years.

But - if two good shops who knew what they are doing set out to do the best they can and both start with the same cores - might their finished products look similar? Probably.

I'll post dyno charts when I get them from these heads. I always do, and when I dont have a "stock" 928 to test things on, (like the intake spacers) I pay for the dyno charts for others so we can share the data. Tell me somebody else that does that.

123quattro

Besides the weird side conversation....those heads look really nice Carl.

Carl Fausett

Whats your point here, Sterling. Do you just want to a) start an arguement, or b) thump your own chest, or c) take over my thread. I dont remember posting all over your variocam threads, nor pissing on your accomplishment.

Its nice you know so much about 968 cams. This thread is about 928 heads.

Carl Fausett

Sterling: yes, my god you caught me. The Titanium valve from Del West in that head is stamped with a 2000 date and was part of the inventory we purchased when we bought out 928 Developments. Although most of the stuff hit the dumpster, some parts were worth keeping. As titanium valves dont really rust away on the stockroom shelves, I still have them.

Did that answer your question?

It sounds like you have an axe to grind with Threshie. Leave me out of it.

Ed MD

Having been involved behind the scenes in AMLS series racing the last two years , I appreciate the R&D developments fueled by the factory racing efforts. Look at the Audi diesel teams and the performance developments that are now seen in their production cars.
Carl, I've always felt your "shop" reflected that same philosophy. Your developments and products are "tested" in the unforgiving enviroment of racing, then what "survives" and gives an "edge" is available for the rest of us who don't have the time nor resources to do that type of R&D.
And as part of the 928 community, I'm able to benefit from your efforts.
Unlike the 911 guys, there isn't a lot of private and no factory R&D for these cars. Thank You.

Good nite, I'm tired, I've done too many ER shifts lately, I'm going to bed.
Ed Meier

Stromius

+1 . Very cool write up. Appreciate the information.

GregBBRD

Having owned my own flow bench for over 25 years and having a zillion hours porting and developing 928 heads, it is always fun to see someone with "new" stuff take a stab at working on heads. The development of ports that actually work well, for both air and fuel flow, is a very difficult and time consuming process. Interesting start.

Here's a few thoughts/ideas that might help..these are my personal ideas. They are not negative, but are intended to be constructive input.

Forget the titanium valve thing. Phil did it for the "wow" factor...and it was silly. On a 928 engine, the weight of the valve is absolutely insignificant, when compared to the weight of one of the lifters, filled with oil. Titanium works ok on valves, when needed. "Needed" usually is with an engine that turns very high rpms and has very aggressive lobe shapes, which requires very stiff valve springs, unless the mass of the valve train is reduced. Note that these engines will also have uber light (solid) cam followers and associated pieces. However, other than weight, there are only "down" sides to titanium for a valve material. Titanium wears fairly poorly and is extremely abrasive to the valve guide material. Even the "coated" stems on the Del West valves will require very special guides. Even the special guides wear poorly. Titanium valves in a 928 engine are like putting titanium wheels on a "Class 1 Motorhome", to reduce weight...may look pretty flashy, but just doesn't make any sense.

Watch what you use for valve seat material on stainless exhaust valves. Berillium is perhaps the absolute worse material that could be used.

Don't bother progaming a CNC machine to port heads until you actually have a port that has been tested and works. You'll find that you have/will continue to waste a bunch of money in programming time. It does little good to carefully duplicate ports that don't work.

As your port development continues...think smaller. 968 ports are way, way too big. Your ports appear bigger than these. Velocity is perhaps more important than actual flow, especially on a low rpm engine, like the 928. Torque is king. Killing off the torque in an engine, just to make more high rpm horsepower almost always results in slower acceleration. Huge ports do just this. The "coffee" can approach to porting almost never works.

Look carefully at a bunch of 928 head castings. Note that the exhaust "floor" is raised on every head, in relationship to the gasket area. You definitely don't want to lower this floor, as you have done. If you figure out a way to raise the floor, it would help the stock head. Lowering just tuning heads to "aluminum scrap metal".

An interesing study in port shape, can be found on the GT-3 Porsche series of CNC "race" heads. Beg, borrow, or steal an assortment of these heads, from various years and study them. You will also learn a whole bunch if you can ever find a "John Milledge" 4 valve 944 head to look at. He has spent a great deal of time, developing these heads, and probably knows more than anyone on earth about these heads. You will find that he is welding..in areas that you are porting. And although you might not think that 968 engines have much to do with 928 engines...they actually do have a couple of things in common.

Keep up the efforts and don't get down about failures. It is a very interesting journey. Save "samples" of your first efforts, for future observation. Years from now, if you keep going down this road, you will find a lot of humor in your initial efforts...I know this from experience.

RyanPerrella

I love how you have your sticker on the milling plate which isnt even for sale lol


now that ive read this whole thing



this is a fantastic thread. Some very good points made here, would love to hear the response by the vendor on these questions.

RyanPerrella

Sounds like sage advice

Carl Fausett

Greg: thats an excellent post and I agree with what you have said.

Titanium valves - I dont know who is going to need these except some guy who insists he build a high rpm 928 engine. Chances are I'll have them on the shelf for a while. Still, they were to valuable to throw away. I am not mariied to the Ti valves, I'm sure most customers will request the Stainless Steel valves we developed instead.

Copper/Berylium seats - yes for Ti valves, bad for SS. We know this. Please understand I know I have not rebuilt as many heads as you have, but thats the point of interviewing and hiring professional rebuilders that know more than I do. So far, they are guiding me well.

I also agree that time will show these heads to be the first iteration, and we will learn how to make them even better. No doubt you are right again on this.

The point of this project was to take the hand-work out of a porting job and try and get reproducable results from the CNC process. We achieved that. And while we may find even more runner profiles that work better in the future, our flow bench work tells us that these profiles are an improvement over stock.

Perhaps you missed my post about the stainless steel racing valves we had made up. While not as light as Ti, they are lighter than stock and Stainless valves fitted with the right seats have a long successful work record (as you know).

At the moment, I am fitting two 6.5L 928 engines with these heads equipped with these stainless steel valves.

Thank you for your input, and for phrasing your input in such a nice way.
Don't hesitate to pipe up again - love to hear from real experts like yourself.

Here are some pics of the SS valves. As you pointed out, they have many more applications than Ti valves do, and perform well at a much lower cost.
I have these valves in stock as well, with titanium retainers.

AO

Very cool stuff, Carl. I hope your venture is successful.

Mike Frye

I for one think these posts are incredible and wish the naysayers would frame their comments and criticisms in a more positive light or just air them somewhere else.

The cost, time, effort, and more cost required on the part of Carl and his team in a project like this, in today's economy is staggering.

I can think of several of these threads that Carl has put together showing different developments that his company is bringing to market in the past year. Some were received positively, some, like this one, got mixed reviews.

Bottom line, this community is lucky to have someone who is actually out there not only developing this stuff and real-world testing it in races, but is offering it for sale to the (very small) community. This, and many other of his products are not directed at me. I don't have an S4, and if I did, it probably wouldn't be on a track so I doubt I would get any use out of it. However, I can appreciate the serious effort and passion involved in even attempting something at this level. My hat is off to Carl for his efforts and his resilience and tenacity in bringing this stuff to market and posting it here.

Keep it up Carl, AFAIK, you're the only one qualified and willing to do all the things you do as well as you do them.