Carl Fausett

I completely agree. Thats why I am going to the trouble of having stainless steel valves made which I think will be the go-to setup for 9 out of 10 engine builders (especially turbo applications).

Titanium valves are very hard on their seats, and because of this, they require more frequent valve jobs. I would not recommend Ti valves unless someone is planning on revving over 7500 or 8000 with regularity.

For most installs, the stainless valves or Iconel valves will provide better service with less maintenance over a longer time.

Carl Fausett

Dave, I think that cam has had it, and I am not aware of any repair method to fix them that I trust.

largecar379

did you also consider using a valve with thinner stems?

there is some flow to be gained from this.

1mm thinner valve stems will make a difference above 6500 rpms.....if you're going to the trouble of taking a fresh start on valves.







--Russ

slate blue

I have done testing with 41 and 39mm valves, without throuting there is little gain to be had by the bigger valves, Porsche use 41 mm head 6 mm stem on the GT3 and the valves are quite cheap straight from Porsche.

Greg

Carl Fausett

you are right in theory, but thinner stems create new problems in the head and are harder on the guides. Nobody cares in a racing engine because they get refreshed so often, but I do on my customers engines that are expected to go 10's of thousands of miles without maintnenance.

So, on the engines that are targeted for applications to and under redline, we leave the valve shaft size alone. This would be the typical iconel or the new stainless steel valves we are now making.

But, for those few customers who want an engine built for high rev's where we will use the Ti valves, we neck the velve stem under the head as shown in these pictures. Then you have the benefits of valve stem diameter for valve stability and guide wear, and also the benefits of enhanved air flow at high RPM's.

The valve on the left is our Titanium intake valve, the one on the right is stock.

mark kibort

guys, we are not talking about 10,000 rpm porsche cup engines where all of these factors could have measureable results. Even racing, we are blipping the engine to 6000rpm, not 9000rpm and the time needed to do this is pretty long realtively speaking. So, with 9,000rpm cup car engine, you might want to lighten the rotating assembly to equal what we can do in a 928 with a 28lb clutch and heavy valve train. as far as HP gains go, again, shaving hairs. 10lbs off the clutch or flywheel, 5 grams off the valve or lifter, all would have imeasurable results. You do it, as Carl is pointing to for reliability, and this reliability will be effected in extreme rpm applications, not with our cars. we all know how many 150 to 200k engines that are out there that have only needed headgaskets after a life of abuse. Or in most racing applications,the bottom ends are built up but the heads are never touched even after many years of all out racing. (I had 105 race days and 20,000miles additional street miles on my engine and all that was needed was a little seat clean up on the heads!)

mk

Jim bailey - 928 International

It is best to keep in mind.....The law of diminishing returns. You quickly reach a point of good enough. Everything about what makes an engine work is a compromise. If the only "race" you plan to win is on the DYNO that is one thing but in the real world plus or minus a few HP makes little difference.

BC

Nice back cut.

BC

You mean there is little gain without also increasing the total port volume, right?

slate blue

[QUOTEQuote:
Originally Posted by Greg Gray
I have done testing with 41 and 39mm valves, without throuting there is little gain to be had by the bigger valves, Porsche use 41 mm head 6 mm stem on the GT3 and the valves are quite cheap straight from Porsche.

Greg
You mean there is little gain without also increasing the total port volume, right?[/QUOTE]

No I mean opening up around the valve seat, I didn't increase the volume of the port.


Carl you are right on the valve stem issue, also some heat is transferred from the valve to the guide, this is crictical for Ti, the valve guide material is important along with a valve that is coated on the stem so that it doesn't gall. Del West has a relatively short lasting coating on the stem as standard as most valves in Nascar are used for one race. other coating can be specified from them.

Also those triple groove stems might be a worry if you are using standard collets, who is cutting the triple grooves for you? If they are cut all at once, not many people have the correct machine unless they are in Europe. I would be interested to know.

Greg

Carl Fausett

Greg - those pics are of Ti valves made to use the stock Porsche retainer. I recommend a Bead-Loc retainer instead - and on Monday I pick up a set of stainless valves made that way for my race car. I'll post a picture then. I like the Bead-loc design because it is a full radius cut and does not produce a fracture point in the valve stem.

From the Bead-loc website:

BC

How much were the valves you made for your racecar?

Hilton

Carl, will you take early 32V (86) cores and modify them as part of this process to work in S4's, as well as the re-grind?

I saw Ken's post about producing S3 cams from S3 cores, but was wondering about S3->S4 (as I have some spare S3 cams - as yet unmodified).

Carl Fausett

Hilton, I dont think I can make S4 cams out of S3 cores. Sorry. I can get cores if you do not have them.

Hilton

Ok thanks for the reply Carl.

Just to avoid confusion, I meant your 32vS2 cam, not standard S4 profile.

Understandable if not - would be outside the scope of your current arrangement with the cam welder.

Hilton.