Tulip Valve Pockets

Does anyone want to talk about Tulip Valve Pockets? Have you ever used them and what was the benifit?

You can make the valve lighter by machining a dish in the face. However, this lowers compression. You can get that back by using a tulip valve pocket.Those pockets have to be plunge cut with a form cutter.

Jay

As you can see, this post is 9 months old. I knew when I asked the question, most people would think, that I was some kind of Dork.

Jay was the only person to give an answer. Now I will attempt answer my own question.

Auto Manufacturers have Tuliped valve heads for many years. They grind an angle on the combustion chamber side, of the valve head to redirect air flow(simple form of supercharging). They redirect air flow to meet their performance needs. Sometimes they will go years with the same angle or sometimes they will change it offen. Car companies never worry much about, tulipping the valve pocket. Their not worried about losing alot of compression.

For racers it's another story. The valve pocket has a raised area (pointed cone shape) to recover any lost compression. It also services as a squish area, redirecting atommized fuel.

Simplely put the valve head matches the raised area in the valve pocket(a male,female fit). Most piston companies charge big $$$$$$, for custom fit valve pockets, then you need the matching valves to go with them.

Would the average guy do it...Hell No! Would a pro stock racer do it....Hell Yes!

In a closely competitive racing class like PS....people will try all kinds of things. At 18:1 squeeze rate and 14000 RPM, I don't think there's much chance that a tulip shape valve pocket does anything except keep the squeeze up for the larger intake valve that needed lightening...

I'll try anything to keep my squeeze rate up.Lol.bj

Pro stocks use titanium valves which are flat faced, so there is no need to tulip the pocket.

That is a mod only used with steel valves to try and lower valve weight.

Wiseco makes some of their pistons with tulip pockets.

hocbj23 wrote:

I'll try anything to keep my squeeze rate up.Lol.bj

Good luck with your squeeke issue.

APE Jay wrote:

Pro stocks use titanium valves which are flat faced, so there is no need to tulip the pocket.

That is a mod only used with steel valves to try and lower valve weight.

Wiseco makes some of their pistons with tulip pockets.

How many currently in pro stock use them? Do the Suzuki's and V-Rods use them? I would almost bet the V- Rods have them, even with titanium valves.

Yes, wiseco makes them and few other piston companies, have produced them for Z1's. Any piston company worth their salt, makes them for cars, bikes, etc. etc.....I wonder why?

I think they are used for more then, just steel valves.

we had a issue on one of our race engnines ( sprint car ) last year, builder mixed titanium and SS valves, the exhaust were replaced with SS, the change in the weight caused a valve flutter, bending several of the ex valves.
he showed me a video if valves at high rpm, surprised the hell out of me how much movement they have