Looks great! I think that design will greatly enhance the scavageing capabilities and serve to reduce the flat spots. So awesome! Where does the line start?

Hey Fred, I trust you worked with Jerry at CP on those?

They look great!

Good job getting them done and pushing the envelope.

Cheers

I am too scared to ask even but I need to, how much $$$?

Details about this design
 

I first used this design in the late 90,s.Dyno test on 2 engines.It has higher sides with about 1mm clearance between the head & piston.This creates the squish area that directs the combustion burn location to center of the piston.By dropping the piston center when it fires it is centrally located.I took the 2.8 race engine apart after dyno test and 2 hours of track time.The carbon trace was in the center.The high rising sides were clean.An added advantage of the dropped center it flows more air and increases CFM flow as the air has lowered resistance to climb over the peak of the piston.It reduces heat to the cylinder head to cylinder sealing surface as well as more heat flows through the exhaust port as combustion point is in the center of the piston.Hank Clarkson Engineering was my dyno guy and Peter Dawes as well.He liked the idea and tried to do that with the engines he built.He was very talented and built a wide variety of engines.Icarp from Pelican used to hang out with him and knows all the different motors he did.The 2.8 built on 76 turbo case with hi flow 3.6 heads made 373hp at 9300rpm.Torque curve from 244 ft.lbs at 4400rpm was flat till its peak at 8900 with 249.5 ft.lbs.It is a very efficient design.Reduces detonation due to charge location so single plug is ok.

Fred, those look great. Can’t wait for my set to come in for the 3.2SS you’re building me. Since they sent you the 3.4 pistons by mistake, maybe we can build a 3.4L from a brand new 3.2 case I have.

Fred, I am so glad you pulled those out of the closet .
I believe this is one of the most secret parts of a 911 , it has been held close for many years .
Well done Fred
I will be buying a set and run them on a few different engines . on eddy brake dyno.

Here we GO !!!!!!

ICARP

Very cool Fred, that is some serious top secret engine porn 😂

Some well written info that may help in the understanding of why these pistons work so well.

It turns out that even in a well-balanced charge of fuel and air, there are highly localized “pockets” of varying mixtures at the “local level.” By “local level” you should think of a bunch of little fuel molecules huddling together “over here” and “over there” in different places inside the cylinder as the piston is rising up towards top dead center and starting down. Some of these pockets may be so lean (or so rich) that they won’t burn at all, some may be in the combustible range, and some may be perfectly mixed, “ready to go,” so to speak.

As an aside, this explains another little mystery. In theory, the “ideal” mixture for our engines is about 15 parts air and 1 part fuel (by weight), which should result in no oxygen and no unburned fuel molecules going out the exhaust pipe. But we’ve long known that a slightly richer mixture would produce slightly more power. Why? Because the theory breaks down a little when the charge contains those little pockets of varying fuel-air mixtures. Some of the oxygen molecules do not find fuel molecules quickly enough to burn, and they remain unused or unburned at the ideal ratio. By supplying just a bit more fuel for the lonely oxygen molecules, more total fuel is burned, a bit more heat is generated, and less oxygen escapes out the exhaust pipe without having had a chance to mate.

Now, somewhere about 20 to 25 degrees before the piston reaches top dead center (TDC) of piston travel, the spark plug lights the fire. The flame front starts spreading from each spark plug, slowly at first, then more rapidly within the cylinder. This flame front plays an important role in all of this. Ever stick your hand up close to a hot flame? Not in the flame, just close? It gets hot fast. There is a LOT of infrared heat being given off by that flame front. It travels at the speed of light. Maybe a few million times (or so) faster than the flame front is traveling across the cylinder. That infrared radiation heats up those little local pockets of fuel and air.

"Striving for somewhere between 14* and 18* ATDC of maximum pressure in the combustion chamber
This depends on , bore, stroke , RPM , Comp ratio , and maybe a few others ." ICARP

Further, since the piston is rising rapidly in the cylinder, those little remote local pockets of fuel and air are also experiencing a sudden rise in pressure.

Still further, because the flame front is a combustion process, it, too, is causing a further and much larger rise in pressure in the cylinder.

Hold that thought for a moment, while we mention the time scale for all this.................

This is the article, It beautifully explains what might take place in your combustion chamber

https://www.avweb.com/features/pelicans-perch-43detonation-myths/

Ian

the truth is coming out
 

Thanks Icarp.This topic is releasing a lot of skeletons from the closet.Those isolated pockets are part of the detonation demise as well.A great commentator on this would have been Chris I think from England who passed away about 2 years ago.But there are people out there that are very sharp who should chime in.10 minds are better than two.I try to learn everyday or this would not be fun anymore.This is a great forum because of the sharing.

What’s the weight of your 98mm piston k

piston weight
 

The piston weighs 430 grams.

Fred, looking at the recessed dome, are these designed for twin plug? Or are you getting the performance gains on single plug?

Cheers

The performance gains work with single plug very well.The 2.8 race engine was twin plugged.The recessed dome contains the charge in that area.

Cool, great product.

Cheers

Hi Fred
I like your "new" design. Very impressive.
One thing we questioned with CP and JE pistons is the sharp transision between valve pockets. We discovered that by simply rounding those "sharp" edges that horse power gains were substantial and compression loss is minimal. A measured 5 HP in 200. Theoretically, it promotes better exhaust gas expulsion. I'm sure you considered this mild modification but I thought I would mention it for people who didn't.
Cheers

http://forums.pelicanparts.com/uploa...1655387413.jpg

http://forums.pelicanparts.com/uploa...1655387413.jpg

smoother edges
 

Thanks Henry.As usual you have great suggestions with learned thought behind it.Thank you for chiming in.All thoughts and inputs are greatly appreciated.

We learned in nascar cup racing years ago that a piston with a parabolic dish will make the most power. (Assuming that it fits with your needed compression.) It might be beneficial to refine the "top" a bit more from a flat machined top to a slight dish.

Mahle has a very informative white paper on Pistons and Engine Testing that might help in other areas.

https://fdocuments.in/document/pistons-and-engine-testing.html?page=1

Change of the flat top to a dish shape
 

Hey Dannobee.Great input. The original two 2.8 SS Engines I built on 76 Turbo case had the dish in the center like a 3.6 piston.Good COMMENT.I have 3 shapes for these as far as design.The 2.8 made 373 hp at 9300 rpm.I copied the dish from the 3.6 piston with higher sides as I wanted to get the squish to force the charge to the center as I figured that all those guys at Porsche were smarter than I would ever be.Thanks for your insight.Fred

corrction from a previous post
 

I spoke with Icarp alias Ian Carpenter a few days ago and I was incorrect to describe him as hanging around at Hank Clarksons shop.He was an employee and the more he learned the more Mr.Clarkson paid him.Well he learned very well as I value his opinion to this day.It is nice to have people like him to contribute to this forum.Ciao

new pistons
 

The last set should be sold tomorrow with a deposit.Thanks Pelican.Fred