An interesting development for 964 and 993 engines.
 

Swindon Powertrain has developed a 24-valve cylinder head kit for the 964 and 993 engines that rocks redesigned four-valve per-cylinder castings to unlock more horsepower and torque. In-house testing has revealed that peak flow has improved by 40% at the inlet and 60% at the exhaust. What’s more, Swindon’s cylinder head reduces weight by 3.5 kg (7.7 lbs) and allows applicable engines to rev all the way to 12,000 rpm.


https://www.carscoops.com/2023/10/swindon-creates-porsche-911-cylinder-head-that-allows-air-cooled-engines-to-rev-to-12000-rpm/

Swindon built the Tuthill 911K engine that runs to 11k revs. Assume this is the base kit

That's interesting.

If they are talking about 12,000rpm they sure would want a beautifully balanced crank and pistons.

Very cool!

Guaranteed I can’t afford it.

"The British company’s complete M64 cylinder head kit is priced from £29,950 ($36,413)."

Gotta pay to play...

Given that it’s ~$20k for Xtreme 2 valve heads, Pauter or Schrick billet rockers, new cams, billet valve covers etc.

Almost seems like a bargain.

Do we know how much more horsepower?

Are they able to do that without watercooling the heads? Must be some exotic materials

I’m just glad they be done it……

A combination of metallurgy and manufacturing techniques?

Another article:

https://www.thedrive.com/news/air-cooled-porsche-911s-can-rev-to-12000-rpm-with-these-new-cylinder-heads

Amusingly (and realistically) this article points out the lack of price details and suggests the old saying: "if you have to ask, you can't afford it."

I certainly agree with the prior comments indicating the heads may enable the stratospheric revs, but I sure hope the engine's bottom end is up to the strain. But then, anyone buying these heads would surely have the rest of the motor "built and blueprinted".

Considering the price of 911 rebuilds and parts these days, honestly that price doesn't seem ridiculous.

Its a pipe dream , but for the 1% !!! Most of us would be happy with a good running , all systems
working , no leaks 911 ...

Hmmmmmm, take a 3.6 and swap in Supertech’s 66mm stroke Supercrank, run the nascar bearings and gt3 rods and these heads and I bet 10-12k redline is there for the taking.

Wonder if there’s effectively a rev limit on a standard case?

Interesting. I was hoping someone would post more info on how the Tuthill build spun to 11K
Sounds like a riot. Unfortunately, I’ll likely never know.

Wild that they don't comment on cooling. I wonder how they do it?