NineMeister

Here are the photos of the new 9m Racing billet cylinder head specifically developed for the 993 GT2 and turbo race engines. The specification includes:

CNC machined all over from solid billet of 2618 aluminium alloy, as used for Formula 1 pistons
49mm & 41.5mm x 9mm valves (930/993tt)
Larger 15mm diameter sintered steel valve guides
Sintered steel seats, shrunk fit & fully finished
Small diameter twin spark plug holes
87cc combustion chamber with improved burn characteristics
Solid lower fin area for maximum strength & stability
High velocity port design, similar to proven 9m Racing 964/993 Billet head

We have no performance data from them to date, so I'm obviously not going to make any bold claims about how good they are, but from what I do know from the shops I have talked to about problems associated with standard heads, the minimum expectation is that with the superior material used, the additional strength of the billet head should result in a much improved life of the part in a racing application.

I have two sets of these heads in stock and I am willing to offer an attractive package for anyone willing to test them on their engine and report back with the results, so if anyone is interested please contact me via email or pm. The retail price of the production GT2 billet head will be around £875 per head, fully finished as shown in the photos.

JBL930

Why don't you test them?

wagongotya

Paging Spartan

V

WOW Colin as always.. . Now we're talking . What kind of software and turbos would you recommend for this setup? Will the stock I/C be enough? Do you anticipate a difference in operating temprature as a result of changing the standard heads for the 9M ones? What kind of pistons would you use? Sorry for sounding like a newbie but will there be an increase in displacement (with new pistons)?

NineMeister

Viggo,
There are three features of the 9m billet head has that may have a positive influence on the performance of a 993 turbo engine, these being the intake port, the combustion chamber and the exhaust port; all the other features mentioned are there to improve reliability under extreme conditions, like the solid lower fins on each side of the head often replicated on stock heads by welding up the fins.

The ports have been extrapolated from the design of the naturally apirated head but with a fractionally larger choke to valve diameter ratio which will better suit the supercharged engine. A straighter, high velocity port has the potential to increase the volumetric efficiency of the engine, in a turbo application this would (in theory) mean that the cylinder will be filled with the same charge density at a lower boost level, which then means that you can make the same power at a lower boost (with less heat loading of intercooler/engine) or more power at the same boost level.

The high velocity exhaust port should also aid in the scavenging (cylinder emptying) process and lower the back pressure as seen by the exhaust valve/combustion chamber, again improving volumetric efficiency.

The combustion chamber re-shape was done to reduce the burn space and improve squish performance with stock pistons. If you can optimise the squish you get more turbulence in the cylinder which normally equates to a faster burn speed - faster burn speed means less ignition advance is required which then means that you get less negative work done by the piston compressing the burning mixture before TDC. The expectation of this would be a power increase and greater threshold against detonation.

It is up to the individual tuner to optimise the complete engine as a package: some may want to use the heads with a low boost/low heat high rpm application (which would be my preferred route) whereas others may want the opposite and capitalise on the additional strength of the material to build a high boost/high torque package.

V

I understand that the principle of increasing "squish performance" stems from the NA billet heads. By recommending low boost/high rpm are you saying that these heads are better suited for track than street use? Or can they be used in any kind of TT build? Obviously it would have to be twin plug regardless, which means it's going to be a monster regardless . Do you have an example of a setup (e.g what turbos/cams/software/boost etc) that you think would suit these heads? It will ofcourse depend on what you are looking for (as you said). Endless posibilities..

I've always been fascinated by your work. As you know we were in negotiations regarding a 3.8L NA 9M build but I went over to the dark side and bought a turbo (which is fantastic btw). Now all of a sudden I feel that temptation again . Obviously this is a new product which opens up endless posibilities.. I will follow this thread very closely.. Still learning about these engines (as you can tell). I will treat my engine with an upgrade during the course of this winter. On the shortlist were RS-tuning (CG kits) and RUF until today. The shortlist just got 50% longer . Great stuff!

Have a nice weekend

NineMeister

Cheers Viggo, hope you have a good weekend as well.

As you say, endless possibilities. With the n/a billet head I have now managed to test around 20-30 combinations of parts, mostly on my own car, all with varying degrees of success. The problem is that I do not have the time nor resources to do the same for the billet turbo heads as all our development budget is going on the GT3 engine development programme - which is exactly why I am offering two sets of the new turbo billet heads at a special price for anyone interested in exploring their potential, the ideal candidate probably having a race GT2 which gets rebuilt two or three times a year.

MarinS4

Put me on the list of interested testers.

I have seen first hand the results of your design theroy on air cooled harley motors. One of the older hemi designed motors (shovelhead) really came alive when welding the combustion chamber for dual squish bands and the floors of the exhaust port to D shape.

From my last build I know cylinder head temps are the limiting factor when squeezing maximum power out of the air cooled motors. Your oil cooled heads should help raise that limit considerably.

I sent you a PM to discuss the details of the beta testing.

chris walrod

must resist As I am preparing to do the guides in my car, I see this.

Good work Colin, as ever!

Steve Weiner-Rennsport Systems

I've seen one of Colin's heads and I'm quite impressed. He has addressed some of the shortcomings of the OEM heads that should translate into improved durability, especially for engines running non-stock boost levels.

For those with the requisite budget and the need for more performance, I think they are worth the outlay.

Acropora

Considering new heads are $1600 that's a great price. Doh...

NineMeister

Lots of interest in the heads, thank you all for the pm's. If, as it looks likely, both initial sets sell quickly (and prove to be satisfactory in all respects) I will schedule another production batch of around 5 sets immediately. So don't worry if more of you want to make a saving as I'll offer a Rennlist group buy price for all 5 sets.


Perhaps now would also be a good time to mention that we are also working on a similar version for the 930 engine which will have the same valve sizes, port designs and combustion chamber? There will probably be around 4 variants of this design to cope with the different material between the n/a & turbo versions in addition to the two different intake manifold (2 bolt) flange heights between the 911SC and 3.2 Carrera.

As a special we are also thinking of offering a 3.0RS/RSR version of the 911SC head with the reduced 3.0RS head stud spacing and in theory we could make a 930 head with a 3 bolt intake flange so you can run the 964 intake system......

Should have the first 930 heads by November.

Guns951

So would these heads work with a former 964 C2 case that is wearing Andial 3.8 P&C's? Looking to do a rebuild on my 3.8tt as we're going for insane power and about 26 lbs of boost...very nice work BTW.

NineMeister

Which head you should use depends on the P&C's. The head shown above is the new GT2 & turbo version which has been designed to fit the shorter 993 turbo cylinder where the piston intrudes into the head at TDC, whereas the n/a version of the 9m billet head is flat across the fire face to suit the longer n/a cylinder. If by chance you need the n/a style flat fire-face design I have in stock some special race versions of the n/a head which were made with fractionally oversize intake ports to favour boosted applications, these heads have 50 & 42.5 x 8mm valves with the same oil cooling chambers as the turbo version and would be ideal for your radical installation....

Tour18

Suddenly I feel like a poseur.

Ach mein Gott!! Those are beautiful.