Geoffrey

It was more like Christmas than Thanksgiving today. Colin from Ninemeister sent me some pictures of the new heads which should mean that I will get mine shortly. I have been very impressed with the quality of Colin's head design and the issues he has been able to address by starting with a clean slate. Now I am finally excited to start putting the engine together.

Heirsh

man. did he give you any sort of idea on the machine time on those? Must be immense. I'd love to see a shot of the chamber, but I'm assuming its proprietary and he doesnt want that plastered on the net.

Geoffrey

Oops, sorry, reposted the chamber.

chris walrod

They look great! Very nice piece!

Curious as to the effect of differences in cylinder head material, cast vs. ?? with respect to harmonics, detonation, natural frequencies etc. Combustion pulsing as well.

Heirsh

Thanks for the additional shot. beautiful. I'd love one of those for my desk at work.

Just pictures, but it really looks like it has more volume than a stock chamber.

N51

Geoffrey,

Will these heads work on a street car? Some have told me there is little to gain from porting the stock heads. True?

Noah

Geoffrey

These heads will work for any 964/993 engine whether street or racing. I believe the chamber is slightly smaller than stock, but you will need to check the details with Colin. As for porting heads, it depends on who ports them, and in what manner they are ported. From flow testing, I have found that hogging out the ports will allow the ports to flow high CFM numbers, however the velocity suffers. You cannot look purely at flow numbers to evaluate heads. I believe that huge ports do not help performance. Now, if you pay close attention to the shape of the port and the transitions, you can gain flow and velocity...this is the key. Since the Ninemeister head starts from a blank, Colin has redesigned the ports which is something that is not easily done with a stock head. This will allow for high flow and high velocity. As for the specifics, I'd rather that Colin answer them as I've not inspected and tested them and would not want to post misinformation. I have done quite a bit of flow work with the various Porsche heads including porting so I have data to compare against once I have them in hand. Once the testing is done, I'll have a cam ground based on my requirements and the measurements of the various engine components.

The Ninemeister head will allow me to run the RSR pistons at a higher compression ratio than the 993 head from the stock engine. because the 993 chamber is quite a bit larger.

KirkF

hmm.

Let me push all the flow and velocity stuff to one side:

THOSE HEADS ARE PRETTY.

Kirk

NineMeister

I will sell them individually and polished especially for use on your more than average desk.

The stock chamber is 90cc, the 9m chamber is 87cc and fully CNC profile machined to get the best from a stock 993/964 piston. Naturally we have also designed the 9m piston to match the 9m head, so we will have combined a more compact combustion space with optimal squish clearance and increased squish area.

Heirsh

beautiful Colin. I envy you for getting to work on designs like that.

Geoffrey

To further expand on what Colin has said, as an example, the stock RSR pistion has the following compression ratios: Stock 964 head 11.3:1, Stock 993 non varioram head 11.0:1, 9M head, 11.7:1. So, for an average 964 engine which has a measured compression ratio of 10.7:1 or so, it will restore it to more like the 11.3:1 that Porsche advertises. This combined with the improved ports, will provide a simple bolt on performance improvement. Additionally, the head is a billet piece, made out of a stronger alloy than the 964 head or the Turbo alloy for that matter makes the head stronger. They have designed the head with a nice solid base for cylinder sealing where the stock head has cooling fins. These design differences provide a head that is more rigid and will seal better with higher cylinder pressure over a longer period of time.

One of the main issues with the Porsche heads have been the valve guides, in both the material they used and the clearances that appear in the assembly line production heads. These heads come with much better cooling, much harder valve guides whch addresses these issues.

Red rooster

Geoffrey,
Have you ever measured the real compression that a varioram motor runs ?
It would be good to get a better real life number for some work I am doing .

The heads look good .The company that makes them has a very good reputation both for machining and R&D .

All the best

Geoff

NineMeister

Thanks for the enthusiasm guys.

As for envy Heirsh, all you need (after qualifying as a mechanical design engineer) is run your own Porsche business for 15 years on a shoestring whilst simultaneously spending most of your spare time learning about engine design and then trying to make a dream come true, whilst at the same time ignoring everyone who tells you that it has been done before/cannot be done/is impossible/etc. Piece of cake!

Red,
Like Geoffrey, we have measured numerous stock 964 engines at 10.6 thru 10.8:1; the 964RS fares better, typically even at 10.8/10.9 for cylinders 1,2,4,5 & 10.7/10.8 for 3,6; the 993 is marginally improved at 10.7 thru 10.9, though I personally have never had one measure over 11.0:1.

The maths of the c.r. change if anyone needs it is:

chamber volume = cylinder capacity/(c.r. -1) so for a 964 at say 10.8:1, this gives
cv = 600/(10.8 - 1) = 61.2cc
The standard head volume is 90cc, so the piston dome volume + squish clearance is approx -28.8cc

With an 87cc head, the compressed volume is 87-28.8 = 58.2cc, therefore the new comp ratio is:
c.r. = (600+58.2)/58.2 = 11.3


We intend to adapt the design soon to suit the 930 head stud spacing and two bolt intake manifold, although we will retain the longer 993 style finning and 4 stud exhaust manifold fixing.

Geoffrey

Since most of what I do is racing oriented, I have not measured a varioram engine specifically. However, most of the Porsche engines are about .5:1 compression less than advertised.