I'm now working on the last bits of the engine assembly. I received the head from Colin at 9M and wanted to do some testing so I can have a custom camshaft made. Here is a picture of my intake, head, and exhaust system on the flow testing bench.

 

young Einstein....

 

Geoffrey, what do you think of the heads?

 

whats the hammer for?

 

fine tuning
Brian

 

I can't wait to see this project done. I am sure we are all going to require many video's so we can see and hear this beautiful 964 in action.

What kind of intake is that? Is it hot film type or what? Give us the specs for what you are planning to build!

 

Your project is just amazing. Leave no stone unturned. It kind of sucks that you're going to have to take that beauty out and muck it all up with road grit, fuel and general wear and tear. It belongs under glass.

 

Geoffrey... Will you need to flow test each head or just one of them?

 

"whats the hammer for?"
In general hammers are for making things fit... Seriously though, any flat surface in a shop is used to set things on...

These heads have been CNC machined which means that they are all identical and in this case I only need to flow test 1 head, although if I was detail oriented, I would flow test all of them just to be sure . I have spent considerable time measuring and looking at the heads and have provided back to 9M my thoughts. I've spent quite a bit of time over the past several years with Porsche heads from 3.2 Carrera / 3.3 turbo through 993 and with my machinist friend have worked out some nice porting options. Colin was where I am 5 years ago and I enjoy talking with him because he says "ahh, I remember...". I like "out of the box" thinkers and Colin is one of them and has taken a different approach to port design than traditional "open the port up" method. This is the one reason why I chose his heads, because I was finding out similar information and looking for a better approach.

"Geoffrey, what do you think of the heads?"
I think the heads solve the 5 main issues I have with the Porsche head:
1) Material - better than even the turbo alloy and resists changes due to heat
2) Sealing surface - has increase rigidity to provide protection against cylinder leakage
3) Compression ratio - has a slightly smaller combustion chamber to restore the compression
4) Port design - a lot of work would have to go into making a stock head port work like this
5) Head components - valve guides and seats are terrible in stock form. I've always changed them for better material. 9M heads come with them already

These heads are built with a port design that has been optimized for port velocity. On the flow bench you use a light spring to keep the valve closed, and I've used these springs on all of the heads I've done with no issues. However, with the 9M head, the port velocity sucked the valve open at the lower lift (where velocity is increasingly important). I switched to a stiffer spring and it still sucked it open. These ports work as Colin designed them and the flow testing has validated it. The flow bench was also rock steady which shows the consistency of these ports. I am eager to see how the engine works on the dyno, but feel confident I'll reach my goals.

"What kind of intake is that? Is it hot film type or what? Give us the specs for what you are planning to build!"

I am using individual throttle bodies, similar to what Colin is using. Each port gets its own stack and is a straight shot from the inlet of the manifold to the intake port. Each "stack" consists of a phenolic spacer for heat protection, a manifold, a throttle body, an extension, a velocity stack, and then is tied together with the others in the same bank with a foam air cleaner. I think I am using slightly larger ones than Colin is using on his 3.9l engine and we'll see how that works out.

My engine is pretty basic and designed to run on 93 octane fuel:
964 case bored to 109mm, shuffle pinned with windage modifications
GT3R crankshaft
GT3R oil pump
Custom Carrillo connecting rods
993RSR 3.8l pistons and cylinders (102mm)
Modified compression ratio
9M heads
Custom grind camshafts
ITB intake setup
Lightweight 2 plate Tilton clutch assembly (12lbs total inc. flywheel)

The weak link in the engine is the RSR piston which I don't like very much, but the alternatives looked worse to me. I am hoping Colin will finish his 102mm piston so I can try his pistons next year.

"Your project is just amazing. Leave no stone unturned. It kind of sucks that you're going to have to take that beauty out and muck it all up with road grit, fuel and general wear and tear. It belongs under glass."

It would be a shame to put the car under glass. I fully intend to run the car hard as much as I can...and sell it when I'm ready to move to the 996 platform.

 

Of course...I would do the same. The quality of work and aattention to detail is just impressive. It was meant as a compliment.

 

Here is the second part of gathering information to have a camshaft built. I need to determine the piston to valve clearance at and around TDC for both intake and exhaust valves. This will be the constraints the the cam will have to conform to for the acceleration ramps of the cams.

 

Geoffrey,
Very interesting to see this motor going together .
I was intrigued by your comments about port velocity. Surely velocity is simply flow divided by area ?
Does this mean that the 9M head design uses very small area ports ??
If that is the case then high rpm operation will take velocity into an area that is not good for power !!

It will be interesting to see how much more bhp this motor produces than a standard 3.6 running on stacks .
Thanks for posting ,

Geoff

 

"I was intrigued by your comments about port velocity. Surely velocity is simply flow divided by area ?"

Only in a constant density incompressible flow.


"Does this mean that the 9M head design uses very small area ports ??"

No, not very small, I would prefer to describe them as optimal.


"If that is the case then high rpm operation will take velocity into an area that is not good for power !!"

There is a velocity level where the energy required to accelerate the intake charge exceeds the energy returned in filling the cylinder. The 9m head is operating at just a little less than this negative energy balance point.


"It will be interesting to see how much more bhp this motor produces than a standard 3.6 running on stacks."

I ran a stock 993VR engine on the same Motec ecu & intake system that is currently on my engine, where it made 321bhp & 390Nm on our dyno whereas the same engine still on Motec but with a non-VR manifold made 327bhp & 405Nm. Previously the same Motec & intake had made 360bhp on a tweeked 964 engine with hairy cams & equal length headers. In other words intake stacks on standard engines are a waste of time unless you tune the entire system. But you already know that, don't you Geoff?

 

Geoffrey,
I really like the degree wheel on the crank, puts my little plastic one completely to shame!
Never seen one as large as this before, can you price one up for me??

 

Hi Colin, try www.powerhouseproducts.com which is owned by Comp Cams. They are listed at $179.95. I like it because it is very accurate with such a large diameter, but more than that, I tend to write on it with a marker when I'm working with cams and then clean it off with brake cleaner when I'm done.

Geoffrey