Billet Cylinder Heads
 

There has been a lot of talk about billet cylinder heads lately, especially 9M heads, and I recommend Colin for the work he has done, but his heads are out of my financial reach. Has anyone had experience with the CMW Motorsports heads, from what I have read they are not 9M heads but at 25% of the cost they may be worth looking at. :cheers:

Thanks

Having modified my car to a fairly hardcore level, I have had conrsations with 9M about billet heads and I have been told that unless you make changes to the intake side (individual throttlebody set up or similar) as well as a header/exhaust system then the heads are not going to make a huge difference on their own. In the UK, I believe an individual throttlebody setup will cost around £2000 plus fitting and taxes alone so it was suggested to me to leave them out of the equation for now....Heads alone are going to be somewhat limited I guess is my HO....

In general, I won't comment negatively on others products, however, in this case, I'll make an exception. I have had experience with the CMW heads and under no circumstances can I recommend them for use on anything, including a Briggs and Stratton lawn mower engine. The machining is the worst I've ever seen and the ports are not ports that work with the Porsche engine (bigger does not equal better).

Is your car back on the road again? Last I remember reading was it had broken something a while back

Thank's Christer and Geoffrey, that is all I need to know, I guess I wil just have to save up for the real thing, how much is a set of heads on this side of the pond ?.

Steen :cheers:

You could say that - a few melted pistons aand an impacted head made another rebuild ncessary...with new 9M 3.8 pistons etc...it is alive agin and collecting very soon. I have a new dyno printout showing the current state of tune which looks pretty good. I will post some details when I get a chance.

The performance gains from fitting any tuning product is always going to be relative to the total state of tune of the engine, hence my comments to Christer regarding the suitability of the 9m head for his 964 engine.
For example, again specifically for the 964 engines for now, we do a Motec +1 package which runs with 9m Sport cams, ported stock heads and a 9m Motec conversion; on our dyno this conversion consistently makes 350hp; if you substituted the 9m head into this engine you would gain less than 10hp. The simple reason for this is that the performance of the complete engine package is limited by the standard intake and exhaust systems, so the potential gains from fitting the heads is restricted because the engine cannot supply enough air to them.
Recently we built a 3.8 engine for a 964RS to a similar spec of Christers but with billet heads. On a stock exhaust the engine made no more than 364hp; when we fitted headers the power increased to 382hp, but when we finally fitted the 9m individual throttle body intake the engine made 405hp (and the customer achieved his objective of being able to out-accelerate a GT3RS). In the case of this engine, I would say that the heads contributed about 25-30hp over stock in this final configuration, whereas at the starting point it would have been less than 10hp.
The 993 engine responds in a different manner due to its poor intake port design, so do not take the above comments out of context when thinking about fitting the heads to a 993 - we see gains on the 993 of up to 40hp from substituting the 9m heads into an engine with just Sport cams and cats.

Steen, I sympathise with you regarding the current exchange rate, however we are not in a position to sell heads cheaper in the USA than the rest of the world because the inevitable would happen and the parts will end up being shipped back to Europe and sold below our UK price. We do have a US distributor lined up, but until this happens the price will be £795 per unit as it is n the UK. With respect to pricing, unfortunately it is always a balancng act - however we are doing our best not to increase prices and we have absorbed recently increased materials prices and will be looking to recover the loss later by investing heavily in new high speed machining centres which will ultimately reduce manufacturing times.

I think that is what I meant...;) Will you be around on Saturday morning Colin - as it looks like I will be collecting the faded guards red example that has been with you for a little while now.....

Look forward to seeing you.
Whilst it was here we have tried to wash the fade off several times but the bad news is that the car still has an overwhelming desire to be Guards Pink. ;)

Maybe it will turn into Rubystone Red if you leave it out long enough :)

Colin - realize that you are across the pond from us here in the USA - but is there any way to obtain the Motec +1 package - 9m Sport cams, ported stock heads and a 9m Motec conversion - for this side of the pond - I am going to assume that this set up requires the engine in your shop for the Motec conversion - which just is not a practical step for us on this side. Of this conversion what can be obtained and installed with a relative increase of HP via shipping across the pond. Thks- you can PM the answer

+100 :D

And is that same "consistent 350bhp" attainable with a 993 engine just like the 964 engine, simply with Motec+1/Cams/Ported stock heads???

Gus. That was going to be my next question, let us know what Colin come up with.

Thanks
Steen

There is an easy answer: you need to all gang up on Geoffrey, persuade him to use one of your cars for proof testing. The work required is all simple stuff for him and his shop - no more than a top-end rebuild, heads porting, build it back up with a 9m Sport cam/spring/retainer package and then fit the new 9m Motec kit that he currently has on his bench. One thing I probably should add is that initially track-focussed 964's need only apply.

Over to you, Geoffrey....

No, the 993 needs the 9m billet heads to achieve the same power due to the poor standard intake port design. You can of course retro-fit ported 964 heads onto the 993 engine, but the exhaust manifold (heat exchanger) will then not fit on the RHS of the engine.