Geoffrey

I stumbled on issue 12 of Total 911 magazine tonight. It had an article on the 964 3.8RS and 964RS which I wanted to read. In any case, there is an excellent article on Colin's head.

Excellent job Colin.

tafkai

did it mention the flashing lights that occur when he's angry ?
or the constant voices arguing over aluminium and titanium and other engineering cobbledigook ?

MeanRex

any reference links for those of us w/ no idea of what a 9m head is or have the mag yet.

Geoffrey

9M Head Information

MeanRex

awesome thread, thanks.
-Ben

Red rooster

Geoffrey,
Have we seen any independent confimation of the power improvements claimed yet ?
I remember that before and after power tests were talked about but havent seen any. Or did I miss that thread ?

Geoff

Geoffrey

You'd have to ask Colin about the independent testing and the control methods used. I'm not aware of any, and I've not yet tested my engine. I have flow tested the heads, and found them to perform exactly as Colin has described, so I have no reason to doubt his claims.

As for chassis dyno numbers, we can argue those forever. I believe Colin did a test on a performance engine with ported factory heads and it was 392hp or 398hp or something in that range and with only a switch to the billet heads and the associated remapping required to support the additional airflow the engine produced 414hp. Further, the numbers he has shared here on Rennlist, including the drivetrain loss are very close to what I've found based on engine dyno and chassis dyno work I've done over here.

Red rooster

Geoffrey,
Thanks for that. So +14bhp including extra remap on a seriously modified motor.
I guess what a lot of us want to see is how much increase on a pretty standard motor from just the heads. It just confuses the investment decision to have other bits /software brought into the equation !
These heads cost quite a bit so I am waiting for a set of third party before/after results !

Very good luck with your race car.

Geoff

Geoffrey

Geoff,

My impression is that you'd probably not purchase just the heads and stick them on a stock engine. You'd do the heads as part of an upgrade package, very likely during a required top end rebuild. Heads, cams, and a live remapping has netted 350hp out of an otherwise stock 993 engine.

You need the remapping when changing the airflow through an engine, whether through exhaust, cams, heads, intake, etc. The performance does not come from the remapping, but the improved components. The remapping allows the engine to be tuned for the improved part or component.

agentpennypacker

I hear that the heads are the single most restricting part of our engines. at 350 bhp, well worth it!

Red rooster

Geoffrey,
I understand what you are saying . It would be good to know what these heads do on a standard motor. My Motronic M2.1 will take care of the increased airflow by mass measurement .
I am trying to seperate heads from all the other bits ! I have seen motors with cams / exhaust/remap make a lot over 300 bhp.
It will be interesting when/if you get your motor on a dyno . Maybe you can estimate what extra bhp the heads may be giving ?

All the best

Geoff

MeanRex

id hate to ask how streetable these motors are, but i guess i just did.

Christer

It is totally impossible to estimate what a particular component *may* be worth in a totally different application. If you are looking at modifications in the Naturally Aspirated part of the world, try to think it of it as a complete package. After all, you wouldn't just buy the turbo pistons but no turbo would you? The only way to find out what the heads are worth in an otherwise standard car is to try it. IMHO there are no shortcuts in na tuning......

Red rooster

Christer,
What I am getting at, is that a properly set up 3.6 with cams etc will make way over 300bhp. The 9M heads will add considerably to the cost, for what benefit ?

At the moment it looks like maybe 14bhp , from what Geoffrey is saying.IMHO there just seem to be too many other variations in build to be able to judge whether these heads are of real value .
As an example there is a debate going on as to the value of rechipping the 964. The judgement is based on running the motor on a dyno standard and chipped . Then compare the results to get bhp improvement.

Why doesnt this apply to cylinder heads ? or would this not give the answers
that are being put around ?

Geoff

Geoffrey

Geoff,

What I think you are saying is that you'd like to see an engine combinatin 'X' which has been optimized for ignition timing and air fuel ratio. Then, have the heads replaced with 9M heads and the system again optimized. This allows the comparison of 9M heads against 'X' heads to determine the addition or subtration of performance. Not unreasonable.

Your Motronic 2.1 MAY compensate somewhat for increased airflow, however, in stock form, it isn't optimized for performance, and even with a modified chip, most likely will not be optimized for ignition timing based on the higher volumetric efficiency.