Wreck Me Otter

Jack of Hearts

Getting back on track with the discussion, Colin, are you saying that your heads won't work with a US-spec 993 in street trim, or just that they won't be optimized because of the engine management? (The idea of bolt-on heads/cams for extra HP is intriguing to me...esp. if it's just a top end rebuild.)

jdistefa

Speaking of bolt-on heads... Are these worth looking at? Experience, comments... Colin? Steve W?
http://www.cmwmotorsports.com/store/...category_1.htm

Reynard38

I can only hope that when the day comes for a top-end that Colin in affiliated with a shop here in the US (hopefully here in Atlanta!)

Jean

The discussion was about upgrading to 3.8Ltrs and its merits.

Unless one is of those who think that everything that Porsche did was strictly to sell more and keep their engineers busy to maintain their products fashionable 10 years later The 3.8 "factory" upgrade certainly seems to yield good results and buck for the money. A gearbox change is also a good way to bring some good response to those engines, only I am not sure it improves straight line performance from point A to B like the 3.8.

Reynard, if you want names of competent top end builders in the US, I am sure many Listers can help you out.

NineMeister

I have been straight and honest with every post that I have ever made. I think I am the only tuner to post every dyno sheet from my own dyno to back up my claims. In my discussions with you about your 964 I sent you all the information I had and gave an opinion as to which way we would tune your engine based purely on the results we had achieved. The summary is that for a 964 we would fit Motec as first choice; for a 993 we would fit heads and cams. In the context of this thread I have found that typical 3.8 "RS" conversions give 310-315hp & 390-400Nm on a typical varioram, whereas our heads and cams make 350hp & 425Nm on a 3.6 for a similar cost.

Since I freely give away information, never spin data to suit my needs and always quote numbers based solely on my personal experience, can you please explain what lessons in honesty that I have to learn, I am intrigued?

NineMeister

I cannot possibly comment......

NineMeister

The 9m heads have the capability of making more power because increase intake velocity and improve the volumetric (cylinder filling) efficiency, which is complemented by the sports camshafts. The increased airflow capability puts a greater demand on the intake and exhaust, so we address these and fully optimise the whole mechanical system. The final requirement is to optimise the fuel and ignition to match the mechanical changes, and this is where the problem lies on US spec cars because of the difficulty in remapping the OBD2 ecu. At the moment 9m does not have the capacity to take on board ecu work so I am looking at other options.

N51

Colin:
With respect to this forum and thread, I'll take my reply to you in private.

To the original topic of this discussion:
Geoff,
While you are correct in your calculation, the accompanying increase in compression should bring the total gains very close to my previously stated ~5.6%. That brings an otherwise stock 3.6L(282hp) close to 300hp and a nice increase in torque. I agree - that's a small number on paper, with a large investment. But I would return to my prior thought that the 3.8L is a sound platform for other engine work. That increase in displacement and compression is a multiplier(that's the key) for everything else one may do: valves, cams, porting, exhaust, etc. That is where the real fun begins, and yes,- before you add it - it gets even more expensive. :-) It's not for everyone, but for those of us willing to take on the financial side of the equation, we'll have our rewards.

Best,
Noah

Red rooster

Noah,
All the very best with your 3.8 ( 3.7 ? ). As human beings we all have a different take on this stuff. I am more interested in raising bottom end torque
for highway cruise without touching the motor. Cars got too much top end for here anyway !!
Look foward to reading your " WOW " posts !

Geoff

Garth S

Geoff,
Next time our paths cross, be sure to save a few moments for beating about torque enhancement ideas on the VRam: top end ponies are of far less utility than smooth and ample torque delivery on these particular roads.

Jean

I am not sure why we think the 3.8 will increase the top end and not the area under the curve when it is rather the opposite, judging by the performance. Now, the 3.8Ltr with a nice varioram intake (or there are other options out there) is a great plus for sure. I would just make sure that my tuner knows what he is doing and balances it all correctly.

carcommander

I think if you want a faster car, you jack up the gas cap and drive a faster
one underneath it. Like the man said, for that kind of money you can buy a turbo.

NineMeister

I thank you for that Noah.

Red rooster

Colin,

I guess another take on this is that the 3.8 gives an opportunity to correct the compression ratio ! It must be well known that the 11.3 number is very much a maximum for an untouched motor ?
Over here where fuel quality is not as good as Europe I would think that very careful thought needs to be given to desired static compression, cam profile used etc,etc to arrive at a dynamic compression that is ok for the avaiable fuel ?

As soon as you start modifying all these questions come flooding to the forefront ! Part of the fun ??

Geoff