Colin,

You might have saved some of us a lot of wasted time by disclosing this information! I have seen a quotation for the heads and complete assembly not too long ago, your information is very valuable.

I guess that a question mark remains however whether the tuner who did the tuning post (the PB) head modifications did not do anything wrong or whether some programming not adapted to the increased air flow was used causing a lean condition etc... I guess you have information proving it was a design flow, which if true is somewhat scary as this looks like a respectable company supplying Motorsports and F1 as well.

Could the spinoff be due to the small demand (expensive product at 500BP per bare head!) and low return on investment (rather than product flaws), since the investment seems substantial judging from your experience. I guess PB would be the only ones to answer this. Thanks for the update.

As far as gears is concerned, I know what you mean! I am experiencing the same issue with taller three first gears with my race GT2 gearbox, I can clearly see on the AX22 a drop in Gs, I have a 62mph 1st gear for instance at only 7000RPMS!! Your third gear is about 2% taller than a Row gearbox so I think it is more of a torque reason (skewed at the higher end for racing?) than purely gearing.
Can you customize head design to fit different uses and needs by the tuners(street, racing, high compression, low compression etc..?)

 

Colin,
You have emails.

Noah

 

Hi Christer,

I am most interested in your experience with the Motec conversion. Is the system stabile, that is, does is require periodic tweaking? As I noted to you in PM, we in the US can encounter fuel quality problems. You've travelled some with your car. What adapting, if any, have you had to make?
Though my present plan is to go with Motec, I am somewhat reluctant to give up the safety of knock sensors.

In a search, I came upon the following comments from Colin:
"The 964 conversion is complicated by the fact that the standard engine management system will not support this hp without modifications, our recommendation would be to convert to Motec but this is not the only solution to getting more fuel into the engine."

"The 964 system has a restrictive air flow meter, no throttle potentiometers and injectors that are on their flow limits with standard engines. You could go down the route that you suggest or fit a Motec system as we recommend, the choice is yours.
The most important aspect is that whichever ecu you choose is that it must be custom mapped to the specification of the engine."

These all the way back from February! And here we are still trying to get 9M's work across the water.
I've put these same questions to Colin via email. Hopefully, he'll have time to respond and bring them to open discussion.


Noah

 

I am a bit like you Jean in that I do not like misinformation, so if what I have told you has helped in some way then all the better.
I have known the engine builder for around 15 years. He definitely did not make any mistakes in building the engine and neither did the company who subsequently ran it on their dyno (another company with significant F1 experience). From what I know there were piston clearance issues due to insufficient clearance on the steel cylinder.

The heads were made with conventional ports, thus there would be no power gain due to radical airflow variations. The theory behind the screw in liner is to eliminate the weak barrel to head joint and thus allow the engine to contain higher BMEP levels (read torque) without blowing on the joint face. We have looked into this as a solution and decided that we would design it in a different way and thus could not see the value of an investment in an unproven product.
Ah, but that was then, this is now: only last week following an unexpected reverse gear lock-in during a track test day I took the opportunity to fit an 8:32 r&p with closer 2nd and 6th gears, so I now have approximately 24mph gaps between the gears with a 47mph 1st and sensible 170mph 6th. The lower 2nd will now pull above 4500rpm from 45mph upwards and will be a joy to use on the hillclimbs on the lower speed bends. I can't wait to try it out - I wonder what it will do for the acceleration?
The intention is to make a one-size-fits-all head for each application (911/930, 964/993 & 993TT). I doubt that many will require smaller ports than our design so at least the heads will be sold in "maximum material condition" which leaves the door open for the serious tuners to modify the heads with larger valves and ports to suit their own requirements. That said, we want to work with other tuners, not against them, so if anyone wants to order a small batch of heads with their own port/valve configuration we could accomodate their needs.

 

Noah, don't worry, I will be on the case with my emails later tonight (no rest for the wicked..)

 

Colin, I can speak from experience that the gearbox change will leave you laughing it is SOO good. Here is my gearchart which is basically what you describe.

 

Colin,

No worries. I'm sure your reply will only foster more questions from me. Please be patient for both of us. I'm most anxious to get on with it and prove out what I believe to be true.

Best,
Noah

 

Geoffry

Nice gear set up, too bad most people forget the importance of the transmission when they build a car.
My CTR-2 was regeared this summer for high speed Autobahn driving and has the following.

Torque is flat from 4300 rpm to redlilne of 6750.
In first 39 mph
from1st 30 2699
2nd 28 1722,
3rd 35 1542,
4th 40 1323
5th 40 1031

Not wanting to hijack tread just sharing.

LAT

 

So, Colin, every cloud has a silver lining. Now you will be even quicker at Cadwell.

 

Hi Noah

Having had the car modificed in this fashion for a couple of years now, I have been back on the dyno a couple of times and have found that that there has usually been a small loss in power (like 2-7rwhp) since the last time I was at 9M....I am not sure why this would be - Colin would be the man to ask! Theselosses are always recouped though through a quick dyno session...

I only use 98-99RON, although I have had to use 95RON on occasion but on those occasions I never give WOT or use high revs and have had no sign that I can detect of knocking.....so my opinion on Motec is very positive. I know also that Colin has put in a saftey margin so the car does not run '*****-out' lean in search of max HP. I don't get any stalling issues with the LWF either

 

Christer's experience is probably the norm.

All engine management systems have your basic fuel & ignition tables. In the case of the 9m 964 Motec conversion these are Alpha-N based, ie throttle position (Alpha angle) versus RPM (N) (rather than the Motronic MAF/rpm), we use Alpha-N because the engine is a lot more responsive to throttle input than any other system, and for motorsport use on n/a engines it is pretty much industry standard. To map the engine for maximum power and torque these are the tables that are used.

On top of the main tables are correction tables which trim the fuel/ignition, the main ones being engine temp, air temp and barometric/manifold pressure. The aim would be to get these correction tables perfectly adjusted at all times and there are industry standards for MAP and AT compensations that are pretty close to ideal, however the fact that we are running an aircooled engine throws these out slightly because of the fluctuations in the temperature of the cylinder heads, cylinders & pistons. A second factor is that there are no common sensors available that accurately measure humidity - most dynos using DIN standards do not correct for this either - and the water content of the air also has a nominal swing on the fuel/ign requirements of the engine.

Hence, on any given day that Christer has his car dyno'd, the 2% (7 bhp) difference we are seeing is probably due to cumulative errors in the corrections, engine running temp differences and a variation in the fuel. The engine still responds to further optimisation and we usually get the 2% back but couldn't guarantee that it will stay until the next time. In our experience the mapping of the Motronic system with its factory corrections is a little better than Motec but we still see similar 1-2% power swings.

As a point of reference, my 993RSR runs on track with a cylinder head temperature of approximately 150C so on the dyno I try to ensure that most power runs are carried out at this temp, however if I test the engine after it has been idle with the dyno cooling fans operating the head temp can fall as low as 110C, a pull at this temp will add 15bhp to my 415bhp average - hence why we don't normally quote "best of" figures for our dyno tests. As an example the 9m 993VR +2 which is the subject of this thread has posted a best of 364bhp on our dyno but we are quoting 350bhp as a typical "hot" result.

It is for this reason that I am now focussing on engine temperature as the next major development area for the aircooled engine which is unfortunately where I have to toff the cap at the GT3 engine with its envious water cooled heads and cylinders.