Christer

Ha ha......

(p.s. you do engine builds for 'only' $20K.....!!!????)

'95 993

Reynard38, you are spot on, the mapping is about the optimisation, and is part of the package, the real key is in the heads (so i understand).

If a spotty youth with a PC and some shareware could get 350BHP and 420 + nm of torque out of a non varioram 993, then i think they would have done it by now, however, if you want a real degree qualified engineer with years of experience racing (and last years Porsche club speed champion in the UK) and tuning this engine and its derivatives, partnered with top motor racing (and it is widely regarded we have some of the best in the UK (flamesuit on)) engine designers then I would recommend 9m / 4tech.

I put my money in this direction, but for the next upgrade I will pop down to the computer science department here at Oxford University and they should be able to rustle something up pretty quickly, cheaply and maybe take me onto a reliable 400BHP? - if my understanding is correct ;-)

Geoffrey

With modern engine management systems, you cannot make large mechancial changes without remapping. This is no different than in the older days with carburators and distributors with weights and springs. On a stock engine you'd be pressed to see a 5% increase in power by just reprogramming the chip, and most of the increase would be by running 93 octane fuel and tuning the ignition timing to match. There is no "holy grail" with respect to engine mangement, no little 50hp dip switch under the cover, nothing that by itself will get you a substantial increase in power.

So, in Colin's case, it is the engine design (cams and head package) that allows for a more efficient and more powerful engine, however it cannot be done without some type of management system, either carbs & distributor, reprogramming of the stock ECU, or fitting it with MoTeC.

graham_mitchell

Colin, as an aside, great to see you became a Rennlist sponsor I think you have a lot to offer the 964/993 community here.

jimbo3

Just curious- what makes 9M heads/cams different from what might be achieved by flowing the stock heads? What could be achieved by re-working the stock heads (HP/Torque) and re-mapping?
In either scenario (9M heads/cams vs modified OEM), how would reliability, drivability and fuel economy be affected and what is the approximate cost comparison? Finally, is a Vario Ram engine a better platform for these mods vs a non-Vario Ram? (Perhaps better drivability from improved low-end torque?)

Thanks
Jim

Lorenfb

"It is the engine design (cams and head package) that allows for a more efficient and more powerful engine, however it cannot be done without some type of management system, either carbs & distributor, reprogramming of the stock ECU, or fitting it with MoTeC."

Sounds like we basically agree, i.e. remapping alone without engine mods yields little.
So, without engine mods, the fuel input basically remains the same as Porsche initially set it.
Then, that leaves the ignition timing to be "pushed" closer to detonation on a stock engine
to achieve the performance "feel".

Geoffrey

From testing the 9M heads here against 964, 993, 993RSR heads, from visual inspection and measurement, and from my experience of porting and flow testing 964/993 heads, the 9M head is different in several areas. The largest difference is in port design. The 9M port is straighter and profiled different than the Porsche port. The only way to duplicate the port design would be to ADD material. This redesign of the port increases the port velocity, especially at the lower valve lift compared to a Porsche port or ported Porsche port.

As for the reliability question, compared to stock, the 9M heads have better guides, seats, valves, springs, and are made from a stronger alloy. This addresses all of the issues with the factory Porsche heads so reliability should be better. Torque is increased, so provided the mapping is correct, drivability is going to be better. Fuel economy will suffer because of all of the WOT driving you'll be doing.

Check the dyno graphs on an earlier post which shows the difference between a NVR and VR engine. They are both good platforms.

'95 993

Jimbo3,

What is the better platform NVR or VR? I may be biased but the main difference is that the varioram has slightly more power at the very top end 150 vs 160 - not noticable on track or when driving and quite a bit more torque up to 3000 rpm beyond which the NVR catches up / matches the VR - see earlier dyno chart.

In the real world, Robins talks of spinning his rear wheels at low speeds whereas i haven't experienced this, still got awesome pick up, but I lack the bottom end torque of Robin, again on track it means that our cars are insperable (apart from driving skills - Robin is a very good driver - see pics of me chasing robin through the Chicane) as apart from moving off you are generally operating in the 3000 - redline rpm range.

So I would echo Geoffrey from a practical both cars up against each other on the track for a day real world perspective nothing to seperate them.

ruffy

Colin,
anything going for a turbo owner?
just curious

Lorenfb

One issue which has not been discussed is the additional engine heat the result
of the additional torque output.

Since:

Energy Output (Torque) = Energy Input (Fuel Charge) - Energy Loss (Engine Heat)

and.

Thermodynamic Efficiency = Energy Output / Energy Input

remains the same for the basic same 993 air cooled engine design.

Therefore the additional torque results in additional heat which is one
of the contributors to the excessive valve guide wear seen on the 993
and other thermo problems (harnesses & rubber failures) over the 964.

That's basically one of the major reasons why a water cooled engine
becomes necessary as the energy (torque) output increases and
why Porsche on the 996 uses water cooling.

Bottom line: An air cooled head can only produce a limited amount
of torque without problematic results and unknown reliability issues.

Red rooster

Loren,
Same old chestnut- re mapping alone achieves nothing !

The flaw in your argument is that it is true only if the OE-Porsche mapping is fully optimised.
For some models there is very little gain as all potential has been used.
The 964 has potential - simple remap for the RS gives +10bhp.

In many car companies Marketing issues can play an important part in final power specifications.Issues involve product range fit and competitive position .


I can understand your scepticism ,living in a part of the USA where fuel quality is poor and so extra performance is hard won. Please remember that in other areas better fuel is widely available.

Your experience of eliminating massive advance found in some chips I guess highlights the dangers of a little knowledge and no experience with motor management.

All the best

Geoff

pcar964

Yeah, but aren't you forgetting about the turbo motors? 930s and 965s and 993s make more power than Colin's heads, and they're still air cooled. I don't think overall engine bay heat will be a problem in light of this. Maybe an additional oil cooler would be prudent (especially for track-used cars used in high ambient temperatures).

wayne325

Actually you only build up more heat if you're burning more gas in the same period of time. On the street this will not realistically be the case because you'll get to your terminal speed in less time but then you back off and the burn rate goes down. It is only on a track that you could burn significantly more fuel given the 9M engine vs a stock engine. I asked this question already - Colin said it's easy to deal with if you're worried - just put a bigger oil cooler.

'95 993

I also asked Colin and interestingly he has the std oil cooler on his car and doesn't experience heat problems and he is running 420BHP and with competition track use in the UK (mainly sprints - I think) so I am leaving mine std at the moment but will monitor closely during the summer as 30 mins hard track time in 30deg C will def test it (on the one sunny day we get here in the UK

Lorenfb

"For some models there is very little gain as all potential has been used.
The 964 has potential - simple remap for the RS gives +10bhp." Red rooster

So what's the purpose of the knock sensors and why have they been used?
Now, let's think real hard now. Hum? Maybe to provide another feedback element
into the engine management system to optimize the ignition timing as the O2
sensor was used to optimize the AFRs? Maybe then the jumpers, switches, and
different DME ECMs would not have to be inventoried like for the 911 3.2s
because of different fuel grades and driving conditions.

"Your experience of eliminating massive advance found in some chips I guess highlights the dangers of a little knowledge and no experience with motor management."

Exactly! Which is the case for most/all performance chip remappings
on stock engines where the timing is "pushed".

Again, read what Andial has posted (www.andial.com) on the FAQ page Question 2,
"Ignition Timing".

Obvious, if you're at the track with race fuel (100+) there exists
an increased detonation margin and reduced probability of the
knock sensors retarding the timing thus compromising performance.