Porsche Enthusiasts Club Forum

I'm both sceptical and enthusiastic about the thought of the MAF conversion, as without getting the whole inlet side on to a flow bench to be honest it's p***ing in the wind to try to guess where the improvements are needed, I've worked on and tuned cars that looked like they had a hugely restrictive air box, yet when it came down to it the original air box was a fantastic design and dropping it out of the system dropped performance. Likewise if the AFM on these cars isn't a bottle neck on the system and the bottle neck is the manifold or the TB then while there will be some small flow gains from deleting it or replacing it with a MAF sensor it will be a relatively small and expensive improvement.

The plan on my car is to investigate these routes and see where the restrictions lie, I have hopefully a scrap 3.0 engine coming to me to test the manifold etc. And see just where the inneficiency lies on this engine, it looks to me on the surface that either the engine doesn't breathe as well as it could or there is a lot of mechanical drag on the engine, the smoothness of the engine confirms there is certainly mechanical drag there, whether a lighter flywheel would improve matters I don't know yet, I haven't even measured the stock flywheel this would certainly improve responsiveness, the balance shafts are also interesting, I can't help but wonder how much coarser the engine would be without them and if the engine could be balanced better to do away with them?

Then I'll start looking at the head and breathing side of the engine which is where I suspect the gains are to be made, hopefully either through small relatively good value improvements, although I could see the only way to get these engines anywhere near 100% VE would be a low pressure forced induction set up.

i have seen reports that you can remove the Balance shafts on the s2, but even with balancing the full motor they still get vibration, things like solid lifters, lighter flywheels and crank work will enable the motor to spin up faster and rev higher,and help loose rotational mass, but the stock inlet manifold re-strikts the flow of air.
im no expert but would it be beter to make a custom plenum to use and retan the single stock TB, and make the inlets to the motor biger with the injectors closer to the head.

DAVE

The problem with the VAF (Volumetric air flow) meter is that it relies on the ECU having to process look up tables combined with air temperature readings from the VAF to calculate the air mass. A MAF sensor provides a signal showing the actual air mass without complicated processor intensive calculations. Combined with this, the standard item is restrictive compared with even the standard throttle butterfly.

The other problem is that the VAF has a delay on throttle transitions, which really does hurt throttle response, which is due to its sweeping door design which has a delay on its generation of a true representation of actual airflow. So a MAF also has benefits of throttle response.

Lastly, the VAF was only designed to generate a signal showing the minimum and maximum airflow as seen by a standard car, which can be maxed out when you start taking the engine 20% beyond standard airflow levels.

On turbo charged cars we will also be swapping the VAF air temperature sensor (not used on a MAF) for an intake manifold sensor to make real time alterations to fueling and ignition based on intake temperatures, which can change from moment to moment even on the same car, dependent on heat saturation of the intercooler.

With the MAP as well as MAF sensor, this makes real gains on letting the ecu know more about load conditions and therefore allow another dimension to the maps used.

Also the free'ed up processor time from no longer using transfer tables which are processed to generate air mass or load, other interesting functions can be introduced.

But it is also important to stress that these features will not be part of our standard chip set, but the next level of tuning which will come with MAF and MAP sensors.

Again, much of this benefits the turbo owner more so than the S2 owners.

Having sketched-out the internals, the design looks to be rather sophisticated.

No internal wadding is used; which may explain why it still works as perfectly now as it did when it was new 28yrs ago.
To the best of my knowledge, it appears the unit is designed as a series three resonating chambers; each having both different volume and geometry to attenuate the sound energy over a wider range than perhaps a single chamber design may be capable of:

Hey Jon

Any news?

This most interesting of threads to me seems to have stagnated.

Have you tested the chips yet? Do the chips marry well with that resonator exhaust?

I am still keen to get one of those decat exhausts from you and will probably get a chip as well if you think it is worth it.

Thanks

Well done Jonny944cs, excellent diagram!

Development of the cat bypass and chips are currently in the phase of testing on a couple of customers cars and one of my own.

Testing on my own car has been slightly sidetracked by a theoretical way of boosting fuel economy in cruise conditions quite massively.

For some time I have had a theory which sprang from a SAE paper some 20 years ago, which outlined the fuel economy paradox of the ideal circumstances when ideal fuel economy would be reached is not possible with steady state driving or current (back then) ECU technology.

I have been having a play with a solution for the fuel economy paradox, with a small box of electronic tricks and new software for the standard DME, which returns about 40mpg on a 944 S2, has no detromental effects on the engine, but has an unusual side effect when activated and the car is set to cruise, which some people may find uncomfortable, but is the tradeoff for ultimate fuel economy.

Not sure if there would ever be a market for it, or if it would need to be tuned to each individual car, but an interesting academic experiment if nothing else.

Hopefully the cars with the updated chip and resonator cat bypass will be back from testing in the new year and we will be able to market the pair as a product.

Any more news? and can i get a bhp or 2 by fitting a janspeed rear box in place off my dansk, or are all boxes about the same.
And i have seen some lovely exhaust manifolds on some american sites but the price is nuts!
maybe if a few people want them someone in the uk can manufacture a batch?

Sorry for the lack of updates, we are closed at the moment but that does mean I have had a chance to come in here and do an update.

Performance increases seem to be consistent across 3 test cars with the chips and the cat delete resonator. I will post dyno charts in the new year, really worthwhile gains.

Also developed a couple of other products over the last few months that have completed the testing phase which I can now announce, which all work for the 944Lux, S, S2 and Lux...

LED instrument cluster illumination kit for 86 onwards cars,
which works with the original factory dimmer, is very easy to install, requires no rewiring (plug and play) and is available in white, blue, red, yellow, orange or green illumination.

Quickshifts (3 different ones) (works on all 944's to replace the original gearbox mounted linkage)

Precision Shift - replacement for the original 944 gearbox shift, will last much longer without developing wear and slop with the following benefits.

Almost entirely made from stainless steel
Replaces the squishy rubber cross brace mounts with spherical rose joints
Replaces the cast plastic pivoting block (that wears) with a machined billet composite item with o-ring seals
Replaces the fixed pressed steel (flimsy) cross brace with an easy to adjust one (so you can adjust the left to right position of the gear lever centre point
Very tight and precise gear shift motion without slop
Replaces the rear gear shift mechanism completely, and easily

Road Quick Shift - Reduced throw quickshift with ultimate precision and slick motion with the following benefits.

Entirely made from stainless steel and billet aluminium
Replaces the quishy rubber cross brace mounts with spherical rose joints
Replaces the cast plastic pivoting block (that wears) with a spherical rose joint
Replaces the fixed pressed steel (flimsy) cross brace with an easy to adjust one (so you can adjust the left to right position of the gear lever centre point
about 10% reduced distance between gears
Very tight, ultimate precise gear shift motion without slop
Replaces the rear gear shift mechanism completely, and easily

Race Quick Shift - More reduced throw quickshift with ultimate precision and slick motion with the following benefits.

Entirely made from stainless steel and billet aluminium
Replaces the quishy rubber cross brace mounts with spherical rose joints
Replaces the cast plastic pivoting block (that wears) with a spherical rose joint
Replaces the fixed pressed steel (flimsy) cross brace with an easy to adjust one (so you can adjust the left to right position of the gear lever centre point
about 40% reduced distance between gears
Very tight, ultimate precise gear shift motion without slop
Replaces the rear gear shift mechanism completely, and easily

So, been a busy bee... Everything will be available as of the first week in Jan 2013 as soon as we can add them to the online shop! (including the chips and cat deletes!)

Good news thanks John.

Reserve one of them resonator pipes and a chip for me!

Hello

Fascinated by the economy at cruise, I thought the only thing you could do was to lean out a fraction at cruise sites, is there more to be done? Appreciate you might not want to let on! What is the side affect?

Also will the shift kits be on your site!?!

Thanks

Andy

Hopefully over the next 48 hours the new quickshifts, chips and cat deletes will be on the online shop.

A lot of people think that the most efficient air fuel ratio happens around 14:1, however 14:1 is approximately where the most complete burn occurs, not the most efficient burn... 14:1 is good for emissions, but not so good for power or economy.

From our experiments we have discovered at which air fuel ratio, ignition timing and another factor (which will remain secret) at each RPM point provide the best fuel economy while not damaging the engine due to detonation, exhaust gas temperatures or any number of other detrimental issues.

Only problem is that when the system is enabled it is not a silky smooth drive, but I am confident that with some work it can be refined until it is no longer a problem.

Interesting stuff, will the box of tricks be able to cope with things that could change the AFR even more? For example poor fuel or altitude?

I saw the quick shift online - its on my (now massive) shopping list to slowly buy up!

The one currently on the online shop is our 9XX precision shift, which is our improved version of the original Porsche gear selector with an amount of adjustability, completely non ferrous construction and a more durable composite pivot point and the rubber crossbrace mounts replaced with spherical/rose joints.

The quickshifts will be joining it on the website shortly )

One of the things I am working on with the 944 S2 (as well as the 944 Turbo) is a kit which has MAP and MAF sensors as well as separate inlet air temperature sensors so will be able to compensate for altitude as well as much more )

The problem is, if we were to wait until all these kits are complete, we would never release anything, there is always another idea in the pipeline... So we are releasing what we have and offering an upgrade path for owners of previous generations of our chips and kits.

That bunch of sensors isn't a million miles off what my Emerald runs - Map from the inlet manifold and intake air temp just before the throttle body. I have the feeling that at cruise I could run a bit leaner than I am as its still quiet and purring along nicely but until I get some proper knock sensing installed I won't be experimenting!

Keep adding toys to the shop - once I have finally bought a house I have already been given permission to actually buy things for the car!

Any more information available?

I've spoken to you guys at JMG last week regarding cat delete, rear box, chip etc. and can't wait to get it all on but was wondering what else I should be looking at.

Hoping to have the car ready to throw up the hill at the Prescot Revival meeting, shame not to as I could almost push the car home from there