Design & Development
The Porsche 996 in recent times has started to become a very popular and much loved modern classic of the 911 models.
One of our team has always had a soft spot for the first water cooled engined cars and we decided to purchase our own 2002 Manual C4S with a low mileage of 39,800 miles and fully bore scope checked. We are all enthusiasts here and like to upgrade our cars. We soon decided to create an intake system.
The process started with 3D scanning the engine bay and creating a model which we then 3D printed in carbon nylon giving us a real world useable prototype
VENTURI INLET TUBE | LARGER AIR FEED | BESPOKE AIR FILTER
Designed from the ground up using a large venturi inlet tube with integrated MAF sensor.
The air filter sits inside a large volume sealed airbox with a larger snorkel / air intake. In comparison to the OEM airbox and inlet tube, our design is significantly larger in volume. Our inlet tube is effectively a very large velocity stack. This in effect aids in creating a much more effective venturi effect in addition to a much smoother path for the air to flow.
Finally, to assist the maximum amount of airflow the inlet snorkel cross sectional area is now twice as large as the OEM allowing for the maximum amount of air to enter the airbox.
Our bespoke short stack high surface area air filter is larger than any cone filter design currently on offer on the market. The opening is a huge 170mm (6 3/4") and is designed to take full advantage of the intake tubes by altering the direction of the airflow towards the outer walls. By placing the air filters in front of the inlet tube we achieve a very large velocity stack as our inlet tube.
Combined with these three attributes we were confident our design would out perform the OEM intake.
PERFORMANCE TESTING & INTAKE TEMPERATURES TESTING
Road tests and road data logs showed promising results with the engine having a more purposeful induction sound, improved throttle response and what felt to be a little more power after 5000rpm. The engine felt more free revving after this rpm and going towards the rpm limiter faster. This cannot be anything but a direct result of more engine power.
Partial load torque delivery was significantly improved and this is the direct result of improved throttle response.
However, as with all of our designs, dyno tests are essential! We do not rely solely on how the performance upgrade feels on the road.
From experience we decided to test the intake on two types of dynamometer.
One on a Maha dynomometer and the other on the more well known Dynojet
The below results are what we realistically expected. The OEM Porsche air intake system is an efficient design and Porsche did not leave much on the table irrespective of what the aftermarket has you believe.
DYNOJET Dyno Test
We used a well known Dynojet in the UK with powerful frontal fans and rear extraction.
With data logging being carried out during the before and after intake tests we noticed that intake temperatures were very high. While ambient temperatures were only 7 degC, intake temperatures at the MAF were in excess of 35 degC for both the OEM intake and our prototype. This is not representative of what happens on the road. As we can see from the shape of the power curves the ECU is retarding ignition timing with it's uneven power delivery.
Irrespective of this, there was a power increase through the rpm range.
+3-4whp between 4500-5500rpm
+6-11whp over 6000rpm
Peak gain of 11whp @ 7000rpm
What is interesting to note is that the engine makes more power as the rpm gets closer to the rpm limiter which clearly demonstrates that the OEM intake is restrictive at higher rpm.
We also noticed a drop in power at the lower rpm. This did not add up to what was felt on the road. Since the dynojet is not a load based simulation and an intertia dynamometer, depending on how the operator goes on the power can make a big difference to the low rpm results where the test begins.
We then decided to test the intake on a Maha dyno which is load based test. The dyno controls the ramp rate and keeps it constant through the entire test.
Maha MSR 500 Dyno Test
We used a dyno cell owned by a company which races GT4 race cars (www.runway42.co.uk) with a dyno cell specifically geared up for mid and rear engined cars.
The dyno cell comprised of three very large fans at the front and three large fans at the rear for extraction. In addition to those, a special cage with downward facing fans were placed over the rear of the 911.
Data logging through the runs showed exactly what we achieve on the road with intake temperatures sitting at ambient + 5-7 degC.
Due to the load based dyno test we did not see a loss in power at the low rpm like we did on the Dynojet. A very small increase is recorded between 2200-2800rpm
Above 4500rpm power gradually increases all the way to the rpm limiter which are the same type of results as what we experienced on the dynojet.
However this time with a much smoother and fuller graph shape.
+ 6-8whp from 4500-7300rpm
Peak Gains @ 6900rpm
Again, a repeat of the Dynojet test where we can see an increase in power from 4500rpm onwards but this time with no power loss at the low rpm due to the way the engine is loaded up on the load based Maha dyno.
INTAKE TEMPERATURES
Intake temperatures are high under slow speed driving with all NA cars. Once out onto the open road where there is enough airflow the OEM intake sits at ambient + 5-7 degC measuring at the MAF through the OBD2 port. This is generally considered to be efficient especially given the location of the engine on the 911.
Intake temperatures with our design are the same at low speeds as expected but lower once out on the open road by approx 1-2 degC. This is the major benefit of having a large sealed airbox.
Achieving low air intake temperatures is very important if power is to be retained.
Once intake temperatures rise there are 2 effects which sap the engine of power. The first is that the hotter less dense air will have a physical effect of lowering the power as there are less oxygen molecules. The second and sometimes even more drastic effect is how the ECU alters ignition timing and fueling once it reads high IAT's. This dual effect has the ability to lose the M96 engine 15-20hp irrespective of how much more free flowing an air intake system is used.
Over the decades we have seen many air intake designs for the 996 and promise very large increases
CONCLUSION
This is a very healthy and REALISTIC result over and above an already very large air intake system.
This equates to approximately 8-12 Flwyeel HP above 4500rpm.
We have worked on similarly powered engines from BMW. The E36 M3 3.2, E46 M3 and Z3M (S50 and S54). We have seen similar gains above the OEM system using a similar strategy.
The owners of those models, having a genuine gain of around 10hp have always been highly satisfied with this level of increase in power.
We are aware that many owners may not think of this as much of a power increase but this is essentially down to the devaluation of horse power as a direct result of companies exaggerating power claims from their products.
The Porsche 996 and 997 market has far too many companies offering intakes with quotes of power increases in excess of 20hp in some cases. In reality they are making less power than stock due to their inferior to OEM design strategy leading to high intake temperatures and no extra air flow at all. Social media channels have reflected this.
A real +8-12 HP is something that will be felt. Combined with improved throttle response, a fantastic induction sound and improved under bonnet looks we believe this product to be worthwhile to develop and make one that belongs in our catalogue.
The question readers will be asking is what will this cost?
The final product will be made in a very high quality pre preg autoclave carbon fibre available in both matte and gloss finishes. You can browse our website to see what our products look like.
We have estimated the the final price of this intake will be in line with our BMW, Honda and Toyota range of similar dimensions (No Porsche tax!)
This product is similar in size, dimension as our Honda CTR FL5 which is priced as below.
$1510
£1208 + VAT
We believe this to be a very reasonable cost for a thoroughly tested, engineered end product in pre preg carbon.
The testing isn't over. We are currently using different shape inlet tubes changing the slope and angle of the venturi inlet tube. We are also testing a differently shaped air filter.
Stay tuned for any updates but it's more than likely this will be the final design or something very similar to it.
We are also Simultaneously working on a carbon inlet manifold!
