Yes I know what you mean

Good luck with everything my friend!

 

We've been working on direct injection fuel system upgrades/research for some time now. Years of experience on the BMW N54 direct injection platform and headaches around fuel limitations have taught us a lot when it comes to solutions that may/may not work. The solutions are basically:

1) Supplementing with meth injection (not ideal at all but it works well with appropriate failsafes in place and the only meth kit trusted in this case would be an Aquamist HFS-4 for the 997.2...to get a little more power out of the car than the OEM fuel system supports this will do fine but it can't and shouldn't be used to fuel more than 30-50whp due to poor meth distribution through the charge piping/intake manifolds and poor injection control),

2) Swapping the in-tank OEM pump/pumps with a higher flowing unit/units right in the OEM bucket (works great provided the OEM low pressure pump can't hold pressure/provide volume). This only makes sense if the high pressure pump (HPFP) manages to keep pressure up with the added volume/pressure from the low pressure side,

3) Adding an in-line booster pump after the OEM bucket. This only makes sense if the high pressure pump (HPFP) manages to keep pressure up with the added volume/pressure from the low pressure side,

4) Combined approach to swapping the OEM bucket pumps with higher flowing units and feeding the HPFP as well as secondary fuel rails on this car with standard port injection type fuel injectors. This is the most/expensive configuration of the ones mentioned and requires the most work but will basically solve all fuel limitations any direct injection platform may encounter in making ridiculous HP gains possible where the PDK transmission and the motor will need to be reinforced sooner rather than later.

 

Hello!

# 1 I tried it and do not work

IMHO the best option is #2 (GTR's do this after full bolt ons)

 

#1 is the only option that DOES work so far (up to a certain point). We've done it using the HFS4-V3 kit, which integrates perfectly into the 997.2 platform.

 

#1 will work but only to a point. How well it'll work and how much fuel it can provide will depend on nozzle size, placement and if you're going direct port 6 nozzles or spraying from much further away. Going far away from the intake manifold is great for IAT control as it provides for the longest path to cool the air charge down, or for those physics savvy, latent heat of vaporization (when phase of substance changes from liquid to gas, see here for a short explanation on why meth works so well: http://physics.tutorvista.com/heat/latent-heat.html). Here's a table showing energy values for water, meth and ethanol which are typically injected via meth kits out there, some working better than others in certain scenarios (sometimes you'd want to inject some water with meth depending on tuning goals: http://www.engineeringtoolbox.com/fl...eat-d_147.html). Where you'd typically install nozzles on a 997.1 turbo with no fuel limitations vs. a 997.2 car with fuel limitations can/will be a little different based on goals.

#2 should be very simple provided there's room to swap OEM pumps for larger units. GTRs though are port injected and have no fuel limitations/dependency related to the high pressure pump. Beauty of port injection is that its really easy to provide the motor with more fuel.

 

Well, I didn't use that meth kit... And I just toll a example of the GTR because is one of many cars that resolve this fuel problem with swap fuel pumps

 

I like this solution. I think it can work with 68's even with the PDK. But would also need a linear boost profile in order maintain torque below 700 (or some safe number to keep the PDK clutches from slipping). Between 6K and 7K rpm 700 lb ft of torque would be

 

What about the motor.....? I hear there's some things in the works regarding upgraded PDK clutches (not sure how soon though)... but I'm told the motor limit is soon after. I'd probably only upgrade the PDK if I did a motor build assuming the motor limits are only slightly higher than the PDK.

Not sure if you've heard differently.

 

Good question. I didn't say it in my post above but creating the linear boost profile would reduce mid-range torque in an effort to both limit stress on the PDK and stock rods.

I have no idea what the limits are of the PDK and stock motor. In that regard I would defer to Champion and BBI for their advice.

 

Thanks!

 

We control the torque in some areas with the COBB on my GTR before I forged the engine... same thing it can be done with the COBB in the .2's

 

Right now I'm using the Meth kit to keep the IAT down in this tropic weather, I will check changing the Vol % on the setting to see if can get a little more fuel on top end...


Yeah the #2 on GTR's is the way to deal with this situation

 

What meth kit are you currently using? I have both a Snow Performance kit and an Aquamist HFS-2 kit from my M3. I'm going to try out the Aquamist kit on the 911 and see how that works.


The Snow kit had a great pump but the flow wasn't linear and caused my fuel trims to go out of whack on the M3 and it actually lost power.

 

I'm using this one, very effecitive system...

http://www.aemelectronics.com/produc...soline-engines


Before I was on R&D of the COBB Stg 3 I was testing this system (low boost) and have to reduce a lot of the % of vol. because is was too rich, so maybe now with High Boost I can turn up a little bit of the % vol. to see if I can get the fuel that I need in top end... Will let you know how it goes

 

Peak boost isn't what causes the fuel cut. Not to mention, we've seen some tuners that just run these cars lean to get more boost which is a bad idea and a major shortcut (not saying those tuners do it, just in general). Just stating something can be done doesn't mean it's done correctly.