Hi there

Ok managed to get a custom silicone hose so I can use my stock Airbox with larger throttle body and plenum.

So hopefully this weekend I can dyno the following:-

1. Softronic tune with larger tb / plenum with stock Airbox with BMC filter and resonator removed for max airflow.

2. X51 revised Softronic tune with larger tb / plenum with X51 Airbox with BMC filters.

I've done some race logic testing:-
0-62 (2nd gear) 2.9s with stock Airbox, 2.8s with X51 Airbox.
50-95 (2nd-3rd gear) 5.8s with stock Airbox, 5.5s with X51 Airbox.
60-110 (2nd, 3rd & 4th gear) 8.2s with stock Airbox, 7.5s with X51 Airbox.
60-110 (4th gear) 9s flat for both air boxes.

To drive, the stock Airbox with softronic tune feels to have more torque and smoother sub 3200rpm, throttle feels better, hard to explain, not response just better, no doubt because of the vario ram system helping with low-end torque. Nothing else is better though.

The X51 Airbox with revised X51 tune is just a responsive now, even more so at higher RPM's, the cars seems to pull harder 3500rpm upwards and even more so beyond 5500rpm. The noise/soundtrack is vastly better.

The on the road test show car accelerates faster when using gears, but as the 60-110 run in 4th shows a little low-down power/torque is lost, marginal but would be nice to get them back.

Maybe Scott can revise the X51 tune to also make use of vario ram so get best of both worlds.

Shall get the dyno to compare / overlap both runs so we can see how the air boxes and tunes effect the power runs, shall also video the runs to record AFR data.

Is the air box worth while? Yes just for the noise and the way the car pulls at higher rpms

 

I must be missing something. You indicated that you are doing 0 to 62 in less than 3 seconds. Are you sure of this?

 

That should be 30-62

 

Wow! Well that's a lot of info to take in. I have a 997.1 s and I'm running a Fabspeed x-pipe with the gunto hack, Bmc filter and evomit tune. On a Dynojet I put down 306rwhp at 6500 rpm with 285rwtq. I'm mad that I didn't get a base line first. I don't know if that's good?

 

you need performance cats to really feel gains - trust me they make a big difference
i had also stated earlier if you do cats save up for headers.. the increased air flor makes the exhaust note very high pitched and really sounds terrible. i found the only cure was aftermarket equal length headers.. AWE tuning makes them.

 

I have no cats.

 

wanted to subscribe...

I experienced the exact same air fuel ratio problems when I did an upgraded engine conversion on a boxster many years ago. I had upgraded the ecu fuel maps to the larger engine but kept the old/smaller maf housing on. I had the exact opposite happen to me. I was running super Rich, rather then very Lean.

So this thread is 100% accurate. The size of your Maf Housing and air flow readings are EXTREMELY important to the calculations used by the factory ecu fuel maps. The factory ECU fuel maps assume you are using the correct size maf housing which creates an assumed air flow speed at certain rpm's.

If you go to a larger diameter maf housing, like an X-51, from stock, then the airflow readings slow down... although airflow "volume" actually increases. The slower/lower voltage reading sent from the maf sensor to your ecu makes it believe you require LESS fuel which creates a LEAN situation in reality.

If you go to a smaller diameter maf housing the reverse happens. Airflow is crammed or rushed through the smaller diameter which then sends a stronger voltage signal to the ecu and calls for more fuel, even though air intake volume is decreased... this creates a RICH fuel situation.

Proper tuning is important, so working with a ecu tuner directly is great. but lots of back and forth when problems arise. I actually solved my issues by using an after market mass air flow tuning computer and air fuel ratio gauge. I used an Apexi unit that allows me to adjust the maf signal every 500 rpms. so I can have the exact air fuel ratio needed every 500 rpms. On that particular project car the horsepower gains were 25-30 hp and 15-20 lbs of torque with proper fuel as compared to too rich or too lean situations.

So as the OP has suggested ... if you have upgraded your maf housing diameter without making the proper adjustments to the ecu parameters... then you may be harming your engine by running too lean too often. especially during the hot summer months. highly recommend you get those fuel maps sorted out.. your car will run WAY better.

 

I think I'm in the same boat with a 997.1 C2s aerokit that has no seal in the lid so that the EVO intake doesn't seal on anything. So is this the part that fits into a "bare" decklid? I suspect whoever installed my EVO intake left this out/removed it for god only knows why.