Intake plenum and 911 throttle body

[JFP in PA]

Originally Posted by eddy

All right everyone, sorry for the delay.

I put 350 or so miles on the car after the 987 airbox and ben plenum/big tb install. It feels significantly stronger and the sound is better/louder than the desnorkeled 986 box i had before. I felt from the midrange up it really woke up the engine. From a "feel" perspective, this has been a wonderful upgrade.

Unfortunately I only got 3hp and 3tq according to the dyno (223 hp up to 226, 196tq up to 199). Temps were within a few degrees of one another, humidity was similar. I was quite surprised about the results. In order to better understand if my car is an anomaly it'd be great to see the results from a couple other cars.

The dyno guy (Hutter performance-- typically a GM tuner, but they had, of all things, a 962 there for a tune when I was there. They're a really well-respected shop in Northeast Ohio) said there was room for more power if I got a tune, but he didn't think there was a lot there to be gained.

So the numbers don't appear to be there, on my car, anyway, but if I hadn't gotten it dynoed I would've thought this was a solid 15 hp+ upgrade. Wish I could have reported a more positive result, and I hope I am an anomaly! I'm still very happy to have done this, though.

From what we have seen, your results are about average, with most of the small gains at the high end of the RPM curve.

[Lapister]

I've been driving for little over a year with this mod and equally surprised at such low numbers. My experience with this mod is a bit of low end sacrifice with great mid/top. I've got to give it more gas out of the hole mostly due to the bigger TB but once past 4k it really wakes up. Acceleration is greatly improved once past that 4K area and quickly reaches redline.

On another note, before I swapped to the larger TB I ran just the stock 987 airbox and that alone made a big difference with the old setup. Just wanted to pass that on in case one would under go that route. So, I'm thinking a lot of the gains were probably mostly due to the 987 air supply.