I'm not sure JRG or my dynos would be helpful as both have a few other changes to the cars as well. I actually think our dynos would be misleading to those that don't really understand how our cars are prepped. Don't you think John ?

 

I'd be happy to post them though as Viking states, I'm not sure they're relevant to street applications. My dyno sheets are in my triailer which is stored. I'll try to get by there today but CJ's pitching this afternoon so it may be Saturday....

 

I typed "regular" 996= should have typed Mk1.

So you are saying that 996 C4 is = 996 C4S? Really?

 

Interesting. There is a local Porsche tuner in town here who tells me that installing headers like FabSpeed or others will actually inprove my low-end torque and performance at lower RPM vs. higher RPM.

 

They will improve his profit margins more than it will improve your low end torque.

 

To be a little more specific on why the dynos are bad comparisons in this scenario. No AC compressor, underdrive pulley, different airbox, different ECU flash, high octane race gas,light weight flywheel, different wheel/tire size, different exhaust, and I am sure there is more. I'm also sure JR has similiar changes to his car so it's not really an apples to apples comparison for a street car.

 

Hey I still use the stock air box with a BMC filter element....

 

Never saw a stock box with orange parts on it .....
I bet the bottom is all sealed up also. If not then seal it up, with the other things you have done it does help a tiny bit.

 

And actually ...... I use a stock air box too !

 

I don't think we'll be able say a street car will make the same power, but if there's a before and after dyno with the headers or with the headers/flash, I think that would be of interest. It's all a numbers game at the end of the day, but I always prefer some questionably relevant data to no data...

S.

 

Quantifing which gains and how much each is worth independent of each would be hard. Many gains are as a package with each improved part helping the other. We improve our exhausts with headers, but also improve our intake, and advance timing beyond what you could do with pump gas so we are getting more air in AND more air out. Just getting more air out won't have the same effect to the hp and the curve. Make sense ? I'm not trying to be an a@# , I just don't like to give people misleading information.
The headers will help, both the 997S and the X51's, how much ? Well that depends on what else you have done to your car. The only true way to tell is to install them and do before and after dynos on your car. Each dyno is different as well, both JR and I dyno'd higher at Miller than in our respected hometowns (his in California, me in Texas). These were the same type of dyno's using corrected numbers with the same smoothing factors. I'm not sure about JR but I have over 300 dyno pulls with THIS car, I know exactly where the power is and how I can change it in either direction.

 

If you seal the bottom, are you trying to get more cool air in from above, versus hot engine air from below? Sealing the bottom doesn't negatively impede the air volume, does it? Why'd they make it that way, then: a drain if it floods?

 

On some of the 996 airboxes there are a number of holes, some boxes have more than others. I'm not sure of Porsches' original design thought although it would allow water to drain out, and also change the sound of the box. For JR and my more race only purpose cars we could care a less about those issues since our cars don't sit idle in the rain and make quite a bit of sound already. So for our purposes it is better to seal it up and make sure all the air that goes into the air intake gets pushed into the engine.

And yes, the cool air is much better than the hotter air.

 

Hey Viking, I had my air box out today and remembered this thread. I've got a bunch of holes on the bottom, so what do you seal them with?....

 

No need IMO.

I do too have holes in the bottom of the airbox with my 03 C2. However, during my freeway drive home, the air is still cold. I have the IPD plenum which is made out of aluminum. I was concerned about heat soak but it is always cold to the touch. It is only hot when I park the car after a drive from engine heat in the compartment.