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YOUR RESEARCH997S headers on a 3.4 996?
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Run 3.8 (997s) headers
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FWIW, I run the 3.8 (997S) headers on my 3.4 race car.
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I guess most of us wonder about the change across the band.
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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.
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These were the same type of dyno's using corrected numbers with the same smoothing factors.
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I was at my mechanics yesterday getting my oil changed and we were just talking in general about the 996. He mentioned that, in his opinion, the best bang for the buck mod for power is to put 997S stock headers on my car ('99 996 C2). He said no remapping is necessary, takes about 1 hr to do and is straight bolt on. He figured it adds about 15-20hp and is by far more effective than any chip, intake, exhaust, etc.
I searched on this and couldn't find anything. Anyone hear of this? I'm doubtful of the amount of increase, but is there something to it at all? He's got quite a few years of Porsche experience, worked as a team mechanic on some 996 race teams, fwiw.
Are you sure that there is no extra welding work to do?
I have the 997 C4S cans installed in my 04' 996 C2, and there were a cut&welding work done to fit them correctly in my rear bumper.
I know you are talking about headers, but I'm not sure they would fit in your engine, just bolted on
https://rennlist.com/forums/showpost...&postcount=479
I remember reading a recommendation on renntech saying to go with the 997 3.8 x51 headers, that they were the only ones worth getting.
Your race mechanic buddy likely knows best here, but I don't think there's any way you'd unlock 15-20 bhp without the headers and a chip to match the new breathing abilities.
Most of the posts on the net re: headers, exhaust, and intake mods on 996s cite "throatier sound" and "improved throttle response". The sound is real, the rest is potentially psychological, but hey who knows? Without some dyno and 1/4 mile or hot lap comparisons on your own vehicle, it's highly debatable as to where in the rev range you would gain/lose power and whether it makes any difference in your life. If you can pick up some 3.8 X51 headers from a wreck real cheap, and he only bills you an hour to put em on, I'm sure you'll do fine. Pay retail? That I don't know about.
I'm in the "sc/turbo or bust" camp when it comes to thinking about performance mods to these cars, so please take what I wrote here with a grain of salt!
thread revive
what is the part number on those 3.8 x51 headers ?
Are they 997 S headers or there need to be a X51 package on them ? If it is second one, I bet they are not that easy to find
I think you need the X51 headers. I remember seeing pictures of the stock 997 headers and they did not even look as nice as the stock 996 headers. Not sure if the S headers are different or just the X51. There is a thread out there on one of the boards with pics of them. Time to start searching I guess.
The issue with most headers is that you trade some additional HP at the upper rev range for a loss of power in the lower range. I love to rev mine up, but frankly I spend a lot more time below 4,000 rpm than above 5,000. One of the reasons I have not done headers.
I have 997 S headers on my 02 996 C4S.
Doug you are right the OEM looks nicer, however the 997 S
headers are tuned to an engine that has 50 or so more hp.
I don't notice too much of a loss or gain, but maybe I just got used
to it.
I think to notice anything, you need to Flash the ECU.
I kept the originals.
Your mechanic will have told you this way because of those 997's have a different diameter?
996 oem 42 mm - 54 mm diameter external
996 x 51 48 mm - 54- ???
997 s mk1 ?
jdsstudios you can control the diameter of the three collectors and exits?
Ale, the 996 C4S has 20 hp more than the regular 996.
The 997 S headers were a straight fit.
I could be wrong but I think the diameter is the same on
the 996 S versions, C4s or S.
The 996 C4S has the same engine as 996 Carrera, Targa, Carrera 4, and Cabriolet versions of MK2 series
3.6 l. = 320 HP
There is no 996 Carrera S version
Mk1 series = 3.4 l. = 300 HP
FWIW, I run the 3.8 (997S) headers on my 3.4 race car. I installed them with a GIAC street flash and switched to 98 octane fuel. I gained 33 rwhp on the same dyno 1 month apart. I don't often have that motor below 4500 rpms so I can't comment on low end torque loss if any. I also don't know if the 3.8 S headers are different than the 3.8 X51 headers...
Any chance you have the dyno to look at? I guess most of us wonder about the change across the band. Since you're only interested at north of 4500rpm this wasn't much of an issue for you. For the daily drivers among us I'm sure we'd love to see it.
-Shawn
FYI - 3.8S and 3.8 X51 headers are different, although not much different in performance surprisingly. I think when the X51 is allowed to breathe better then the x51 headers may come more into play over the 3.8S headers. I'm in the same boat as JRG, we only see below 4500 rpm twice each time we drive.
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....
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.
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.
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.
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.
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.
its interesting to note that a company like cargraphic makes different headers for the 3.4 and 3.6 and they are not interchangeable... I always thought that headers gave you more in the upper at the expense of low end torque.. so for tracking this is great... now add to that a set of 100/200 cell xpipe cats which apparently boost up your midrange quite a bit (more than traditional non-xpipe cats) and that may be a good formula for still having mid *and* high end power with these two mods?
Stock 997S headers are funny looking. X51 headers look nicer. Negatives are slightly higher weight (for the X51 headers) and some mid-range loss of torque.
Sorry, but there 'difference between the headers 996 3.4 3.6 and 997 3.8 mk1 ? the last pictures are from the 997 mk2 but from 2009 .
996 oem 42 mm - 54 mm diameter external
996 x 51 48 mm - 54- ???
997 s mk1 ?
I realize this thread is 100 years old, if you're still active can I send you a message and pick your brain about your tuning on the 3.4 more so what and who you used if they're still around.
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