Dyno Proven 231WHP 986 Boxster S.
 

For all those who reckon it's waste of time and money trying to extract more power from the already fine tuned Porsche Boxster here we have the results that will make you think twice.

My baseline dyno graph

http://i235.photobucket.com/albums/e...seline1024.jpg

This was dynoed when the car was completely stock. Done in 4th gear. Didn't bother to open up the engine compartment thus no rpm readings.

As you can see at higher speed(=rpm) there are many inconsistent dips on the graph this is where I expect an aftermarket headers would improve over stock headers. Im also interested to hear what do you think the cause of these "dips" might be?


Dyno comparison, stock vs aftermarket headers

http://i235.photobucket.com/albums/e...dersHP1024.jpg

In this graph the power curve explains itself. Noticeable gain across the whole rev range. 7WHP increase at the peak.

How much is this mod you ask. $475US and you can install it yourself.

Let me know what you think ;)

I am a little confused here. What changes did you make to your car to get the 5hp increase in your first set of graphs? What changes did you make to go from 167hp in the first set to 224hp in the second graph? That is a sizeable power increase. As I read it the second graph shows a before/after header install increase of 7hp which is pretty close to others findings. Can you clarify?

I dont know, 77hp increase from only Headers.... Doesnt sound right.

I too am a bit confused... especially since, generically, I have experienced a 15-20% difference between Whp and flywheel hp.. thus 231 whp x .15 yields 265 flywheel hp, which isn't far off Porsches typically conservative HPO rating of 252-258 depending on year.

While I have never said you couldn't get more HP, one should realize that for a "world" market that uses the car under all sorts of conditions, certainly Porsche leaves some HP on the table...

Look at the graphs a little closer...

1st graph ( baseline ) is metric - Speed ( km / hr ) & Power ( kW ).

2nd graph is Speed ( mph ) & Power ( hp )


1st graph is showing stock with no work ( but in metric measurements ) with four runs of 162, 163, 164 & 167 kW ( not hp )

2nd graph is comparing no headers ( blue line - 224 hp ) and headers ( red line - 231 hp )

Nick

Hell, who cares about 7 hp at the peak. There's a difference of 25+ hp at 103 mph in the measured gear! Not to mention all the area under the curve throughout most of the range tested.

He doesn't say what brand or who made the headers either?

I wonder what they are. 4-2-1 or 4 into 1??? Please let us know where you bought them and what brand they are.

I see. So what you are saying is he had a 7hp increase during his baseline runs with no changes, under very similar run conditions (margin of error) and a 7hp increase after header install, 8 months later, 25F cooler ambient temp., higher barometric pressure, higher humidity, different tank of gas, different tire wear etc. etc.

Don't misunderstand me. I believe a 7hp increase is possible and I appreciate his efforts to document performance changes to his car. I just get frustrated when I see a margin of error that exceeds reported gains. Everything below the margin of error is just background noise. I am afraid we have not learned very much.

I think Bisimoto has some of the most detailed and carefully controlled dyno runs I have seen on a Boxter and still there is some margin of error. By repeating before/after results he has proven a measureable hp increase which exceeds the margin of error by desnorkling his car. Clearly the snorkle is a Porsche compromise for intake noise abatement and to prevent possible water injestion. I hope more studies are done this way so we can get "proven results" on performance mods. Until then we don't really know what increases in performance are possible.

Topless,
You raise some good points, and I appreciate your attention to detail.
Most of the factors you cited as variables that could invalidate the findings are corrected for using SAE standards. Yes, I know that's not ideal, but it's the best we have to work with. I am not as concerned with the differing test conditions as you are.

wow, how do you post results without telling what product/brand you used?

Nick is spot on. First graph is showing figures in KW, all 4 runs were performed within minutes of each other, no variables been changed and 167kw was the best of them.

Second graph is showing in Horse Power. 224hp(167kw) vs 231hp. Only modification been a set of aftermarket headers.

Other than different room temperature and humidity, I tried my best to keep everything else constant. same type of fuel (BP Ultimate 98RON). same set of tyres with the same tyre pressure. I don't drive the car much so there were minimal tyre wear (about 2000kms of 80% highway driving).

Therefore there were indeed variables in test conditions, However the most important finding is what PAT mentioned "There's a difference of 25+ hp at 103 mph in the measured gear! Not to mention all the area under the curve throughout most of the range tested."

Now for the non believers, yes it is possible to get a few horse power gains here and there due to a cooler room temperature but looking at the graph how do you explain major gains of up to 25hp across the entire rev range. If you still think it was due to margins of error, well, you obviously know better than me and I have no reason to prove to you any further.

Im not going into too much details of the brand of headers I used as Im not promoting anyones business. What I can say is they are 4 into 1 design headers that you can buy off ebay for around $500US (I believe there are at least 3 different vendors that are selling them under their own brand names but are sourced from a same manufactorer) Again Im not associated with any of them, just trying share my findings with fellow boxster owners of a worthwhile performance "enhancement" that I would recommend.

Dyno graphs are great tools.
What I care about, however, is how the car drives. How much of a difference would you say this made in your car's seat-of-the-pants performance/feel?
Yes, I know this is subjective, but if you could expand on how the car feels before and after I would appreciate it.

Thank you again Panameras for posting your dyno results. Your curves do look promising and are consistent with others findings. This just adds another piece to the 986 knowledge base and raises even more questions about realistic performance gains on these cars.

The next step is for someone to test how much real world gain these headers produce by running some 1/8 mile, 1/4 mile, and lap times on a track they already have wired to get a good baseline. Then repeat the process after installing the headers. That is the kind of testing most racing teams are doing. A 1/2 sec. per lap over a day long race often is the difference between 1st and 20th place.

Just my two cents, I tried to control as many variables as possiblw when I did before and after dyno runs with the addition of German-made TTP headers to my 2000 2.7L Boxster.

Depending on the run, I only saw a 3-5 hp increase at the wheels, less than I expected, but the headers sure make the exhaust system sing, at least to my ears. The downside is that I have been messing around with check engine light after the headers went on.

Ed

:cheers:

Well, seat of the pants feels MORE SMOOTH is the best way to describe it. The engine feels more free-reving (especially from around 4000rpm) but not by much.

You can definitely feel the difference though as I have already driven the car in stock from for a few years so it's easier for me to pick up any improvements. I wouldn't expect much more than that though it's not a magical mod like increase boost in a turbo car which would totally alter the behavior of the car.

In this case the car is smoother with a little bit quicker acceleration which is a nice cost effective enhancement consider the relative low cost and ease of installation compared to say, an evo cold air intake or an aftermarket muffler.

For those who like to talk numbers. $475/25whp= $19 per hp at the wheels!
Now you all know how much a performance software costs which typically "claims" 15-20hp at the engine.

However the point I'm trying to emphasize here is not how much more power it delivers but how it makes the engine breath just that little bit better everywhere in the rev range and how the car drives a little smoother.