Dyno Proven 231WHP 986 Boxster S.

[panameras]

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



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



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

[Topless]

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?

[CJ_Boxster]

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

[racer_d]

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...

[NickCats]

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

[Pat]

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.

[porsche986spyder]

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.

[Topless]

Originally Posted by NickCats

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

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.

[Pat]

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.