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Old 01-08-2017, 11:46 AM   #1
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How much power can you squeeze out of a 986 Boxster S?

We fit a sports exhaust, 987 airbox and 996 throttle body to a 986 Boxster S. What's the final horsepower figure?



https://www.youtube.com/watch?v=kja5LSsUT_g

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Old 01-08-2017, 12:38 PM   #2
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very nice. i would question the role that the old tune is playing - both in increased hp, and in the fueling issues. on an unmodified ecu you should be running at stoichometric at low load (to say 4000 rpm) regardless of what you have done to the intake - air and fuel mix is monitored by 02 sensors and kept at stoichometric. you can make the intake and exhaust paths bigger, but the amount of air can still be measured. even if the amount of air is not being monitored properly (ie maf issues, air leaks, etc.) the ecu will trim (add/subtract fuel) to try and maintain stioch. if ecu finds itself having to add/subtract more that 20% or 25% fuel to maintain stoich then you will get a cel. so, you have no cel and are not running at stoich at low load - it must be the aftermarket tune.

i ran that same arrangement and monitored my idle and low load trims and everything stayed well within acceptable ranges.
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Old 01-08-2017, 04:38 PM   #3
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Neil,

Great videos...

It wasn't explicitly clear.....Is your buddy running a 987 MAF housing with the standard diameter? 80mm diameter was mentioned. How are you deeming the engine to be running rich?
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Old 01-08-2017, 04:55 PM   #4
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Nice!
I haven't had time to watch it completely, I jumped straight to the end, but it is some nice gains!
But... you've remapped it before the mods???
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Old 01-09-2017, 12:32 PM   #5
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Nice video. So, do I understand YouTube correctly-this part 1 was posted 4 days ago and parts 2 and 3 are still to come?

Ben, my understanding is the car was bought with the exhaust upgrade and tune already installed-the plenum and TB were added by the current owner. Parts 2 & 3will be interesting to see how it all turns out.

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Old 01-09-2017, 12:50 PM   #6
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Neil makes the best Boxster videos by far !
There was an excellent Thread recently which gave the tech details of mods. The Thread title was similar to "why is the 3.4l M96 engine in the 996 so much more powerful than the 3.2l in the 986"
How can a 911 3.4 have so much more HP than a 3.2 Boxster S?
and this:
987 v 986 Air box
I can't wait for the video from Neil of removing the stock airbox and replacing it with a 987 -allegedly a 10 hour job of hacking ,smashing and bending up the Boxster.There is a better way if you use Search diligently.I have recently done it.But not for performance or CAI.I really,really needed easier access to the fuel pressure regulator and #4 injector.
I nominate Ben as the guy to make a kit for this project!

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Old 01-09-2017, 05:45 PM   #7
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Neil's videos are clean uncomplicated, easy to understand and succinct.

Good job!
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Old 01-19-2017, 12:04 AM   #8
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Originally Posted by jaykay View Post
Neil,

Great videos...

It wasn't explicitly clear.....Is your buddy running a 987 MAF housing with the standard diameter? 80mm diameter was mentioned. How are you deeming the engine to be running rich?
Thanks Jay! Richard is running the 987 airbox but has kept the MAF and housing from the original airbox to try to avoid any ECU problems.
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Old 01-19-2017, 12:06 AM   #9
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Nice!
I haven't had time to watch it completely, I jumped straight to the end, but it is some nice gains!
But... you've remapped it before the mods???
The previous owner did it before Richard bought the car. We will discuss this in part 3 - stay tuned!
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Old 01-19-2017, 12:07 AM   #10
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Nice video. So, do I understand YouTube correctly-this part 1 was posted 4 days ago and parts 2 and 3 are still to come?

Ben, my understanding is the car was bought with the exhaust upgrade and tune already installed-the plenum and TB were added by the current owner. Parts 2 & 3will be interesting to see how it all turns out.
Cheers Paul! Yep, part 2 goes up today and part 3 in the next week.
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Old 01-19-2017, 12:09 AM   #11
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Neil makes the best Boxster videos by far !
There was an excellent Thread recently which gave the tech details of mods. The Thread title was similar to "why is the 3.4l M96 engine in the 996 so much more powerful than the 3.2l in the 986"
How can a 911 3.4 have so much more HP than a 3.2 Boxster S?
and this:
987 v 986 Air box
I can't wait for the video from Neil of removing the stock airbox and replacing it with a 987 -allegedly a 10 hour job of hacking ,smashing and bending up the Boxster.There is a better way if you use Search diligently.I have recently done it.But not for performance or CAI.I really,really needed easier access to the fuel pressure regulator and #4 injector.
I nominate Ben as the guy to make a kit for this project!
So kind Gelbster! Glad you like them!
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Old 01-19-2017, 12:13 AM   #12
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Part two is now up! Does fitting an underdrive pulley give more horsepower? We fit one then go to the rolling road to find out!

https://youtu.be/CvFdH11y4EI

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Old 01-19-2017, 06:58 AM   #13
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Originally Posted by neil_b View Post
Part two is now up! Does fitting an underdrive pulley give more horsepower? We fit one then go to the rolling road to find out!

https://youtu.be/CvFdH11y4EI

Is this 273 wheel hp or does the dyno convert to crankshaft hp?
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Old 01-19-2017, 07:00 AM   #14
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Is this 273 wheel hp or does the dyno convert to crankshaft hp?
It is calculated, in one of the videos (maybe this one somewhere or another rolling road video, maybe the one with the 996) the dyno guy briefly changes the screen to show the actual wheel HP read by the dyno - it is a fair amount lower.
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Old 01-19-2017, 09:43 AM   #15
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Part two is now up! Does fitting an underdrive pulley give more horsepower? We fit one then go to the rolling road to find out!
So if I understand correctly, the Dyno's calculated total horsepower is still 273 after fitting the underdrive pulley. Do you have the wheel horsepower figures for before and after? Would like to see if there is a small bump in the net amount reaching the rear wheels, that is what I think the underdrive pulley gives you. (Besides saving your power steering pump at the track.)

PS, great video! If you decide to improve editing quality as discussed in the comments to the video, that would be a bonus, but they are teriffic as is!
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Old 01-19-2017, 10:31 AM   #16
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So if I understand correctly, the Dyno's calculated total horsepower is still 273 after fitting the underdrive pulley. Do you have the wheel horsepower figures for before and after? Would like to see if there is a small bump in the net amount reaching the rear wheels, that is what I think the underdrive pulley gives you. (Besides saving your power steering pump at the track.)

PS, great video! If you decide to improve editing quality as discussed in the comments to the video, that would be a bonus, but they are teriffic as is!
Yes, please post the wheel hp differences, if there are any.
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Old 01-19-2017, 11:43 AM   #17
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flywheel hp is extrapolated from wheel hp (ie, increase by 15%) so pretty arbitrary, and can mask/over-emphasize actual gains, esp when dealing with small hp changes. wheel hp is the best measure in these situations i think.
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Old 01-19-2017, 02:36 PM   #18
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The only thing the dyno can measure is wheel horsepower. If it shows crank horsepower its an estimate, depending on the dyno it can be a fixed offset or a percentage offset.
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Old 01-19-2017, 06:51 PM   #19
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The take home from this is that Neil paid for a trick part+ a serp belt, hacked off a boss from the engine that is rather useful and spent a bunch of time and other money for no gain of any sort.
The Track guys would claim a benefit in not over-reving the p/s pump ?
The pro-u/d pulley guys claim there is no loss of cooling efficiency or a/c with driving those pulleys slower. Really?
At least Neil did not use the disintegrating version of the u/d pulley.He used a solid one.
I was surprised that when doing this project he did not check the bearings in all the other pullies & ancillaries. At least give the w/p pulley a wiggle ? Maybe that was done in another video?
If Neil wants a trick part that really works for about the same money, he should talk to Ben006 in Post #4- hint ! Ben;s trick part may work particularly well with the 987 bigger airbox?

Last edited by Gelbster; 01-19-2017 at 06:56 PM.
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Old 01-19-2017, 10:02 PM   #20
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A dyno doesn't measure hp. It measures torque. HP are calculated from torque and rpm.

There are different parameters that can affect a measurement:
- Temperature
- Humidity
- Grip
- Fuel quality
- Air filter, sparks…

If you don't use a calibrated and certified dyno, measurements are just written lines on a piece of paper.

Funny how people are hunting for 5 hp at the top end. Useless to say that this doesn't affect the driveability of the approx. 250 hp car in any way.

But keep on searching. Always funny to me.

Just my 2 cents.

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