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?

http://986forum.com/forums/uploads02...1483908384.jpg

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

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.

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?

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???

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.

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"
http://986forum.com/forums/performance-technical-chat/49364-how-can-911-3-4-have-so-much-more-hp-than-3-2-boxster-s.html
and this:
http://986forum.com/forums/performance-technical-chat/32074-987-v-986-air-box.html
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!

Neil's videos are clean uncomplicated, easy to understand and succinct.

Good job!

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.

The previous owner did it before Richard bought the car. We will discuss this in part 3 - stay tuned!

Cheers Paul! Yep, part 2 goes up today and part 3 in the next week.

So kind Gelbster! Glad you like them!

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

http://986forum.com/forums/uploads02...1484817212.jpg

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.

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.

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.

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.

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?

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. :D

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. :D

Just my 2 cents.

Markus

I do. The cheapest and most effective way to boost my Boxster car I've found so far is using one of these. Easy to use:

Wind blows south = take the highway
Wind blows East = use the back roads
No Wind = take the Volkwagen Turbo instead

etc... etc... works like a charm.

http://986forum.com/forums/uploads02...1484909663.jpg

On their own most single mods are small gains, but incrementally and packaged together they can make a noticeable difference.

Oh absolutely, I have zero doubt, but at a cost. Performance mods, those with significant gains anyway, does not come cheap.

As Neil did, looking for cheap ways to pump up the mood of the Boxster car is not all that easy to find. Well, if they ever work.

Share your tricks if you can/have

@ Nine8Six

SUPERB! :D

@ edc

Maybe. But the main restrictions done to the 986S are for shure not done by a pulley. :D

Always funny to see what "clever" salesman can sell to people with money. :D

Maybe i should found a Porsche tuner online shop. Seems to be a good business idea. :D

Regards, Markus

I've done all the relatively cheap bolt on mods, measured on the dyno as best I could (for what I wanted to spend) the change. Once you've done throttle body and intake, exhaust, sports cats, manifolds/headers, remap there's not much left unless you spend big. I don't think anybody is suggesting to start with a pulley change if you want to make power. It's pretty much the last thing to do. I don't pretend to be an engine builder but let's remember it's done for fun and a hobby and with a budget that I deem to be disposable.

The recipe is simple, generate more noise and the customer believes he is getting more power.

Thanks for that very informative and simple-to-understand answer. Very informative and sums it all.

Fun first, hobby later, I'm 100% with you on that one. Priceless :cool:

If Bang-for-the-buck is of concern there is one mod that has been quite well tested and seems popular among those who tried it:long read.
http://986forum.com/forums/diy-project-guides/55966-intake-plenum-911-throttle-body.html
I wish Neil had evaluated this mod and not one that had already been discredited by some users.

well, note that the sharks were pretty quick to come out as soon as they saw some blood in the water; one non-back-to-back dyno result on a car with improper fueling and an arbitrary fwhp conversion that says it doesn't work is not necessarily grounds for writing off underdrive pulleys, let alone calling out anyone who sells them or chooses to install them. a google search shows multiple instances of non-biased dyno evidence where they do make hp, much more so than folks who have not encountered hp increases. you can call the validity of these other results into question if you like, but would then have to accept that this result has no meaning as well.

Neil was kind enough to provide a data point. If others have conflicting data it would be helpful(as Neil requested) if they post it.
The value of Neil's work is that it provides video data. It may be imperfect but afaik it is the best video+dyno data in the public domain.
If we are to discuss the issue effectively and helpfully it seems important to distinguish between published data and anecdotes.
The anecdotes are interesting but....

I would start with simple measurements of the intake and exhaust system followed by some air flow calculations. Pretty easy to see where the restrictions especially for the 3.2 were made.

And no - a sport muffler is not the solution. Ugh, did i write the word solution. Bah, maybe someone will hit me with a patent right now. :D

But hey, no offense. Love that entertaining videos. :D

Regards, Markus

It's all well and good people criticising but it does cost money to mod and dyno the car. Scepticism of suppliers claims and dyno runs is rightly placed but end users have little agenda to push. I have lots of graphs of my car with the mods done but only one with each dyno run overplayed onto one graph and it happens to be the crank figure graph. The wheel horsepower ones show a similar trend. If I really wanted to I could get all the wheel horsepower ones printed onto the same piece of paper as I know my data is still stored but I've got no motivation or intention to for the time being.

@Markus. Havin one of those bad day huh lolll

Easy yes but not that simple (apparently). It's well known that a small TB will restrict air intake however the 'infamous' larger TB idea may actually reduce velocities even more than the stock TB for a particular engine. I already have the formula to solve the TB-vs-Size air flow but without the combustion domain, ratio and valve m/sec specs, its nearly impossible to find where the imposed limitation(s) are - less helpful to find the optimum geometry for the air delivery.

Using CFD(nastran) of course and already asked onto another forum a few weeks ago. Unfortunately and as you know your country folks, as soon as you mention about their Porsche-performance-anything, they get offended and shut down on ya leaving you guessing. It's never cool but I respect that. No offense to you personally bud.

Without hijacking this thread's subject, if you have 'any' pertinent info or contact locally RE the M96 please PM :cheers:

The biggest problem of the boxster is that it is built as a daily driver.

Unless you put a turbo kit. On a naturally aspirated engine you will just be constantly loosing drivability. What is the point of gaining 20 hp in the top end if driving around feels sluggish everywhere else. Unless there is major restriction(low flow rate exhaust or manifold, changing anything and remapping it will just push the torque curve higher and higher in the power band making the lower portions weaker and weaker. For a racecar or track car go for it everyone else I would suggest otherwise.

I did all of that many times over. Having a car being able to idle, use reasonable amounts of gaz and be reliable beats having the most powerful thing at that time. Turbo's make it easy where you can have an extra 50hp to pass someone, like a pesky GTI where they have a crazy amount of power compared to their cornering ability.

@ Nine8Six:

Start with the exhaust system measurement of the 3.2. :D Calculate the diameter you'll need for an optimal airflow at max rpm. Check header length. You'll be surprised. Same to the intake. And important - take a look at the heads. ;)

Bad / good news - i don't know no correctly dimensioned after market solution right now - they all build the same crap. :D

But hey, i don't know nothing. Maybe i should install a patented underdrive pulley. :D Ugh, did the word again. :D

Regards, Markus

Dude, I don't know nothing also, trying to learn and doing it right. I do know however that I shouldn't be putting a 'whatever' 996 TB onto my 2.5L or the velocity will nearly stall @6,500RPM lolll

http://986forum.com/forums/uploads02/tb1484942303.jpg

I'm out Markus (PM if you have anything). That's for another super dupper DIY. Our mighty 2.5L will become faster than your 3.2 for twice less dosh in the drain -mouhah

hmm . a 3.2 litre engine moves 1.6 litres per rotation. at 7000 rpm that's 11,200 litres / minute = 11.2 cubic meters per minute = 0.187 m3/s.

with w 74 mm ID TB, thats an area of 0.0043 square meters.

0.187 / 0.0043 = 43.5 metres/second (say 156 kmph - fyi, that's why ram air intakes don't work - you have to be going faster than 156 kmph to out push the suck, other aerodynamic inputs notwithstanding).

same analysis with the oem 67mm TB gets you 192 kmph.

i wouldn't call 156 kmph (100 mph) slow. i would say that the added work required to accelerate air (which is what the engine has to do - accelerate the air from zero to hero every time you blip the throttle) from 156 to 192 kmph is significant. this doesn't even take into consideration the friction losses associated with a smaller diameter tract. ps, may math could be wrong hey.

here's a good quote from a good article:

"The act of increasing the air velocity is not desirable when it does not contribute to the harmonic tuning of the intake pulses in the intake manifold. Since the intake duct is ahead of the throttle body and MAF sensor, these harmonics do not come into play."

Easy Performance | CAI System Design Consideration Primer

that is, we read about using a decreasing diameter intake to accelerate the air to facilitate cylinder fill at low rpms, and that opening up the intake track, while reducing friction at high rpm and increasing max hp, is detrimental to low rpm torque. however, note that most of this tuning is happening in the intake runners and resonance tube, and what is happening upstream of the throttle body is moot - just a supply of air, so best just ensure it gets there with as little friction and resistance as possible.

hijack! this is good discussion for video #1 of the series however, so i only feed kinda bad.

Thanks for the equation TRK. Tidy, all starting to make sense.

edit: won't get into a debate here, I'll need your help soon though

Neil,

Retaining the 987 MAF housing could itself can cause ECU issues as the diameter is larger than the 986 housing iirc. I have heard, stories where the ECU may adapt but I tend to take these with a grain. Unless your friends custom tune is geared for a larger diameter, he will likely get mixture issues.

987 Airbox +986 MAF tube+986 MAF sensor is no problem on my 986 S . The airbox is not critical within reason. Boxster CAI systems have no real airbox at all.
http://986forum.com/forums/performance-technical-chat/32074-987-v-986-air-box.html