How much power can you squeeze out of a 986 Boxster S?

[Nine8Six]

Originally Posted by Smallblock454

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.

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.

[edc]

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

[Nine8Six]

Originally Posted by edc

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

[Smallblock454]

@ Nine8Six

SUPERB!

@ edc

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

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

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

Regards, Markus

[edc]

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.

[Anker]

Originally Posted by Smallblock454

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

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

[Nine8Six]

Originally Posted by edc

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.

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

[Gelbster]

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.

[The Radium King]

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.

[Gelbster]

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....

[Smallblock454]

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.

But hey, no offense. Love that entertaining videos.

Regards, Markus

[edc]

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.

[Nine8Six]

Originally Posted by Smallblock454

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.

Regards, Markus

@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

[WorkInProgressK]

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.

[Smallblock454]

@ Nine8Six:

Start with the exhaust system measurement of the 3.2. 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.

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

Regards, Markus

[Nine8Six]

Originally Posted by Smallblock454

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

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



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

[The Radium King]

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.

[Nine8Six]

Originally Posted by The Radium King

that is, we read about using a decreasing diameter intake to accelerate the air to facilitate cylinder fill at low rpms

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

[jaykay]

Originally Posted by neil_b

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.

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.

[Gelbster]

Originally Posted by jaykay

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 gear 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