Tuned Boxster S lacks of power

Hello everybody, I got a low mile 987S 3.2 Boxster , 280 HP stock. My car has a Softronic remap, IPD plenum , 74mm throttle body, Evomsit V-Flow system and a cat-back DesignTek Valvetronic exhaust ... So it should be at least 300hp or more, but it has only 271 on crank. Any suggestions where are the HP's?

Sounds like you're back to basics. Injectors clean, plugs OK, compression normal, etc, etc? Good luck! Joe Henley

This is a rabbit hole of a topic. But, first, all cars “lose” hp as they age. Also you are comparing crank hp (at the engine, magic manufacturer measurement) to wheel hp (at the wheels - dyno measurement). Expect 15-20% less hp at wheel from crank. So 280 crank could be 250-ish at wheel. If you’re getting 271 at wheel then the hp gains are there. Also those mods are questionable on actual hp gains. Get headers .

After 68000kms I do not think a Porsche should lost that much power... I am the second owner. It has 271 on crank. 271 on wheel would be the goal... So actually it is 9 hp less than stock.

So that dyno chart is BHP not WHP? I don't see where it's listed. Regardless, a good set of catted headers should do the trick. Your Softronic tune can adapt to those. If you go catless, you'll need to pay for a remap. Nice smooth power curve though!

Dynos don’t measure at the crank, they measure at the wheel. If they’re giving you crank numbers, they’d just be estimating your drivetrain loss multiplier and I don’t know why any shops would do that.

There are actually some that do measure at the flywheel/crank/engine. I think they are located mostly in Europe where OP might reside according to his flag (Italy perhaps). Regardless, without a baseline run, his numbers really don't mean squat.

I've read a few times here that Plenum on its own without upgraded headers , intake etc can actually rob power.

Unless you removed the engine and put on an engine dyno you can't get crank horsepower; you can estimate it based on wheel horsepower but you can't read it. Here's the problem with chassis dyno's - the operator can make it read anything they want. Also take the car to 3 different shops and you will have 3 different results. Dynos are calibrated, when and how varies, they have slippage, if you get more tire slippage, you get less hp, weather conditions change everything Use the same dyno, on the same day with the same weather conditions and you can learn something otherwise it's pretty much a waste of time I had a shop dyno my 06 CS and they claimed it produced less hp than stock Why, because they didn't do the mods and they wanted to discredit shop that did plus they wanted to sell me changes in car and then show how wonderful & better their work was. Not saying your shop is doing this but am saying 1) every dyno reads differently and 2) the operator can make it show whatever they want, either better or worst than actual. I worked with a shop that built engines for offshore racing boats, mostly big block Chevy turbos for Cigarette Racing. They dyno every engine they build 1) because they are dual engines and need to be pretty equal in power and 2) you have to be sure there are no leaks since you have to remove the engine to fix them and stuff leaked inside the hull is not good.

There are too many unknowns to reasonably give a good answer, however the first thing I noticed in the graph was the speed/velocity of the test (232km/h). Seems to indicate that the car was in 5th gear if manual. My knowledge is a bit rusty but I am pretty sure Porsche manual 6-speed transmissions should be dynoed in 4th gear as that is as close to 1:1 gear ratio as possible. My first question to OP would therefore be - what gear was the dyno done in? If in any other gear than 4th, the numbers might be inaccurate.

I have a 2005 RS370 3.2L. Immediately some major issues are glaring. 1. Many "racing oriented" tune and parts suppliers do not tune for max power, they tune for reliability and standardization. Softronic is one such company. for max HP the only answer is the EVOMS RS370 software. 2. You do not have an RSS underdrive pulley, believe it or not this one is huge for the build. 3. You do not have headers . Fabspeed catted headers will improve it some, but to go for gold you need to have the Fabspeed long tube headers . Again, exhaust manufacturer is key, not all make the same gains. Mine uses the Supercup exhaust for max HP, PCA Clubracing uses SOUL , But they use them because even with their catless they dont add much power, and being made overseas they are cheap to replace and have an unlimited warranty. The organizer even stated they went with this header because it didnt add power to keep them from running up on other classes. I have this conversation in screen shots for those who will try to deny this. 4. I can see from the dyno that the IPD has leveled out the notorious mid range dip in power so its working there. What gear was this ran in? what temperature was it? engine already hot or from a cold state? Also you used a 74mm TB. I am using the Competition 82mm. Another big difference is weather or not they put a direct fan into the intake, or just put them at the front. You also need to "desnorkle" the car to take advantage of the EVOMS intake. PDP Composites scoops (sold here on P9) also help scoop the air at speed. they wont show on dyno but on the road you can feel the difference. My RS370 can hold the new Shelby GT and 458 doing high speed pulls. 80+ rolls. This build is all about top end power from 4k+. You will be running the car consistently at high rpm in the corners and canyons. It's primarily for Togue style racing. Not really for tracks and highways where the GT3 's and turbo's will just blow by you with higher top speeds. You may also want to consider a light weight aasco flywheel as you get to the power band faster and easier rev matching while driving.

I’ve been doing “dyno runs” for 20 years. And ya know what I’ve learned. They’re damn near worthless. What does your *** tell you? Are you HAPPY with the performance? That’s really all that matters. Never forget .... races aren’t won on a damned DYNO... they are won on a track or at least the street. Blessings Jehu (10th King of the Northern Region)

I put K&N filters, IPD plenum , 82mm TB and FVD tune on my 981 base. Sounds better. Pulls better. Better mileage with your foot out of it. I am considering headers but I’ve read here and on ******** the stock headers are about as good as it gets. The biggest restriction are the cats. A person can spend anywhere from $1600 fo “equal length” headers with 200 cell cats all the way up to $4000. How do you know which one is the best all around choice? Or, should one just replace the cats and call it good? Modification is a slippery slope eh. And, hrspwr for the base is listed at 275. Is that at the crank or at the wheels? TIA dlb

Surprised to hear so many discussions about the headers on a 3.2 S. These were significantly different to the later 3.4 and 2.7 models in that they are equal length performance design. The rear silencers also used a 55 rather than 47 mm bore tube between the header and rear silencer ( as latterly found in the caman R and spyder 987 Gen 2) I have done some work on tuning the 987 3.2 myself, its a difficult beast to get much power from , mainly due to the fact the M96 engine lacks the variocam plus found on the later M97 engine and has smaller valves. Ive found you get the best results by fitting the larger 74 mm Throttle body from the later 3.4 and 2.7 models (fitted with M97 engine ) in conjunction with the factory oem plenum from the same , this way you retain the linear torque curve of the original car. Regarding exhausts , the 3.2 like the 3.4 and 3.7 uses two sets of 400 cell cats, one in each manifold / header , the other in each of the rear silencers. In order to get the best from a remap ideally it needs to be tweaked to the other performance modifications to ensure fuelling and valve timing match the gas flows from intake and exhaust mods. Its also critical that there is some back pressure retained in the exhuast to ensure the pulsing effect which helps clear the combustion chamber rather than reliance on piston movement alone. Generally its better to fit a complete system rather than headers and silencers from different suppliers, so the gas flow is consistent ( the design tek valved exhuast is more a sound tuning than performance enhancement) . The length of the primaries in the header effects the torque curve by moving the peak left or right of the original point ( it rarely increases it without other modification) , ideally you need a remap that takes this into account , for that reason on my car I experimented with modification to the standard headers . What I found was that decatting or fitting 200 cell cats retains the engine characteristics but gives an overall gain ( peak was 308hp with decat 3.2 manifolds , stock exhaust , 74mm TB and plenum and ECU tune) . The decat is the less preferred option as you actually lose a little torque but get the power at the top end. The 74mm TB with a cayman plenum should give you around 5-8 hp on its own , so if you are down on power its probably worth checking the intake plenum connections are not leaking which would weaken your mixture , if it gets too weak, the AFR runs high and out of limits which can cause the engine to run hot so the ECU dials in adjustment to prevent damage. The air filter on a 987 is not the restrictive part like it was on the earlier 986 as its a cylinder rather than panel filter with probably double the capacity. Its unlikely unless you have a turbo you will see any gain on a rolling road as the car has enough air and you are getting no ram air effect , removing the baffle plate probably helps more than an expensive BMC or K&N filter. Ive since experimented with various tubular manifolds which though sound great actually lose performance over the stock 3.2 ( again probably due to the ECU not being tweaked to the mods and the fact the manifolds I trialed were not equal length).

You guys are great. A little over a year ago I purchased a six speed manual 2006 Boxster S with 21,000 miles which I use as a daily driver-I now have 30,730 miles on it and no intention to track it. Nevertheless, I have spent countless hours contemplating and researching performance upgrades. Though I did not initiate this thread, I am grateful for all of the responses because the collective advice which people so generously shared has saved me money. But more importantly it has cause me to appreciate, learn, maintain, and love driving this car.

I've had no reliability issues with the car after 50k miles driven. (80k on car) I have every bolt on under the sun and a full RS370 package with Fabspeed racing exhaust products. No CEL, and nothing other than a waterpump at 75k. I drive the car on canyons and mountians keeping the RPM over 4500 running her out to redline consistently. It is a large cost to do these mods, but its worth it. If you dont plan on driving your car in this manner, then just get a maxflow exhaust and call it a day.