Most cost effective HP+ modifications?
 

Does someone have a list of the most cost effective modifications to boost HP? That is, which mods have the higher HP to $ ratio?

De-amberibg and airbag sticker removals do not count. ;)

Most cost affective? Take **************** out... Enough said.

See that spare tire? Get rid of it... Have your bowling ball/ golf clubs from last weekend still in there? Take them out.

50lbs doesn't sound like much, but if you pull out that much, or more, I promise you'll feel the difference. When you go to the gas station from an empty tank to a full tank, i know i can feel the difference. 10 gal of gas is only 80lbs. Now take that to perspective when you take out another 100lbs

And for how much? FREE! Unitl you get serious and start putting on light weight wheels/seat/steering wheel/ battery/ etc.

An Underpully is a mod you truly feel, I don't know how it would be in a place like Az where you need max AC but other than that you truly feel the difference.

+1 on the underdrive pulley.
The one I bought from Flat6 fitted perfectly and you can feel the difference in the low to medium rev range where 90% of your driving is....

Here are some thoughts from a previous thread:

1. A comprehensive and methodical approach to revamping the vehicle's exhaust system; i.e. headers, cats, cat back ect...
2. Light weight under drive pulley
3. Larger throttle body and plenum
4. ECU re-programming
5. Lighter wheels (a potentially faster and better performing vehicle by means of
reducing unsprung weight and rotational mass)
6. Reducing weight in general; i.e. spare tires, oem seats, lighter battery ect.. (this is
more aimed toward tracking your boxster .
7. Suspension upgrades (though not a direct increase in power, a faster vehicle can be
had by means of better handling and performance .
8. Increasing airflow to the engine, i.e. cold air intake or filter replacement
9. A divorce (a major reduction in weight by means of one less passenger, as well as financial freedom to do more mods)

and the list goes on ...........
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My current thoughts on the matter in terms of cost effective performance improvement:

1. Under drive crank pulley.
2. Weight loss (fly-weight buckets, remove AC equipment, remove spare, light weight back box). Will probably also remove and store the remove roof motors and transmissions - roof works really well manually when disconnected from the transmissions, oddly enough!

Even that won't be cheap if you buy everything new. But a used back box might not be too pricey, ditto buckets.

Question I have - is there any reason to be wary about fitting the underdrive pully? Don't think the factory one is damped, but even so...?

To add a bit more to Johnny's #8 (edited, previous reference to #9 was incorrect), I'd say smoothing out this airflow will also be a benefit. The stock plumbing could be better, as well all know, so one could consider replacing the hoses with smooth, straight tube and a couple of smooth elbow pieces, and that'd be a cheap and effective DIY. I'm sure, depending on your level of perfectionism, you could make it look very clean and like it belongs there.

Buy a used 911TT :D

I've got a UDP for sale in the classifieds:

http://986forum.com/forums/boxster-parts-sale-wanted/30366-fs-4-underdrive-crankshaft-pulley.html

I think everyone pretty much agrees it's at the top of the list for most cost effective hp modifications.

Ya know he says it jokingly, but in reality, if you want a fast car, you're probably better off selling your boxster and buying like an older C5 corvette or something, because unless you do an engine swap it's never going to be fast. And even if you do that, you would have been better off spending your money on a stock, faster car...:ah:

I said it half jokingly. For the exact reasons you list, you'll be spending thousands of dollars to chase 30 to maybe 50 extra HP.

I think the rule of thumb is $50 ~ $75 / hp
I think the max you can reach with "all tricks" is maybe an additional 50 hp = $3 ~ $4k
After that it gets real expensive with either an engine transplant > $15k or a turbo, also > $15k, so at this point it really might be cheaper to get a different car....

You turbo or supercharge your boxster and it will blow up.... I promise you... You may get even a full year out of it, but this engines will go out on you unless you fully build them... And again, Naturally Asperated is the way to go if you want fast, useable power..

For my money, a turbo Boxster would be ghastly anyway. For me one of the core appeals of these cars is the finely honed driving dynamics - and that includes sharp throttle response and linear, progressive power delivery Then there's the clarity of induction and exhaust notes.

An S-charger might be just about tolerable. But a turbo? Faggadaboutdit!

Something to consider .

$1,000's and $1,000's later = 25 or so hp at the wheel .

Totally agree - I had an Audi TT a while back, and while a total hoot, the dynamics are completely different. I briefly considered another TT, then test drove the Boxster, and never looked back.

I looked at all the power adding mods available for the Boxster and added the HP claims all together. I excluded superchargers and turbochargers.

I got $90 per HP. Parts include performance intake, low temp thermostat, underdrive pulley, headers with sport cats, secondary bypass pipes, performance muffler, ECU upgrade, Pedro's Plenum upgrade, added 2HP for desnorkel and iridium sparkplugs.

I say most cost effective mods are ECU upgrade combined with performance intake and bypass pipes. $1700 for 20-25HP according to claims. That is about $78 per HP.

I'll say it again... A car with 200hp that weighs 3000lbs is a lot slower than a car with 200hp that weighs 2500lbs.... Like WAY slower...

Granted, unless you totally strip your car you're not going to get 500lbs out. But even 100lbs is feelable... Just take stuff out of your car! It will be faster..
And thats like $0 per hp lol. Cuz you're not gaining any horspepower or spending any money!! lol

If you want a car in a fast line, boxsters are not the car for you. If you want a great handling, fun, gorgeous car, then you should buy a boxster... Enough said.

I can assure you that the above mentioned equipment alone will not achieve 20-25 hp . Not at the crank, wheels or otherwise .

True weight make a big difference. I think I read somehwere 0.2-0.3 second 0-60 improvement for every 100lbs lost. Problem with lowering weight-I drove without the engine cover carpet. I removed the carpet on top and the carpet behind the lower driver/passenger seat.

The car sounded horrible. It did not sound sporty at all. Those 5-10lb carpets make a huge difference in how good the engine sounds.

I thought of replacing front spare tire with Fix-a-flat spray, but idk how it effects my rim when trying to get a new tire? Has anyone used fix-a-flat? And I believe there are only 2 or 3 aftermarket rims for this car that are actually lighter than stock rims unfortunately.

Idk. I just looked at the dyno videos for the ECU upgrade and secondary cat bypass pipes from fabspeed motorsports on youtube. They did add roughly 17-20HP with the exhaust and ECU as well as a BMC Air Filter. Was guessing a Evo or Agency Power Cold Air Intake would add 2-3HP more than a BMC performance Air filter so that is how I reached 20-25HP.

As Fabspeed advertises.
8HP and torque for bypass pipes
10-12 HP for ECU Upgrade
Up to 5HP on BMC Filter(my guess is more like 1-2)

No offensive, but Fabspeed would love all of us to believe that their by-pass pipes and ecu program accomplishes those figures. Realistically, however, once a person has completed his or her upgrades, a good ecu tune more or less "tweaks" the air/fuel parameters . In turn, this can create better engine response and fuel efficiency . The actual gain is hp is negligible . As far as the effectiveness of bypass pipes are concerned, one can shed a good deal of weight from the vehicle, as well as open up exhaust flow which is caused by the restrictive nature of oem secondary cats. Again, this equates into a very little actual hp gain . It's probably the drop in BMC filter that gives things a slight bump . LOL !

Is BMC really that good? I hear lots of good things about it. Much better than a K&N filter, right?

I've had good results with one . However, nowadays I have the EVO high flow air intake on my vehicle . It's all about the sound ! :)

^^^Note: Johnny is clearly stating that he is using the EVO intake purely for sound enhancement and not a performance enhancement for the car. One should always take the manufacturer's numbers with a grain of salt until you see it for yourself. ;)

I would say, just my personal and not nearly expert opinion, that the most effective modifications are also some of the most expensive, and aren't going to net a ton of power. Jake Raby has developed some great improvements that both bulletproof the engine and increase its performance, but you're looking at a really high cost for it, at which point you're going to want to keep that car and get your money's worth. From what I see and read, Jake's done some incredible things, and for them you'll pay an equivalent price.

If you're not that attached to the car then for the same potential $20,000 you could be spending, you might as well combine that with a trade of your Boxster and knock out 1/2-2/3 of the cost on a new Corvette Grand Sport. It's no Porsche, but it's also not going to take much to pull an easy 50 more horses out of the thing when it already has more than double the Boxster's grunt. That was just for the sake of example.

What I didn't mention in my first post in this thread is where that plumbing change idea came from. Pedro's garage, where Pedro has come up with some great and pretty cost effective mods for the car, is another good place to look. Again, you're not going to get gobs of horsepower, maybe you'll get 20, but you'll get as much out of those horses that you do have as you possibly can when you start chipping away at Porsche's compromises. Have a look if you haven't already.
www.pedrosgarage.com
be forewarned, this site can really tax your computer's resources, so don't have too many things running at the same time when you go to it.

All too true re taking the carpets out. Just makes the car sound rough as hell, doesn't it?

I drove round in the stripped out track-prepped BMW for three years. No spares, no gunk, just winged it.

Actually, I've never had a flat...

Haha well then take the weight from some where else :P Also, fix-a-flat is supposed to work if you also carry a bike pump and tire pressure gauge with you. The tire will still be flat after you fix the hole unless you reinflate it... But in reality, just get insurance that provides "free" towing. Tow it back to your house, take the tire to be fixed in another vehicle, call it good.

Flats are so rare, that i don't think the 20lb spare tire is worth it..... I've never had one, just avoid pot holes....

But the carrera 5 spoke wheels weigh A LOT less than the turbo twists that come with most boxsters...

The oversight here is when one is travelling and isn't anywhere near home, which we have a few members on here who do, and is usually when life decides it's time for you to experience a flat tire. Jäger just recently went on a road trip over the summer that he shared with us on here, and he experienced a rear flat on the craptastic highways of OK not even halfway through his round-trip journey. And he had that car packed to the gills, but he didn't leave home without that spare.

One of those reasons why I don't beat myself up too much about not going with a 987...I still have a spare.

If you're traveling why do you need weight reduction? Are we not talking about spirited driving/racing here? I mean why else would you need extra hp? For cruising down the highway? Its not like it takes 5 hours to put your spare tire in... Just put it back in when you're going to travel, if you're around town, take it out....

Stop being so irrational.... Or don't take my advice, and turbo/supercharge your car and wait for it to blow up...

Where does a flat rear wheel go if you take it off?

Guess it is the GF or wheel??

Just lean it back in the frunk. It fits fine. I always carry a full sized spare there on track days.

First, chill. Second, I'm not the one asking about turbo and supercharging my car, so ease up there, too. I was not saying you're wrong, I said there was an oversight in what you said. I may not work in an auto shop, but that doesn't mean you know everything there is to know already, either, so don't take everything said in response to you as a personal shot.

I was referring to this more than anything else from your previous statemt:

You don't think the 20lb spare is worth it, you've never had one, and your advice is just to avoid potholes? So unless I'm reading your statement wrong, you're saying you don't believe in having a spare because you can avoid all dangers to your tires, and you get the performance advantage of 20lb less in the car. And I'm being irrational? A flat tire can happen anywhere and for many reasons, and I'm sure you've seen them all, from running over nails or glass, to potholes, to who knows what the heck you ran over that sliced your tire apart. I've seen a golf ball-sized rock somehow embed itself in the sidewall of a co-worker's tire and break the bead, so when he came out of work he found his vehicle sitting on a rear flat with a rock jutting out of his tire. He has a 65 mile commute...make sense to have a spare then?

I've picked up nails several times, thankfully none with the Porsche, yet. Yes, it's a very infrequent occurence considering how long I've been driving, so I won't disagree with you there. All the nails my tires have picked up have been local, within 10 miles of home, and even in my own driveway. It just happens, and it sucks every time because there's a chance it compromised the tire. I've just been lucky that only 2 required a patching of the tire. And if my tire did go flat, I'd much rather take less time jacking my car up and throwing on a spare to get home on my own power than wait around for AAA or some other "free" roadside service. To me that's just invonvenient when I have it right there in front of me to DIY.

For tracking and any other racing, you are 100% correct, and I'm not disputing that every pound lost will count there. But you didn't stop there. You also said toss the spare out when you're around town. How much of an advantage is your local spirited driving experience really going to see without the spare tire in front? As you said, we're talking around town, right? How usable is that 20lb weight loss even in Sunday traffic? It might net you a thousandth or two of a second less approaching that next red light/stop sign...aka negligible. But sure, in the name of spirited driving, which just can't be had with an extra 20 lbs sitting up front, let's just say your statement's completely rational. :rolleyes: I know that if I ever get a flat a mile from home I'll be glad I have my spare and jack ready to go.

Maybe you've got better roads where you live, but around here the roads are complete crap and only get worse as the winter comes and goes...you'd think someone mortared the streets sometimes (though we've got nothing on Boston, MA). I don't feel I need to be on a road trip to need my spare, because you never know what can happen on public roads.

If anyone has thought of getting the Autothority Turbo Kit for the Boxster, I already called and asked for pricing.

8psi on stock internals(not good for our high compression engines) and promise of 380HP after they are done with it.

$30,000 for the kit. That can't be justified. Turbo Kits on normal cars cost $1000-5000.

Ah, you must have spoken with Minh . The kit is offered through TTP in Germany . The proprietor's name is Pietz, and he's the penultimate sh**t head next to Fabian Roock.
LOL !! Stay away ! It will be 380 hp alright - just in time for the 4th of July !