345 HP power kit

Can you all tell me what exactly the 345 HP power kit entails? Is it worth it? Will the car be less reliable with it? Many thanks.

it includes modified cylinder heads, camshafts, exhaust manifolds, control unit and aluminum intake manifold. costs about $13k as an option, someone else might know if it's retrofit able to existing cars. my guess would be no. reliability? if it were my car with my recent luck, not very

The power kit is OEM, Porsche designed, not aftermarket tuning. Based on that, reliability should be on par with any Porsche 996. It is available as an aftermarket item, check out Carnewal. Is it worth it? The people that have it say so. HP is increased by 25 horses. BUT, there is some loss at the low to midrange. Torque, which determines the true "power" as in how much is translated to the wheels for acceleration, is the same.

Porsche claims the 40th aniversary 996--which has the x51 as standard--goes 0-100 mph in a second less than the 320 hp car.

Don't believe it--torque is unchanged, and that's what mostly affects 0-60 mph times--unless they changed weight or gearing, which I don't believe they did.

i'm going with the "X430" (hehe) kit from evo ( www.evoms.com ) instead. for less than the factory 25 hp, you get 100 to 130 hp (and it's all available much earlier in the torque curve than the X51 OEM upgrade)!

How do you know EVO's claims are accurate? I hear they are one of the more reputable, but many of these companies have been know to lie or mislead their gains.

It's worth every dime ! I have an '03 X-51 and it will dust a '02/'03 911 coupe -I've done it. I've driven 2 '03 coupes and an '03 cab and there is no comparison. I drove an '03 GT3 yesterday(200 mi.) at the local dealership(Aristocrat Motors -ask for Arnie), and I'm sorry to say that although it is a fantastic car and I'd like to own one, it wasn't much faster than my X-51. As a track car it's obviously a better choice but those of you on the fence about the X-51 should buy it if you can afford it. I love the debate about low end torque -based on that silly chart on Porsche's website.I endlessly agonized about wether to spend 13k on this ,I took a chance and won. My observation/opinion: Porsche sandbags it's performance #'s. I don't believe that it is 345 H.P. -I think that it's more. There is NO perceptible loss of low end torque and mine feels noticably torquier (is that a word?) than a stock 911. I have 3500 mi. on mine and no reliability problems. Would I retrofit an X-51 kit ? No. My car cost me 91k -was it worth it? To me it was.It may not be to you. If you are worried about fast, buy an '01 turbo (I did't because I wanted a new car the way I wanted it). Bottom line: X-51 is faster in every way than a stock '02/'03 N.A.. -blustem

do you think the factory is stupid? the went to 3.6 L for teh 320 HP but Evo needs just a airfilter or cold intake? also for another 25 HP they spend $12000 other claims just a a filter and an exhaust? Also I get sick when i see all these HP loss of 17% oir waht ever. why is not possible to buy a really expensive dyno to check the TRUE engine HP as the factory all other factorys and Good Tuners do. Many Tuners were disapointed after tehy mesured teh HP at the Manthey dyno (same as in the factory) You can always claim a couple %more or less on the wheels but a good dyno leaves no space for guesses. It tells you exactly what you have on the engine! claims for 24 HP with just a cold intake or bolt on stage 5 kits with 700 Hp are S....t (smart?) I bet these guys do not even kinow how much work is neccecary to make a reliable 700 HP 996TT. It takes more money than the whole car is worth have you ever checked this site? http://www.autobild.de/aktuell/neuhe...f2e7aa9d425e7c some 700 HP tuners would be surprised when they see that their 700 HP monster has only 550 HP! Konstantin

this is true! I would say this is the "poor mans GT3" You don't have to spend over $60000 for a GT3 engine since the 345 HP engine delivers "similar performance". Of course this is for street driving. At the track neither the car nor the engine from the 996 can be compared to the GT3. the GT3 is one of the best engines Porsche ever build and can make up to 480 Hp if you fine tune it. no way you can ever make 480 Hp out of a 996 engine. Konstantin

do you think the factory is stupid? the went to 3.6 L for teh 320 HP but Evo needs just a airfilter or cold intake? if porsche is stupid u won't drive one. if u do, someone is stupid. i think porsche limit the power for a reason. if a airfilter or cold intake would do such difference, porsche will do it. i just don't turst aftermarket engine mod. my view is if u have the $, always go with OEM stuff. btw, X51 does lose mid range torque.

I think the reason the 40th anniversary model accelerates faster is it has LSD, so it can get the power down better.

There is an answer to this question, it's not black magic, we are not trying to predict the weather next year. We can get this over and done with once and for all... Lets start a pool and anybody who wants to know can put some $$$ into finding the answer. We'll find people on this board who have: 2003 Carrera 2003 Carrera with X51 Power Kit 2003 Carrera with EVO cold air intake 2003 GT3 Arrange to meet somewhere with a 'Manthey dyno' and we can dyno all these cars on the same day, same air temp, same humidity, same fuel. I would be willing to throw $100 into the pool.

exactly my thoughts. the X51 has less low torque on the paper but not in the real world performance. The test data from 0 to 125 mph that can be found in every good German magazin comapared both cars and the difference is there. someone said it feels more like 40 HP and not only 25 more! Konstantin

There is NO WAY an x51 996 can even compare to a GT3 - street, track, or value. No shot... Goto the Porsche website and build a 996 for yourself. Add x51 option, sport seats, etc, and see how much it costs you. I did it with a C4S before I bought my GT3, just to see where I was at. The car came out to $114K with all the comparable options my GT3 had - thats $7K more than my GT3 cost, still has 35HP less and not as good of a base powerplant - still does not have lightened wheels, does not have 6 Piston calipers up front, does not have the race suspension... Should I continue?? Even if you paid $91K for your 996 x51, start adding up the other items you have forgotten about. You will be very close to the cost of the GT3 and still not even in the same league. Please do not make that comparison again - that is just foolish..

GT3 is here for a reason...

the Gt3 is a race car for teh street the 996 powerkit is a steet car that can be taken to the track. Big difference and yes If you compare both and you want the same power and good track times the GT3 is MUCH cheaper. exactly the oposite is with the 996TT and the GT2. the 996TT can be much faster for less money than you spend for a GT2 Konstantin

ADOGNY Please do not make that comparison again - that is just foolish..

"How do you know EVO's claims are accurate?" dyno "the went to 3.6 L for teh 320 HP but Evo needs just a airfilter or cold intake? also for another 25 HP they spend $12000 other claims just a a filter and an exhaust?" evo also uses tuning of the ecu. pre and post dynos are were run. just how much more can a tuner do to provide proof than a pre and post dyno? there will always be naysayers who have preconceived notions that they're unable to change. "Also I get sick when i see all these HP loss of 17% oir waht ever. why is not possible to buy a really expensive dyno to check the TRUE engine HP as the factory all other factorys and Good Tuners do." the 17% hp and 15% lb loss IS from a dyno. there was a baseline 996 used which showed 17% less rwhp and 15% less rwlb than advertised by porsche the crank. "The test data from 0 to 125 mph that can be found in every good German magazin comapared both cars and the difference is there. someone said it feels more like 40 HP and not only 25 more!" porsche's own published dyno at the crank show it to indeed be only 25 more. "There is NO WAY an x51 996 can even compare to a GT3 - street, track, or value. No shot... " yep, it's a joke for anyone to compare an X51 996 to a gt3 on a performance basis.

I knew a 996 owner would take offense to what I said... However, that was not an opinion - it is a fact. Drive both and you will see what I mean. I am far from an expert, but the difference can be seen and felt immediately, even by a novice like myself.

I couldn't get a GT3 since I got my car a year ago so the X51 was my only choice. With alot of track time in it, I have to say it is FAST. It is probably closer to 360 hp that 345 hp. There is no loss of mid range torque and it revs much freer. I have driven it back to back with a std 3.6l and it is like going from a Honda to a Porsche. As for EVOs claims, maybe they can get peak HP up but it will give up alot somewhere else. Ask ANYONE who has driven an X51 and you will get the same response... WOW.

That actually makes a lot of sense. The powerkit gives you the 25 HP more or less across the enitre rpm range where as the cold air intake only gives you a power increase at a certain RPM which only spikes for a moment so you probably don't feel it. A moment of Zen...

"where as the cold air intake only gives you a power increase at a certain RPM which only spikes for a moment so you probably don't feel it. " where'd you see that? i'm guessing not from the actual dyno results at evoms.com (incidentally it's more than 25 hp cause as you can see the drivetrain loss is about 17% on the hp and 15% from porsche's advertised at the engine numbers):

There are fundamental problems with testing this way. If you run dyno's on the same motor on different days, you can come up with different resutls, sometimes even alot. You need a second control car to do a better comparison. Also keep in mind that the X51 does not have a cold air intake and in theory you would gain even more HP on the X51 car than the std car with this change as the restriction has more of an effect at a higher flow rate. BTW, what does the EVO kit require fuel wise? I have seen a few ECU upgrades that will not run on anything shy of 94 octane, where as Porsche, even with the X51 will run peak at 92/93

"If you run dyno's on the same motor on different days, you can come up with different resutls, sometimes even alot." a 4 day diff in the summer in arizona is not going to result in meaningful diffs. note too that both runs were within almost a 1/2 hour of being the same time of day. "Also keep in mind that the X51 does not have a cold air intake and in theory you would gain even more HP on the X51 car than the std car with this change as the restriction has more of an effect at a higher flow rate." of course, but what's your point? i think this thread revolves around Evo's $1590 solution relative to porsche's $13k + tax one. for that much cash, Evo will set your 996 up with power = to the 996TT. "BTW, what does the EVO kit require fuel wise? I have seen a few ECU upgrades that will not run on anything shy of 94 octane, where as Porsche, even with the X51 will run peak at 92/93" 91

Sounds great, how is that cold fusion project of yours coming? Dyno the same motor a few times and you will come up with different results, been there done that already. Even differences in the fuel can add or remove a few horsepower quite easily. The bottom line is I do not believe you can get 25 hp from the motor running on 91 octane with an intake and chip change and definielty not on the 3.6l motor, which is much more tuned to start with. And this thread is about the X51 powerkit, not your EVO kit.

"Dyno the same motor a few times and you will come up with different results, been there done that already. Even differences in the fuel can add or remove a few horsepower quite easily. " so i guess we can't believe ANY dynos - including porsche's on the X51. what an expensive investment if it's merely worthless. "The bottom line is I do not believe you can get 25 hp from the motor running on 91 octane with an intake and chip change..." yeah, no matter what the power measurement device says :-) funny everyone yaps about testing claims but whenever the claims ARE tested, the results are deemed bs. how can a reliable tuner with integrity ever win with such an argument? "...and definielty not on the 3.6l motor, which is much more tuned to start with. " it has a larger displacement and some vario cam diffs. i'm sure you can get the same if not MORE out of modifications to the 3.6. don't know about evoms.com supercharger as relates the 3.6 but TPC's was producing incremental results on the 3.4, 3.6, and 3.6 X51. "And this thread is about the X51 powerkit, not your EVO kit." it's not "my" kit, but you're right. i went back and looked and indeed it was me that started the evo discussion within the thread. sorry.

Porsche is dynoing hundreds of engines on engine dyno's, not one on a chassis dyno. There is alot more to improving performace that bigger motor will get more gains. There are ALOT of changes to the 3.6l and that is a big part of why it makes so much more hp and tq even in a base configuration. I know you are proud of your kit, but do some more research and you may find some of what I am saying has merit. I have built numerous race motors from 1.5l to 8.8l and have achieved over 130hp per liter in some of them without forced induction. Do some more reading.

I often read that the x51 kit has a greater BHP than it's stated 345. Has anybody / any magazine accurately tested it to see exactly what the bhp is cos those who have it say it's greater than 345 and GT3 owners/fan's say it's no where near there babys BHP. Can Porsche not shed some light on the subject as they designed it. Donny J

Ed, You're right on. Every internet car board in the world has people making outrageous claims for their cars, but it's often the same story-- cold air intake and chip--BOOM, 25 extra hp! When some people started having doubts, the makers of these kits starting posting dynos. But it's FAR more complicated than that to prove their claims. And when INDEPENDENT dynos are done, using proper methodology, you can flip a coin as to whether there is any performance improvement at all. Disclaimer: Aftermarket tuning of turbos is a different story. It's very possible to obtain significant increases in power with a re-map of the ECU at the expense of reliability/engine life.

to make it short I will reply for the last time. you can trust ONLY a very accurate expensive dyno or an engine dyno. Both gives you rear HP on the engine without gessing for % of RWHP loss! you can not trust the cheaper tuners dyno! as somebody else said do the samme test in different days and you will get different results. (unless you have a really high tech dyno.) Porsches dyno are with 2-3 hp on the same car, it doesn't matter how often you check it. Dyno is not same dyno and you can not compare the Porsche dyno with the kind of dynos that most US shops use. I saw at least 5 different dynos on the same car with at least 60 HP difference.(on 996TT) In Geramny ALL teams who use the same dyno get the same HP for the same car (+ or - 2-3 hp) Only this is accurate Last but not least there are many road tests with accelaration data on both cars the x51 and the stock 996. It is a big difference there. The x51 is in real world much faster The GT3 is even faster and hit easilyover 300 km/h top speed. the 996 with the X51 can NEVER do that all in all the x51 is a very good solution for someone who want a faster 996 with factory reliability. The GT3 is for the guys who want to be fast on the track! The engine came from the GT1. it is not an updated 996 engine. (like the X51) Konstantin PS yes many German magzines has real world data for the 996 the x51 and the Gt3. I would get the X51 for every day or the GT3 for the track. As we say in geramny the 996 is for Mercedes drivers who want a porsche. the X51 is for sporty Porsche drivers.(more street seldom on the track) The GT3 is for Porsche racers (more track soldom on the street just on the way to the race track) And if you want a fully race car buy the GT3 Cup car.

I always take chassis dyno numbers with a grain of salt. Generally useful for relative comparisions only. If you really want a real hp number, use an engine dyno. Any good racing engine shop should have one. Konstantin, what do you hear in Germany about a flat 8 in the 997??TIA

I think my GT3 is just fine for the street.. Drove it to the Hamptons and back today and rode quite nicely.

If only they had the Gt3 last year.... actually if I had to say I have a regret it is not doing what I wanted, but didn;t think I could afford which would have been a cup car and a boxter. I went for a hybrid instead and a year later, the hybrid became track only and I got a boxster. Oh well.

One of the big benefits from the X51 was that until recently, it was the fastest Porsche cab. The turbo cab has changed that though.

ED - Where in LI are you? Going to the Poconos tomorrow?

I'm in Islip. I'll be at the Metro PCA Pocono in October. I'm also doing the Potomic region club race at Summit netx weekend

When I said the GT3 wasn't that much faster,that's all I meant. My opinion/observation of GT3: better car than my X-51 in all ways,period.Better clutch,awesome shifter,FASTER,killer suspension,redline was 8000 rpm's.It was lighter,nothing in the trunk,no sunroof,no back seats,lightweight wheels -the car is awesome!BUT, driving it on the highway I was dismayed to find that it wasn't that much faster -it was noticably faster but not that much -very suprising to me but also a testament to the X-51.My response was not meant to be a comparison of the two cars. I was merely trying to communicate to the gentleman MY experience with X-51 and my test drive of GT3.Spending 13k on this is a tough decision and when I had to do it I had almost no input or info save Ed's extremely helpful observations regarding his own experience.It is still much cheaper to go with X-51, 21k cheaper if you compare my X-51 to the GT3 I drove.What the test drive did for me was to totally reinforce my decision to do X-51.