GT3 6.2 on Rolling Road, - Page 4 - 911/Carrera GT - PistonHeads UK

Putting 100 cel Cup cats on so pre RR power run to see what's what.

Very weird power curve IMO 370 BHP. Maybe needs a remap.

Not the best picture to gauge much from?

ttdan said: Not the best picture to gauge much from? Not best, but the curve is very bouncy

This one is better

Slightly surprised with power output. Thought standard was 385, and Porsche, were being slightly conservative. 37k on the clock. Never been a tracked car

Pretty sure standard is 381.

Sorry 381.

Two 996 GT3's both at about 385hp on a RR day I attended last Summer. TX.

Terminator X said: Two 996 GT3's both at about 385hp on a RR day I attended last Summer. TX. Can you remember from memory the curve? Did it look similar to mine?

Was a thread on here at the time to drum up attendance, may be some graphs on there? I'll try to find it a bit later. TX.

96.2 was quoted at 381 PS not hp, thats about 375bhp they all make at least that as the engines were all individually dyno'ed during manufacture and rejected if they didn't make it. RSs have the same quoted output but are even more likely to exceed that

Hi, the dip in middle is the resonance flap changing the inlet manifold characteristic... Is it completely stock as far as exhaust and air intake ?

sportsandclassic said: Hi, the dip in middle is the resonance flap changing the inlet manifold characteristic... Is it completely stock as far as exhaust and air intake ? Has a Cone K&N, standard exhaust I think, but the resonance flap , has changed to stay open at all times

rallyeman said: Has a Cone K&N, standard exhaust I think, but the resonance flap , has changed to stay open at all times Why... This is vital to the engines torque and power characteristics... .?

sportsandclassic said: rallyeman said: Has a Cone K&N, standard exhaust I think, but the resonance flap , has changed to stay open at all times Why... This is vital to the engines torque and power characteristics... .? I might be wrong, but I'm sure it was changed by previous owner for a better sound, does this sound right?

Not sure, get the air filter taken off and put back to stock and get someone to check the resonance flap valve is working correctly. The slightest modification to cats / intake or exhaust can have effects on the power and torque curve.

sportsandclassic said: Not sure, get the air filter taken off and put back to stock and get someone to check the resonance flap valve is working correctly. The slightest modification to cats / intake or exhaust can have effects on the power and torque curve. Does this sound right then? That the resonance flaps, have been permantly opened for better exhaust sound, all the time?

rallyeman said: sportsandclassic said: Not sure, get the air filter taken off and put back to stock and get someone to check the resonance flap valve is working correctly. The slightest modification to cats / intake or exhaust can have effects on the power and torque curve. Does this sound right then? That the resonance flaps, have been permantly opened for better exhaust sound, all the time? Has it got some sports exhaust with bypass flaps built in ?

The pink/purple line is with my DB killers on the end of my exhaust. The blue line is without! Drops quite a lot in midrange. Car is running full car graphic system and IPD with 997GT3 throttle body. Standard map. The green line is an overlay of a modified RS car. Edited by sportsandclassic on Friday 3rd January 20:38

sportsandclassic said: rallyeman said: sportsandclassic said: Not sure, get the air filter taken off and put back to stock and get someone to check the resonance flap valve is working correctly. The slightest modification to cats / intake or exhaust can have effects on the power and torque curve. Does this sound right then? That the resonance flaps, have been permantly opened for better exhaust sound, all the time? Has it got some sports exhaust with bypass flaps built in ? Yes, I remember the previous owner saying they were sports boxes. 105db at Bedford. Edited by rallyeman on Friday 3rd January 20:49

Ok, so the intake is different and the exhaust and you are making less than standard power.... Put some proper stuff on the car or put it back to standard. Are you ever going to do track days...? If not get a car graphic system and fit standard air filter.

Thanks for all your help. So I should dump the filter?

Was going to have these 100cel Cup cats fitted, when we blank off some of the race plugs. Yes to trackdays, in Europe.

rallyeman said: Thanks for all your help. So I should dump the filter? Yes, and I'd think about fitting a new MAF to be on the safe side while you're at it.

[Image-only or quote-only post; no author-written text.] http://thumbsnap.com/sc/19VLj5Ik.jpg

Throw that in the bin and try another power run out of interest.

sportsandclassic said: Throw that in the bin and try another power run out of interest. ^^^ Ditto, bin that. Here's my print out from RR day, running M&M rally style 200CEL X-CAT with stock muffler combo - stock air filter: No before for baseline. I've just been to DMS in Southampton for remap and now at 417, Rob is hopefully sending print out tomorrow but having MAF issues at the moment causing stalling.

s_mcneil said: sportsandclassic said: Throw that in the bin and try another power run out of interest. ^^^ Ditto, bin that. Here's my print out from RR day, running M&M rally style 200CEL X-CAT with stock muffler combo - stock air filter: No before for baseline. I've just been to DMS in Southampton for remap and now at 417, Rob is hopefully sending print out tomorrow but having MAF issues at the moment causing stalling. Wow, that's impressive graph. What's this M&M rally style 200 cel x cat?

rallyeman said: Wow, that's impressive graph. What's this M&M rally style 200 cel x cat? Hi Neil, read this http://911uk.com/viewtopic.php?t=74295&postday... A long and painful process... And my mistake, the graph above is for system with 'afterhours' muffler combo, see page 2 of link.

s_mcneil said: rallyeman said: Wow, that's impressive graph. What's this M&M rally style 200 cel x cat? Hi Neil, read this http://911uk.com/viewtopic.php?t=74295&postday... A long and painful process... And my mistake, the graph above is for system with 'afterhours' muffler combo, see page 2 of link. Hi Stuart, just realised who you are lol

417 Bhp is even a bigger pub bragging rights figure. But forget about Bhp, surely people can see below 6.1k the engine not a nice place to be. And on the road keeping it above 6.1k is ni on impossible. Drop it below and your torque dropping off like a stone about 5k and no more Bhp is on tap. But hay oh cannot say a bad thing on that car/engine. Still the perfect road car in fanboy land. Edited by mrdemon on Saturday 4th January 00:06

Really not bothered about figures, I'm more concerned about the odd, curve.

mrdemon said: 417 Bhp is even a bigger pub bragging rights figure. But forget about Bhp, surely people can see below 6.1k the engine not a nice place to be. And on the road keeping it above 6.1k is ni on impossible. Drop it below and your torque dropping off like a stone about 5k and no more Bhp is on tap. But hay oh cannot say a bad thing on that car/engine. Still the perfect road car in fanboy land. Edited by mrdemon on Saturday 4th January 00:06 http://en.wikipedia.org/wiki/Dunning–Kruger_effect The Dunning–Kruger effect is a cognitive bias in which unskilled individuals suffer from illusory superiority, mistakenly rating their ability much higher than is accurate. This bias is attributed to a metacognitive inability of the unskilled to recognize their ineptitude. Theres a whole other section on here where you can regale the assembled masses with your insights. Some might even believe them. Edited by fioran0 on Saturday 4th January 02:12

Since its not been mentioned (amazingly), the dyno folks have the dyno setup for a forced induction engine during your runs. I presume you arent smuggling a supercharger in there? Also take a look at the difference between your intake temp and ambient temp. Two comments to make there. If that is your actual intake air temp, get that intake set up thrown into the bin. Having a big difference here is also a nice way to get a higher dyno number (assuming its not an accurate reading of the intake temp). Stick the probe somewhere where it will measure hotter air than the engine is physically seeing and the system "corrects" and gives you a handy power bump. as for the rest of the thread, are y'all for real? I really dont want to single anyone out, this whole thread is wandering through fantasy land. However I feel I need to post some sort of comment to lend some credibility to that statement. The link posted above shows a figure of 326.9HP at the rear wheels for the run that provided the 391.8HP calculated engine figure graph plot. Thats almost a 20% transmission loss factor being used (19.855% if we want to be detailed) to get that 392HP figure. That engine wont be making even 360hp at the crank given that wheel figure. Edited by fioran0 on Saturday 4th January 03:45

Just to put this in context, we know dyno hp figures are not gospel, the purpose of posting was to show curve and delta, not peak. I don't care about the overall, it's about the drivability and tying in the mods. If I, or Neil most probably, wanted bhp bragging rights we'd have probably bought turbos.

fioran0 said: http://en.wikipedia.org/wiki/Dunning–Kruger_... The Dunning–Kruger effect is a cognitive bias in which unskilled individuals suffer from illusory superiority, mistakenly rating their ability much higher than is accurate. This bias is attributed to a metacognitive inability of the unskilled to recognize their ineptitude. Theres a whole other section on here where you can regale the assembled masses with your insights. Some might even believe them. I take it that's a self diagnose ? keep on topic and stop the personal attacks, or don't respond to my posts if you cannot keep it civil. I see you deleted your 1st post which was a slagging post to the others here :-) (it's ok I won't quote it so you can save face) if you like to diagnose here is one just for you which fits the bill well, and fits in with your slagging and deleting of posts as seen over and over even in this thread. Bipolar disorder "also known as bipolar affective disorder, manic-depressive disorder, or manic depression, is a mental illness classified by psychiatry as a mood disorder. Individuals with bipolar disorder experience episodes of an elevated or agitated mood known as mania alternating with episodes of depression." Edited by mrdemon on Saturday 4th January 09:54

Mr Demon STOP! Stop demonising anyone who likes the GT3, it is what it is and some people like it, others don't, just accept that. You sound like those people who say the Cayman is not a 'proper' Porsche and we all know how stupid that sounds so just give it a rest please. Just because someone posts a thread on a GT3, it does not automatically give you the right to slag GT3s off with your opinion. I have half a mind to go out, buy a Cayman R, run it for two months and then take any and every opportunity to say what I didn't like about it on every Cayman based thread on PH. Can you see how annoying that would be? In fact, I might just go out for a 20 minute test drive in one just so that I can.

Here is my printout from a couple of months back. I have no idea what it means or if its good or bad, it was just a bit of fun to go to a shootout The car has a Hayward and Scott bypass, sounded amazing in the enclosed room!

V8KSN said: Mr Demon STOP! Stop demonising anyone who likes the GT3, it is what it is and some people like it, others don't, just accept that. You sound like those people who say the Cayman is not a 'proper' Porsche and we all know how stupid that sounds so just give it a rest please. Just because someone posts a thread on a GT3, it does not automatically give you the right to slag GT3s off with your opinion. I have half a mind to go out, buy a Cayman R, run it for two months and then take any and every opportunity to say what I didn't like about it on every Cayman based thread on PH. Can you see how annoying that would be? In fact, I might just go out for a 20 minute test drive in one just so that I can. AS you know I'll help any one. he was slagging off people here and dyno's and then must have thought better of it and deleted his 1st post. I have said many times the GT3 can be the perfect car , I am fair but do post on FACTs and ownership. I don't get upset if people slate the R, the press did it, Chris harris did it, many here say it's no GT3, I am happy with that. It not a race car, it has no pedigree, it's 100bhp down on a GT3, it has no sus ajustments etc etc, it's not a 911 (what ever that means) SO NO it would not be annoying those are the facts of the car, I know that lol slag away. I have owned 50+ cars and know good and bad points with all of them. I can post dyno plots coming out your ears regarding what happens to the map if you drop below 6k revs with a GT3, your torque drops and your BHP is going no where. take that baby off the boil and you are dumped in no mans land. these is NOT my opinion they are facts of the map !!! I said why I sold mine because of not being able to keep it over 6k 100% of the time even when trying hard. but people swear black is white here and disagree, so I'll post a few GT3 dyno's :-) I'll point out the bad bits on my cars and do while owning them, I just don't like the high status the GT3 has and owners will fight till the death to protect the image.

mrdemon said: I'll point out the bad bits on my cars and do while owning them, I just don't like the high status the GT3 has and owners will fight till the death to protect the image . Thank you but the thing that stuck out of your post for me was this line. Why not? Surely you can accept that some people love their car more than any other car they have ever driven or owned and as a result, they elevate the GT3 to a higher status. I absolutely love my 997.1 GT3 and I don't think I will ever sell it. Improve it, change it, tweak it etc of course but sell it? No!

I was enjoying this thread and lookng forward to learning a little more about GT3 engines. But, in a split second or two, some anti GT3 paratrooper sees an opportunity to drop in with their hobnail boots and starts a row for no other reason than to make sure we don't all get too much enjoyment from our cars because they didn't.

V8KSN said: Mr Demon STOP! Stop demonising anyone who likes the GT3, it is what it is and some people like it, others don't, just accept that. You sound like those people who say the Cayman is not a 'proper' Porsche and we all know how stupid that sounds so just give it a rest please. Just because someone posts a thread on a GT3, it does not automatically give you the right to slag GT3s off with your opinion. I have half a mind to go out, buy a Cayman R, run it for two months and then take any and every opportunity to say what I didn't like about it on every Cayman based thread on PH. Can you see how annoying that would be? In fact, I might just go out for a 20 minute test drive in one just so that I can. I see what you did there. Like it. Totally agree though and I did start writing a reply last night but thought "don't waste a second on the troll". Sod it though I will - mrdemon said: 417 Bhp is even a bigger pub bragging rights figure. But forget about Bhp, surely people can see below 6.1k the engine not a nice place to be. And on the road keeping it above 6.1k is ni on impossible. Drop it below and your torque dropping off like a stone about 5k and no more Bhp is on tap. But hay oh cannot say a bad thing on that car/engine. Still the perfect road car in fanboy land. So it's the GT3 engine that is the problem now!? It was the gear ratios last month. How different do you think your CR or Spyder are to a GT3 below 6K rpm? From the ones I've driven the differences are this - Spyder has similar low down engine feel to a '6 GT3 but with a more muted engine note when revving, even with PSE (apart from at tick over or low engine speed, where it's obviously louder), so what. It's more like a Carrera than a GT3 in noise characteristics, which makes sense, as this is what the engine is nearer, rather than the Mezger. The Spyder feels almost as quick, on the road at least, but without the top end pull of the '3 and without the neck-hair stand-up scream after 5k revs. The Spyder felt more supple, read "softer" but less pointy because of it. Does that make it better? Obviously to you, but not to me. It just felt like I could use it as a daily, which isn't what I want from a weekend toy. I want special. Also the wind-noise is laughable. Even at 50mph. I turned to my mate, the owner and said is that normal? He said "Yeah its just what the car is about. I always have the roof down." Great, I thought. So to me the Spyder felt like a watered down, softer, (wind) noisier GT3 missing the shrill top end scream and feeling more "normal". It didn't in the slightest make me think "I NEED one of these", which is exactly what my first drive in a GT3 made me feel like, all those years ago. Stop trolling Mr Demon. It's like you're magnetically drawn to GT3 threads as you can't bear anyone enjoying the cars because you say you didn't. Equally the Spyder/CR don't offer the be all and end all to everyone else, as they seem to for you. The Spyder is a great car but at the end of the day it's a Boxster with some nice suspension settings and a silly roof. To now start on the GT3's engine is just pure fantasy land stuff. Do us a favour and stick to your Spyder threads. Apologies for the off topic-ness to everyone else. <Note to self. Must ignore Demon. Must ignore Demon. Must ignore Demon.>

rallyeman said: Can you remember from memory the curve? Did it look similar to mine? If you have a look at Cargraphic.com and search engine tuning there are some before graphs taken from engine dyno for your engine, IIRC they do go up and down a bit like what you have here, the GT3 is not a smooth torque curve, it follows the cams and breathing of the engine set up. Edited by TB993tt on Saturday 4th January 11:54

Incase the OP ever returns and misses the post a page back.... Your dyno run was conducted in a mode set up for forced induction. I presume you havent added forced induction to your GT3? Your intake temp was way higher than ambient air temp. IF this is an accurate intake temp, throw that intake setup into the bin. High intake temps are a nice way to gain a power bump on a dyno graph too though so be aware of this. Stick the probe somewhere that it will see air hotter than intake air (which should be around ambient) and the dyno corrects and gives you more power. Along with all the other reasons that a dyno may give you whatever it gives, you have these two things going on. Edited by fioran0 on Saturday 4th January 12:55

fioran0 said: as for the rest of the thread, are y'all for real? I really dont want to single anyone out, this whole thread is wandering through fantasy land. However I feel I need to post some sort of comment to lend some credibility to that statement. The link posted above shows a figure of 326.9HP at the rear wheels for the run that provided the 391.8HP calculated engine figure graph plot. Thats almost a 20% transmission loss factor being used (19.855% if we want to be detailed) to get that 392HP figure. That engine wont be making even 360hp at the crank given that wheel figure. Edited by fioran0 on Saturday 4th January 03:45 You sound like an expert on Dynoing, you must have many years of experience operating a Dyno to post with such conviction?

MrDemon, What about the post you deleted where you said you were the world kerplunk champion? ok you didnt post that, I was making a joke about clutching at straws but do you see how I could have continued to claim that you had since it was no longer there? While you are endowed with almost unending opinions, having an opinion is not the same as knowing something. The distinction may be difficult for some to understand however its one that is important and one that can be critical in many situations. Perhaps the remoteness of virtual interactions engenders a difficultly in making this distinction for those in the modern age. Gone are many of the additional cues one would pick up on during personal interactions. (Thats now a topic where there are only opinions, feel free to opine away). I assumed you were a sophisticated troll, intent on operating to some sort of unique agenda however it may simply be that you genuinely display strong dunning kruger effect, whereby your lack of understanding prevents you from being aware of your lack of understanding, in addition to your own raft of more common cognitive biases. I am sure others have their own opinion. Dunning kruger is a cognitive bias, we all display cognitive bias in our daily lives as far as I am aware. Here is a list of the common ones, http://en.wikipedia.org/wiki/List_of_cognitive_bia... I am sure we all can spot some of our own. Bipolar disorder is a mental illness which ruins many lives. The irony that you are demonstrably unaware of the difference in these two regards; but that this lack of understanding did not compel you to read or research anything before posting, nor did it prevent you from posting at all is not lost on me. Edited by fioran0 on Saturday 4th January 12:59

[quote=fioran0]Since its not been mentioned (amazingly), the dyno folks have the dyno setup for a forced induction engine during your runs. I presume you arent smuggling a supercharger in there? Also take a look at the difference between your intake temp and ambient temp. Two comments to make there. If that is your actual intake air temp, get that intake set up thrown into the bin. Having a big difference here is also a nice way to get a higher dyno number (assuming its not an accurate reading of the intake temp). Stick the probe somewhere where it will measure hotter air than the engine is physically seeing and the system "corrects" and gives you a handy power bump. You have something there, as to start with, it only reached 350bhp, then they mentioned about the intake temp, moved a probe and ran again and reached 371

As a side note Neil, how are those top mounts working out for you? I need to look at changing the coffin arms on mine this winter!

V8KSN said: As a side note Neil, how are those top mounts working out for you? I need to look at changing the coffin arms on mine this winter! Not used them yet, going to keep them as a just in case back up. The play is minimal at mo.

mrdemon said: I can post dyno plots coming out your ears regarding what happens to the map if you drop below 6k revs with a GT3, your torque drops and your BHP is going no where. take that baby off the boil and you are dumped in no mans land. these is NOT my opinion they are facts of the map !!! Your statement above is not supported by the map; there's plenty of torque below 6k; in fact there's MORE torque at 5k than at 6k and what's more there's over 260ftlb from about 2900rpm onwards....your "no mans land" below 6k rpm is in fact only 30ftlb off the peak even down at 3krpm...so what on earth are you on about... unless...oh, of course, you're just trolling...

As someone with no skin in this game, I looked at those dynos and thought 'good torque below 5 or 6k and a lot thereafter'. I don't see any no mans land. The GT3 is less usable on the road than a Spyder or Cayman R because it is a lot faster. The gear ratios are silly on all Porsches. The torque curves probably aren't hugely different either - they are rev happy!

mrdemon said: AS you know I'll help any one. he was slagging off people here and dyno's and then must have thought better of it and deleted his 1st post. I have said many times the GT3 can be the perfect car , I am fair but do post on FACTs and ownership. I don't get upset if people slate the R, the press did it, Chris harris did it, many here say it's no GT3, I am happy with that. It not a race car, it has no pedigree, it's 100bhp down on a GT3, it has no sus ajustments etc etc, it's not a 911 (what ever that means) SO NO it would not be annoying those are the facts of the car, I know that lol slag away. I have owned 50+ cars and know good and bad points with all of them. I can post dyno plots coming out your ears regarding what happens to the map if you drop below 6k revs with a GT3, your torque drops and your BHP is going no where. take that baby off the boil and you are dumped in no mans land. these is NOT my opinion they are facts of the map !!! I said why I sold mine because of not being able to keep it over 6k 100% of the time even when trying hard. but people swear black is white here and disagree, so I'll post a few GT3 dyno's :-) I'll point out the bad bits on my cars and do while owning them, I just don't like the high status the GT3 has and owners will fight till the death to protect the image. Can't see where the torque "drops like a stone" in OP's trace - or in the one you posted. Looks pretty flat which fits with driving a GT3 - you get the fireworks at the top, but I always found my 996.2 surprisingly torquey too.

Well, it would appear we've all done Mr D a great disservice. Knowing he's a big fan of the Porsche Boxster, we all assumed that when he said he owned a 550, it was one of these fine limited edition models : When in reality he meant he owned one of these : Accordingly it would appear the "lack of torque" comment was well founded on The Demon's part. It transpires there were two cars in the Demon household, Mrs D drove a 381hp Mk2 996 GT3. Mr Demon drove an F10 BMW 550D, which ironically has 381hp too. They both have keyrings which are boldly engraved and enamelled with that horsepower figure. Mr D's is enamelled in blue, Mrs D's in Pink. During a "domestic" (apparently over Mr D spending too much time on THAT bloody forum, in addition to getting the pair of them into "a spot of bother" at Donington last year) Mr D stormed out of the house, picking up what he thought were his BMW 550d keys along with his front door keys. When he came to unlock the door to his BMW, he found he couldn't as he had Mrs D's car and front door keys. Unwilling to lose face (who'd have thought it eh ?) he elected to take Mrs D's car for a thrash whilst the situation back home with 'err indoors diffused itself. He duly headed out to his usual driving roads. Once upon on them, he was shocked to discover several massive shortcomings in the GT3's dynamics. Firstly the Porsche's front end was rather light and flighty, and secondly it was easily deflected by bumps. But the problems didn't end there, oh no. Whereas the automatic gearbox in his 550d 5 series could be left to its own devices and seemed more than capable of finding a ratio suitable for any type of road/conditions encountered, the GT3 required use of a quaint stick like object protruding out of the centre console to maintain any kind of decent momentum. But worse still, left in sixth, the engine had no meaningful low down power or torque whatsoever. Put bluntly, the gear ratios were ill-considered. But to add insult to injury, the frankly hopeless engine in the GT3 was lacking what we all know to be the single most important ingredient to making rapid progress on the road. That being torque. Now I have to concede he does have a point, and a quick look at the torque curve for 550d below will only serve to emphasize the issue he's alluded to. I think you'd all agree, there is no "No mans land" in the 550d's torque curve (all 740nm of it) Suffice to say, Mr D returned home a chastened man, and now never, ever leaves his keys on the sideboard in the hall next to Mrs D's. So to all those doubting Mr D's credibility in these matters, I suggest you re-consider his words. His opinions are after all based on experience and are thus FACT. Perhaps in future you'll show a bit less animosity towards an esteemed fellow PH contributor. P.S I don't want any f*cker on here quoting the above. Gottit ? Edited by Slippydiff on Sunday 5th January 23:00

That is top class

mrdemon said: 417 Bhp is even a bigger pub bragging rights figure. But forget about Bhp, surely people can see below 6.1k the engine not a nice place to be. And on the road keeping it above 6.1k is ni on impossible. Drop it below and your torque dropping off like a stone about 5k and no more Bhp is on tap. But hay oh cannot say a bad thing on that car/engine. Still the perfect road car in fanboy land. Edited by mrdemon on Saturday 4th January 00:06 Demon, you have a very low opinion of other people's intellect. We all know what you are doing here and its all very transparent, punishing others because you owned a car that you couldn't drive very well and then had to sell, losing money in the process. You know you won't convert any GT3 owners or admirers. The cars credentials and brilliance is way too potent and established to be affected by anyones peurile trolling. All you're doing is coercing people into thinking that you're a bit of a plonker when i'm certain you're probably an ok bloke in real life. Give yourself a break heh ?

Very good! Edited by robmug on Sunday 5th January 23:19

I dont get why people dont just ignore MrD'S posts and therefore wont/can't be 'trolled'? He can only troll if people respond and are therefore trolled....

sportsandclassic said: Hi, the dip in middle is the resonance flap changing the inlet manifold characteristic... Is it completely stock as far as exhaust and air intake ? Ok, I've found out the boxes are Porsche Boxes with PSE, but open all the time for better sound. So this shouldn't cause a problem No?

rallyeman said: Ok, I've found out the boxes are Porsche Boxes with PSE, but open all the time for better sound. So this shouldn't cause a problem No? Pretty sure there wasn't an official switchable PSE option for the GT3 ? If that's what you've got, I'm guessing it's something somebody has retro-fitted. Can't remember if the C2/4 pipework is smaller bore than that used on the GT3 system ? Either way, I'd be looking at putting the car back to standard or considering getting some upgraded silencers on it.

Slippydiff said: rallyeman said: Ok, I've found out the boxes are Porsche Boxes with PSE, but open all the time for better sound. So this shouldn't cause a problem No? Pretty sure there wasn't an official switchable PSE option for the GT3 ? If that's what you've got, I'm guessing it's something somebody has retro-fitted. Can't remember if the C2/4 pipework is smaller bore than that used on the GT3 system ? Either way, I'd be looking at putting the car back to standard or considering getting some upgraded silencers on it. It sounds like your car has been messed around with as the system you are describing is probably off a 996 standard version and will have different exhaust system to GT3. Get it put back to standard and start moving forward from there. You should get more power with the standard air filter in place to start with, swap it back and do a run if power still down then swap exhaust back to standard. Is the exhaust switchable by means of a button or are the valves locked open? Mike

sportsandclassic said: Slippydiff said: rallyeman said: Ok, I've found out the boxes are Porsche Boxes with PSE, but open all the time for better sound. So this shouldn't cause a problem No? Pretty sure there wasn't an official switchable PSE option for the GT3 ? If that's what you've got, I'm guessing it's something somebody has retro-fitted. Can't remember if the C2/4 pipework is smaller bore than that used on the GT3 system ? Either way, I'd be looking at putting the car back to standard or considering getting some upgraded silencers on it. It sounds like your car has been messed around with as the system you are describing is probably off a 996 standard version and will have different exhaust system to GT3. Get it put back to standard and start moving forward from there. You should get more power with the standard air filter in place to start with, swap it back and do a run if power still down then swap exhaust back to standard. Is the exhaust switchable by means of a button or are the valves locked open? Valves locked open Mike

Valves locked open. Purely for sound, I must admit it does sound good.

sportsandclassic said: The pink/purple line is with my DB killers on the end of my exhaust. The blue line is without! Drops quite a lot in midrange. Car is running full car graphic system and IPD with 997GT3 throttle body. Standard map. The green line is an overlay of a modified RS car. Edited by sportsandclassic on Friday 3rd January 20:38 Hi Mike, was interested in your DB killers. How much of a difference did they make in static DB reduction (I'm touching 105 at most trackdays these days). Any cost/where to buy them from? Many thanks

BrendonJ said: sportsandclassic said: The pink/purple line is with my DB killers on the end of my exhaust. The blue line is without! Drops quite a lot in midrange. Car is running full car graphic system and IPD with 997GT3 throttle body. Standard map. The green line is an overlay of a modified RS car. Edited by sportsandclassic on Friday 3rd January 20:38 Hi Mike, was interested in your DB killers. How much of a difference did they make in static DB reduction (I'm touching 105 at most trackdays these days). Any cost/where to buy them from? Many thanks Hi, they will knock off 3db on static BUT I lost 50BHP through midrange and you can feel the torque drop off out of a bend. They will only fit a car graphic system as made for them. Out of the circuits I do Oulton park is only place I struggle for noise as they static test. Mike

I fail noise tests at Bedford, with those PSE boxes on. 105db

rallyeman said: I fail noise tests at Bedford, with those PSE boxes on. 105db I fail static at Bedford as wel (OEM system)l. But they always let me on and tell me to stay away from other similar cars etc

http://www.youtube.com/watch?v=gyVYZjUI8So&sns...

An update as Austec have fitted my 100 Cup cats, and map to smooth out the curve. Very happy with the result, pulls lovely right from the bottom to the top, the cats sound lovely. Austec fitted original new Porsche clamps, so can be changed back to stock easily. Which wasn't easy, as the cat pipes were short, and needed some extra pipe. Old Run

New Map

Hi there I done a lot of tuning on my Carrera S, in short leave the intake ALONE! The stock intake system from Porsche is a cold air intake design, it won't heatsoak, certainly not easily anyway. If you want to change the intake what I did on my 911 was take the stock airbox and I dremeled out the resonace chamber and plugged it. I then used a silicone hose connecting air box directly to the throttle body and put a BMC filter into the air box. Result: The car gained 3-4BHP, dyno tested and there was a nicer sound note, but really you won't improve upon the stock design, Porsche did a great job here, leave it alone. That K&N open cone filter you have will be heat soaking like crazy and loosing you a lot of power! Throttle response was also much better! Throttlebody/plenum: Leave it, GT3 has the larger items, on a Carrera/Cayman fitting the larger GT3 throttlebody gives some nice gains. Cats: 200 cel is the best, you will maintain low-mid range torque/power and gain some power beyond 4500rpm all the way to redline, a very worthile modification, but still with the standard straight pipe crossover design by Porsche, again this works best. If low-down power is not important then a full de-cat will give you excellent top-end gains, especially if its an X-Design, scavenging to accelerate exhaust gases, I did this on my car and the result was superb, I went from 378BHP upto 394BHP with a de-cat with 40BHP gains in the 5000-6500rpm region. Unfortunately I lost 40BHP/40Lb/Ft below 4000rpm and the cars drivability was poor, but for a track/race car this would be perfect! My final spec:- Stock airbox, dremeled, silicon hose, BMC filter. X51 manifolds 200 cel cats PSE Third radiator kit Hartech low temp stat Softronic remap Car is making 374-378BHP. Dyno: If you want accurate engine power, then you need to use a Mahaa dyno, as it calculates flywheel power on the coast down accurately. Other dyno's just use a set calculation for all cars, of say 15% or 20%, whatever the operate has set, this is in-accurate for flywheel/engine power. Would I do it again, I spent a lot of money for very small gains, though I do love how my car drives and Mike at S&C will also state my car is a very quick Carrera S, we've had a few runs together. But if doing it again I'd spend far less and just modify stock airbox, fit the highflow cats, 3rd radiator, temp stat and softronic map and leave it as is. Throttlebody / plenum is worth it as well as those items are quite cheap, but then that is it and should net you 370ish BHP from a Carrera S with a map.

Edited by rallyeman on Tuesday 18th March 10:22

Interesting read Gibbo. The reason I took the route I did, was the 100 cel cats came with the car, and was hoping when fitted the cats, would improve the flo and maybe give a better exhaust note. The K&N was already fitted. When removed on the rollers, the difference was only 1 bhp, so left on. Personally I don't think the K&N is affected by heat soak, as it has a cold air box design around the filter and forced air coming in from a carbon scope under the wing, ( see pic ) Even though I had a bouncy torque curve before the acceleration felt fine, but since the map, it's super smooth and pulls hard, right from the off. Edited by rallyeman on Tuesday 18th March 10:23 Edited by rallyeman on Tuesday 18th March 10:25

rallyeman said: Valves locked open. Purely for sound, I must admit it does sound good. I wonder if your neighbours agree... This thread says a lot about the mentality of the PO of your car and many people like them. I wanted more power from myM5 yet every exhaust site bar none had downloadable sound files and no dyno graphs. Some people never grow from playing cards in bike wheels and don't care how much power the setup takes away as long as the kids down the chip shop think it's kewl innit. They might also be causing catastrophic engine damage at high revs by fitting shoddy parts.

As an interesting reference/comparison, here is the output from a dyno run I did on my 996 GT3 mk2 last weekend at Surrey Rolling Road. Surprisingly, the car posted some fairly strong numbers (even if you allow a margin of error for transmission losses). This car being relatively new to me I am not fully sure of what it is running. I know it has some form of Porsche Switchable Exhaust (seems to be factory/dealer fitted with the std PSE switch on the cental dashboard). Potentially the cats could be high flow cats. All else (e.g. air filter) standard.

supermono said: rallyeman said: Valves locked open. Purely for sound, I must admit it does sound good. I wonder if your neighbours agree... Its quiet on start up, that's the beauty of this exhaust, and way quieter than my old Tiger, with a ZZR fitted. This thread says a lot about the mentality of the PO of your car and many people like them. I wanted more power from myM5 yet every exhaust site bar none had downloadable sound files and no dyno graphs. Some people never grow from playing cards in bike wheels and don't care how much power the setup takes away as long as the kids down the chip shop think it's kewl innit. They might also be causing catastrophic engine damage at high revs by fitting shoddy parts. Blimey, I doubt it, they are only standard Porsche PSE exhaust boxes, but its like having PSE, button switched on at all times, and a K&N, its hardly going to cause catastrophic engine damage is it? They are hardly shoddy parts? Thanks for the useful imput anyway Edited by rallyeman on Tuesday 18th March 20:33

I am well aware that some aftermarket exhausts can add sound at the expense of a decent power/torque response. A recent revelation for me is that some 996 GT3s did come with switchable/PSE exhausts which were fitted by Porsche and not aftermarket seconds. And judging by the performance on my car it is not robbing the engine, reducing power, etc, etc.