GT3 6.2 on Rolling Road,
Discussion
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.
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.
Valves locked open
Mike
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.
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?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
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.
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?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
Many thanks
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
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.![](http://thumbsnap.com/sc/SgwGkRjY.jpg[/img]</a> <a href="http://thumbsnap.com/wivNmKuF" Target="_blank">[img]http://thumbsnap.com/sc/wivNmKuF.jpg)
Old Run
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
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.
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.
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.
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.
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.
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.
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.
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