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    Re: High performance intercooler for tt/GT2

     

    What I was worried about with getting a typical RS Tuning tune on the GT2 was basically having too much torque. The way RS likes to tune he gives as much area under the power curve as possible by bringing on the boost early, this will also limit the unltimate maximum peak power as the early boost onset heats up the IAT to the detriment of maximum peak power however it does make for a very fast car IF the car can deploy the torque to the road.
    This IF is the important bit. For a 4WD turbo no problem. I have scanned in my power curve for my 993tt 3.8litre 8.4:1 CR 
     
     
    You can see it has over 550hp from 5000rpm until 7000rpm. This was difficult to achieve and involved specific cams and timings. The result is a very fast car but the power (torque) from 5000 to 7000 is very savage and puts the 4WD system right at the limit of grip even in the dry. I did try and run the 993tt in 2WD mode for a while and it proved just too dangerous with this power curve.
     
    I felt that for the 997GT2 I didn’t want to upset the car’s power delivery as it felt really “right” with the factory settings.
     
    I knew roughly how much torque and power one could expect from various components and especially since I now had the special intercoolers. I actually got hold of an RS engine dyno torque diagram and plotted my own torque curve to what I felt would be right for the car. It basically had lower peak torque ~820NM but then keeping that level as far up the rev range as possible which basically results in a 45 degree straight line power curve with power rising in a linear manner and peaking right at maximum revs.
     
    I left my hypothetical dyno diagram with explanatory notes to why I wanted said curve and truly expected to be ignored since RS usually DO know best.
     
    As mentioned in posts above my intercoolers were tested and were deemed to be virtually as good as Secan, controlling the very high GT2 intake temperatures effectively.
    Once I had indicated that I would go with the bigger turbos (the lure of 650hp was simply too great) RS tried their two offerings on the dyno. They have a unique design of compressor wheel which apparently was designed by a student who works for KKK Race dept, they had the wheels made in three sizes and the biggest size did not work causing a stalling at specific revs. My engine ended up with the bigger of the two effective wheels which fits inside a new bigger compressor housing.
     
    The engine was on the engine dyno for two days for programming. This programming should not be read in the same way as the chassis dyno tuners, this is done as the manufacturers do it with ALL the maps being altered and is very meticulous and can only be done with the correct tools and the experience of turbo race engines and focuses on making the engine completely like standard to drive with no hiccups or holes or surges or silly noises (I was intrigued that Cannaga likes to switch programs – why on earth would one need to on a properly programmed engine ?).
     
    RS use a water cooled intercooler for the tuning and he uses this device to replicate on road intake temperatures so he knew that my intercoolers had Secan like effectiveness so could use lower IATs for the tuning (for standard intercoolers it would be pointless using lower IATs as the timing would be pulled immediately once on the road).
     
    Bottom line is that RS did as I asked !!! 827NM max at 3000rpm then a straight 45 degree line as a power curve peaking at 6880rpm and 660hp.
     
    The car is perfect on the road driving just like standard, no noisier than the 200cell cats (wears 100 cell now) and response in lower revs feels very similar to stock. The torque (apart from not breaking the rods) is perfect in the dry with the smooth delivery allowing the rear tyres to maintain traction, the engine revs up the range like factory curve but just a lot faster with the power just “pouring” on as the revs rise.
     
    Driving back through Germany I did lots of logging of IATs and in the 30degC ambient the maximum intake with prolonged blasts up to 300kph never rose above 54degC. I couldn’t find the conditions to do a proper 100-300 run although from the stuff I did I am confident that this is a 25 second 0-300kph car.
     
    Back to the topic of the thread. It looks very likely that RS will be using these intercoolers and discussed the possibility of getting one made for a Ford GT which they have their, apparently they are attempting to tune to 700hp and the IATs are the problem, it needs proper (Secan style) intercooling.
     
    I will share some more acceleration numbers etc as/when I do them but for now am enjoying the engine in all driving.
     
    BTW the uprated clutch is a joy to use as a DD, it doesn’t feel heavier than before yet somehow seems smoother to use than the stock one !

    --


    2009 997 GT2 659PS/827NM DIN


    Re: High performance intercooler for tt/GT2

     Toby,

    That sounds fantastic. The acceleration numbers should be very impressive. Are you planning on taking the car to a VMax event?

    regards

    Guy


    --
    2001 Ruf R-GT2 Clubsport

    Re: High performance intercooler for tt/GT2

    Wow, well done tobby! I am very interested to see if you 'll break the 6 second mark 100-200kms (starting with 3rd gear). My guess is that you will since the uninterrupted power/torque delivery that you describe is key.

    Quick question; at which revs do you feel on the road the maximum torque? Also do you know if the compressor wheel on those VTGs is 48 or 50mm?


    Re: High performance intercooler for tt/GT2

    Guy, will no doubt be taking it down the runway at some point Smiley

    GT

    ln 30 degC in Germany running weight ~1600kg here is a clip from a 100-200 1 gear change below: 6.1s


    --


    2009 997 GT2 659PS/827NM DIN


    Re: High performance intercooler for tt/GT2

    Hey Toby,

    Thats a great run!  Looks like we are running neck and neck these days...

    12506335536436.10s 100-200 km.jpg


    Re: High performance intercooler for tt/GT2

    Toby , congratulations on the fantastic results from RS!!! as i asumed before after the tuning it will easily do 24-25 second till 300 kmh if not better...

    did the tuining package include there carbon air pipe set?

    Enjoy in good health


    Re: High performance intercooler for tt/GT2

    Posted this on Rennlist, thought some of you guys may be interested:

    100-200kph starting in 3rd is about 6s

    0-300kph I haven't managed to do properly and it depends on where it is done, the surface plays a massive role. On a smooth flat surface I would reckon on ~26s maybe slightly under. At Bruntingthorpe where it is uphill and very rough I would guess at ~28s - should be able to test that at some point......

    Just thought I would add some notes for the benefit of those interested.

    This is NOT a drag car, RS Tuning build engines for race Porsche turbos so they know intimately the limits, for road cars they use the race engine experience and work to certain criteria:

    Smoothness in torque delivery...... this sounds almost a contradiction when you want a fast accelerating car but it is a massive factor in how well a car puts its power to the road. Poorly tuned tts can have the big torque but the manner in which it is delivered is not conducive to getting around a race track fast. For sure the car will feel fast as the torque rush will nail you a nice 0.9G slug briefly and that may be all most thrill seekers want but it is no good for a race car.
    All tuners talk the talk about smoothness and fine tuning but ask yourself how fine tuning is possible without an engine dyno, it isn't......

    Sustaining the power......... this is down to the fine tuning, matching components and tuning to the intercooling capability. Again for street racing, not totally necessary since a 60-130mph squirt or 1/4mile, 1 mile drag may be all the car does but for a race engine the torque must be able to be delivered lap after lap without fading - a Schmirler trademark.

    Longevity, goes without saying but these engines are tuned to last with longevity similar to stock.


    --


    2009 997 GT2 659PS/827NM DIN


    Re: High performance intercooler for tt/GT2

    Toby,

    What AFR's are you running after RS tuning ECU?

    12.8 AFR @ max power on pump gas is too lean.. It causes high EGT's and engine becomes more prone to knock.

    I would aim for 11.8 AFR's @ pump gas, which will give you lower EGT's thus better acceleration in a long high-speed run.


    Re: High performance intercooler for tt/GT2

    WhiteKnight:

    Toby,

    What AFR's are you running after RS tuning ECU?

    12.8 AFR @ max power on pump gas is too lean.. It causes high EGT's and engine becomes more prone to knock.

    I would aim for 11.8 AFR's @ pump gas, which will give you lower EGT's thus better acceleration in a long high-speed run.

     

    "I" won't be "aiming" for anything Smiley, two days of Schmirler mapping on the engine dyno for all combinations of load means I don't have to make guesses on AFRs...... it's what I paid for Smiley

     


    --


    2009 997 GT2 659PS/827NM DIN


    Re: High performance intercooler for tt/GT2

     

    :)

    Do you have a dyno sheet?

    What parts do you have on your car?

    Thanks,

    Emre


    Re: High performance intercooler for tt/GT2

    RS have VTGs with a proprietry compressor wheel designed by a "student" at KKK. 3 sizes were produced (with modified larger compressor housings) and the larger of the 3 did not work properly causing a stalling under certain conditions.

    My engine was put on the engine dyno and had installed the big carbon air pipes, and the 200 cell HJS CG cats were replaced by 100 cell race HJS cats (apparently they are 3 times the cost). Next both of the 2 working bigger VTGs were tested - this is done because different engines can perform better with either the smaller or larger VTG depending on the compression ratio of the standard engine. Mine appeared to be at the high end of the CR tolerance and worked best with the larger VTG (essentially meaning the higher CR would spin up the larger compressor quickly - on lower CR engines the smaller wheel VTG can be better - all this starts with the RS philosophy of power under trhe curve rather than maximum hp which would obviously favour the bigger wheel).

    I have an engine dyno sheet but do not really want to post since it means nothing, especially compared to the chassis dyno nonsense sheets posted on the net. Suffice to say peak torque is at 3000rpm and the power curve is a straight 45deg line to maximum power at 6900rpm.

    This engine is mapped and built not as a dragster, doing one 0-300kph - the cheap tune can easily do that, it is tuned as a race engine (in terms of keeping its hp) which will maintain its optimum temperatures whatever the test. The throttle response and torque delivery are just so "creamy" that I can't stop grinning when driving.


    --


    2009 997 GT2 659PS/827NM DIN


    Re: High performance intercooler for tt/GT2

     

    You might want to consider moving to Germany - would give you the chance to enjoy this great car/engine even more Smiley 659hp... Sounds just perfect for long-distance Autobahn travels Smiley


    Re: High performance intercooler for tt/GT2

     

    Congratulations Toby,

    Do you know if they done anything to the exhaust side of the turbochargers?

    (like clipping exhaust wheel, porting exhaust housing etc...)

    Also, what octane fuel do you use in UK?

    Thanks,

    Emre

     


    Re: High performance intercooler for tt/GT2

    Marcus, you are so right, I spent a few days "blasting" after picking the car up and the thrill of wringing it out through the gears whenever a gap appears is one of the wonders of the world IMO

    Whitekhight

    Thanks for the congtrats although apart from the intercoolers (which I am supremely pleased about ) all I did was shell out the requisite amount of dough 

    Exhaust side is unmodified stock GT2 AFAIK.

    In the UK we get Shell V Power rated at 99 RON

     

     


    --


    2009 997 GT2 659PS/827NM DIN


    Re: High performance intercooler for tt/GT2

    Tobby you mentioned "even bigger turbo housings". Did they change housings on your GT2 vtgs? The stocks one are already bigger than the ones in the tt..

    Re: High performance intercooler for tt/GT2

    GT:
    Tobby you mentioned "even bigger turbo housings". Did they change housings on your GT2 vtgs? The stocks one are already bigger than the ones in the tt..

     

    GT,

     

    I think he means the compressor housing because they are using a bigger compressor wheel.

    No one could made a bigger custom exhaust wheel and housing yet as far as i know.

     


    Re: High performance intercooler for tt/GT2

    GT:
    Tobby you mentioned "even bigger turbo housings". Did they change housings on your GT2 vtgs? The stocks one are already bigger than the ones in the tt..

     

    Yes bigger than GT2 compressor housing


    --


    2009 997 GT2 659PS/827NM DIN


     
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