Re: High performance intercooler for tt/GT2
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2009 997 GT2 659PS/827NM DIN
2009 997 GT2 659PS/827NM DIN
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?
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
Sep 6, 2009 3:02:44 AM
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.
Sep 6, 2009 8:01:47 AM
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 , 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
2009 997 GT2 659PS/827NM DIN
Sep 6, 2009 9:03:17 AM
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
Sep 6, 2009 9:12:24 AM
Sep 6, 2009 9:36:12 AM
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
Sep 6, 2009 11:04:06 AM
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.