Ultimate VTG engines
11-06-2011, 06:18 PM
#61
On same day a 722ps 997gt2 (that is engine dyno'd Porsche power) did 14.6 second 200-300kph.
Built engine with custom vtgs and u ran 14's?... stock engine with Old modded vtgs on tip car ran 200-300 in 14-15sec.
U.S tuners used 997tt manifold on
997 GT2 with bolt on GT30 kit made high 800rwhp
997 GT2 with bolt on A30 kit made mid to high 800rwhp
997 GT2 modded vtgs made 670rwhp
997 GT2 built 3.8l w/GT35 made +1200rwhp
Built engine with custom vtgs and u ran 14's?... stock engine with Old modded vtgs on tip car ran 200-300 in 14-15sec.
U.S tuners used 997tt manifold on
997 GT2 with bolt on GT30 kit made high 800rwhp
997 GT2 with bolt on A30 kit made mid to high 800rwhp
997 GT2 modded vtgs made 670rwhp
997 GT2 built 3.8l w/GT35 made +1200rwhp
re vtgs kits - it's built for torque and has more power under the curve (logical if you consider powerband) vs kits you've listed - unless destructive programming.
ultimately it's how you want that power to be deployed and on what chassis (awd vs rwd) - what is great for the dragstrip is THE opposite you want for a road layout (and pretty sad if try to deploy it on streets). good to see that internals re-work allows to have power builds with VTGs as an interesting alternative.
11-07-2011, 01:46 AM
#62
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Enjoyed a day at the airstrip earlier in the week in beautiful weather, low wind and 14degC.
There were a few 996 turbos on hand in various stage of tune with componentry from well known US tuners so I was very interested to evaluate what these cars were like.
All the 996tts had manual boost controls and various types of hybrid turbos, the one in the video below is a manual and I believe had K24/20Gs and it had that big shiny intake piping, the owner said it had rods and had 800hp at full boost....
I passengered in this 996 and can report it had a nice dollop of torque between about 4000 and 5XXXrpm, it felt strong and I understand that it can run the sort of acceleration numbers which appear to indicate certainly 650+ real hp....
The really interesting bit which I was here for was the element which no performance box or number data can really tell you and anecdotes flourish about how responsive various engines are and how they spool early and have full boost by 3500rpm etc - this element of an engine is for me the most important one as it dominates the driving experience and it was the raison d'etre of my 3.9 l RS engine build to have the VTG response experience....
Checkout the video below. It looks like I am getting the drop on the black 996tt (ie hitting my throttle before him) when we both go WOT (3rd gear in vid) but I'm not and we did this a few times in different gears. The 996tt was in his sweet spot rev wise (~4000rpm).
The results are quite startling and a great visual representation of how Porsche has moved the game forward with VTGs.
Once on boost the black 996tt actually kept up reasonably well and the 20 odd metres which the VTG response intially gave was no more than 30m once we hit 190-200mph....
http://www.youtube.com/watch?v=9cQWMDhQ7W8
There were a few 996 turbos on hand in various stage of tune with componentry from well known US tuners so I was very interested to evaluate what these cars were like.
All the 996tts had manual boost controls and various types of hybrid turbos, the one in the video below is a manual and I believe had K24/20Gs and it had that big shiny intake piping, the owner said it had rods and had 800hp at full boost....
I passengered in this 996 and can report it had a nice dollop of torque between about 4000 and 5XXXrpm, it felt strong and I understand that it can run the sort of acceleration numbers which appear to indicate certainly 650+ real hp....
The really interesting bit which I was here for was the element which no performance box or number data can really tell you and anecdotes flourish about how responsive various engines are and how they spool early and have full boost by 3500rpm etc - this element of an engine is for me the most important one as it dominates the driving experience and it was the raison d'etre of my 3.9 l RS engine build to have the VTG response experience....
Checkout the video below. It looks like I am getting the drop on the black 996tt (ie hitting my throttle before him) when we both go WOT (3rd gear in vid) but I'm not and we did this a few times in different gears. The 996tt was in his sweet spot rev wise (~4000rpm).
The results are quite startling and a great visual representation of how Porsche has moved the game forward with VTGs.
Once on boost the black 996tt actually kept up reasonably well and the 20 odd metres which the VTG response intially gave was no more than 30m once we hit 190-200mph....
http://www.youtube.com/watch?v=9cQWMDhQ7W8
11-08-2011, 01:35 PM
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Fingers crossed for fair weather tomorrow. Flying out of O'Hare 7am to FLL, testing the car in the evening at PBIR. Preliminary data shows very healthy power from 3500rpm to a 7300rpm redline. Base "street" tune for 93 octane is around 650whp with lots of torque early. Race fuel (110 octane) on the "race" map is supposedly quite stellar, 800whp and well over 700ft/lbs torque early in the rpm range. Champion has programmed two DME units for my car to be swappable, each with three files per my request. I don't think anyone else has done that yet.
11-08-2011, 06:41 PM
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11-09-2011, 10:16 AM
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I thought tuners were using on the fly dual mode EPROM installations, ie chip switching module installed inside the ECU using 2 different EPROM’s that can be accessed from a console mounted switch. Would this a possibility? Seems easier than removing the ECU.
11-10-2011, 11:51 AM
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So...
PBIR isn't quite big enough for 6th gear pulls.
Sorted out the handling issues. Unlike most interwebbers I don't have Motons, JRZs or Penskes- I have Ohlins shocks, fronts triple adjustable, rears double adjustable. But I digress.
Power is everywhere with the 3.8l kit. On two of my files I had requested a drivable tune, one for 93 octane and the other for 100 octane. Both came out exactly what I wanted with some minor corrections needed before delivery to me next week. I didn't even bother trying the second DME tunes because I didn't have C16 nor did I need the power for this tiny track.
About the dual DMEs- both are programmed by Champion with GIAC coding so I use the Garrett OBD flashloader to change the files. Both DMEs are installed in the car, changing them is as simple as swapping the harness plugs over to the other one.
Fun factoid about my car- it has the factory sub belt and rollbar mounts. Apparently that is a hit/miss thing with Porsche with no rhyme or reason to why one may or may not have them.
PBIR isn't quite big enough for 6th gear pulls.
Sorted out the handling issues. Unlike most interwebbers I don't have Motons, JRZs or Penskes- I have Ohlins shocks, fronts triple adjustable, rears double adjustable. But I digress.
Power is everywhere with the 3.8l kit. On two of my files I had requested a drivable tune, one for 93 octane and the other for 100 octane. Both came out exactly what I wanted with some minor corrections needed before delivery to me next week. I didn't even bother trying the second DME tunes because I didn't have C16 nor did I need the power for this tiny track.
About the dual DMEs- both are programmed by Champion with GIAC coding so I use the Garrett OBD flashloader to change the files. Both DMEs are installed in the car, changing them is as simple as swapping the harness plugs over to the other one.
Fun factoid about my car- it has the factory sub belt and rollbar mounts. Apparently that is a hit/miss thing with Porsche with no rhyme or reason to why one may or may not have them.
11-16-2011, 10:55 AM
#69
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I decided to do a build thread on here and RT since I have been dribbling out bits of info on forums here and there but would really like to detail everything.
Car is a 2009 GT2 GT Silver
Brand spanker
I had a build slot deposit paid on a GT2RS but after reading the full spec when the details came out decided that I would modify my existing GT2. The GT2RS engine has very little differences to the GT2 and I wanted to build something special around the VTG platform. I need rear seat belts as I have kids and the GT2RS does not have the reinforcing metal so seat belts cannot be retrofitted, ditto no roof racks on the GT2RS so no surfboard (altho not tried that yet). Centre lock wheels, never liked them and looking at posts from C/L owners I am glad I don't have them. Finally my GT2 is specced lightweight and I guessed (correctly) that customer spec GT2RSs would come in within 25kg of my modified GT2, mine weighs about 1450kg full of fuel (64l tank)
So car disappeared to RS Tuning in July 2010 to have a new development, a 3.9l piston and cylinder kit and special 997 turbo based intake manifold.
The engine was built using proprietry Carrillos and pistons which RS Tuning had developed during racing which had slightly longer rods and shorter pistons which gives lower drag and more power.
Carrillos, special ones on left
Piston
The engine was completely dismantled and built up using all the RS Tuning tricks, head work, cams etc then it was put on the dyno wearing bigger VTGs for testing.
The engine dyno showed that the GT2 expansion manifold could not flow more than 690hp and simply not big enough but to get the GT2 factory electronics to work with the 997 turbo manifold proved very difficult also the exhaust, 100 cell cats with standard rear OEM Akrapovik was too much of a restriction.
First long delay was waiting for Cargraphic to build me a bypass exhaust system which exited 35% of flow directly out of the cat to atmosphere when the valve was open, this took weeks, the final system can be seen here on the CG website.
http://www.cargraphic.de/index.php?/s,6,7,18,3647,3804/
Work continued with the new exhaust fitted and a problem was occurring on the engine dyno, it would read the torque and then suddenly an erroneous reading, it totally baffled them until BANG the engine dyno broke......
Basically they were exceeding the torque limits at 3000rpm of the engine dyno and had hot wired it to bypass the safety features. They had to order up a new engine dyno from Borghi & Saveri with a third retarder (two previously) to be able to be able to brake 900+NM at 3000rpm.
http://www.borghisaveri.it/English/R...eferenze1.html
More time ticked on, they could get full power out of the engine but weren't happy with the part throttle running and in particular the VTG vane control. They hired an engineer who worked for OEM supplier to show them how to do the programming, they spent three weeks solid on the engine dyno learning how to program this sophisticated engine, it was tortuous by all accounts, the project was nearly abandoned at a few stages.
The engine had to be fully rebuilt following its engine dyno work after using 5000 litres of fuel and the equivalent of 70000 miles hard work.... it broke 3 Porsche drive shafts from the torque at 3000rpm, each shaft needing 4 hours labour to replace....
The engine was almost done and the full power dyno sheets were sent to me all that needed now was road testing.....
Or so we thought......
On the road it didn't run as they wanted with the part throttle not being as smooth as they wanted and on top of that the full throttle was producing too much heat and intake temperatures were rising too high meaning the full power seen on the engine dyno using water cooled intercooler were not replicable on the road.
The engine came back out and went on the dyno, they dragged out a set of prototype VTG turbos with even bigger compressor wheels and housings, the theory being they could run less boost and have the required power at lower intake temperatures.
The OEM engineer came back in, for him it was a mission to get it right and eventually he signed the program off.....
Whilst the engine was being finished they fitted and set up some suspension parts which I had collected, dog bones, rear lower control arms and rear lower track rods and front tarrett bushing for the front adjustable lower control arm together with Bilstein B16 Damptronics.
Lower rear cup arms
All in situ
The engine went in, the racing season had begun, I flew out to see how they were progressing and it was alive although it was quite raw, the way the boost came on at lower revs was fairly abrupt and lumpy and the traction control didn't really know what was going on so progress in first and second gear was pretty messy......
During the road tuning there was a problem with blowing exhaust sensors, mine ate three of them, it turned out this was a parts problem and the latest Porsche part (a changed number) seemed to work......
http://www.youtube.com/watch?v=OnoptMSIzzk
I pushed and pushed and finally got a date for collection.
http://www.youtube.com/watch?v=nJLZv4sDTb0
I drove off and there seemed to be a problem, it stalled and would not start then started perfectly WTF !!!
The engineers were all over it, it read “flywheel sensor error” so they checked inder the car and the sensor looked good, installed a new battery, took out the ECU and adjusted it to fire up after reading less flywheel notches, car fired up and ran back to the UK flawlessly.
Back in the UK I had accumulated various parts. After seeing the pic below suddenly my GT2 looked old and after waiting so long for the engine to be done I wanted a rebirth.
The car went straight to Tech 9 my preffered workshop in the UK and its transformation was completed in a day, GT2RS “look” but subtely different wearing the beautiful BBS Fi wheels with 5mm rear and 6mm front spacers to give the right look.
The car was perfect, I was very happy, then a few days later it wouldn't start, then it started and ran very rough.... back to Tech 9 who found the same fault code “flywheel sensor fault” engine dropped flywheel measured, new sensor, wiring tested, ECU back to Germany to be checked..... Started first time....
Couple of days later we ran a test day at the airfield and it ripped, felt superb...... Then when we went to leave it all of a sudden wouldn't start......Ended up on the back of a truck back to Germany. Bottom line it was the ECU, they couldn't find the fault it was nothing they could see but a brand new ECU with the exact same program (bought from Porsche Zentrum Munchen coded to my chassis) cured it, totally although the ECU fault will remain a mystery but theories were it could have been an electrical surge through welding or something similar ?
All these trips to Germany were very tedious and taking their toll
So car is back and is on full song, did a vmax event the other day and did a terrifying 209mph
http://www.youtube.com/watch?v=4h-673XWbBc
Exhaust pipes following some high speed runs.
Porsche Motorsports front radiator was fitted to try and combat the extreme heat these VTG engines generate
But as I posted elsewhere this is at the limit of the currently available VTGs due to the size of the hot side, the intake temperatures reached limit the hp to around 700 but this is plenty for the 997GT2
Some data from running fast
Car is a 2009 GT2 GT Silver
Brand spanker
I had a build slot deposit paid on a GT2RS but after reading the full spec when the details came out decided that I would modify my existing GT2. The GT2RS engine has very little differences to the GT2 and I wanted to build something special around the VTG platform. I need rear seat belts as I have kids and the GT2RS does not have the reinforcing metal so seat belts cannot be retrofitted, ditto no roof racks on the GT2RS so no surfboard (altho not tried that yet). Centre lock wheels, never liked them and looking at posts from C/L owners I am glad I don't have them. Finally my GT2 is specced lightweight and I guessed (correctly) that customer spec GT2RSs would come in within 25kg of my modified GT2, mine weighs about 1450kg full of fuel (64l tank)
So car disappeared to RS Tuning in July 2010 to have a new development, a 3.9l piston and cylinder kit and special 997 turbo based intake manifold.
The engine was built using proprietry Carrillos and pistons which RS Tuning had developed during racing which had slightly longer rods and shorter pistons which gives lower drag and more power.
Carrillos, special ones on left
Piston
The engine was completely dismantled and built up using all the RS Tuning tricks, head work, cams etc then it was put on the dyno wearing bigger VTGs for testing.
The engine dyno showed that the GT2 expansion manifold could not flow more than 690hp and simply not big enough but to get the GT2 factory electronics to work with the 997 turbo manifold proved very difficult also the exhaust, 100 cell cats with standard rear OEM Akrapovik was too much of a restriction.
First long delay was waiting for Cargraphic to build me a bypass exhaust system which exited 35% of flow directly out of the cat to atmosphere when the valve was open, this took weeks, the final system can be seen here on the CG website.
http://www.cargraphic.de/index.php?/s,6,7,18,3647,3804/
Work continued with the new exhaust fitted and a problem was occurring on the engine dyno, it would read the torque and then suddenly an erroneous reading, it totally baffled them until BANG the engine dyno broke......
Basically they were exceeding the torque limits at 3000rpm of the engine dyno and had hot wired it to bypass the safety features. They had to order up a new engine dyno from Borghi & Saveri with a third retarder (two previously) to be able to be able to brake 900+NM at 3000rpm.
http://www.borghisaveri.it/English/R...eferenze1.html
More time ticked on, they could get full power out of the engine but weren't happy with the part throttle running and in particular the VTG vane control. They hired an engineer who worked for OEM supplier to show them how to do the programming, they spent three weeks solid on the engine dyno learning how to program this sophisticated engine, it was tortuous by all accounts, the project was nearly abandoned at a few stages.
The engine had to be fully rebuilt following its engine dyno work after using 5000 litres of fuel and the equivalent of 70000 miles hard work.... it broke 3 Porsche drive shafts from the torque at 3000rpm, each shaft needing 4 hours labour to replace....
The engine was almost done and the full power dyno sheets were sent to me all that needed now was road testing.....
Or so we thought......
On the road it didn't run as they wanted with the part throttle not being as smooth as they wanted and on top of that the full throttle was producing too much heat and intake temperatures were rising too high meaning the full power seen on the engine dyno using water cooled intercooler were not replicable on the road.
The engine came back out and went on the dyno, they dragged out a set of prototype VTG turbos with even bigger compressor wheels and housings, the theory being they could run less boost and have the required power at lower intake temperatures.
The OEM engineer came back in, for him it was a mission to get it right and eventually he signed the program off.....
Whilst the engine was being finished they fitted and set up some suspension parts which I had collected, dog bones, rear lower control arms and rear lower track rods and front tarrett bushing for the front adjustable lower control arm together with Bilstein B16 Damptronics.
Lower rear cup arms
All in situ
The engine went in, the racing season had begun, I flew out to see how they were progressing and it was alive although it was quite raw, the way the boost came on at lower revs was fairly abrupt and lumpy and the traction control didn't really know what was going on so progress in first and second gear was pretty messy......
During the road tuning there was a problem with blowing exhaust sensors, mine ate three of them, it turned out this was a parts problem and the latest Porsche part (a changed number) seemed to work......
http://www.youtube.com/watch?v=OnoptMSIzzk
I pushed and pushed and finally got a date for collection.
http://www.youtube.com/watch?v=nJLZv4sDTb0
I drove off and there seemed to be a problem, it stalled and would not start then started perfectly WTF !!!
The engineers were all over it, it read “flywheel sensor error” so they checked inder the car and the sensor looked good, installed a new battery, took out the ECU and adjusted it to fire up after reading less flywheel notches, car fired up and ran back to the UK flawlessly.
Back in the UK I had accumulated various parts. After seeing the pic below suddenly my GT2 looked old and after waiting so long for the engine to be done I wanted a rebirth.
The car went straight to Tech 9 my preffered workshop in the UK and its transformation was completed in a day, GT2RS “look” but subtely different wearing the beautiful BBS Fi wheels with 5mm rear and 6mm front spacers to give the right look.
The car was perfect, I was very happy, then a few days later it wouldn't start, then it started and ran very rough.... back to Tech 9 who found the same fault code “flywheel sensor fault” engine dropped flywheel measured, new sensor, wiring tested, ECU back to Germany to be checked..... Started first time....
Couple of days later we ran a test day at the airfield and it ripped, felt superb...... Then when we went to leave it all of a sudden wouldn't start......Ended up on the back of a truck back to Germany. Bottom line it was the ECU, they couldn't find the fault it was nothing they could see but a brand new ECU with the exact same program (bought from Porsche Zentrum Munchen coded to my chassis) cured it, totally although the ECU fault will remain a mystery but theories were it could have been an electrical surge through welding or something similar ?
All these trips to Germany were very tedious and taking their toll
So car is back and is on full song, did a vmax event the other day and did a terrifying 209mph
http://www.youtube.com/watch?v=4h-673XWbBc
Exhaust pipes following some high speed runs.
Porsche Motorsports front radiator was fitted to try and combat the extreme heat these VTG engines generate
But as I posted elsewhere this is at the limit of the currently available VTGs due to the size of the hot side, the intake temperatures reached limit the hp to around 700 but this is plenty for the 997GT2
Some data from running fast
I have a little question:
I notice on your Durametric log that while your IAT reaches >60°C your timing and Lambda keep the good values (with a TT intake).
My logs show my timing and Lambda starting "pulling" once my IAT reaches 40°C, did you modify the ECU control?
(I have to present myself: French, owner almost as you of both one tuned 993TT and one tuned 997.1TT I'm still working on, I'm a high perfs machines true lover from my 14 years old
)
11-16-2011, 01:47 PM
#70
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Wonderfull machine, congrats and glad to discover it!: biggulp:
I have a little question:
I notice on your Durametric log that while your IAT reaches >60°C your timing and Lambda keep the good values (with a TT intake).
My logs show my timing and Lambda starting "pulling" once my IAT reaches 40°C, did you modify the ECU control?
(I have to present myself: French, owner almost as you of both one tuned 993TT and one tuned 997.1TT I'm still working on, I'm a high perfs machines true lover from my 14 years old)
I have a little question:
I notice on your Durametric log that while your IAT reaches >60°C your timing and Lambda keep the good values (with a TT intake).
My logs show my timing and Lambda starting "pulling" once my IAT reaches 40°C, did you modify the ECU control?
(I have to present myself: French, owner almost as you of both one tuned 993TT and one tuned 997.1TT I'm still working on, I'm a high perfs machines true lover from my 14 years old
)
The programming is totally bespoke written especially for the turbo intake working with special very big compressor VTGs by a Bosch specialist who was involved with the original 997tt VTG programming.
I know for a fact that my boost is reduced in stages as the IATs increase, I have the data tables and at 60C the boost is at 95% (from memory) of maximum boost which it can have at say 40C IAT so whilst timing and mixture remain good the boost is reduced slightly. I have full logs where the IAT will peak at say 60C at ~300kph and then start reducing to be 56C by 320kph, this is because of the ECU reducing the boost - also the EGT is controlled in this way.
I think it is important to consider that the IAT of a tuned VTG engine is dependent not just on how good the intercoolers are but on how much boost is used and how long that level of boost is deployed eg if you have 1.5 bar in 6th gear from 3300rpm to 7000rpm for maybe 20s then that is an awful lot of heat energy being produced and a lot more than say a 1.5 bar normal turbo engine which produces the 1.5 bar boost for a much shorter duration.
My setup was optimised for my intercoolers which are on a similar plane to the revered Secan so it runs a lot of boost and STILL has the high IATs, if I tried to stick say 997tt.2 coolers I guarantee that the IATs would be heading towards 90-100c (obviously they wouldn't reach that as the ECU would reduce boost etc)
This is why there is another dimension to looking at intercooler efficiency particularly on VTGs, the tune MATTERS and has to be taken into consideration..... What sort of data are you seeing, can you share ?
11-16-2011, 02:23 PM
#71
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Just to note also that as well as boost being reduced from optimum in the data trace above at 65c I checked on the rest of the data and the fueling is also richer than earlier in the run where at IAT 41c at 200kph the lambda is around 0.83.....
TBH the dancing around between fueling/timing/boost/IAT/EGT etc etc is quite difficult to understand, it is not as straight forward as one would hope. If you PM me an email address I will send a full log and would be interested to see what you make of it ?
TBH the dancing around between fueling/timing/boost/IAT/EGT etc etc is quite difficult to understand, it is not as straight forward as one would hope. If you PM me an email address I will send a full log and would be interested to see what you make of it ?
11-16-2011, 05:33 PM
#72
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Hi TB, I'm surprised you know my 993?
I love it: built motor by Hahn first and Ofzky secondly, went to Sportec for first tuning, several times improved by Ofzky because I was not satisfied, and now fine, torquy and powerfull until the redline like I love it!
I'm now working on my 997TT (will give you details on PM) and want to keep the VTGs, staying the nearest as stock configuration but..."ultimate"! (not at your point)
I currently use Durametric and Performance Box which are always in the car for datalogging.
Pascal
I love it: built motor by Hahn first and Ofzky secondly, went to Sportec for first tuning, several times improved by Ofzky because I was not satisfied, and now fine, torquy and powerfull until the redline like I love it!
I'm now working on my 997TT (will give you details on PM) and want to keep the VTGs, staying the nearest as stock configuration but..."ultimate"! (not at your point)
I currently use Durametric and Performance Box which are always in the car for datalogging.
Pascal
Last edited by K24F; 11-16-2011 at 06:03 PM.
11-29-2011, 08:32 AM
#73
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My "perfect programming" is obviously not as perfect as it should be.....
When the boost ramps up at 2500-3000rpm it does so with such speed that the VTG mechanism does not seem able to control it all the time.
When the weather was warmer +15C it is OK, one can hear a very dynamic "fluffing" noise as the boost ramps up which I'm guessing is the mass of air overshooting the program's target numbers but it is controlled and apart from the very dynamic violent almost sound of the air cavitating and swirling (or whatever it is doing) the engine runs through this onset and runs perfectly.
The temperature has now dropped and air masses have gone up and the program does not know what to do with this violent VTG onset of air..... it stutters and misfires as it hits the peak torque at ~3000rpm - something is out of range and a limiter is cutting in.
Anyway, did it the other day and the ****ty plastic intake manifold decided that enough boost was enough boost
When the boost ramps up at 2500-3000rpm it does so with such speed that the VTG mechanism does not seem able to control it all the time.
When the weather was warmer +15C it is OK, one can hear a very dynamic "fluffing" noise as the boost ramps up which I'm guessing is the mass of air overshooting the program's target numbers but it is controlled and apart from the very dynamic violent almost sound of the air cavitating and swirling (or whatever it is doing) the engine runs through this onset and runs perfectly.
The temperature has now dropped and air masses have gone up and the program does not know what to do with this violent VTG onset of air..... it stutters and misfires as it hits the peak torque at ~3000rpm - something is out of range and a limiter is cutting in.
Anyway, did it the other day and the ****ty plastic intake manifold decided that enough boost was enough boost
11-29-2011, 11:29 AM
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My "perfect programming" is obviously not as perfect as it should be.....
When the boost ramps up at 2500-3000rpm it does so with such speed that the VTG mechanism does not seem able to control it all the time.
When the weather was warmer +15C it is OK, one can hear a very dynamic "fluffing" noise as the boost ramps up which I'm guessing is the mass of air overshooting the program's target numbers but it is controlled and apart from the very dynamic violent almost sound of the air cavitating and swirling (or whatever it is doing) the engine runs through this onset and runs perfectly.
When the boost ramps up at 2500-3000rpm it does so with such speed that the VTG mechanism does not seem able to control it all the time.
When the weather was warmer +15C it is OK, one can hear a very dynamic "fluffing" noise as the boost ramps up which I'm guessing is the mass of air overshooting the program's target numbers but it is controlled and apart from the very dynamic violent almost sound of the air cavitating and swirling (or whatever it is doing) the engine runs through this onset and runs perfectly.
The temperature has now dropped and air masses have gone up and the program does not know what to do with this violent VTG onset of air..... it stutters and misfires as it hits the peak torque at ~3000rpm - something is out of range and a limiter is cutting in.
11-29-2011, 11:50 AM
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Nick
I think you are right on both counts, yes it is like a shuffling noise..... boost is probably around 1.6 bar but it must have been some sort of spike when the torque limiter was interrupting which caused the manifold to explode (it sounded pretty impressive !)
I guess I am lucky it didn't ingest any of the manifold fragments. The other side was cracked also......
They don't have an answer for me yet on a cure but are developing a new manifold, bigger and aluminium so maybe a chance to spend some more money next year
I think you are right on both counts, yes it is like a shuffling noise..... boost is probably around 1.6 bar but it must have been some sort of spike when the torque limiter was interrupting which caused the manifold to explode (it sounded pretty impressive !)
I guess I am lucky it didn't ingest any of the manifold fragments. The other side was cracked also......
They don't have an answer for me yet on a cure but are developing a new manifold, bigger and aluminium so maybe a chance to spend some more money next year