Ultimate VTG engines
09-10-2011, 12:15 PM
#46
Three Wheelin'
Join Date: Oct 2010
Posts: 1,291
Likes: 0
Received 0 Likes
on
0 Posts
Actually it was a speedo indicated 17xmph. No idea what the rpms were, at that speed glancing at the digital readout while rapidly approaching the brakezone is dicey at best.
T5 is even crazier since it's a downhill corner. I only truly ran out 6th a few times.
Canada Corner is crazy for a different reason- After the Kink the two left hand bends connect together for one big sweeper and the brake zone is ridiculously short for the speed you can attain.
But yes, all three areas should be solid 6th gear pushes in my car.
T5 is even crazier since it's a downhill corner. I only truly ran out 6th a few times.
Canada Corner is crazy for a different reason- After the Kink the two left hand bends connect together for one big sweeper and the brake zone is ridiculously short for the speed you can attain.
But yes, all three areas should be solid 6th gear pushes in my car.
09-10-2011, 12:44 PM
#47
Three Wheelin'
Join Date: Oct 2010
Posts: 1,291
Likes: 0
Received 0 Likes
on
0 Posts
Let me chip in here as well if I may. Nick you are right about what you say above but you can't achieve ignition timing over toby's engine without the expansion intake that cools the air significantly at high rpm. This is the inherent weakness of vtg technology thhat p tried to address and now has this intake on all turbo models including then the .2 turbo and 2 rs.
So the compromise at the end is simple. Do you get better results with turbo intake, more boost, less ignition timing, more fuel or with expansion intake were you sacrifice boost but get 10-15 degrees colder air and thus can use 25+ degrees ignition and run much leaner lambda? Before my tune I also thought by listening to everyone (except sported and apparently Pierre Ofsky and few other race teams) that the 1st option was the way to go. But after seeing how much power we got in the top end in my engine when the expansion intake does it's thing and power goes crazy with less boost but more ignition I think that maybe they were right. The feeling is that you get a turbo engine with huge torque build up from around 3k to 5.5k then power flattens until 6.5 and then it feels like an n/a engine making more and more power until the sad reality of the rev limiter hits at 7.8k lol! If we could rev to 8k + this setup would make more and more power for sure. (not advised without changing the variable valve mechanism).
So the compromise at the end is simple. Do you get better results with turbo intake, more boost, less ignition timing, more fuel or with expansion intake were you sacrifice boost but get 10-15 degrees colder air and thus can use 25+ degrees ignition and run much leaner lambda? Before my tune I also thought by listening to everyone (except sported and apparently Pierre Ofsky and few other race teams) that the 1st option was the way to go. But after seeing how much power we got in the top end in my engine when the expansion intake does it's thing and power goes crazy with less boost but more ignition I think that maybe they were right. The feeling is that you get a turbo engine with huge torque build up from around 3k to 5.5k then power flattens until 6.5 and then it feels like an n/a engine making more and more power until the sad reality of the rev limiter hits at 7.8k lol! If we could rev to 8k + this setup would make more and more power for sure. (not advised without changing the variable valve mechanism).
I need to try some runs with 18 ambient to see what happens compared to Toby s ultimate vtg build that went with option 1 to evaluate really what happens. At 10 ambient the data were quite good in mine but need to try in more difficult conditions now.
The thing is that champion will not attempt to tune your car with the gt2 intake in my understanding as they don't believe in what I mentioned above for 700 real hp possible with the expansion intake.
But it's difficult to tune and required experience.
But it's difficult to tune and required experience.
The issue with most US tuners is that they don't tune for power, they tune for numbers- ie. a simple max output for simpletons to quote to their friends. There were only two "shops" I was going to take a car to in the USA (both have extensive motorsports backgrounds, one significantly more than the other though), and that depended upon where I was at the time, since they are on opposite coasts. I won't do hackjobs like removing MAFs or going to conventional turbos.
---
edit- Please note, like I said before, I am not a tuner, shop, or engineer here. So I completely erred when I earlier commented on larger EXHAUST housings on the VTGs. They are larger COMPRESSOR housings. Quite a big difference, sorry!
Last edited by Nick Wong; 09-10-2011 at 12:49 PM. Reason: faulty facts
09-10-2011, 12:50 PM
#48
Instructor
Join Date: Jan 2006
Location: London
Posts: 130
Likes: 0
Received 0 Likes
on
0 Posts
Mod500 are you referring to Toby's car? Did you drive it?
I like your description above. It perfectly describes my (and probably many other's around here) addiction for this experience that makes us throw so much time and ££ to recreate lol!
I like your description above. It perfectly describes my (and probably many other's around here) addiction for this experience that makes us throw so much time and ££ to recreate lol!
09-20-2011, 10:36 AM
#56
Addict
Rennlist Member
Rennlist Member
Thread Starter
10-27-2011, 01:51 PM
#57
Three Wheelin'
Join Date: Oct 2010
Posts: 1,291
Likes: 0
Received 0 Likes
on
0 Posts
Update-
The motor is back together and is going back in over the next week or so. I'm going to test it at PBIR when it's complete before it goes back home so I should have some preliminary data.
The motor is back together and is going back in over the next week or so. I'm going to test it at PBIR when it's complete before it goes back home so I should have some preliminary data.
10-28-2011, 07:05 AM
#58
Addict
Rennlist Member
Rennlist Member
Thread Starter
As well as acceleration data I am particularly interested in logs for the following Durametric parameters:
rpm
kph
boost press kpa
ambient temp
IAT
MAF kg/hr
ignition timing
lamda 1
lambda 2
throttle position %
We can learn loads from the above data about how the engine is working under what loadings...
11-04-2011, 07:03 AM
#59
Addict
Rennlist Member
Rennlist Member
Thread Starter
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....
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....
11-06-2011, 05:24 PM
#60
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