Agree with this 100%. I assume the horizontal axis is miles per hour?


I will start my own thread shortly based on my recent track day with vtgs and high boost and high iats, but basically my experience and data mirror yours.

 

^^^ This all points to monster build VTG cars being barely quicker 0-300 kph than stock engined VTG cars

 

lol you are right sir.only numbers

 

I don't know because I never went to 300. Do you know if the horizontal axis in the graphs is mph?


The cars are tuned in North America for best performance up to about 140mph, and imho it makes sense to do that. vtgs are pretty good in this range but I agree that above that speed one may be better off with a different turbo.

 

Why still use 60-130 thing in all races. Weather, passengers, fuel quantity, fuel quality, incline/decline road...etc can make huge difference!

 

^^^^^ that may be so, but it is still easier to find the right conditions for a 60-130 run than a 0-300km/hr run, at least in North America. No airstrip events anywhere near me...

 

Even in dragstrip. Depends on DA, there is fast and slow drag strips...etc
What a headache!
If not all cars compare in same road, same dragstrip in same time it doesn't matter all those results.

 

I've always said that you need a gt2 turbo to put a big compressor as some do. It's funny how a many buy into the compressor wheel size marketing. The hot side is tiny on a 997.1 Tt and you create lots of back pressure and high exhaust temps. Anyone that ran these cars hard will quickly realize if they log how the car doesn't like heat. Yet I still come across high end tuned 997.1s worh big vtgs and 1.5 bar logs - but the timing is at 1.25 deg timing or even dropped to a negative at peak tq and that's one 3rd gear pull. Imagine what your doing to the car at 140 mph full throttle. It's easy to boast or better yet post dyno numbers. Log your cars guys and you will see what's really going with these upgrades. If it's too good to be true it probably is.
Just saying.
Markski

 

Hi Buddy, those IAT graphs 9e have posted are for GT2 based hybrid VTGs. If you measure their compressor wheel like 9e measure them they are actually 62mm VTGS. If you measure them like other vendors measure their compressor wheels for 68mm VTGS they are 66mm compressor wheels.

Even with the GT2 based turbos with larger compressor wheels and all the tricks i.e. larger billet compressor wheel with cut backs, motorsport bearings , recirculating valves which only GT2 VTGS have, larger hotside etc etc look at the sharp rise in IATS from third gear onwards. This graph only goes up to 80mph and there is an 8 degree C variance in IATS (massive) when running higher boost so imagine what the difference in IATS is going to be when they guys at 9e are VMAXing their turbo above at 210mph somewhere?!

Sure the car above Ken mentions is rapid 60-130 mph running 6.75 secs and 100kph to 200 kph approx 6 secs on pump gas but Ken is not sure thats its all going to hold together and be a quicker car when they run higher boost above 140 mph. As you say with standard 997.1 VTG housing hot side is tiny so these tuned cars with crazy high IATS at above 140 mph are often slower than stock cars when running all the way to 300kph!

Its a fine art tuning VTGS and often more troublesome then its worth but on my experience 700bhp at the crank and thats on a built 3.8l forged engine is about the max if running all the way to 300kph regularly. I've been in a friends car built 3.8 l with VTGS like this and its very fast bit it is no way anywhere near the 9e packages I've sat in based on conventional turbos. The conventional turbo based car was a 9e XX mind which can crack 230mph in just over a mile lol!

 

I understand and agree. A many throw compressors wheel sizes around to sell turbo kits with some really poor tuning - everything maxed out - 1.5 bar on pump with big compressors and a oem 997.1 l turbo. Ice seen logs over and over and sure you can take the exhaust temp ceiling out of the way. But take it too far and watch your piston melt.
Either way, gt2 based turbos are a lot better then non gt2 turbos as a base for upgrade. Two different worlds.
As far as Intake temps well that also depends on Intercoolers. For the 997.1s the bigger the better- I don't want to bring up the controversy over gt2 rs Ics and other bar plates , but I tuned remotely for a shop 2 997.1s both with rs Ics on dyno and the results were shocking. In one 3rd gear pull with and on Ics the temps went up to 61 deg C. Starting was 40 I think. It was hot. But aren't they supposed to be the best cooking ic on the market ?
That was not a fluke either. Happened to 2 cars same shop same dyno. I have the logs. My point is, if something is too good to be true it probably is. I've been doing 4.5" and 6 " Ics since 2004. Tried just about every combination of core I can get my hands on. It's also about flow too. A many don't measure that either.
As far as no Vtg turbos on a 997.1. Of course u will make a lot more power with a gt3082 boost for boost then any Vtg hybrid. That's just common sense.
But the one issue I have is when people compare Ics or turbos or whatever without keeping everything constant. How can anyone make a statement that xxxx is better then yyyy if you changed more then 1 variable in question. It's just bad statistics 101 and I've seen this ever since rs Ics came out. Same with Vtg turbos. I have 63.5s that make same hp as the 65mm on pump for half the price yet guys think the bigger the better. Sure I agree some measure the wheels differently.
Bottom line is if it's too good to be true it probably is. I leaned that many years ago and that applies to Porsche tuning too .

 

OK, so you have logged some dyno or 0-80 mph pulls...fine. Now show me how these upgraded VGTs or superduperIC really act when installed in a car driven as it was designed.

Example here, includes speed, rpm, boost and intake temperature. Some 30 seconds flat out 4-6th gears, 997.1 VGTs and GT2 RS ICs.

 

I'm not debating Anything in particular. Not promoting any super duper turbos nor Ics. I'm just saying that I shake my head sometimes when I read some posts. That's all.

 

I don't think anyone believes the vtgs are the ideal solution for 0-300kph runs. I'll start another thread shortly but my Champion 68s have timing in the upper rpms of 11-14ish with 22.5psi boost held all the way up. Mind you, when the iats did go above 120F (with .2tt I/cs) the performance did drop off. That happens around 140mph. We all know that there is only so much you can do with these vtgs...


I'd love to see proof that another I/c would keep the iat below 43C for a pull up to about 150mph. I only do it once a year at the track but it would be nice to show that pesky modded Z06 my taillights, lol. As it is, neither of us can pull the other one.


As far as "marketing" goes, I can "prove" the Champion 68s are better than the Proto 63s. I owned both. The Proto 63s are the best bang for the buck out there but there is more midrange punch and top end pull from the 68s. Is it worth the extra money? To me it is because I don't plan on switching from vtgs. But I emphasize, the 63s from Markski with 5 recalibrations is a deal that I would recommend to everyone. Todd never tried to upsell me from the 63s to the 65s for the reasons you mentioned. But the Champion 68s do perform better on pumpgas, and probably even more with higher octane fuel and supporting mods.

 

Added one opinion in bold above.

In the reply quoted below is an example how differently VTGs (or any turbo'd engine) can be tuned.
Ie one can stuff mismatched compressor/turbine turbos into a car and with tuning tricks plus short dyno runs still quote massive (read: IRL excessive) power gains and fast times in third/fouth gear runs. Or at 1/4 mile... Yet if that combination is pushed to the edge at one mile run the real nature of this system is revealed.



Unfortunately this test was stopped too early (at 80 mph / 130 kmh), I also would have liked to see what would have above 250 kmh (155 mph) with this turbo/IC combination. According to my own experience the IAT (with GT2 RS ICs) starts to stabilize after that with increasing airflow through the ICs. See the graph above. Total deltaT was 27C and IAT stayed well below Ign pull threshold (55C / 131F).
That airflow just can't be duplicated in chassis dyno runs, unless you perform it in a windtunnel... Engine dyno is a different animal, there you can simulate that flow increase with controlling air-to-water ICs' water temperature.

 

I thought that ignition pull etc... occurs somewhere between 43 and 50C iat? If it is indeed 55C/131F then there are other things happening in my car other than high iat causing changes in lambda, boost, timing....