I agree the .2 ics are really good, the thread title wasn't meant to be misleading. I am learning though that there may not be a good practical affordable intercooler that would be of value in my particular case. Perhaps a tapering boost curve would keep my iats and egts cooler and it may not even affect performance that much. I will ask Dzenno at some point. Currently peak boost is held from about 4k rpm to redline. This is where dyno pulls and pbox data will be of value (i.e. to see if it is actually worthwhile working the turbos to keep boost up all the way)

 

I would love to buy them if I could find the so called proven performance graphs comparing iats vs the .2 intercoolers.

 

Yes, but what I was trying to say was that, even if there was an IC that would lower your IAT's to ambient, it won't really help. Your EGT's are still to high if you are pushing VTG's out of their comfort zone. Even a magic IC (for 5k it should be) isn't improving backpressure and exhaust temps.

Meth on the other hand helps with IAT's AND EGT's + detonation (higher effective octane to support a un-retarded timing curve and prevents knock)

 

I need to check egts to see what's going on. And to muddy the waters further, there was a thread on Rennlist and here somewhere too where a guy mentioned that the EGT probes were "faulty" and reading too high which led to timing pull, rich lambdas, dropped boost. Apparently the current exhaust temp probe is on revision 5. The only problem is that they are like 800 bucks each probe so I'm not terribly interested in trying it out.


The underlying problem may be trying to get too much out of the vtgs at the track. For the street there is no issue at all. Not too often where you can get anywhere close to 140mph so maybe I will just leave things as is, and get a slightly detuned version of the file for track day. But first I will log egts and hopefully the Cobb AP can do it, otherwise I'll have to break out the old laptop.

 

Remember when my car was down for almost two months with low boost issues and a certain shop couldn't find it during that time?


Well when I took my car to Engineered Automotive, within two days they found what was causing my issues of low boost was one of my EGT probes where bad. It was reading 500 degrees and as soon as you touched the throttle it would shoot up to 1100 degrees. What was happening is that on driver side bank it would cause the ECU to think it was running real lean and cause the car to shut boost down below .6BAR and literally flood that side of the engine to 9.4 AF.


Todd has a whole bunch of these sensors sitting around, as most of his customers do non VGT turbo upgrades and they do not use these sensors.


Trust me if one of those EGT probes starts dying on you, you will feel you are driving a N/A car one moment and then bang, beast mode again of boost, but when it fully dies on you, you have almost a N/A 911 all the time until EGT is replaced!


Couldn't believe such a simple thing cause me so much turmoil, but even Todd K said the guys at Engineered Automotive must know what they are doing to find that issue so quickly and precisely!

 

Yeah I was thinking of you Bobby when I read about the egt sensor probe. Do you know which version you got from Todd? I understand the latest version is version 5


I'm not having any boost issues at the moment. When I was at the track the boost got pulled back a little bit at the top and iats were a little bit high. But since then I've read about other people's cars with way higher iats. I need to see what the egts are doing. Again, this was only an "issue" 1 day of the year at the track. I just have to be prepared for next year in case my friend with the c7 z06 shows up with more power, lol

 

You'll obviously need to speak to 9e about their "fix" for VTGS and I know they insist you have to start with OEM GT2 VTGS to start with as they have a few unique properties.

Having hybrids with 997.1 housing is fine for street use but on track or mile events etc they'll always pull timing after a few runs. Run these modded cars based on 997.1 turbos and after a few runs they're often slower than stock cars believe it or not.

Remember GT2 is a track car and its turbos are designed for track use.

GT2 and GT2 RS turbos are identical but even these will suffer from too much back pressure if not tuned properly. Run too much boost and the ECU will also pull timing.

 

I love that completion spirit!!




Concerning which version it is, I remember Todd saying that there are different versions and the one he is sending me came off a car that had only 1600miles on it. To tell you the truth I do not remember what he said about which version he shipped me, as at the time I didn't care as I just wanted my car to work and see what was causing the issue.... didn't care about anything else.

 

Your high IATs are a consequence of way too high EGTs. Yes, better intercooler can help with this situation, but this is only a bandaid. The problem will still come up, just a few seconds later.

Exhaust backpressure is way too high on these turbos and hence temperature is building up in the system. Timing is being pulled dramatically and at the same time fuel gets dumped to the problem by the ECU. This in turn makes the problem even worse, because you have a late very rich burning that is directed more into the exhaust as before. More heat.

48C IAT is nothing that makes the ECU react. The problem goes deeper and a good tuner can help with it, but you can't really fix it because it is a physical limitation of the turbos. GT2 hot sides don't help much.

In my opinion water/meth is the only thing worth a try if you want that power level. Or lowering boost, but if you turn it up again, the problem will show again.

 

^^^ There is no fix especially for regular 997.1 based turbos. Its the larger 68mm compressor wheel exceeding the capability of the hotside not the 68mm hybrid VTG exceeding the capability of the GT2 RS intercooler.

I believe this is why we have never seen logs and VBOX for 68mm VTG turbos all the way to 300kph and beyond. They do not work efficiently beyond 300 kph as far too much heat and back pressure!

GT2 based VTGS hybrids bit better but I agree even they suffer exactly the same issues if run hard with high boost. Wish certain people would just put their hands up and admit it rather than feeding us snake oil about 885 whp VTG builds based on a few secs on a third gear pull on an overly optimistic dyno. Even these 775bhp packages are running 640bhp at best.

Seems as though everyone waking up to the BS.

 

E85 helps as well for similar reasons as meth/water. Best is of course to do both E85 and meth/water is an efficent workaround for a exhaust side choked engine.

But it would be great if a vendor would build a set of turbos with better flowing turbine side but still keeping boost control in the dme. Not sure if it's a viable approach though.

 

In fact temperatures go down a little if you keep the car running. I did tests with speeds up to 335-340 kph (210 mph) and if you know what to do, everything stays stable. I also kept that speed for a while and temps are stabilizing and even go down after a while.

There is a heatwave going thru the car, that you even can see in a single 100-200 run. Watch your outside temp immediately after a run. The sensor sits near the front coolers and goes up 1-2 C because of the heatwave rushing thru the coolers.

I did well over 1500 miles of logging, programming, logging and so on and know pretty well what's going on. As if the temperature is not enough of a problem, there also is a very knock sensitive area around 5200 rpm that keeps you from going higher with boost and/or timing (the reason for this is not temperature). Raise it too early and you run into knocking and recovering from that takes way too long. You end up running low timing for too long and when it recovers, it is time to change the gear.

Needless to say, that low timing and low boost are both not helpful for creating power.

There are ways to make these cars fly, but it is a quite complex system.

 

Yes 9e have run their 9e 28 package based on GT2 VTGS to 205 mph within 1.3 miles and IATS/EGTS all under control over 50 back to back runs. 0-300kph run in circa 26 secs. I do not believe VTGS can run much quicker time 0-300 kph personally. You may be able to knock a second or so off that 0-300kph time with a built engine but thats about it. Impressed you managed to get 210mph out of your VTGS. Not heard of a VTG set up run faster than this although I think my set up may be good enough for 210mph not had enough space to run her up to 210mph and hopefully beyond yet!

 

I've been told different numbers from 43 to 50 to 55. I'm not sure what the true number is for iat before the ECU reacts.


Anyway, I think I owe the intercoolers an apology, lol. Xbox may have been right about the title after all. It now makes more sense to me that egts would be too high. I am running catless and I believe the exhaust is at least 2.5 inches (AWE gen 2). The turbine wheel is "clipped" just like it is in the GT2. The GT2 has a bigger turbine and slightly different entry geometry into the turbine housing, but the Champion 68s do something similar to the entry geometry if I understood correctly. Beyond that I don't think there is much more different with the GT2 housing.


I don't really have much to say about the dyno hype of any of the vtg hybrids because I was never a part of it. I am quite happy with the performance of the hybrid vtgs because I can only rarely exceed 200km/hr. If I was in the UK at those airport events or on the autobahn and wanted max speed then I'd either get different turbos or just turn down the boost a tad. I will experiment with a track version of the tune next year and back off on the boost so that there is minimal intervention by the ECU up to about 250km/hr. Hopefully that doesn't mean zero boost, lol.

 

Here is a vid that shows one part of our temp tests. Basically some runs above 200 km/h and then 200-300. One goes to 307 and the other one to 323. A friend of mine was sitting next to me with a Porsche tester and we were looking at the exhaust temps while I was doing some pulls. This was just a temp test, so no contest at all.

The car was pulling strong to 323 and would have pulled higher, but I saw a suspicious car in front and I slowed down a little to 280 - then he pulled over I had to test the brakes

That's about 3 minutes of different heat levels at Autobahn speeds. Completely different to single 1/4 mile runs or short highway pulls.

This is a heavy 997.1 cabriolet running 100-200 in 6.1 seconds.