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We finally go the Xonas dialed in last Friday at the track. In summary they feel amazing. Throttle modulation is fantastic and the engine basically feels like a 700whp GT3 engine. There is no sudden rush of torque down low but instead a nice smooth progressive build as rpms climb very much like a high revving normally aspirated engine. 50% throttle input gives about 50% power, and 100% input gives 100% power in a nice linear fashion. There is simply no comparison to the K16 hybrids I ran before. We tweaked the wastegates on the Xonas by softening the preload on the green spring another turn to start cracking at 7.5psi and be fully open at 13.5psi. We are running 1.3 bar which is achieved at 80% N75 duty cycle and holds all the way to the 7500 rpm redline. 1.5 or 1.6 bar would be easily achievable in this configuration with a race gas file at 85 or 90% N75 duty cycle. It's super easy to drive at the track....
Interesting, why do you think that Tial put in the stiffer springs initially if they proved horrible to drive with?
Tial makes turbochargers but does not really have any idea on the application of the end users. The XR980 3073 turbos I have are typically run by straight line guys at up to 2.0 bar and as such the blue springs are more appropriate for that application. Tial told me that we are basically blazing the trail using these for a low boost road course application and have given them a lot of feedback on how we have managed to set these up. The XR980 and XR770 have different compressors, turbines, cases and also slightly different wastegates, larger on all accounts with the XR980. At its lowest setting, wastegates with the blue springs crack at 11-12 psi on the XR770 while they crack at 14-15 on the XR980. No matter how you slice it, if your waste gate does not crack till 15psi, you have absolutely no boost control mechanically below that amount. You can control boost to a certain degree via timing but to do it correctly you need to have the hardware side working properly and use your tune to fine tune the whole set up. My engine builder told me this from the get go and Tial also confirmed this. With the gates cracking at 15psi, the car was undriveable.
To answer your other question, yes, my engine is built. Hope this helps....
I also remember pwd is running the larger 3071 turbos would the the same waste gate settings apply to the the smaller 2871 turbos?
I have the smaller xona xr770's. I think they are 28 frame 68mm compressors. I setup mine almost exactly the same as John with the green wastegate. I can confirm, that this is the way to do it if your goal is 1.2-1.3 bar. Read my first post...
I have the smaller xona xr770's. I think they are 28 frame 68mm compressors. I setup mine almost exactly the same as John with the green wastegate. I can confirm, that this is the way to do it if your goal is 1.2-1.3 bar. Read my first post...
Originally Posted by pwdrhound
Tial makes turbochargers but does not really have any idea on the application of the end users. The XR980 3073 turbos I have are typically run by straight line guys at up to 2.0 bar and as such the blue springs are more appropriate for that application. Tial told me that we are basically blazing the trail using these for a low boost road course application and have given them a lot of feedback on how we have managed to set these up. The XR980 and XR770 have different compressors, turbines, cases and also slightly different wastegates, larger on all accounts with the XR980. At its lowest setting, wastegates with the blue springs crack at 11-12 psi on the XR770 while they crack at 14-15 on the XR980. No matter how you slice it, if your waste gate does not crack till 15psi, you have absolutely no boost control mechanically below that amount. You can control boost to a certain degree via timing but to do it correctly you need to have the hardware side working properly and use your tune to fine tune the whole set up. My engine builder told me this from the get go and Tial also confirmed this. With the gates cracking at 15psi, the car was undriveable.
To answer your other question, yes, my engine is built. Hope this helps....
I have the XR770's on my engine build (3.8, Carrilo Rods and ARP Headstuds).
The trans is also built.
Which spring should I run in the waste gates? The green ? Then again, I don't have to worry about bending rods.
How much boost are you going to run? The green only gets to 1.25 bar on my car with something like 70% duty cycle on the n75. Honestly, I'd start with the green springs and tune, if you need more wastegate, you can add more spring. It's not that hard to do with the turbos on the car.
Weird John gets more than that from his xr980 and so do I from my xr770, we both run green. My advice is still the same, you want to control the output, start low, add more spring if tuning can't get to your peak goal
Weird John gets more than that from his xr980 and so do I from my xr770, we both run green. My advice is still the same, you want to control the output, start low, add more spring if tuning can't get to your peak goal
I get 1.35 bar at 85% N75 duty cycle with the green springs. My WG is set up to start cracking at 7.5psi and fully open by 13.5psi.
Last edited by pwdrhound; Mar 26, 2020 at 02:49 PM.
Here is a Mustang Dyno from 2008 of old school K24/18G's (before the billet versions) with full supporting mods on my 996TT. I am not an expert on dynos by any means, so I am not sure if this is a good or bad looking dyno, but have always thought the car was very responsive down low and made good power up top, too. Since you are discussing dynos, I thought some of you may find it interesting, as a turbo comparison data point.
