I'm nearing the end of the remote tuning phase of a TVS gen 2 install on my '04 Cobra. I'm running a 2.8 pulley, 60# injectors, a VMP MAF, VMP pump booster, and a hybrid JLT RAI / some other filter housing. I did install the S-hook. I am running a 30 / 70 ratio of coolant / water, with the Water Wetter in the recommended amount, in the intercooler system. I've got an SCT X4 for datalogging, but its gauges only show IAT2 voltage (which seems dumb and pretty much useless), so I hooked up my OBD2 bluetooth adapter and started monitoring with the OBD Fusion app on my Amazon tablet.
This morning, after I got to work, I opened the app. IAT2 was at 130 and IAT1 was at 110 with the car idling. Engine coolant was at 205. I got out on the highway nearby at 65ish mph and IAT1 dropped to around 80F after a couple miles. IAT2 pretty much hung at 130. When I turned around, I got into boost a little bit and the IAT2 dropped immediately to the low 120s. I slowed and boosted a little more (like 10 psi--not WOT), and IAT2 dropped to 119-120. I tested a few more times, and boosting would drop IAT2 as low as 116, but as soon as I let out of it, IAT2 would climb back up to the low 120s.
Previously, with my 2.76-equipped Eaton, IAT2 would stay 10-15F over IAT1 under normal cruising conditions. That's definitely no longer the case.
Surely it can't be normal for IAT2 to be this much higher with a TVS.
My gut feeling is that the problem is caused by the S-hook. Here's my thread on initial problems installing the S-hook, which has pictures and an explanation of how it is supposed to work, according to VMP. https://www.svtperformance.com/forums/threads/installing-tvs-s-hook-not-flush-problem.1143639/
This is how VMP says that the S-hook affects airflow. Supposedly all air flows past the rotors, and the S-hook causes some air to be recirculated through the rotors again so that it goes through the intercooler again as well. (Pic by VMP support.)
This is how I assume that the S-hook affects airflow. Since the boost bypass is open under light throttle, air would go past the boost bypass valve and only hit a small part of the intercooler on its way into the engine. When under boost, air would go past the rotors and hit the rest of the intercooler. (Pic drawn by me.)
Based on my numbers thus far, I feel like I'm right about airflow, and VMP is wrong. Assuming that I'm right, air that's going through the boost bypass valve only hits a small portion of the intercooler, so it gets warm quickly and doesn't cool off, even when cruising. When in boost, air that goes past the rotors touches the rest of the intercooler (but presumably not the part that's blocked off by the s-hook) and gets cooled better, though not as well as it would have if there was no S-hook.
Sigh. I'm going to ask VMP support what their opinion is about my numbers, but I have a feeling I'm gonna be pulling the blower to remove the S-hook.
This morning, after I got to work, I opened the app. IAT2 was at 130 and IAT1 was at 110 with the car idling. Engine coolant was at 205. I got out on the highway nearby at 65ish mph and IAT1 dropped to around 80F after a couple miles. IAT2 pretty much hung at 130. When I turned around, I got into boost a little bit and the IAT2 dropped immediately to the low 120s. I slowed and boosted a little more (like 10 psi--not WOT), and IAT2 dropped to 119-120. I tested a few more times, and boosting would drop IAT2 as low as 116, but as soon as I let out of it, IAT2 would climb back up to the low 120s.
Previously, with my 2.76-equipped Eaton, IAT2 would stay 10-15F over IAT1 under normal cruising conditions. That's definitely no longer the case.
Surely it can't be normal for IAT2 to be this much higher with a TVS.
My gut feeling is that the problem is caused by the S-hook. Here's my thread on initial problems installing the S-hook, which has pictures and an explanation of how it is supposed to work, according to VMP. https://www.svtperformance.com/forums/threads/installing-tvs-s-hook-not-flush-problem.1143639/
This is how VMP says that the S-hook affects airflow. Supposedly all air flows past the rotors, and the S-hook causes some air to be recirculated through the rotors again so that it goes through the intercooler again as well. (Pic by VMP support.)
This is how I assume that the S-hook affects airflow. Since the boost bypass is open under light throttle, air would go past the boost bypass valve and only hit a small part of the intercooler on its way into the engine. When under boost, air would go past the rotors and hit the rest of the intercooler. (Pic drawn by me.)
Based on my numbers thus far, I feel like I'm right about airflow, and VMP is wrong. Assuming that I'm right, air that's going through the boost bypass valve only hits a small portion of the intercooler, so it gets warm quickly and doesn't cool off, even when cruising. When in boost, air that goes past the rotors touches the rest of the intercooler (but presumably not the part that's blocked off by the s-hook) and gets cooled better, though not as well as it would have if there was no S-hook.
Sigh. I'm going to ask VMP support what their opinion is about my numbers, but I have a feeling I'm gonna be pulling the blower to remove the S-hook.