IAT2 weirdness after TVS install. Caused by S-hook?

TheFleshRocket

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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.)
supercharger_airflow_vmp.jpg


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.)
supercharger_airflow_tfr.jpg


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.
 

94slowbra1

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in for results. i installed my VMP recently and did install the s-hook. would like to know if it hurting or helping.
 

TheFleshRocket

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in for results. i installed my VMP recently and did install the s-hook. would like to know if it hurting or helping.

Would you mind checking your IAT1 and IAT2 and see if they behave similarly to mine? IE, IAT2 is pretty high under cruising but drops somewhat under mild boost?
 

TheFleshRocket

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Could I have screwed up anything when I filled the intercooler? I filled the reservoir with the engine off. After starting the engine, it sucked in all the fluid so I filled it up. I watched until the intercooler pump kicked on and then topped it off. Since then, the coolant level has stayed at the full line.
 

TheFleshRocket

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The pen drawing you made. No air will come from that area under boost.

Could you clarify? In my pen drawing, when not in boost, I assume air will enter the engine through the boost bypass valve, and when in boost, the boost bypass valve will close and all air will go past the rotors. What's not correct?
 

Black02GT

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Could you clarify? In my pen drawing, when not in boost, I assume air will enter the engine through the boost bypass valve, and when in boost, the boost bypass valve will close and all air will go past the rotors. What's not correct?

I think the term "bypass" valve is misleading and makes you think the air bypasses the rotors (your drawing). The rotors move at a fixed rate based on RPM and move a fixed amount of air. When the valve is open it allows air from the lower intake back into the inlet side of the blower so the air isn't backed up in the lower intake and create boost. VMP drawing is correct, the concept from my understanding is the s-hook forces the air through the IC when the bypass valve is open. Without it the bypass valve can be sucking air from the space between the bottom of the blower but above the IC recirculating none cooled charge back through the hot blower again. All the air always goes through the rotors I (at least that's my understanding). Essentially a closed loop boost leak.

The reason why the IAT is hotter in boost isn't so much the air being heated by the blower as the thermodynamics of compressing air Pv=nrt where temperature is proportion to pressure.

Sorry for any bad spelling/grammer on my phone.
 
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whitedevil95

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I think the term "bypass" valve is misleading and makes you think the air bypasses the rotors (your drawing). The rotors move at a fixed rate based on RPM and move a fixed amount of air. When the valve is open it allows air from the lower intake back into the inlet side of the blower so the air isn't backed up in the lower intake and create boost. VMP drawing is correct, the concept from my understanding is the s-hook forces the air through the IC when the bypass valve is open. Without it the bypass valve can be sucking air from the space between the bottom of the blower but above the IC recirculating none cooled charge back through the hot blower again. All the air always goes through the rotors I (at least that's my understanding). Essentially a closed loop boost leak.

The reason why the IAT is hotter in boost isn't so much the air being heated by the blower as the thermodynamics of compressing air Pv=nrt where temperature is proportion to pressure.

Sorry for any bad spelling/grammer on my phone.

Yeah I agree with him. Based on my knowlege of the blower the VMP drawing is correct.
 

TheFleshRocket

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I think the term "bypass" valve is misleading and makes you think the air bypasses the rotors (your drawing). When the valve is open it allows air from the lower intake back into the inlet side of the blower so the air isn't backed up in the lower intake and create boost. VMP drawing is correct, the concept from my understanding is the s-hook forces the air through the IC when the bypass valve is open.

Thanks for the explanation. Assuming that VMP is correct, why might my IAT2 so much farther above IAT1 than it was when I was running the 2.76 Eaton?
 

whitedevil95

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As someone who has had aeroforce gauges in car since it was stock I have watched my charge temps for a long time. They vary quite a bit depending on how open the throttle blade is, ambient temps, engine temps, and air flow to IC. I am assuming it probably pretty warm where you are because its august. Maybe the last time you checked it was cooler out or you were on the freeway?
 

TheFleshRocket

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It's 80F here right now. While cruising at highway speeds a little bit ago, IAT1 a little bit ago was about 88F, and IAT2 was around 125F. This is with good airflow, low load, light throttle--pretty much the optimum conditions for IAT2 to be as close to IAT1 as possible.

How far *should* IAT2 be above IAT1 for a car like mine in conditions similar to mine?

Is there any trick to filling the intercooler coolant?
 

BLOWN9646

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It's 80F here right now. While cruising at highway speeds a little bit ago, IAT1 a little bit ago was about 88F, and IAT2 was around 125F. This is with good airflow, low load, light throttle--pretty much the optimum conditions for IAT2 to be as close to IAT1 as possible.

How far *should* IAT2 be above IAT1 for a car like mine in conditions similar to mine?

Is there any trick to filling the intercooler coolant?

My iat2s are usually always ~30-35deg over iat1 in warmer weather
 

TheFleshRocket

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My iat2s are usually always ~30-35deg over iat1 in warmer weather

Fair enough, but your sig says "04 Cobra - ported e85", so I'm guessing that you're overspinning the Eaton a lot. 16-17 PSI, perhaps? I feel like the TVS, with the S-hook that is specifically supposed to lower IAT2 under non-boost conditions, should have IAT2 temps that are a lot lower than an Eaton, especially one that's being overspun.
 

Black02GT

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It's 80F here right now. While cruising at highway speeds a little bit ago, IAT1 a little bit ago was about 88F, and IAT2 was around 125F. This is with good airflow, low load, light throttle--pretty much the optimum conditions for IAT2 to be as close to IAT1 as possible.

How far *should* IAT2 be above IAT1 for a car like mine in conditions similar to mine?

Is there any trick to filling the intercooler coolant?

While I can not answer your question about the temperature delta directly I can add a little more science as too why it would make sense IAT2 (out of boost) would be higher with a bigger blower that's running at a higher boost level (when in boost). If the amount of cold air coming in is fixed by the amount of air the engine is ingesting (and the same as with your Eaton since the engine setup is the same) but you increase the amount of air the blower is moving with a bigger blower, the amount of air that will re-cycle through the blower via the bypass valve will increase and there fore allow more time for heat from the blower casing and intake manifold to absorb. Especially since out of boost the cold air from the filter is being mixed with the hot bypass air not replacing it. In boost the new cold air is essentially replacing the hot air.

Without turning this into a calculus class there is a math problem where you pop a hole in the bottom of a tank of salt water that is being stirred and start pouring fresh water in the top. The amount of salt doesn't go down linearly because your also letting some of the fresh water out the bottom as you mix it. The math works similar to a half life (but not exponential), if you really want to know look up "differential mixing problems" and picture heat as salt and the cold air as the fresh water, the bypass becomes the mixer. When in boost you essentially stop mixing the tank (yes, over simplification if @James Snover comes out of hiding and pops in here).
 
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TheFleshRocket

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Haven't read the above post yet, but will.

I just went out for quick highway run with a buddy in the car watching the AFR and IAT2. IAT2 started out around 150 (car had been parked hot and heat soaked), and we drove about 5 miles until it was down to about 130. We turned around and I gave it WOT in second, and it started breaking up pretty badly around 3500-4000 so I let it. I tried again a couple miles down the road, I tried in third and the same thing happened. Plugs are NGK TR6ix that have been in the car for 20K miles, so I'm going to pull a couple after letting the engine cool overnight to see what kind of condition they are in.

BUT, after getting back, we touched the intercooler hoses. The two that go to the reservoir were warm to the touch, but the one that comes out of the heat exchanger on the passenger side of the car was cool. My buddy thinks that I may have an air pocket in the heat exchanger--the same thing happened to his GT500 when he had an Afco installed. So I've got to figure out how to burp it to get the air pocket out.
 

Black02GT

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Haven't read the above post yet, but will.

I just went out for quick highway run with a buddy in the car watching the AFR and IAT2. IAT2 started out around 150 (car had been parked hot and heat soaked), and we drove about 5 miles until it was down to about 130. We turned around and I gave it WOT in second, and it started breaking up pretty badly around 3500-4000 so I let it. I tried again a couple miles down the road, I tried in third and the same thing happened. Plugs are NGK TR6ix that have been in the car for 20K miles, so I'm going to pull a couple after letting the engine cool overnight to see what kind of condition they are in.

BUT, after getting back, we touched the intercooler hoses. The two that go to the reservoir were warm to the touch, but the one that comes out of the heat exchanger on the passenger side of the car was cool. My buddy thinks that I may have an air pocket in the heat exchanger--the same thing happened to his GT500 when he had an Afco installed. So I've got to figure out how to burp it to get the air pocket out.

Is coolant running back to the tank? Should be able to see motion.
 

BLOWN9646

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Haven't read the above post yet, but will.

I just went out for quick highway run with a buddy in the car watching the AFR and IAT2. IAT2 started out around 150 (car had been parked hot and heat soaked), and we drove about 5 miles until it was down to about 130. We turned around and I gave it WOT in second, and it started breaking up pretty badly around 3500-4000 so I let it. I tried again a couple miles down the road, I tried in third and the same thing happened. Plugs are NGK TR6ix that have been in the car for 20K miles, so I'm going to pull a couple after letting the engine cool overnight to see what kind of condition they are in.

BUT, after getting back, we touched the intercooler hoses. The two that go to the reservoir were warm to the touch, but the one that comes out of the heat exchanger on the passenger side of the car was cool. My buddy thinks that I may have an air pocket in the heat exchanger--the same thing happened to his GT500 when he had an Afco installed. So I've got to figure out how to burp it to get the air pocket out.
Did u jumper the relay?
 

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