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Our cars have Coolant running through the Throttle Body, thus heating up the Throttle Body. When installing a Cold Air Intake (CAI), you are bringing cold air into the engine, thus giving the car more power.
With the throttle body being heated, that cold air can warm up, thus not getting the best results possible out of a CAI. Bypassing the coolant passage way can help the air keep colder.
CarBibles.com mentions this as an important mod to consider when you install a Cold Air Intake. Source
Quote:
Throttle body heater bypass
Cold air induction kits work pretty well but you need to do your homework first. A lot of cars have throttle body heaters, whereby coolant from the engine is circulated around the throttle body casing. The idea is to warm up the throttle body to prevent icing in cold weather. The problem is that these systems are hard-wired and don't take account of external air temperature, so even in the heat of summer, hot coolant is routed around the throttle body. This is a problem for CAI kits because you've gone to all the trouble of putting a nice kit in to suck cooler air into the engine, but at the final hurdle it runs through a 75°C throttle body which heats it up again, negating the whole point of the CAI kit in the first place. The solution to this is a throttle body heater bypass, which essentially involves pulling the coolant hoses off either side of the throttle body and patching them together with a length of copper pipe and two hose clamps. When you do this, the throttle body stays at ambient temperature and the CAI kit gets a chance to do its job. The only downside to this is if you live in a cold, humid climate, you might suffer from icing in the winter. But hey - if you do, reconnect the coolant hoses for the winter...
WARNING! The coolant was designed to run through the throttle body for a reason, to keep the butterfly from freezing shut or open and to keep the coolant temperatures lower. If you live in a cold area, I would avoid doing this. I personally will go back to stock in the winter.
I will honestly say it is not too great of an idea to go this route with a Daily Driver car. A better choice is to go with the ThermoBlok Spacer Kit. They have a Intake Manifold/TB spacer. This will give you bigger power gains and a piece of mind
This is a fairly simple mod that shouldn't take longer then an hour to install :bigthumbup:
Items Needed
Pliers
1 1/4" Hose Coupler (3/8" might work better)
2 Hose Clamps (You might get away with stock ones with 3/8" Coupler)
2 Rubber Caps to block off old pipe.
Screw Driver
Steps
Take out the Intake to free up some space, disconnect the TPS and other Sensor
Locate the the two hoses that send the coolant to the Throttle Body
Disconnect the two coolant hoses
Then cap off the two coolant lines
Put in the coupler into the one end of the hose and tighten the clamp
Plug the other end of the couple into the other hose and tighten the clamp
Finished Product
Now I noticed that my water temperature was higher then normal. So that means that the intake does actually cool the water pretty well. I think Redline Water Wetter might do the trick at keeping the water temperatures down though. :bigthumbup:
Onto some numbers, now these are not 100% accurate and are not dyno proven. These numbers are from ScanGauge II, and are BHP numbers.
Base Number: 159 BHP (15% Drivetrain Loss 138 WHP) with 82*F Intake Air Temperature After Number 164 BHP (15% Drivetrain Loss 142 WHP)with 83*F Intake Air Temperature
IF you have any suggestions let me know! :bigthumbup:
Base Number: 159 BHP (15% Drive Terrain Loss 138 WHP) with 82*F Intake Air Temperature
After Number 164 BHP (15% Drive Terrain Loss 142 WHP)with 83*F Intake Air Temperature
anyone experienced idle issues after doing this mod? i had bad idle so put it back to normal and its fine
doing this should not effect your idle.
i could theoretically see the air entering your mani being more dense and messing with the IACV reading. but thats VERY hypothetical.
did you unplug any of your vac lines when you did this, then happen to forget to put them back in.
__________________
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So I really like this "How To" a lot. I've got an SR20de RR with an SRI. I don't know if I would do this mod, but I might. I work in the aviation business (Air Force actually) and one of the planes I flew was the DA-20. We have to study the systems pretty in depth. One thing that I liked about the plane was that it had something called a Vernatherm, which is just a thermal actuator.
So to get to my point, a lot of ppl won't do this mod for fear of their butterfly freezing open/closed. But what if there was a way to control when the coolant would flow through the throttle and when it wouldn't? The Vernatherm is operated by temperature. If it could be made to fit the the tube housing it could possibly work. I'm not as technically inclined as most on this forum, but I just thought I would add some food-for-thought and maybe be a segway to making this mod even more reliable for daily drivers.
So I really like this "How To" a lot. I've got an SR20de RR with an SRI. I don't know if I would do this mod, but I might. I work in the aviation business (Air Force actually) and one of the planes I flew was the DA-20. We have to study the systems pretty in depth. One thing that I liked about the plane was that it had something called a Vernatherm, which is just a thermal actuator.
So to get to my point, a lot of ppl won't do this mod for fear of their butterfly freezing open/closed. But what if there was a way to control when the coolant would flow through the throttle and when it wouldn't? The Vernatherm is operated by temperature. If it could be made to fit the the tube housing it could possibly work. I'm not as technically inclined as most on this forum, but I just thought I would add some food-for-thought and maybe be a segway to making this mod even more reliable for daily drivers.
VQ35 motors have kits with thermal actuators for the bypass, they work just as you might expect - can't beat them for hands-off, no hassle operation. My personal favorite, the simple brass valve you turn one way for normal operation, another way for bypass. Since that is seasonal if it is an issue, that approach to me seems best. The bypass works the same way as our Sr20's, for the same reasons.
These TB heaters really heat the intake, I have COBB AP and monitoring the IAT and Coolant temp in realtime, sitting still at normal op temp at idle, the IAT was easily 140+ deg F while the coolant temp was ~199 deg F. Thankfully the G has a reasonable and effective hybrid CAI, an enclosure that grabs air from centerline of the car over to the filter - Nissan "Power Duct", a classic name. It pulls outside air, just not enough at idle to overcome heat soak from the motor and the coolant pumping nearly 200 deg fluid around the TB.
Once moving, temps quickly dropped to ambient +10 deg F, so it works pretty well.
stock:
today: Once you close the hood, 99% of intake air is coming from outside and the realtime IAT shows it:
VQ35 motors have kits with thermal actuators for the bypass, they work just as you might expect - can't beat them for hands-off, no hassle operation. My personal favorite, the simple brass valve you turn one way for normal operation, another way for bypass. Since that is seasonal if it is an issue, that approach to me seems best. The bypass works the same way as our Sr20's, for the same reasons.
These TB heaters really heat the intake, I have COBB AP and monitoring the IAT and Coolant temp in realtime, sitting still at normal op temp at idle, the IAT was easily 140+ deg F while the coolant temp was ~199 deg F. Thankfully the G has a reasonable and effective hybrid CAI, an enclosure that grabs air from centerline of the car over to the filter - Nissan "Power Duct", a classic name. It pulls outside air, just not enough at idle to overcome heat soak from the motor and the coolant pumping nearly 200 deg fluid around the TB.
Once moving, temps quickly dropped to ambient +10 deg F, so it works pretty well.
stock:
today: Once you close the hood, 99% of intake air is coming from outside and the realtime IAT shows it:
Nice! I do like the brass valve idea. I've thought about it, but that's about as far as I've gotten. And for a couple more bucks than the regular throttle body heater bypass, it can be a bit "safer" for the car, especially if you live somewhere with actual seasons.
I should mention that bypassing the throttle body lead to higher coolant temperatures. So even if you have a temperature activated TB bypass, it would bypass it in the summer when you need the intake to cool the coolant.
Right now with heating issues on a DET, I would NEVER do a TB bypass hehe.
I respectfully disagree. Unless you are already running your coolant system at its max capacity (producing as much heat as it can handle), it shouldn't matter at all.
Given the extremely small % volume/time of coolant that passes the intake, how much cooling takes place there compared to the rest of the cooling system?
IDK but I don't believe the primary or even secondary function of the TB coolant loop is to cool the motor. That big-ass Koyo in front of mine does that job all on its own just fine. Even after back to back (2 drivers) sessions and hours of track time last week in 70-ish weather with ~65% humidity, running 90% of the time well above 5000 rpm not a hint of overheating. I have A/C, but I also have the UD pulley on the water pump, which by avoiding cavitation is a significant help when running extended time at high rpm's.
The only reason I have ever seen cited by credible sources for the coolant loop is to keep the TB warm in cooler weather. Also given this change is mostly done by people in warmer climates, I can't see how it would matter - if the motor runs hot, it's not going to be changed much there.
i saw this part :
"Now I noticed that my water temperature was higher then normal. So that means that the intake does actually cool the water pretty well. I think Redline Water Wetter might do the trick at keeping the water temperatures down though."
I'm planning to do this on my VE. I live in Malaysia. It does gets pretty hot out here (32-35 degrees C)...Would it be a good idea to do it if its gonna raise the water temp higher than normal??
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. In your case I would really consider a ThermoBlok kit, it will be more useful 
