HOW TO: B14 Throttle Body Heater Bypass

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 (http://www.carbibles.com/fuel_engine_bible_pg2.html)
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 (http://www.sr20-forum.com/showthread.php?t=9874). 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

http://i160.photobucket.com/albums/t188/covertrussian/Sentra%20SE-L/Performance/Throttle%20Body%20Coolant%20Bypass/CIMG2050-1.jpg



Steps

Take out the Intake to free up some space, disconnect the TPS and other Sensor
http://i160.photobucket.com/albums/t188/covertrussian/Sentra%20SE-L/Performance/Throttle%20Body%20Coolant%20Bypass/CIMG2051.jpg
http://i160.photobucket.com/albums/t188/covertrussian/Sentra%20SE-L/Performance/Throttle%20Body%20Coolant%20Bypass/CIMG2055.jpg

Locate the the two hoses that send the coolant to the Throttle Body
http://i160.photobucket.com/albums/t188/covertrussian/Sentra%20SE-L/Performance/Throttle%20Body%20Coolant%20Bypass/CIMG2054.jpg
http://i160.photobucket.com/albums/t188/covertrussian/Sentra%20SE-L/Performance/Throttle%20Body%20Coolant%20Bypass/CIMG2052.jpg
http://i160.photobucket.com/albums/t188/covertrussian/Sentra%20SE-L/Performance/Throttle%20Body%20Coolant%20Bypass/CIMG2053.jpg

Disconnect the two coolant hoses
http://i160.photobucket.com/albums/t188/covertrussian/Sentra%20SE-L/Performance/Throttle%20Body%20Coolant%20Bypass/CIMG2057.jpg

Then cap off the two coolant lines
http://i160.photobucket.com/albums/t188/covertrussian/Sentra%20SE-L/Performance/Throttle%20Body%20Coolant%20Bypass/CIMG2058.jpg
http://i160.photobucket.com/albums/t188/covertrussian/Sentra%20SE-L/Performance/Throttle%20Body%20Coolant%20Bypass/CIMG2060.jpg

Put in the coupler into the one end of the hose and tighten the clamp
http://i160.photobucket.com/albums/t188/covertrussian/Sentra%20SE-L/Performance/Throttle%20Body%20Coolant%20Bypass/CIMG2064.jpg

Plug the other end of the couple into the other hose and tighten the clamp
http://i160.photobucket.com/albums/t188/covertrussian/Sentra%20SE-L/Performance/Throttle%20Body%20Coolant%20Bypass/CIMG2065.jpg

Finished Product
http://i160.photobucket.com/albums/t188/covertrussian/Sentra%20SE-L/Performance/Throttle%20Body%20Coolant%20Bypass/CIMG2069.jpg


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 (http://gofastdepot.com/store/catalog/product_info.php?products_id=51) 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:

anyone experienced idle issues after doing this mod? i had bad idle so put it back to normal and its fine

anyone experienced idle issues after doing this mod? i had bad idle so put it back to normal and its fine

Hmm weird!

It's a better idea to go with Thermoblock spacers (http://www.sr20forum.com/group-buys/239105-thermoblock-spacer-groupbuy.html), they will benefit you way better and are safer not to have icing...

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

the temp went up...

and do you mean drivetrain not drive terrain...?

Good pics.. been thinking about doing this since the car no longer drives in freezing temps (sunny ca).

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.

and to CovertRussian, the b13 is the same way

the temp went up...

and do you mean drivetrain not drive terrain...?

See this thread took a while to get approved. I already made changes to the thread on the Dash, but didn't get a chance to post them up here haha.

Good pics.. been thinking about doing this since the car no longer drives in freezing temps (sunny ca).

Thanks :). In your case I would really consider a ThermoBlok kit, it will be more useful :biggthump

and to CovertRussian, the b13 is the same way

Yep I recently found this out, because I now have a highport :biggthump

I've considered it.. but installation would be a pain... or expensive. I can do this for less than 20 bucks. Bang!

I've considered it.. but installation would be a pain... or expensive. I can do this for less than 20 bucks. Bang!

Haha good point, if you have a low port, I suggest doing the same for the IACV heater :biggthump

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.

Here is some information on the actuators:

http://www.rostravernatherm.com/thermal-actuators.htm

Thanks again for a great mod/how to

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.

Here is some information on the actuators:

http://www.rostravernatherm.com/thermal-actuators.htm

Thanks again for a great mod/how to

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:
http://homepage.mac.com/stracy01/.Pictures/Photo%20Album%20Pictures/2003-12-30%2008.53.32%20-0800/Image-4789D71B3AE811D8.jpg

today: Once you close the hood, 99% of intake air is coming from outside and the realtime IAT shows it:

http://homepage.mac.com/stracy01/.Pictures/V35_Intake/IntakeSept0704.jpg

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:
http://homepage.mac.com/stracy01/.Pictures/Photo%20Album%20Pictures/2003-12-30%2008.53.32%20-0800/Image-4789D71B3AE811D8.jpg

today: Once you close the hood, 99% of intake air is coming from outside and the realtime IAT shows it:

http://homepage.mac.com/stracy01/.Pictures/V35_Intake/IntakeSept0704.jpg


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 honestly saw up to 10*F increased water temperatures read directly from the ECU. This was on my NA motor.

Results may vary though :rofl:

A heated TB also reduces emissions I believe.

guys,

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??

i think you'll be fine

Did the bypass..the throttle feels lighter resulting in a better response..tried it the other day with 99 octane gas...pretty sweet!!.. :)