Coolant Bypass

Cobb: "Removing the coolant lines to the throttle body is proving to be a "significant" modification as far as the ECU is concerned. Removing these coolant lines will likely allow for poorer fuel economy as another side effect. As will setting your fans to turn on at colder coolant temperatures. Combustion chambers are more effective at warmer temperatures and having coolant warm up your throttle body helps increase the intake air temperatures to a more efficient temperature for internal combustion. We are just stating this so you have an understanding that much of what Honda did was done correctly for a performance street vehicle. We are simply trying to do our best to explain what could be going on with your vehicle after a recent mechanical change."
 
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Getting an intake "ruins" your car internally also, but who cares. As well as other parts. To each their own opinion and facts. Anyone and everyone can do as they please. All cars from manufacture are "good" from the factory and have gone through engineering. So it's like telling everyone to keep their cars stock and not to mod it.
 
Just wanted to put it out there since its a very common "mod" to k series(since i go on k20a.org and 8thcivic.com), people with cold airs/intakes, aftermarket TB's, etc.
 
I don't really understand what Cobb is trying to say. There are so many cars with Cold Air Intakes and Aftercooled superchargers and Intercooled turbos. These put so much cold air in the engine. And Cobb doesn't like the idea of 'cooled' throttle body?

I think VitViper can help everyone who's thinking about doing this coolant bypass.
 
judging by some quick calculations, air is moving so fast past the throttle body that it probably doesn't have a chance to heat up. that's probably why you don't see much in terms of gains. For example, let's take a look at the k24 in the Si. since it's a 4-stroke motor, it takes two revolutions to inhale 2.4 L worth of air, or 1.2L/revolution. so for 1000 revolutions, the engine would inhale 1200 L. thus, at 1000rpm, the engine is moving 1200L of air every minute. this works out to approximately 42.38 cubic feet of air every minute. with a 64mm throttle body opening, the throttle body has a cross-sectional area of about 4.99 square inches, which is equivalent to about 0.03 square feet. if you divide the 42.38 cubic feet of air by the cross-sectional area of the throttle body, you see that the air needs to move at 1223.82 feet per minute (the equivalent of 13.91 mph), just to deliver the 1200L/min that the engine uses at 1000 rpm. Basically, this means that at just 1,000 rpm, air is rushing past the throttle body at almost 14mph. At 7,000 rpm, air has to move past the throttle body at 97.35 mph to deliver the 8400L of air that the engine displaces every minute. so although the throttle body is being heated by the coolant lines, the air doesn't stay in that small area long enough for it to make a difference.

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of course, the engine isn't 100% efficient, so it won't always suck in exactly 100% of the displacement (especially at very high rpms), but you guys get the idea.
 
We've been doing this mod for years, it won't hurt economy in the least. The mod is mainly to prevent heat soak -- you know, that thing that happens when you're hard on the throttle frequently or sit in traffic a lot?

For those of you who don't believe in heat soak... try spending an hour or two tuning, then stop and let the car cool off for 5-10 minutes, then do a pull. Shocker, it makes more power.
 
VitViper said:
We've been doing this mod for years, it won't hurt economy in the least. The mod is mainly to prevent heat soak -- you know, that thing that happens when you're hard on the throttle frequently or sit in traffic a lot?

For those of you who don't believe in heat soak... try spending an hour or two tuning, then stop and let the car cool off for 5-10 minutes, then do a pull. Shocker, it makes more power.
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i agree that heat soak is definitely an issue in some cases, and you're right that the bypass definitely wouldn't hurt, unless you live in the arctic or something. but i don't think the main reason for it is the heated throttle body. like you said, being hard on the throttle a lot and sitting in traffic a lot are two conditions that cause heat soak, but ultimately, they are caused by two different reasons. heat builds up in stop and go traffic because of the lack of airflow through the radiator. while the fans do help a little, it's forward motion that really forces air through and allows the cooling system to work optimally. when you're hard on the throttle, although you may be going fairly quick and forcing lots of air through the radiator, the engine itself through combustion is generating more heat than the cooling system can effectively dissipate, even if it's working at peak efficiency.
 
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It's not even the flow across the radiator that's the issue -- it doesn't need that flow when you're stopped idling because the cooling system can pretty much keep on it's own (cooling demands are very low at idle and in stop in go).

The heat soak that sucks in stop and go is the heat build up under the hood -- there is no forward motion of the car so your motor is quite literally breathing stagnant air from under the hood (think extremely poor air circulation), this compounds into heat soak as the motor just bakes in hot stagnant air. The coolant going through the TB just bakes the air entry even more -- trust me, the air in the intake manifold gets VERY hot VERY fast, even at cruise situations.

This could be seen very clearly if Honda had actually mounted the intake air temperature sensor on the intake manifold on these cars (like they used to on the old B/D series) instead of integrating it into the MAF on the intake -- with a fast enough sensor, you would easily see a ~20* drop in intake air temps from stopped to moving, and another 20* from moving to hard acceleration -- but even with all that air rushing through the manifold, it takes quite a bit of time for it to shed the heat after getting baked, all that time the motor is choking on hot air.

Anyway, the point of my rant -- if you can prevent (or at least help reduce it) the heat soak, you spend that much less time ingesting hot air into the motor -- the heat in the aluminum has to go somewhere.
 
TuanSi said:
Is there any reason why Honder doesn't go this route?
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Dar-Dar said:
One of the main points of the coolant going to the throttle body is to keep it warm during the winter or colder conditions so it would not freeze up and fail. Many car manufacturers use this method because they build every car so they can work on different conditions. But for people who live in warmer areas have to deal with the TB getting too hot resulting a 'low level' heat stroke. I would do the bypass if I'm circuit racing, dd'ing during the summer, or when the temperature is above freezing.
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So just curious I like in ma would doing this be a bad idea it doesn't often go below 10. I don't want to screw this car up.
 
I wouldn't recommend it. It's too cold and the tb plate might freeze up.
 
well i did this modification today with the hose left over from my K&N SRI it worked out great! :rockwoot:
I live in south Florida there is no need for hot coolant on my TB. we might see 60* weather here on a good winter lmao

so why not try and decrease IATs what can go wrong?? i have yet to confirm if this mod coupled with a TB spacer can have any gains like it did on the K20.
 
12aay_e said:
I already did it. No noticeable difference but just know your IAT's are cooler.
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No noticeable difference because there is none. The intake manifold immediately after your throttle body has the same hot coolant running through it. This "mod" is right up there on the stupidity meter with those "insulating" gaskets.
 
John Kirkland said:
No noticeable difference because there is none. The intake manifold immediately after your throttle body has the same hot coolant running through it. This "mod" is right up there on the stupidity meter with those "insulating" gaskets.
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Lol. Thermal gaskets do more than you think. I guess you need to do more research about thermal conductivity before saying negative comments without using actual proofs about it.
 
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