Bean's Beginner's Guide to the TB Coolant Bypass Mod

[thebeansoldier]

* Make sure your coolant is actually cool when doing this mod. Have fun! *

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[three]

What does this do for the 3???

[thebeansoldier]

What does this do for the 3???

basically reduces heat soaking in the throttle body.

there's a line of hot coolant (~140F) that goes through your TB. After driving around open up your hood and touch your throttle body. HOT. This modification bypasses that to remove any heat going through the TB and keep your intake charge cool especially during bumper to bumper traffic where the air gets ingested slowly.

great mod especially for summer weather. you can possibly gain back 1-2hp (could be more) from less heat soak in hot driving conditions, especially with the A/C on putting additional load on the engine.

[three]

So your just basicly taking one hose (which pushes the coolant through the throttle body) off and taking the other one (which gets the fluid that has already gone through the throttle body) and skipping the throttle body.

How long have you had this modification on your 3? Has there been any problems with the mod?

Also would there be any way to rig up some kind of system to pump some kind of cool coolant through just for the TB?

[thebeansoldier]

So your just basicly taking one hose (which pushes the coolant through the throttle body) off and taking the other one (which gets the fluid that has already gone through the throttle body) and skipping the throttle body.

yep.

How long have you had this modification on your 3? Has there been any problems with the mod?

a little more than a week ago (needed to do something during my day off). A lot of members have done the mod- no problems of the throttle plate sticking reported. The reason why the coolant passes through the tb is to keep the throttle plate from sticking [from the small amounts of debris and sludge in the TB, so it's good to clean that area too] during winter weather.

Also would there be any way to rig up some kind of system to pump some kind of cool coolant through just for the TB?

no need for that because as your speed/rpm increases, the rate of which the air moves into the throttle body is increased as well so it (the air) doesn't have enough time to become warm.

[goldwing2000]

What does this do for the 3???

Basically, nothing good. I had it done to mine and it didn't change anything. I changed it back and it still didn't change anything. The throttle body is such a small part of the intake tract that any heat-soak from it is a non-issue.

However, if you live in a cold climate, it can cause your TB to frost up in the winter and screw up all kinds of fun stuff.

And who cares if it heat soaks in bumper-to-bumper traffic? Who needs 1-2 more hp (which is pure speculation, btw) for going 0-5mph? In that instance, you're much better off with a warm intake charge to help vaporize the fuel in the combustion chamber.

Anyway, that's my opinion, fwiw.