Heated Throttle Body: The Why and Wherefore
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Joined: May 2001
Posts: 11,851
Likes: 2
From: Rancho Palos Verdes, CA
Vehicle: 2008 Toyota Prius 2006 Suzuki SV650S
The TB's are heated for one reason, and one reason only. To prevent the TB from sticking open due to condensation turning into ICE in the TB venturi section (where the TB butterfly is).
If you don't drive in sub-freezing temps, you can remove the coolant lines to the TB.
You'll still get a much hotter than ambient intake air charge due to the aluminum (great conductor of heat) intake manifold resting against the HOT Aluminum(great conductor of heat) head...which has direct contact to the combustion chambers, not to mention HOT oil and HOT coolant running through it.
Removing the Coolant lines from the TB will Maybe, MAYBE add 1-2 hp when the engine is cold, during the first 5-10 min of running. However after that, the heat transmitted to the Intake manifold also warms the TB after that time, to the point where the coolant lines make little/no difference.
if you doubt it. Give it a try. Get a tempature probe (fluke 54 II is what I used) or a non-contact inferometer. Measure the Temp of the TB when cold. Go drive for 5 min. Then pull over and check the temp of the EXTERIOR of the TB via the Inferometer. Then go drive for another 15, check the temp again. It heats up quickly. That's why the Intake manifolder Phenolic spacers were invented (and Phenolic spacers for TB as well)
The Aluminum in the Intake Manifold and TB's still get hot after extended runs (30+ min) but they don't get AS hot, AS quickly when you use the spacers.
Now...what difference do the spacers make?
I can tell ya. From the testing that I did, air temps in my intake manifold got as high as 20-40 degrees above ambient (this is the temp of air INSIDE the intake manifold 3" before the head, not the temp of the metal itself) during Stop/Go city driving @ low throttle openings.
Steady state freeway cruising, the air temp was +10 to +20 degrees higher than ambient (higher @ the start of the freeway run, and lower as the run ran on, but always a minimum of +10).
Full throttle runs would drop the air temp back down to ambient +2-3 degrees. This was WITHOUT a spacer.
So...the difference in air temp at full throttle, which is they only place people care about HP...is 2-3 degrees. That tells you that the HP difference is not measurable. And again, this is WITHOUT a spacer.
I posted an excel chart and a graph showing intake air temp/ambient air temp, throttle position and vehicle speed many years ago. It should still be on the site somewheres.
If you don't drive in sub-freezing temps, you can remove the coolant lines to the TB.
You'll still get a much hotter than ambient intake air charge due to the aluminum (great conductor of heat) intake manifold resting against the HOT Aluminum(great conductor of heat) head...which has direct contact to the combustion chambers, not to mention HOT oil and HOT coolant running through it.
Removing the Coolant lines from the TB will Maybe, MAYBE add 1-2 hp when the engine is cold, during the first 5-10 min of running. However after that, the heat transmitted to the Intake manifold also warms the TB after that time, to the point where the coolant lines make little/no difference.
if you doubt it. Give it a try. Get a tempature probe (fluke 54 II is what I used) or a non-contact inferometer. Measure the Temp of the TB when cold. Go drive for 5 min. Then pull over and check the temp of the EXTERIOR of the TB via the Inferometer. Then go drive for another 15, check the temp again. It heats up quickly. That's why the Intake manifolder Phenolic spacers were invented (and Phenolic spacers for TB as well)
The Aluminum in the Intake Manifold and TB's still get hot after extended runs (30+ min) but they don't get AS hot, AS quickly when you use the spacers.
Now...what difference do the spacers make?
I can tell ya. From the testing that I did, air temps in my intake manifold got as high as 20-40 degrees above ambient (this is the temp of air INSIDE the intake manifold 3" before the head, not the temp of the metal itself) during Stop/Go city driving @ low throttle openings.
Steady state freeway cruising, the air temp was +10 to +20 degrees higher than ambient (higher @ the start of the freeway run, and lower as the run ran on, but always a minimum of +10).
Full throttle runs would drop the air temp back down to ambient +2-3 degrees. This was WITHOUT a spacer.
So...the difference in air temp at full throttle, which is they only place people care about HP...is 2-3 degrees. That tells you that the HP difference is not measurable. And again, this is WITHOUT a spacer.
I posted an excel chart and a graph showing intake air temp/ambient air temp, throttle position and vehicle speed many years ago. It should still be on the site somewheres.
Thread Starter
Super Moderator
Joined: Sep 2001
Posts: 10,795
Likes: 5
From: Pflugerville, TX
Vehicle: 2000 Elantra
I would have hoped he would chime in on the subject so I didn't have to go digging . . . but he never comes around anymore. He don't call, he don't write *snif* What happened? Spidey senses told you I was remembering your research? :unsure:
