Throttle Body Coolant Line Bypass

[Gary6586]

Anyone have any experience with the throttle body coolant line bypass? Seems kinda silly for GM to have designed this in the first place, but all Corvette suppliers offer this bypass kit.

Before I go further, I want to canvass friends for their opinions and experiences.

[Drjohn]

I made my own. I did it while I had everything apart fixing a different leak. I may not have bothered otherwise.

[Aurora40]

Originally Posted by Gary6586

Seems kinda silly for GM to have designed this in the first place

My understanding is that otherwise with the very high velocity of air that whips by, in cold conditions it is possible for icing to form on the throttle body. I think that's the main reason for them having coolant.

That said, I can't imagine a coolant bypass having a very large effect on anything. But if you are digging for that last little bit...

[WNH]

Originally Posted by Aurora40

That said, I can't imagine a coolant bypass having a very large effect on anything. But if you are digging for that last little bit...

I did it because I like working on my Vette, and now I can take the TB off without spilling coolant all over the place. It keeps the plenum and runners from getting too hot also.

[Mad-Mic]

Originally Posted by Aurora40

My understanding is that otherwise with the very high velocity of air that whips by, in cold conditions it is possible for icing to form on the throttle body. I think that's the main reason for them having coolant.

That said, I can't imagine a coolant bypass having a very large effect on anything. But if you are digging for that last little bit...

it's a 3 fold thing with the TB Bypass.

1. heat. colder the air coming in the more HP you make.
2. colder the air = more compact air + leaner condition = more HP
3 under hood temps arent hot uptop due to the plenum being 200+ degrees.

radiation heat from the block and heads disipate sp? quicker on the cooler intake and plenum. probably good for 5+ rwhp or more.

just my 2 cents worth

[Agent 86]

Add me to the list of do-ers
I went one step further and eliminated the coolant passages on TB. I'ts not that i don't like nipples, I do, just not sticking out the side of my TB

[Aurora40]

Originally Posted by Mad-Mic

it's a 3 fold thing with the TB Bypass.

1. heat. colder the air coming in the more HP you make.
2. colder the air = more compact air + leaner condition = more HP
3 under hood temps arent hot uptop due to the plenum being 200+ degrees.

radiation heat from the block and heads disipate sp? quicker on the cooler intake and plenum. probably good for 5+ rwhp or more.

just my 2 cents worth

Yeah, I understand how heat affects air. But it's just the TB, not the whole plenum being heated. I doubt the air temperatures going into the cylinder are all that much different whether you have the bypass or normal TB. But maybe they are, who knows.

For #3 and the part about heat radiation... You think the upper part of your engine bay is cooler from the TB bypass? That seems highly dubious given that the engine itself is quite hot, and that heat rises... Also, if you feel a non-coolant-filled TB radiates engine heat away, thus cooling everything, wouldn't that mean it is radiating engine heat into the incoming air, which is the whole thing you are trying to avoid with the coolant bypass?

I would be surprised and impressed if you could show a 5 horsepower gain to the rear wheels purely from the coolant bypass. But as I said, if you are going for every last bit, then perhaps this makes sense. If you think it adds a noticeable gain in power, then certainly do it. All I wanted to point out was that there was some reason GM did that, it wasn't because it made the design cheaper or easier or anything. And then offered my opinion that I wouldn't think it adds very much heat into the incoming air.

[Mad-Mic]

Originally Posted by Aurora40

Yeah, I understand how heat affects air. But it's just the TB, not the whole plenum being heated. I doubt the air temperatures going into the cylinder are all that much different whether you have the bypass or normal TB. But maybe they are, who knows.

For #3 and the part about heat radiation... You think the upper part of your engine bay is cooler from the TB bypass? That seems highly dubious given that the engine itself is quite hot, and that heat rises... Also, if you feel a non-coolant-filled TB radiates engine heat away, thus cooling everything, wouldn't that mean it is radiating engine heat into the incoming air, which is the whole thing you are trying to avoid with the coolant bypass?

I would be surprised and impressed if you could show a 5 horsepower gain to the rear wheels purely from the coolant bypass. But as I said, if you are going for every last bit, then perhaps this makes sense. If you think it adds a noticeable gain in power, then certainly do it. All I wanted to point out was that there was some reason GM did that, it wasn't because it made the design cheaper or easier or anything. And then offered my opinion that I wouldn't think it adds very much heat into the incoming air.

actually with a 160 t-stat and the tb bypass it's more of a 20 rwhp gain and it's proven. hot lapping my vette above 200 degrees (normal operating temp from the factory) to less than 160 degrees is 2 tenths in the 1/4 mile for my car. it's a fact proven by many that races all the time.

radiational heat from the TB leaks back into the plenum. this causes air temps hotter entering the combustion chamber = loss of HP. why do you think Ram Air was invented? it's not necessarily the "Forced" air making more HP although it does help but it's the "Cooler" air making the HP. cool air holds more oxygen which in return makes more HP. so although the gains might be minimal, it's still a gain. heat travels quicker/faster in iron compared to aluminum thats why we have aluminum heads now which in return you can increase compression. radiational heat from the iron block hits the heads/intake and dissipates quicker than if it was iron but still retains heat as a metal. it just disspates quicker. if a cooler intake didn't make more HP we'd still have iron heads and iron intakes.

[Aurora40]

Originally Posted by Mad-Mic

radiational heat from the TB leaks back into the plenum. this causes air temps hotter entering the combustion chamber = loss of HP. why do you think Ram Air was invented? it's not necessarily the "Forced" air making more HP although it does help but it's the "Cooler" air making the HP. cool air holds more oxygen which in return makes more HP. so although the gains might be minimal, it's still a gain. heat travels quicker/faster in iron compared to aluminum thats why we have aluminum heads now which in return you can increase compression. radiational heat from the iron block hits the heads/intake and dissipates quicker than if it was iron but still retains heat as a metal. it just disspates quicker. if a cooler intake didn't make more HP we'd still have iron heads and iron intakes.

Well, I'm not really trying to get into an argument, but there are a few errors in what you are saying. For one, air doesn't hold oxygen. Cooler gasses have more mass in the same volume (assuming the same pressure) so yes, a given volume of cooler air at atmospheric pressure has more mass of oxygen, nitrogen, etc in it. The way you say it sounds like air dissolves oxygen much like more salt can be held in warm water rather than cold.

Anyway, aluminum transfers heat more effectively all else equal to iron. I don't quite know what you mean by the whole heat travelling quicker/retaining-yet-dissipating thing. But suffice it to say, aluminum heads and ram air induction aren't quite the same thing as coolant in your throttlebody.

Like I said, if you like it, use it.

[Achilles]

Not trying to be a smart azz, but I always thought air had oxygen in it Or does oxygen have air it?

Regarding the TB bi-pass - This theory may be way out there, but I have always wondered...What if the radiant air temperature around the engine bay is warmer than the coolant (assuming you have a 160* stat) passing through the TB. Wouldn't the coolant actually be cooling the incoming air from the radiant engine heat?

Like I said, this theory may be way off base. But it is why I never did the bi-pass. It does sound like many of you have had some positive results from this mod though.

BTW, I hate the coolant hoses on the TB too!

[speedmaster4]

GM builds cars to operate in any reasonable environment--to "normal" people that means summer/winter/tornados/whatever...if gm spends a nickel on anything on a car, its necessary for 'normals'

i've had a c1 vette and an 80's (?) caprice that had 'carb icing' due to no "flapper" at the end of the exh mfld to push hot exh thru the intake mfld...my snow plow (350 chev/holley) has no flapper and will occasionally loose power after 5 min run--shut it off and wait 5min and no problem--thats carb ice

anytime ambient air temp is below +40* F, carb icing may occur ( dx cooling effect lowers carb temp below freezing)

btw: since i'm not normal (above-right?) i did bypass,and like agent86,took a hacksaw to remove nipples (ouch)..dont know if it added any power but sure is easier to work on and looks less cluttered

[aboatguy]

The TB coolant bypass will increase HP under certain conditions(IE conditions not causing TB icing) . However, I have not performed a TB coolant bypass for obvious reasons. If I get stationed somewhere in the deep south I will perform the TB bypass. Mike

[Rogier]

Isn't it meant to be helping the throttlebody functioning very well when it's very cold (freezing) outside?

[motorman]

Originally Posted by Gary6586

Anyone have any experience with the throttle body coolant line bypass? Seems kinda silly for GM to have designed this in the first place, but all Corvette suppliers offer this bypass kit.

Before I go further, I want to canvass friends for their opinions and experiences.

it will help a C-4 because the "dog house" is aluminum which picks up heat from the heated TB BUT is does not help a C-5 because the manifold is a composite that does not pick up heat like aluminum

[WhalePirot]

While I have a lot of respect or Mic's results, I'm with Aurora on this one, as is my local Vette expert.

With the intake air racing past the TB is milliseconds, how much can it possibly warm? I do, however, understand (having witnessed) the power loss from high underhood temperatures; therefore hot intake air.

I had a Civic once that got carb icing (can you say Minne-snow-ta?), plus from flying airplanes, I understand Charle's Law. http://www.grc.nasa.gov/WWW/K-12/airplane/glussac.html
Moving air has a lower pressure than the static air plus the relative vacuum of the intake drops intake temperature. Intake icing is possible even at 40*F.

I'd love to see scientific proof that a TB bypass, alone, makes any significant power.