I've currently got my TB off the car so that I could clean it out and clean the IAC valve. While it's off and the coolant is out I'm wondering if I should just bypass it when putting it back together.

Are there any disadvantages to bypassing the coolant from the throttle body?

Robert

 

If you live in a very cold climate the TB blades can ice up. Ive never seen it happen though. I live in Florida so no problems here.

 

I have cold winters where I am but the TB will heat up once the engine has been run for a short time, would it not?

 

Let me know if I'm dumb but just think about this....If the blades ice up when the engine is cold then would the Ice melt when the engine warmed up..shooting water into the intake, causing probelms?? But I would think the constant cool air from outside would keep it from thawing...But if I were you I would only do it if you are goin to drive it in the summer and store it in the winter... But I would like to know what everyone else thinks...Am I right or from from correct

 

This is my only disadvantage. A hose running across the engine.

 

Also I drive mine in the winter and I have not had any such problems.

 

Can u post some pics of the Bypassed hoses.... I dont know which ones need ro be bypassed...is it the L shaped one and the one that runs up from the intake??? Pictures would really help...

 

I read a tech article a long time ago. It said the coolant going to the throttle body is to prevent it from freezing up, which everyone knows. The freezing was not from cold weather, it was from testing a corvette at the salt flats or daytona. This was full throtttle for an extended period of time that most people will not ever see. The constant high velocity of air caused the throttle plates to freeze. Nothing to do with weather.

 

Fbirdta878787...There is a tech article on this site, it tells you how to do it. Lots of good stuff in there.

 

Just run a hose from your heater core to the front of your intake manifold. Take off the coolant hose on your TB. THen you should be all set.

 

Digging deep for this one: It still applies though

https://www.thirdgen.org/techbb2/sho...threadid=72675

HTH,

 

That can be avoided by using a different routing scheme.

 

AAH thats what i wana do... only i dont want that hose like that.. where else can you route the hose?

 

I bought a long hose with a 90* bend at the end. I ran it behind my alternator (Remember that 85-87 cars have the alternator on the passenger side) over to the body where the other heater core hose runs to the radiator. I have a black engine bay, so by using black hoses instead of red, it disappeared from sight, and since it's not running across the top of my valve cover, you don't really notice it anyway. The only thing that bugs me is that the section of formed hose I bought was a c-hair too short, so I had to butt it with another length of hose, so you see 2 hose clamps in view.

 

Mine has been bypassed since october, havent had any problems, we have had single digit weather here in PA this winter too. If it would happen to get ice and melt it, it wouldnt cause major proglems anyway, its not like its dumping galons it, it would be minimal, and gradual, (anyone read the posts on cleaning carbon with a spray bottle, it would do the same thing, but not even that much)

and arent LT1 and aftermarket throttle bodies built without coolant lines through them.

Oh yeah, one last point, When its running, it wont freeze cause under hood temps wont allow for it even if it was like -20 outside. So the only time it could freeze is if the car was off for a while, therefore even with the coolant lines through it, it would freeze and heat up and dump ice into the manifold if that were the case.

 

I believe it would only freeze, if you park you car out side, and there is no coolant in the TB for a couple of days. That plus it would have to be -30* or something. Once the engine is started, it doesn't take long to warm it up enough to un-freeze the blades.


Fbirdta878787 <--
Not a dumb question. There is not a freezing of "ice" on the blades. It is just the metal freezing to metal. It would have to be pretty freaking cold.

You could get the block heater from the canadian cars and plug it into the wall if you ever have that problem. 20k cars have it on there as an option.

 

I've ran the TB bypass since this summer with no problems. Just your average -10 weather with no humidity, so I figure I'm safe up north but with the humidity down south you might tend to ice up more.

 

Can anyone validate the true performance of this mod? In theory, the mod is used to prevent heating of air coming into the TB by re-routing the hot engine coolant away from the TB. Therefore, ensuring cooler air entry into the manifold.

However, I question the validity of this mod due to the large quantity and speed of the air entering the TB. With that much air moving through the TB, it would seem that the air would not have time to get warmer as it passes through a TB.

So, I am not saying that this mod is "snake oil." However, I would really like to know if anyone has seen or felt any significant performance increase by doing this?

 

I have mine bypassed. It makes sense that a warmer TB would tend to heat up the incoming air but at the same time the air being sucked in is moving quite fast (I put my hand in front of the TB one time and opened up the throttle blades real quick and it felt like it was gonna suck my entire arm in there).

I didn't feel any gains but it's a free mod so there is nothing to lose (except for some antifreeze on the ground) by making this bypass.

 

From a performance standpoint it's virtually useless. If you see a .5 degree difference in air temp I'd be shocked. I did it for appearance and to make TB removal easier.

 

i posted this in another thread...

The formula you refer to is bernoullis equation, is actually PV=NrT. It cannot be used in this case however because it assumes a closed system and an ideal gas. In Boston, where i live, it was the coldest day of the year last saturday, 3° not counting wind chill(wind chill was -15°). The car started and idled fine after sitting for a week. I feel the mod is more for convience and less places to leak. Even if the TB is 40° cooler, the shear mass of air flowing through it at WOT doesnt have time to heat up any appreciable amount. Lets take teh stock throttle body at WOT and flowing say 600CFM of air. Area= 48mm*2 butterfly valves=pi*r^2=.0389 ft^2 , (600ft^3/min)/.0389ft^2=15400ft/minute, divide that by 60 sec/min and you have a velocity of 256.6 ft/sec or 175.7 miles per hour. if the throttle body is 4 inches long the air is in the TB for .00116 seconds! not nearly long enough to make a large difference in the temp of the incoming air. If you can't follow my math(it's hard to show without the greek letters LOL) or find a huge error, let me know. -Mike

 

Bernoulli's equation doesn't only work for ideal gasses, but it is used specifically for laminar flow in a streamline path for incompressible fluids. Obviously it doesn't apply here.

As far as the air only being in the throttle body for .000xx seconds, that's true for each particle of air, but there is constantly that 3 degree or -15 degree air incoming, which is below freezing and could potentially cause the throttle blades to freeze and stick. Of course the ability of incoming air to freeze the throttle blades is pretty minimal considering the heat exhausted and then absorbed by the engine.

If you think about how it could help performance.. it would be only between the time when the engine is at normal operating temperature and hot coolant would flow through the throttle body but now isn't, and before the heat of the engine could dissipate into the plenum/throttle body. You're looking at a period of a couple minutes at most.

I did the mod to clean up my engine bay and to not spill coolant every time I removed my throttle body.

 

I don't believe you have a threat of it freezing in very cold weather. In order for it to freeze, you need moisture. When the air is that cold it doesn't hold any moisture. I believe the only time there could be a potential problem is when the temperature hovers around freezing and the air is dense with moisture. All of the air running past the TB can cool it enough that ice can build up. I believe this is a pretty rare situation.

 

Ditto...keep in mind GM designs this stuff for the worst case scenario, for the average driver.

I also really don't see this as performance mod...just a cosmetic one, and ease of maintenance.

 

I did this mod awhile back. I don't drive the car in the winter so it's not a big deal for me. All you are doing by bypassing the TB is just keeping the antifreeze from heating up the TB as much, which in turn heats up the air going into the engine. It has been dyno proven on a website somewhere to be worth like 7 hp. As for the water going into the motor being harmfull, I seriously doubt it due to the fact that it wouldn't be pouring gallons into the intake. Supercharger apps use water injection system which spray water directly into intake (course they do have alchol mixed in to counter it), but still it doesn't effect there cars only helps reduce air temps which in turn helps reduce denotation.

Probably not a big gain in power but hey all the little freebie stuff probably adds up a little. As for the ports you block if you look at the TB with air ducting off you can see a hose leading from front of intake up to underside of TB then out of the TB off a port on the passenger side which goes to a valve. All you have to do is just take the hoses off the the TB and put a longer hose from intake to valve. I did this mod with pieces of hose I had laying around in the shop.

 

The only time that I see it heating the air up would be in the summer time, 100+* and sitting in traffic. That would only be 1-2* at the speed that it is moving in. I'd do it, nothing to worry about. If you have problems, hook it back up.

 

1 thing no one mentioned, maybe because I'm wrong, but I live where it get's to be 115 degrees easy. Wouldn't under extremly hot conditions in traffic, the coolant actually cool the throttle body down?

 

Not unless the outside air temp gets above 195 degrees or so, but even with a 160 degree thermostat it would still have to be above 160. And more likely 200 to see any cooling effect. By then your cars cooling system wouldn't be doing its job ie. no delta T and you'd be parked on the side of the road.

 

In reference to the above calculations...

You must not ignore the fact that there is heat transfer to the intake tubing, plenum, and base due to the coolant's presence. All of these associated parts will transfer thermal energy to the air. An element of air might reside in the throttle body for .000XX seconds, but do not neglect that it spends time in these other heated areas. The gains from the tb bypass are still minimal, I agree, but not as minimal as you previously calculated.

 

posted by rezinn
I agree there is a constant flow coming into the TB, my point about the small amount of time the air is in the TB is to prove that it is neither heated nor cooled to any great degree.
Now to look at the throttle blades icing let us consider a reasonable senario. When we talk about throttle blades sticking to thier bores we mean that water freezes and holds the metals together. Without mouisture, no matter how cold, metals do not stick together. Therefore it doesnt matter how cold it is, only that it is below the freezing point of water. If it is far colder than that, well your antifreeze is solid and you've got bigger problems to worry about.
So assume a reasonable amount of water collected in the TB and does indeed freeze the blades. Doesnt the car normally idle with the throttle blades closed? If you cant force the blades open with the throttle pedal, unlikely?, just wait for the car to warm. I dont think having below freezing coolant circulate in the TB for the first few minutes helps very much.
Some people claim that the air velocity can ice the blades even in warm weather. I would like to see some logic behind this as it doesn't make alot of sense to me. Cooling 600CFM of 80° to below freezing is impressive. 80°F is 299°K and according to the phase diagram of water Here it can never be a solid at 80° even under extreme pressures. Therefore i assume the mixture of air/water is cooled to low enough temps at sea level (100Pa) to freeze? I don't quite understand how this happens. anybody care to explain? thanks -mike

 

I have a K&N clamp on filter personally so the calculations would be very close to correct for my car. If i knew the radius of the intake runners i could come up with that figure and estimate the length. say the intake is 3 inches in Dia, and 3 feet long, the air is still only in the tubing for .0353 seconds, again my car doesnt have this so i left it out. If we really want to get technical we can introduce the no-slip condition ,which is applicable, which states the first layer of air touching the inner pipe surface is stationary, the layer above that move a slight amount, the next layer etc. Bascially the velocity is highest in the center of the pipe due to friction along the inner walls. This stationary layer (and other near stationary layers) would serve to insulate the main mass moving along from the hot TB, pretty small effect though .

Edit, also since most intake tubing is a plastic polymer design it wouldnt conduct much heat all along its length from the TB, it would be much more affect by underhood temps, such as headers radiating heat etc, then by a slighty cooler TB.

 

I agree to the above no-slip at the-wall condition. Basicly it is impossible to model or quantify the horsepower gain because the heat at the boundry wall varies, the flow is turbulent, etc. The only real way to tell is to put it on a dyno. And even then, there are so many variables that would need to be strictly controled for such a small power gain. The hp gain would also be related to the ambient temp and humidity of course because the the temperature differential depticts the "speed" of the heat transfer.

A thousand ants can buld a den with miles of tunnels. A thousand little things can add up to significant gains. Do the free mods and be happy. :lala:

 

I have a ws-6 T/A i am happy! LOL, just like a little engineering thought on our cars.

 

Honestly, i can see how water condensting, then freezing on the tb would cause the blades to freeze and stick, but i think its a little more than that. If you think about it, what water vapor exists at 3 degrees, unless its already miniature ice crystals or snow, sleet, etc. (I'm no no weather man, but i think this is a bit true).

What i think it really means is that when the tb freezes, the shaft with the blades will stick in the the bore for the shaft. This happens because i believe aluminum (TB) has a larger expansion/contraction rate than steel (TB shaft). Now, when theres a hole in the metal, that hole will expand/contract with respect to temperature. Since aluminum has a larger expansion rate than steel, it will contract on to the steel, and it will stick. This is in theory, because i don't exactly know the clearances between the TB and the shaft. And like cars, no 2 are the same.

As far as the bypass, IMO, i just see it as a way to make tb removal easier, with less connections. oh yeah, what everyone else said. Other than that, i'd say doit. I think its worth it.

 

If that were the case it would happen more often. I believe it's due to moisture in the air when it's at or near 32 degrees.

 

I recall looking through a website that had an 88 Trans Am with the 350 dynoing the car with and without the coolant bypass. The gain was about 5 rwhp, which, you probably wont notice ( unless its psychological) . So you will gain some, but not enough to notice it on the street. But its free, so hey, what do you got to lose?

 

i had my trottle body ice up on e one moring when i was in maine, n the end of january.it was like .20 degrees and when ur doing like 75. the wind chill is something like -50. (i also didn't let the car warm up) anyway it iced up on me, and the motor started to jump really bad, so i pulled over and turned it of ora couple of minutes and walked into a local store. came back out 5minutes later and she was fine.

imo- doit everlittle bit counts.

 

Huh, that is interesting. The weather out here has been a little jumpy. Gone from warm to cold to really cold back to warm. I haven't had mine ice up yet

 

i wasn't to smart about it ethier, i didn't let her warm up, got in,started her up and put her in gear.
it was like -20 outside, w/ a 10mph head wind.
so now i'm doin 5 on a highway so the wind into the ramair setup is doin 100mph at -20 egrees. the windchill has to be below -50 at least.
so i called my boss and he told me to let it sit w/ the engine off, so the warmth will travel threw the intake and into the trottlebody warming it up. and she ran fin after that. i was also doin 55 instead of 85.

 

This has been interesting reading.

Ok, for those that have done it, how the heck did you do it? I figured it would be a 20 minute job but after a few hours of pulling things off and moving other stuff out the way it is near impossible to get a hose to the heater control valve. I had originally thought about under the throttle body, but the IAC housing takes up all the room.

Suggestions?

What about removing the heater valve? You have 3 hoses to it. 1 from the TB. 1 goes to the heater matrix. and the 3rd goes to a T-junction with another radiator pipe. Seems easy appart from the T-juntion pipe.

How did everyone do this?

Thanks again.

Robert

 

i was thinking the same thing.. but im not sue if a tube must send collant to that opening under the throttle body... it took me 30 mins to do... you just have to move some stuff, and it eventualy works.... i have an 87, so i have a little different set up then some on here with a serpentine belt set up.

 

I had a question too. Do I have to cap off the open ends of the throttle body at all?
Where the hose used to go?

 

bigals87z28

Do you have a pic of yours?


Thirdgen,

I see no reason why they would have to be plugged off.

 

i don't have pics, but if get a chance i will snap a pic o two friday afternoon. but the line that goes out of ur trottlebody you take off and then take off your intake. and there a tightly bent hose. remove that one too. then reroute a piece of hose (i think 5/8") one to the other, it does look a little funny. but that should work,

also if you do this- leave your self extra hose so you don't kink it.

 

Yeah, just get another piece of hose go straight from the intake to the valve. So really all you're doing is cutting the TB out of the route.

 

I've got it routed now. The hard part was to find a way to route the hose without it looking messy.

 

nah, i dont have any right now.. but i should have them some new pics after next week.. i go home for break and im gunna wash, wax and clean my car.. Ill take engine pics and all other cool stuff..