Question for all Mechanical Theorists!

Submitted: Friday, Mar 10, 2006 at 11:35
ThreadID: 31614 Views:2443 Replies:7 FollowUps:8
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Ryto, the surf has a "Throttle Body Heater", which basically is just a 3/8" hose that comes out of the block, passes through the thorottle body and then goes back into the block running the engine coolant through the throttle body.

Why is it there IMHO?

Ummm, well I reckon it's there because the surf comes from a cold climate (Japan) and probally helps on those cold winter mornings to keep the beast running smoothly by heating the air before it enters the combustion chamber.

My Understandings (right or wrong, please correct me):
- Diesels run better when hot, it makes the fuel air mixture burn more efficiantly.
- Air is more dense when cooler and therefore carries more oxygene, which in turn will help the engine beathe better, have more power and use less fuel.

So what do I do?
Well my coolant is running between 90c and 110c on the highway and I'm assuming that it will be heating the air to between those same temps. Because it's after the turbo, I wonder if maybe it also works as a basic small air to water intercooler and is actually cooling the air straight after the turbo, but I really have no idea how hot the air out of the turbo is going to be.
Do I take it off and have a potentially higher O2 level and a better running vehicle, or leave it on?
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Reply By: V8troopie - Friday, Mar 10, 2006 at 12:19

Friday, Mar 10, 2006 at 12:19
having never heard of such a thing I went straight to Google;-)
The very first hit after typing in 'throttle body heater' has an explanation and detailed instructions how to bypass it.
Hopefully its useful to your application.

Some of the toyo 2h engines had an electric intake heater that came on brifly at startup. this application makes more sense to me than a permanent heater.
AnswerID: 159689

Follow Up By: Member - Jeff M (WA) - Friday, Mar 10, 2006 at 12:47

Friday, Mar 10, 2006 at 12:47
Well there you go, insturctions on how to bypass it would mean to me that perhaps my origional theory is right and that all it's doing is making my burn less effficiant!

Peice of cake to bypass as that's where I put the sender for my aftermarket temp guage. I just whacked a "T" piece in the 3/8" hose and put the sender in there, so all I need to do is swap the hose on one end of the "T" piece so it comes out of the block, into the "T" and then back into the block... Then just block up the two holes on the throttle body with silicone or something.

Yeah I know the earlier imports (the ones comming in now, like the short wheelsbase cruisers and stuff) have a grill type heater in the air line that comes on momenterily.

Oh well, might get out the screwdriver and silicone and get to work on it then! ;-)
FollowupID: 414328

Reply By: Geoff M (Newcastle, NSW) - Friday, Mar 10, 2006 at 13:30

Friday, Mar 10, 2006 at 13:30
These ideas are not uncommon.
They stop the inlet manifold from icing up.
My FJ40 (2F Motor) had the inlet and exhaust manifolds bolted together. It used the exhaust gas as the heating source. This created another problem.
In the exhaust manifold was a deflector plate that after a while broke away. It'd turn turtle and block the exhaust pipe where it left the manifold. Very effective exhaust brake.

Your quite accurate, they are really only useful in very cold climates.

When my mate had fibreglass kitted VW's he'd fit extractors and a different inlet manifold. The original exhaust and manifold passed exhaust gas across the base of the inlet manifold just under the carby stopping manifold icing.
On real cold nights, I'm talking down to zero the inlet manifold would ice up and the car would stop. Most effective way to cure it was get out and pee on the inlet manifold.

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AnswerID: 159705

Reply By: Member - Jeff M (WA) - Friday, Mar 10, 2006 at 14:04

Friday, Mar 10, 2006 at 14:04
There you go, done! Now I might be able to rev the car while I'm working on it without burning my friggin fingers!! :-)

I wonder if I'll see an improvment in fuel economy...
AnswerID: 159709

Reply By: Member - Reiner G (QLD) 4124 - Friday, Mar 10, 2006 at 14:14

Friday, Mar 10, 2006 at 14:14
VW motors had pre-heater pipes coming from the exhaust system and running to the carby mounts. I had a 1600 twin port which had the pre-heater pipes removed and blocked and coming down from Toowoomba one year in winter the carby was one big block of ice when I got to the Helidon Petro station.
Thats what the pre-heater pipes do.......... keep the carby nice and warm.

AnswerID: 159712

Follow Up By: Member - Jeff M (WA) - Friday, Mar 10, 2006 at 14:27

Friday, Mar 10, 2006 at 14:27
Hmmm, yeah I don't reckon I'll have that problem here in Perth hey, if it's bellow 15 degrees we all hibernate anyway! ;-)

Once the motor's warm there'll be plenty of heat under the bonnet to stop it icing up I'd reckon, the under bonnet temps on the thing are herendous... If it posses a problem trying to start it while camping down south or somthing, I'd dare say a quick boil of the billy would solve the problem.
FollowupID: 414354

Reply By: 120scruiser - Friday, Mar 10, 2006 at 15:14

Friday, Mar 10, 2006 at 15:14
So long as there is no sensors in the throttle body that rely's on coolant.
Most japanese cars have them and even magnas have them.
In a petrol they have been using it for years. Even the old HQ holden had either the preheat coming from the exhaust manifold or had water running through the inlet manifold. In them cases it helped with atomisation of the air fuel mixture aiding in stoichiometric (spelling??) but in a diesel there is no air fuel ratio only air so no harm done by by-passing it.
Let us know if it makes a difference.
AnswerID: 159722

Follow Up By: Member - Jeff M (WA) - Friday, Mar 10, 2006 at 16:09

Friday, Mar 10, 2006 at 16:09
Nah according to my workshop manual there is only one sensor in the throttle body and it's a throttle position sensor. The Air temp sensor is in the pipe that comes out of the air box.
FollowupID: 414376

Reply By: Mike DiD - Friday, Mar 10, 2006 at 15:59

Friday, Mar 10, 2006 at 15:59
If you plan on removing hoses and plugging with silicon rubber make sure it's reliable - if the plug comes off it will be very expensive for the engine.

An easier and more reliable way to stop throttle body heating is to fold a piece of aluminium into a U shape and use it to clamp the water hose to the carby. If it falls off - no damage.

AnswerID: 159733

Follow Up By: Member - Jeff M (WA) - Friday, Mar 10, 2006 at 16:06

Friday, Mar 10, 2006 at 16:06
hmmm, i can't see the silicone being a problem in the throttle body as it would only be a small circut through the body and out again, the hoses are not blocked with silicone, they are joined together with the origional hose clamps on to my "T" piece that has me aftermarket temp sender in it.
FollowupID: 414374

Follow Up By: BenSpoon - Friday, Mar 10, 2006 at 17:34

Friday, Mar 10, 2006 at 17:34
Grab some of the blue loctite under-bonnet silastic. I am told your run of the mill silastic fumes can screw with Oxygen sensors and other sensitive sensors. For the extra $3, I figured it wasnt worth finding out if they do break or not.
FollowupID: 414390

Follow Up By: Member - Jeff M (WA) - Friday, Mar 10, 2006 at 17:37

Friday, Mar 10, 2006 at 17:37
Yeah I can't see it being an issue as like I said before, it just goes in and out of the throttle body, no sensors there. Besides I'm using some $70 a tube silicone I managed to get for nothing, so I'm sure it'll probally do the job! ;-)
FollowupID: 414393

Reply By: Member - David 0- Saturday, Mar 11, 2006 at 09:37

Saturday, Mar 11, 2006 at 09:37
Although carburetor icing is frequently associated with winter, it can be a problem any time of year. Conditions favourable to icing are a combination of moist air and temperatures in the range between -13º C and +38º C. The temperature range most conducive for the formation of intake ice falls between approximately -5º C and +15º C.

Given moisture in the air—a relative humidity of at least 50%—and the correct temperature range, the formation of ice is likely.

Carburetor ice forms as a direct result of activities taking place within the carburetor itself, given the right conditions. The function of a carburetor is to vaporize liquid fuel, mix the vaporized fuel with air in correct proportion for combustion and deliver that mixture to the intake manifold for induction into the cylinders.

The process of vaporizing fuel—converting it from a liquid into a vapour—requires energy. That energy is available as heat stored in the fuel itself and in the air being used to transport it. As heat is used to assist the vaporization process, the temperature of the fuel and air decreases.

It takes energy to produce change.

Incoming air can decrease as much as 30º C in temperature as it passes through the carburetor.

The drop in temperature resulting from vaporization of fuel may cause water vapour carried by incoming air to freeze onto the carburetor barrel or the butterfly valve, also known as the throttle valve, which regulates the amount of fuel/air mixture being drawn into the intake manifold. This type of icing is called fuel vaporization ice because the icing results from the heat decrease of fuel vaporization.

AnswerID: 159875

Follow Up By: Member - Jeff M (WA) - Saturday, Mar 11, 2006 at 10:47

Saturday, Mar 11, 2006 at 10:47
Hey David, that's pretty cool, I can see that making perfect sense and I would have never thought of it that way, however I still don't think it's a problem for two reasons. 1. My vehicle is turbo'd, so the air going into the throttle body comes directly from the turbo which would be pre-heating the air under boost and also just purley because of the EGT's through the turbo, secondly the throttle body in a diesel has no fuel going into it, only air. Also, the metal air pipe that comes from the turbo goes over the top of the rocker cover (is bolted to it) so there is going to be a small amount of heat rising from the engine into the pipe anyway. So with all of those things, I don't reckon the air tempeture (in
Perth's climate anyway) would (under normal running temps) ever get below 15c. So I still think that the only time I could possibly experience a problem would be on a cold start, but even then I reckon it would be pretty unlikley.
FollowupID: 414535

Follow Up By: Member - David 0- Saturday, Mar 11, 2006 at 11:32

Saturday, Mar 11, 2006 at 11:32

I agree it is unlikely to be a problem.

Just provided the info, becasue as a pilot, I understand it doesn't require low temperature, just the right combination of temp and humidity. Fuel injected vehicles though similarly susceptable, are less so.

FollowupID: 414539

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