[Sankar]

Originally Posted by im_srini

When I was trying to source Black-Phenolic-AA grade sheets a few years ago for the intake gasket, I was told that Phenolic-AA material was not made anymore (instead was directed to G-11/FR-5 Epoxy Sheets).

Did you manage to make the insulating gaskets? If yes please share the details, we are now planning to make one for the Esteem.

The ones readily available for the G13B is expensive at $79!!

Similar thing here. Surprising that coolant circulation through the throttle-body was present, then removed in later models, & now appears to have been reinstated !?!

Maybe its reinstated for better fuel efficiency and safety reasons to prevent any possible instance of icing.

[thoma]

Since I got some time to think over this post, some queries propped up in my mind.

Going by the temperature and temperature difference in the post with the graph, that means a density difference of ~ 0.04 kg/m3. IIRC, the air-fuel ratio calculated by the ECU is by weight than by volume. So that equates to more fuel pumped in to compensate the additional air weight. And thus more power per stroke?

Do we really have a sensor in the car to measure the intake air density? Or is that arrived-at from the exhaust readings?

Originally Posted by Sankar

But since an engine runs best with colder air
...
In our climate i see no reason why the TB needs to be warmed up as it doesn't help in performance and it doesn't get anywhere close to freezing here.

Originally Posted by Sankar

Yes its done to preheat the air in colder climate and also to prevent the icing of throttle body.

If colder air was better, then why should the manufacturer spent additional resources to heat up the TB? I am sure this is not for cranking purposes as the coolant itself will be cold at the time of cranking. There should be some reason this has been provided. But what exactly? Is it to make the engine more frugal at the cost of power/torque?

[vikram_d]

Originally Posted by thoma

Do we really have a sensor in the car to measure the intake air density? Or is that arrived-at from the exhaust readings?

Most of the fuel injected cars I have seen make use of a manifold air pressure sensor to determine the amount of air going into the engine. But the final determination of fuel to be injected is done from the exhaust readings. That is why in stock cars if you connect a air fuel ratio gauge, you will notice that the fuel injection continuously cycles between rich and lean.

[Sankar]

Originally Posted by thoma

Since I got some time to think over this post, some queries propped up in my mind.

Going by the temperature and temperature difference in the post with the graph, that means a density difference of ~ 0.04 kg/m3. IIRC, the air-fuel ratio calculated by the ECU is by weight than by volume. So that equates to more fuel pumped in to compensate the additional air weight. And thus more power per stroke?

Do we really have a sensor in the car to measure the intake air density? Or is that arrived-at from the exhaust readings?

Colder air is denser, denser air exerts more pressure so i believe that a MAP equipped car can compensate for the denser air that flows into the manifold. In my car the IAT sits before the Tbody whereas the MAP sensor is on the manifold. MAP's input is also taken for fueling, O2 sensor is the eye of the ECU since its telling ECU what it sees in the exhaust and how the fueling should be altered to maintain AFR.

If colder air was better, then why should the manufacturer spent additional resources to heat up the TB? I am sure this is not for cranking purposes as the coolant itself will be cold at the time of cranking. There should be some reason this has been provided. But what exactly? Is it to make the engine more frugal at the cost of power/torque?

Not all cars have the coolant circulating in the Tbody, my friend's 2007 Esteem doesn't have this and like im_srini said in the post above its not there in his car either. As to reasons why its there its mainly to prevent icing while the car is in use.

[dhawcash]

Going by the temperature and temperature difference in the post with the graph, that means a density difference of ~ 0.04 kg/m3. IIRC, the air-fuel ratio calculated by the ECU is by weight than by volume. So that equates to more fuel pumped in to compensate the additional air weight. And thus more power per stroke?

Do we really have a sensor in the car to measure the intake air density? Or is that arrived-at from the exhaust readings?

Most suzuki engines do not have a mass air flow sensor. They rely on intake air temperature sensor and manifold pressure sensors. Not an expert in fluid dynamics, but pressure and temperature are mathematically related to density of air (which in turn can be used to calculate the volume), if some constants are known, and thats how the ECU calculates the amount of air available.Inputs from the lambda sensor also help to keep the mixture slick.

[Jeroen]

There is of course a reason why the original manufacturer design has the throttle body heated.

In general there are two reasons:

Firstly atomized fuel mixes better with warm air than with cold air. In particluar relevant with carburator engines and the early injection systems where air/fuel were mixed prior to entering the cilinder. In theory you lose a bit of efficiency as you let warm air into the engine. But that is offset by the gain of having a better mixture.

The second reason is still very relevant for all engines: Freezing!!
The airpressure drops after across the throttle body and that means condensation and freezing can occur. Contrary to popular believe the ambient temperature doesnt need to be that low before this happens. It's really a combination of humidity, ambient temperature and air pressure.

So for instance driving in mountains (higher altitude means lower air pressure means earlier condensation) even at ambient temperatures this phenomena is known to occur.

There might be also be a third reason; it keeps the throttle plate clean of carbon deposits. On most cars some of the blow by gasses are re-introduced to the inlet side of the throttle body. Having it heated will prevent the carbon deposits to crystalize on the plate and body, thus preventing built up.

If you ever suffered from a stuck throttle plate you will know what this looks like. Believe me, it does happen, some cars/engines are more prone to it then others.

Each to its own, but I make it a general rule not to mess with something I dont fully understand. Each car might be different, but before I would attempt to "enhance" the design of any component of my car, I would really like to understand why in this case the throttle body was heated and how big the affects could be.

Engineers never do anything by chance. If anything producing an engine with a heated throttle body is more expensive then without. More complicated body to cast/manufacture, extra plumbing etc.

So they must have had a very good reason for designing it the way they did. Lots of post in this thread, but very little understanding about why its heated in the first place. So be aware.

Jeroen

Jeroen

[Sankar]

Originally Posted by Jeroen

There might be also be a third reason; it keeps the throttle plate clean of carbon deposits. On most cars some of the blow by gasses are re-introduced to the inlet side of the throttle body. Having it heated will prevent the carbon deposits to crystalize on the plate and body, thus preventing built up.

In most cars including mine the EGR exhaust gases are almost always introduced after the throttle plate and the throttle body.This is done for the reason to keep the tbody clean, be it heated or not.

But what is introduced before the tbody (in some cars including mine) is crankcase gases by means of PCV valve, these gases may condense in the tbody when the conditions are right, but whether that is a cause of concern for me needs to be tested.

If it does happen then the solution for this is an oil-catch-can.

Each to its own, but I make it a general rule not to mess with something I dont fully understand. Each car might be different, but before I would attempt to "enhance" the design of any component of my car, I would really like to understand why in this case the throttle body was heated and how big the affects could be.

When the manufacturer builds a car they do it for the general public and whatever regulations that need to be met. If the tbody coolant was that important then the manufacturer would standardise the presence of it in all of their models.

If someone is of the kind that they believe manufacturer knows the best then its better not to fiddle with their cars. I don't believe that a car rolling out of the factory floor is as perfect as it gets, maybe its the perfect car for the masses but i see everything in it as a compromise.

Engineers never do anything by chance. If anything producing an engine with a heated throttle body is more expensive then without. More complicated body to cast/manufacture, extra plumbing etc.

So they must have had a very good reason for designing it the way they did. Lots of post in this thread, but very little understanding about why its heated in the first place. So be aware.

Jeroen

Jeroen

So what explains this?
2007 MPFI Esteem doesn't have coolant running through the tbody but the earlier MPFI Esteem does? Same case with Alto.

And before i embarked on this i did a lot of reading and came across many posts like this which said manufacturer knows the best, and some saying the gains are too little to be noticed. There were also posts from people who have actually done this and found unexpected gains. Depends on the car too!

[thoma]

Originally Posted by Jeroen

Engineers never do anything by chance. If anything producing an engine with a heated throttle body is more expensive then without. More complicated body to cast/manufacture, extra plumbing etc.

Originally Posted by Sankar

When the manufacturer builds a car they do it for the general public and whatever regulations that need to be met. If the tbody coolant was that important then the manufacturer would standardise the presence of it in all of their models.

If someone is of the kind that they believe manufacturer knows the best then its better not to fiddle with their cars. I don't believe that a car rolling out of the factory floor is as perfect as it gets, maybe its the perfect car for the masses but i see everything in it as a compromise.

Aren't there two ways to it? Manufacturers got resources much more than the individuals to try out various combinations and to record them. That does not mean that the enthusiast in us should not try modifying anything. From the start of time, if everybody were running on stock cars, there won't be these much manufacturers themselves.

But if the manufacturer puts and removes a thing from their car, he knows the exact reason for that, even for a compromise. Need not be the case with an individual; on the other hand, if the enthusiast come to know better than the manufacturer, well and good.

I'll term this thread as a good initiative and we may achieve good results; but en route, the real challenge is to get to the bottom of why exactly the manufacturer put in and removed the item.

[im_srini]

Originally Posted by dhawcash

I am working on a suzuki G16B unit ... I noticed ... the coolant pipes running to the throttle body ... the coolant circulates only at a corner of the throttle body ...

Originally Posted by im_srini

Yes, you're right, the coolant is circulated through a small chamber at the back of the throttle body & basically serves to heat up the throttle body. Will post pics of the Swift's throttle body.

1st Pic : Swift G13B throttle-body, looking at it from the intake manifold end, & TB's inverted. The IACV has been placed on the TB & the arrows point to where the plumbing for the coolant pipes go in.



2nd Pic : Swift G13B throttle-body, looking at it from the intake manifold end, & TB's inverted. The IACV has been removed & the arrow points to the chamber in the TB where coolant is circulated.



3rd Pic : Swift G13B throttle-body, looking at its underside, the chamber in the TB where coolant is circulated can be seen clearly. As mentioned by Dhawcash the coolant's circulated in a small corner of the TB.



4th Pic : Swift G13B throttle-body, looking at it from the intake manifold end, & TB's inverted. The IACV has been positioned so that air-flow through the TB & IACV can be visualized. The port marked "A" opens upstream of the throttle-butterfly & the port marked "B" opens downstream of the throttle-butterfly. The corresponding ports on the IACV have been marked A' & B'. The passage from A' to B' within the IACV is controlled by a flap which is moved back-&-forth by a servo motor. When idling, i.e. the throttle-butterfly's completely closed, air flows from A -> A' -> IACV -> B' -> B. In essense, the IACV allows a controlled "leak" or "bypass" of air around the closed throttle-butterfly, thus controlling idling speed of the engine.



5th Pic : Swift G13B throttle-body, looking at it from the front & TB's right side up. The arrow is pointing to the opening of port "A".



6th Pic : Swift G13B throttle-body, looking at it from the intake manifold end, TB's right side up. The arrow is pointing to where port "B" opens into.

Originally Posted by Jeroen

Engineers never do anything by chance. If anything producing an engine with a heated throttle body is more expensive then without. More complicated body to cast/manufacture, extra plumbing etc. So they must have had a very good reason for designing it the way they did. Lots of post in this thread, but very little understanding about why its heated in the first place.

Hi Jeroen, your point is very valid, but why remove it & then put it back in again ?
Is it possible that the removal of the Throttle-body coolant bypass was a failed experiment (?).

Here's some information regarding the "Speed-Density" system used to estimate air-flow.

[Sankar]

Originally Posted by thoma

Aren't there two ways to it? Manufacturers got resources much more than the individuals to try out various combinations and to record them.

Of course they have vast resources, and from posts made by Behram sir on various threads i realised that all that is good fo the car or the enthusiast doesn't always come out in a production vehicle. Often some things are compromised.

Originally Posted by im_srini

Is it possible that the removal of the Throttle-body coolant bypass was a failed experiment (?).

What were they experimenting? What results were they expecting?

[vikram_d]

My Swift with the G13B never had any coolant pipes going into the throttle body. Strange to see that it has a provision for it.

[Sankar]

The Esteem's tbody too had holes in it like in the pic posted above but there weren't any connectors for the coolant pipes to connect like in the pic below.


Maybe from 2007 Esteem onwards they eliminated this in the G13B engine which also powered the Swift.

[thoma]

Originally Posted by im_srini

Swift G13B throttle-body

Nice details with the pictures. Till now, I had only dealt up close with carburetors and this is the first time I see a disassembled throttle body and practically relate to IACV and so on; even though I have a G16B at home for the past 7 years, I never tried to learn further. I was thinking that these were too complex. No, nothing when compared to the sensitive diaphragms and needles in the carburetor. Thanks for the pictures.

As mentioned by Dhawcash the coolant's circulated in a small corner of the TB.

So, should we say that the exchange of heat is more useful for idling than at other times?

EDIT: OT: Checked my G16B to have the coolant pipes running from the throttle body (marked red). But it has some additional pipes (marked green) running from the engine head to before and after the butterfly.

[vikram_d]

Originally Posted by Sankar

Maybe from 2007 Esteem onwards they eliminated this in the G13B engine which also powered the Swift.

My car is registered July 2006. So I'm guessing they started this trend with the Swift petrol.

[Sankar]

Originally Posted by vikram_d

My car is registered July 2006. So I'm guessing they started this trend with the Swift petrol.

Yep, that might be the case. It skipped my mind that Esteem and the Swift coexisted for couple of years.