For 13 years my 91 Firebird was my DD. 100 degrees or 20 below. No freezing in spite of the car being outside 100% of the time.

Not sure how to measure that but winter fuel would suck whatever you gained.

 

Honestly, if it truly doesn't perform it's function for winter driving, then my only guess as to why GM would have designed the throttle body to run coolant through it would then be to intentionally heat up and reduce the density of airflow for a marginal increase in fuel economy. I want to make it known that I did this modification on my own car in the past and from memory, I hardly noticed any performance improvement but during winter the car seemed sluggish and it did consume more fuel. The only reason my car is back to using the factory set-up was that my mechanics shop reversed my modification without me knowing it and I didn't discover this fact until some time later, the bastards, they kept my end caps and everything. However, the car really didn't suffer *AND* fuel economy was marginally better, but that was with the factory WS6 ram air box, but plastic degrades and this factory mold was starting to split apart allowing unfiltered air into my motor, which is why I have a much better factory LS1 air box from a Camaro on my car! My fuel economy improved a tad and driving around winter with deactivated ram air nostrils in the hood, the motor actually seems to run better with warm engine bay air, despite the obvious reduction in power. This is how a mad scientist with a sports/muscle car finds ways to balance power with fuel economy.

 

1. likely hood of freezing is essentially nil
2. you're not heating the blades. You're heating the housing. Even if there were a fuel economy gain, it would be for different reasons than you cited, and it would be just as MARGINAL as your power loss (worthless)
2a. if you really want to see an improvement in vaporization of fuel due to hotter inlet air, a heat stove on the exhaust (like seen on older carb'ed cars) would be massively more effective.
3. The OP removed the feature b/c it was leaking...not b/c he was "really that pressed for a marginal gain in HP".



No. If you want to reduce the density of the air inside your plenum (and this is why you are wrong in #2 above) you simply reduce throttle opening....and there is your reduced air density. The marginal gain that you could get from warming intake air would come from better/faster vaporization of the fuel as it's injected into a warm stream of air, rather than a cold one. Sorry, but you missed the science behind your "mad scienceing"...again.

Nope, GM did not add a coolant passage to the TB, to reduce air density (on a performance car). They did it because that they have to meet criteria that we don't and we don't care about. Like running at 40* below zero, for example. Most of us don't operate under those conditions, so we can make changes that have no meaningful negative impact.


Can someone quote this so Penix can see it please?

 

Not in WI but then this car might be sold in the north most section of Alaska which might see this condition. Now IF I drove this car to Fairbanks Alaska and started it in winter and ran into an issue, the common thing is to call my lawyer, etc, etc. Bottom line is I tend to view the manufacturer with a jaundiced eye. I agree that they know much more about the car than others. That said, what they reveal to you, the general public is unlikely the whole story.

I generally dismiss what people say they felt, feel or will feel simply because the butt dynos are too crude and subjective. You won't feel a 1 HP difference, for example. Show me a dyno sheet and I believe you.

IDK if I call the subjective assessments science but others might.

 

If you are driving in subfreezing weather, especially in below 40 degrees zero, freezing does occur. Lets not overly simplify this matter. GM would not have spent the extra money to flow coolant through these throttle bodies if there was not some particular reason, whether it being as minor as winter driving purposes to possibly trying to warm up incoming air by having it collide with a hotter throttle body versus one without hot coolant running through it.



We are not talking about the size of the inlet for the throttle body, we are talking about the nature of warmer/less dense air to colder/more dense air. This property is already well known by those trying to squeeze more power out of their internal combustion engines. So, yes, despite the throttle body coolant system NOT being something connected to the hottest part of the exhaust system, it still serves to improve fuel economy, and even a marginal gain per mile is an improvement during the winter.


Again, for profit sake, GM would not have added the throttle body coolant system if it served no purpose. Even, then if it is better to drive your car with the throttle body coolant system in use during the winter, then what is the problem? As I have said, despite the obvious loss of power which I don't need it for winter driving, the car runs very smooth, and I have noticed the mileage is a little better before encountering below 30 degree temperatures and snow. I am willing to try driving around in the spring with the ram air hood deactivated to see how much of a mileage gain this set-up gives me. It may have me considering a custom cowl hood using my factory WS6 hood with whatever engine modification I decide to go with.

Oh, by the way, let me help you with your poor illiterate spelling. It's Phoenix, p.h.o.e.n.i.x! I can forgive you.

 

Well I just bypassed mine and I can feel the improved acceleration. No question.


Wait maybe it was the new plugs, wires, coil, opti, TB cleaning. Nah, I think the real horsepower gains came from rerouting a 1/2" cooling line.

 

With sufficient moisture and that temperature and the engine sat overnight, sure. While it is running, I have my doubts.

IIRC, the intake was a truck intake? For a truck that sits outside in cold areas, it could make sense. If so we might be getting a "hand me down", essentially.

How marginal? As marginal as the loss of fuel economy with winter fuel? We know that has less BTU.

Agreed but whether that purpose is useful to a C4 is the question.

How much loss? How sensitive is your butt? How did you determine the fuel had no effect?

 

Or the wind direction? Or maybe the angle of the dangle or the road?

 

I am definitely not talking about while the engine is already hot.


Well, I noticed a difference of at most two miles per gallon compared to my mileage without the use of the throttle body coolant. I log it on the EPA fuel mileage site like the Eco-Modder dork that I am. So, using the throttle body coolant system, it makes up for the loss you experience in fuel economy during the winter BUT come spring and summer you should be able to gain that much to your normal fuel mileage. Basically it is just playing a balancing game between fuel economy and how much power to give the motor, or really, modifying the motor to breathe in more warm air! It sounds self defeating but I am crazy enough to play around with the notion.

 

How did you negate the loss with respect to summer gasoline vs winter gasoline? These and other issues may be responsible for the mpg difference. To evaluate these things, you are going to need to stabilize everything and not just pounce on heat in the TB. What have you used as a control group?

 

Weird. I've been driving in sub 40* weather for ~30 years. Never had a TB freeze. I told you why GM did it; criteria that we don't have to meet. Posters in this thread have pointed toward "Alaska" as an example. I said "40 below"...which is VERY different than what you just said; "below 40". Many of us drive in weather "below 40" with no issues. In fact, I did today -it was 16* when I left my house this morning! I must have gotten super lucky, b/c my TB didn't freeze! "40* below" is quite different; nearly none of us drive in those conditions, but GM DOES. Most if not all of us will never have TB icing that affects us...but if we were running in -49*F temps like GM does...then we might. Can you "get it"? GM has to meet criteria that we do not...and we don't care about.





We (you) were talking about air density. That is controlled very easily, with the gas pedal....not the TB temperature.

While a warm TB MAY provide an infinitesimal increase in fuel economy it's not because of the reason you WAG'ed (lower density). You control air density with the gas pedal. For the second time, any minute increase in fuel economy would be as a result of better vaporization.

FYI, I'm still getting the same (hand calc'ed) -or w/in 1 mpg- gas mileage that I got all summer. What ever the diff...IF there is any, is too small to observe in hadn't calc's every tank... in my TB bypassed car, so...You're really grasping at straws here with the fuel economy thing.

Let me ask you this; if you're so convinced that fuel economy is a meaningful factor in implementing the TB/coolant feature...then why didn't GM run coolant through the entire intake plenum? Imagine the fuel economy!! In fact, with the LT1, they removed coolant from the intake that the previous L98 had.
OR
Why didn't GM retain the "heat stove" philosophy that was in place on earlier carb'ed TBI engines? That would likely be cheaper than the TB coolant passages, it would be WAY more effective at feeding HOT air...and just Imagine the fuel economy!!




Yikes. I already told you why GM did it; criteria that we don't have to meet. Why does GM use muffled air inlet tracts (and we install "open element CAI")? Why does GM use quiet mufflers (and we install loud ones)? Why does GM install air bags (and we take 'em out for "Grant GT steering wheels?) Why does GM sell a 300 hp engine (and we install a cam, heads and exhaust to get 400 hp)?

All this from the guy that thinks more vacuum = better fuel economy, strokers will ruin fuel economy and gears will cause him to accelerate too fast. I told you why GM did it; criteria that we don't have to meet and don't care about.


.

 

Was our intake a "hand me down" from trucks that could possibly be sitting in sub zero weather?

 

That I have no idea about that. Never heard of any such thing, but our TB WAS a "hand me down" from the TPI....which should have been a truck engine.

Interestingly, the GM TBI truck engines of the era didn't have any provisions for a TB coolant system. They did have head stoves though. Anyway, their replacement, the L31 Vortec had no heat stoves nor any TB coolant provisions. How to they manage!? Can you imagine the fuel economy that's been left on the table with those engines!?

 

Enough to buy a newspaper although I haven't bought one in eons?

 

Actually, air density is not controlled by the gas pedal (throttle opening). The gas pedal controls air flow only.

Air density is determined by other factors, most of which we have little to no control over (air temp, altitude, barometric pressure, dew point, etc.)

 

I think you might be missing some context. Did you read the posts above?

The air density inside the plenum/runners/cylinders is managed with the throttle pedal. Pheonix (the poster who I was replying to) was talking about air density inside the plenum. You manage that with your right foot.


If you want to argue semantics, then yes, TB controls air flow. What do you suppose happens to the density of the air in the plenum when we increase airflow (with the gas pedal) into the plenum? The density increases. What happens when you take your foot off the gas pedal? Throttle plates close, air flow dwindles, density in the plenum drops. We control the density of the air in the plenum with the gas pedal....not the temperature of the TB (which phenoix was trying to claim when he said this:

"my only guess as to why GM would have designed the throttle body to run coolant through it would then be to intentionally heat up and reduce the density of airflow for a marginal increase in fuel economy."

I was responding to that. No. GM is NOT trying to manage air density in the plenum using temps and/or heated TB's. You control air density in the plenum with the gas pedal.

.

 

Well, I DO care about it, and especially after noticing a marginal increase in fuel economy from driving without the throttle body coolant for a year to driving with the system restored, thanks to a mechanics shop that stole my mod kit. It doesn't matter if you drive in Sub-Arctic cold or not, this throttle body coolant system does not hurt our motors any bit, and I SERIOUSLY DOUBT that tid bit of cooler and marginally denser air will make it worth your while when you are burning more fuel during the winter time, which is where I noticed the mileage difference in my years of logging.


Well, when you warm up air and mix a small spray of gasoline, don't you produce a better vapor from this? There is something to having all those incoming air molecules striking the hot throttle body and blades before making their way to the intake runners and ports for combustion.


Well, you guys modify your cars for high horsepower performance, and I respect that! Me, I am on the opposite side of the spectrum, trying to improve the daily driving experience of my car which does not require high horsepower performance since I can't use it and since the police love to single my car out for being a sports car! Plenty of people around me drive dull and average cars, I don't see them getting the attention that my slower driving sports car gets from law enforcement!


Easy, the cost to make such an intake! Furthermore, the aluminum throttle body alone would transfer heat to the intake plenum, so there really wouldn't be the need to flow coolant through the intake plenum as well! Also, the airflow in the plenum wouldn't strike enough of the surface area to generate the added benefits given from running coolant through the plenum, this is where pumping in superheated exhaust gas comes in to play.


Well, don't you sound like a smart fellow, removing those dorky air bags for a daily driver? Well, explain to me how more vacuum pressure does NOT relate to fuel consumption! The winning combination, in my mind, is increased low end torque and plenty of vacuum production. Being the dork that I am, I am thinking that pairing the TPI intake with my factory camshaft along with complimentary bolt on parts, shall give me the lame duck performance boost I seek while helping me maintain, IF NOT, marginally increase my fuel economy a bit more.

 

I agree.

Now take your laser light and go, before everyone decides to make a concerted effort to get you banned from this forum.

 

Ban me for what? Having a conversation about fuel economy modification on a performance forum for Corvette owners?! I know I am not the only one asking about daily driving upgrades to their motor, so why am I singled out when I contribute to the conversation?

 

You know what your doing, and its pretty effing far from contributing. You also know, that I know what your doing, even if no one else does, and its time to stop.