Throttle body heater delete (Page 4/5)
Yellow-88 SEP 03, 11:30 PM

quote
Originally posted by 82-T/A [At Work]:
This thread had me thinking earlier today when I was working on the car with my daughter. The A/C lines run right along the fuel lines for the 4 cyl / Iron Duke Fiero. I was wondering if it would make any difference in engine efficiency if I wrapped the pressure fuel line next to the pressure line from the A/C compressor... haha... it would cool the fuel line and provide some cool fuel into the TBI unit. Perfect for icing... and that's when I changed my mind.



Would cooler fuel increase the rate of evaporative cooling? Or maybe just cool the body a bit?
At what point along the air flow is the fuel injected on the TBI? Is there a venturi in it?
I forgot.
armos SEP 04, 01:03 AM
On the V6 - the first time I needed to remove the coolant lines, I left them off. They just complicate the engine bay and get in the way.
It's hard to imagine they add much capacity to the system, or improve the cooling capacity much, but I can accept that as a minor plus. But really if I thought I had a problem in that regard I'd just upgrade the radiator.

I first tried blocking the lines with rubber caps - but the caps weren't strong enough and in a week it was leaking.
A short bypass hose connecting the 2 points worked fine, that's how I left it.


Theorizing some more - these lines could be a minor negative for the ECM's performance.
The ECM wants to know the air temperature in the manifold, but the sensor isn't there. The sensor is in the air cleaner housing - upstream of the throttle.
The coolant lines in the throttle body and the EGR heat both add variables that would hurt the repeatable accuracy of the ECM's "estimate" of what the Manifold air temperature actually is.

Presumably GM tried to account for this when they dialed in the tune, but they're working with limited information and a limited computer.
For someone doing a custom tune, removing both of those variable heat sources could be seen as an advantage.
82-T/A [At Work] SEP 04, 08:22 AM

quote
Originally posted by Patrick:
Don't be so quick to dismiss the effects of fuel atomization on carburetor (and/or TBI) icing.




I didn't mean to suggest that the fuel wasn't a contributing factor in the cooling process... it has the same cooling effect as alcohol on a wound. I simply meant that it's not the fuel itself that is freezing, but the water vapor in the ambient air. There's a word for this, but I cannot remember.



quote
Originally posted by Yellow-88:
Would cooler fuel increase the rate of evaporative cooling? Or maybe just cool the body a bit?
At what point along the air flow is the fuel injected on the TBI? Is there a venturi in it?
I forgot.



Well, every liquid transfers heat. Obviously not the transfer of coldness, but the shedding of heat. The injector on the TBI Fieros sits directly above the throttle body, and injects directly into it vertically as the air passes around it.

This is a picture of a Holley TBI replacement unit for the 2.5 Fiero (and CFI F-bodies and Corvettes). It's 95% identical to the stock one in the Fiero, it just has a larger bore and throttle plate. Otherwise, it's intentionally designed to be identical. It was just the first image that came up.
Raydar SEP 04, 11:27 AM

quote
Originally posted by Patrick:

On the contrary, it seems to me that everybody has mentioned that the 2.8's TB doesn't ice up.




Over the years, I've seen lots of threads/posts, that seem to say that we (people who remove the tubes) are all going to die in grinding crashes caused by iced up throttle bodies.
Just seems to be the way of things, here. You know how we get.

Don't even get me started on EGR...

[This message has been edited by Raydar (edited 09-04-2024).]

ArthurPeale SEP 04, 02:18 PM

quote
Originally posted by Yellow-88:


Why would you have an EGR with no vacuum line? Yeah, you do need a cold start injector. I think you mentioned once that you have to crank a long time to get started. Could that be the problem?



I had been experiencing long start times. Unplugged the cold start injector, and now it starts within moments. I think mine may be putting too much fuel into the intake.
Yellow-88 SEP 05, 08:55 AM
Thank you for the enlightenment. Now I get it.
The TBI unit is basically a carburetor with its fuel injected instead of being sucked out of the bowl. Carburetors rapidly evaporate fuel thus sheading heat, cooling the TB. There is no evaporation in the MPI throttle body so it won't get any cooler than the air coming in. Apparently the parameters needed to grow TB snowballs are pretty narrow because I ran multiple side draft carbs for many years often in what seemed like ideal conditions but only saw TB snowballs once. That day was just above freezing and very humid. I was running about half throttle for a hour steady. Yeah, the throttle sticks and could cause problems but the snowballs melt pretty quick.

So ..... I'm loosing the heat tubes on Yellow because they do nothing but just get in the way.
olejoedad SEP 05, 09:33 AM
IMHO, GM included the water lines to eliminate the possibility of icing simply due to the possibility that the icing could occur under some very specific set of conditions. The cars were warrantied by GM, and sold all over the country.

Are the lines needed under most circumstances? Probably not.
Will some cars that have had the lines removed experience the icing problem? Maybe, maybe not.
Will the modification void the warranty? I think we all know the answer to that!
Raydar SEP 05, 06:06 PM

css9450 SEP 06, 09:15 AM

quote
Originally posted by olejoedad:

IMHO, GM included the water lines to eliminate the possibility of icing simply due to the possibility that the icing could occur under some very specific set of conditions.



Something about pressurized humid air moving through a narrow orifice can cause icing. I probably really should look into the science behind it, but I remember when I had a job inspecting pile-driving jobs (I had to count however many blows per foot) the pile-driving hammer would constantly develop frost and chunks of ice where the compressed air was exhausted out of it. Even on 90-degree days in the middle of summer. It was the craziest thing I ever saw.

olejoedad SEP 06, 10:05 AM
When a manufacturer issues a product with a warranty, it behooves the manufacturer to cover all of its bases.

Thermodynamics is very interesting.