DIY: Throttle body bypass mod
Just to clear up the reason why some manufactures run coolant through the throttle body. It is for emissions, The same reason cars run a min 195 degree thermostat. The less dense air means less fuel, less fuel means more complete fuel mixture burns. More complete fuel mixture burns mean less emissions coming from the tail pipe. For those that don't know, the rotary engine was always bad on fuel mileage and emissions, Emissions was the reason the RX-7 was not sold here for years. If you take the coolant out of the throttle body it is kinda like the old trick of putting a lower thermostat in, Colder air=dense air. Dense air=more air, More air=more fuel, more fuel=more power. more fuel also = less mpg, more emissions. So please stop with the stupid BS of icing T-body plates.
Lubricious
Joined: Oct 2003
Posts: 3,425
Likes: 4
From: SF Bay Area, California
Originally Posted by RxJaye
Just to clear up the reason why some manufactures run coolant through the throttle body. It is for emissions, The same reason cars run a min 195 degree thermostat. The less dense air means less fuel, less fuel means more complete fuel mixture burns. More complete fuel mixture burns mean less emissions coming from the tail pipe. For those that don't know, the rotary engine was always bad on fuel mileage and emissions, Emissions was the reason the RX-7 was not sold here for years. If you take the coolant out of the throttle body it is kinda like the old trick of putting a lower thermostat in, Colder air=dense air. Dense air=more air, More air=more fuel, more fuel=more power. more fuel also = less mpg, more emissions. So please stop with the stupid BS of icing T-body plates.
Before you call BS on the icing issue, take time to read some of the references.
give 'er some stick!
Joined: Apr 2007
Posts: 7
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From: State of Denial
Yep - emissions reasons are BS. Higher combustion temps yeild higher emissions (well, NOx / SOx anyway, CO comes down with combustion temp...). Read any combustion textbook. Also, absolutely not enough heat transfer area to conduct heat to the air (the TB is not designed like a radiator). The "coolant" was there to keep the TB hot.
It took you guys 2 years to come up wityh this BS. It is emissions related, ask anyone with a history in Vehicle performance.... Sorry im just a Master Technician, i have no idea what im talking about. Collage training, Factory training and accually working on cars everyday shouldnt make my opinion any more valid, Just the simple fact that I understand how a car works does. But if you guys want to debate it for another couple of years go ahead, I find it amusing.
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Joined: Apr 2004
Posts: 8,625
Likes: 5
From: USA
Originally Posted by RxJaye
It took you guys 2 years to come up wityh this BS. It is emissions related, ask anyone with a history in Vehicle performance.... Sorry im just a Master Technician, i have no idea what im talking about. Collage training, Factory training and accually working on cars everyday shouldnt make my opinion any more valid, Just the simple fact that I understand how a car works does. But if you guys want to debate it for another couple of years go ahead, I find it amusing.
Carburation? No one said anything about a carb. Anyway, Ill let you all debate on this for another couple of years. I stand by my explaination, because it is right. By the way the heat of the engine compartment would thaw out a throttle body if it was to freeze anyway, but they dont. Thats just ignorance.
Lubricious
Joined: Oct 2003
Posts: 3,425
Likes: 4
From: SF Bay Area, California
Here's an alternative explanation of what the coolant line may be for -- activation of the FIAV (fast idle air valve). I don't know if this has been mentioned. I will still stand by my assertion that the purpose is NOT to warm the incoming air, because that is just physically impossible given the amount of flow and the surfaces involved.
Anyway, this FIAV thing makes a lot of sense.
http://www.stealth316.com/2-3s-tb.htm
So, it would seem that blocking the line isn't going to give you performance boost, but might give you idle problems.
What say you, Master Technician?
Anyway, this FIAV thing makes a lot of sense.
http://www.stealth316.com/2-3s-tb.htm
So, it would seem that blocking the line isn't going to give you performance boost, but might give you idle problems.
What say you, Master Technician?
Last edited by Nubo; Apr 27, 2007 at 03:02 PM.
for hire
Joined: Aug 2005
Posts: 172
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From: broward
Originally Posted by RxJaye
Just to clear up the reason why some manufactures run coolant through the throttle body. It is for emissions, The same reason cars run a min 195 degree thermostat. The less dense air means less fuel, less fuel means more complete fuel mixture burns. More complete fuel mixture burns mean less emissions coming from the tail pipe. For those that don't know, the rotary engine was always bad on fuel mileage and emissions, Emissions was the reason the RX-7 was not sold here for years. If you take the coolant out of the throttle body it is kinda like the old trick of putting a lower thermostat in, Colder air=dense air. Dense air=more air, More air=more fuel, more fuel=more power. more fuel also = less mpg, more emissions. So please stop with the stupid BS of icing T-body plates.
all cars are controled by ecu or pcm now. fuel injection requires a computer. Aisian auto manufactures are big on coolant heating the incoming air charge by heating the throttle body. this is an easy inexpensive way to save on fuel milage and to help with emissions. idle air valve is controled by a stepper motor ever heard of an IAC? it is PCM controled the pcm uses IAT, MAF, ETC, O2 sensors to adjust the fuel injector pulse width to be as lean as possible without causing damage and keep idle up. The RX-7 used 40% more fuel at idle then the 8, and the 8 get crap for gas milage, so anything will help. Its not hard to understand if you think about it. Im not guessing here by the way like most of you guys.
And by the way if your thottle body freezes up the car wont even start, so the cold coolant wont be able to warm up to thaw out your "frozen" throttle body. Another thing if you have a problem with water getting on the throttle body where it could possibly freeze you have worse problems than just a frozen throttle body. The reason airplanes used this is because in upper atmosphere things are cold, especially traveling a couple hundred MPH or so, plus there is alot of condensation in the air up there so things can freeze. Like i said use your brain its common sense people.
Throttle bodies don't "freeze up". That is a carburettor behavior because of the presence of fuel. Since there is no significant drop in temperature across the TB (venturi effect), the only real reason for heating the intake charge is emissions.
Also, the RX-8 doesn't have an IAC.
Also, the RX-8 doesn't have an IAC.
Last edited by MazdaManiac; Apr 30, 2007 at 08:52 PM.
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Nubo-
Here's an alternative explanation of what the coolant line may be for -- activation of the FIAV (fast idle air valve). I don't know if this has been mentioned. I will still stand by my assertion that the purpose is NOT to warm the incoming air, because that is just physically impossible given the amount of flow and the surfaces involved.
Anyway, this FIAV thing makes a lot of sense.
http://www.stealth316.com/2-3s-tb.htm
So, it would seem that blocking the line isn't going to give you performance boost, but might give you idle problems.
What say you, Master Technician?
all cars are controled by ecu or pcm now. fuel injection requires a computer. Aisian auto manufactures are big on coolant heating the incoming air charge by heating the throttle body. this is an easy inexpensive way to save on fuel milage and to help with emissions. idle air valve is controled by a stepper motor ever heard of an IAC? it is PCM controled the pcm uses IAT, MAF, ETC, O2 sensors to adjust the fuel injector pulse width to be as lean as possible without causing damage and keep idle up. The RX-7 used 40% more fuel at idle then the 8, and the 8 get crap for gas milage, so anything will help. Its not hard to understand if you think about it. Im not guessing here by the way like most of you guys.
Here's an alternative explanation of what the coolant line may be for -- activation of the FIAV (fast idle air valve). I don't know if this has been mentioned. I will still stand by my assertion that the purpose is NOT to warm the incoming air, because that is just physically impossible given the amount of flow and the surfaces involved.
Anyway, this FIAV thing makes a lot of sense.
http://www.stealth316.com/2-3s-tb.htm
So, it would seem that blocking the line isn't going to give you performance boost, but might give you idle problems.
What say you, Master Technician?
all cars are controled by ecu or pcm now. fuel injection requires a computer. Aisian auto manufactures are big on coolant heating the incoming air charge by heating the throttle body. this is an easy inexpensive way to save on fuel milage and to help with emissions. idle air valve is controled by a stepper motor ever heard of an IAC? it is PCM controled the pcm uses IAT, MAF, ETC, O2 sensors to adjust the fuel injector pulse width to be as lean as possible without causing damage and keep idle up. The RX-7 used 40% more fuel at idle then the 8, and the 8 get crap for gas milage, so anything will help. Its not hard to understand if you think about it. Im not guessing here by the way like most of you guys.
Originally Posted by RxJaye
all cars are controled by ecu or pcm now. fuel injection requires a computer. Aisian auto manufactures are big on coolant heating the incoming air charge by heating the throttle body. this is an easy inexpensive way to save on fuel milage and to help with emissions. idle air valve is controled by a stepper motor ever heard of an IAC? it is PCM controled the pcm uses IAT, MAF, ETC, O2 sensors to adjust the fuel injector pulse width to be as lean as possible without causing damage and keep idle up. The RX-7 used 40% more fuel at idle then the 8, and the 8 get crap for gas milage, so anything will help. Its not hard to understand if you think about it. Im not guessing here by the way like most of you guys.
So if the "theory" of what RxJaye and Nubo are saying are correct than...
1. Would you not see a difference in idle rpm after the throttle mod?
2. Also, would you not see an overall difference in gas usage before and after this mod?
Since a number of people have done this mod, they can give information about the above 2.
Everyone that has done this mod, what do you think?
Originally Posted by sosonic
So if the "theory" of what RxJaye and Nubo are saying are correct than...
1. Would you not see a difference in idle rpm after the throttle mod?
2. Also, would you not see an overall difference in gas usage before and after this mod?
Since a number of people have done this mod, they can give information about the above 2.
Everyone that has done this mod, what do you think?
1. Would you not see a difference in idle rpm after the throttle mod?
2. Also, would you not see an overall difference in gas usage before and after this mod?
Since a number of people have done this mod, they can give information about the above 2.
Everyone that has done this mod, what do you think?
2. No difference
I forget the Rx8 has ETC and doesnt need IAC for idle. But you should have no idle issues since it is pcm controlled. There will be fuel milage concerns but very minute. More noticable if you put a lower thermostat in.
can someone point me to where the bottom hose is again? if I'm facing the engine, is it the one kinda' buried beneath the throttle body to the left a litte? Obviously the top was a piece of cake, just want to make sure I'm yanking the correct hose from the bottom. (pretty sure I may have the right one, it's the only one connected and has the same heat blanket type covering as the top, just would like to verify first) Thanks!!
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Joined: Apr 2004
Posts: 8,625
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From: USA
can someone point me to where the bottom hose is again? if I'm facing the engine, is it the one kinda' buried beneath the throttle body to the left a litte? Obviously the top was a piece of cake, just want to make sure I'm yanking the correct hose from the bottom. (pretty sure I may have the right one, it's the only one connected and has the same heat blanket type covering as the top, just would like to verify first) Thanks!!
https://www.rx8club.com/showpost.php...&postcount=121
car's too hot to play anyway, so I'll be finishing this up this evening, thanks again :thumbup:
Has it really gotten so bad that people ask for direction in an existing thread that already has ALL of the answers?
I've run into this a couple of times this week already and its frightening.
Is it something in the water?
It is bad enough when newbs post new threads about obviously available stuff, but for an established forum member to screw up that bad means there is something else at play.
Maybe its just hand-holding...
I've run into this a couple of times this week already and its frightening.
Is it something in the water?
It is bad enough when newbs post new threads about obviously available stuff, but for an established forum member to screw up that bad means there is something else at play.
Maybe its just hand-holding...
Registered
Joined: Sep 2003
Posts: 197
Likes: 1
From: Ocala, FL
Throttle bodies don't "freeze up". That is a carburettor behavior because of the presence of fuel. Since there is no significant drop in temperature across the TB (venturi effect), the only real reason for heating the intake charge is emissions.
Also, the RX-8 doesn't have an IAC.
Also, the RX-8 doesn't have an IAC.
be turned on." There is no fuel any near the cowl(intake) of a jet engine. It is less likely to occur in a car since throttle position is constantly changing. Aircraft throttle plates tend to be set and stay there for a long period of time. I have had a piston engine develop ice. It got my attention as the engine sputtered as it swallowed chunks of Ice. The outside temp over Miami was about 5 C at 10,000 ft.
I wouldn't worry about it in our cars since they are at wide open throttle on a regular basis.
Original Turbo 'd Auto !!
Joined: Mar 2004
Posts: 2,136
Likes: 5
From: Surprise, Arizona
MM, To answer your question about all of the "dumb" questions lately, It's the heat causing the "dumbness"...around here..
as for Mr Corbitts comments: I had a Bug whose carb would ice over. That was in Chicago with humidity. I rarely get to WOT the car. I run out of road too quickly.
The majority of us that did this mod live in hot arid environments.
I see intake temp of 120-170 degrees and coolant temps of 205-212.
just trying to keep as much heat out of the intake air that I can.
as for Mr Corbitts comments: I had a Bug whose carb would ice over. That was in Chicago with humidity. I rarely get to WOT the car. I run out of road too quickly.
The majority of us that did this mod live in hot arid environments.
I see intake temp of 120-170 degrees and coolant temps of 205-212.
just trying to keep as much heat out of the intake air that I can.
I doubt any normal driving scenario will yield a 3000 PSI difference across the TB.
That would be one hell of a turbo.
