Electric throttle bodies and exhaust cutouts

[Guest]

Anyone besides me think of taking the electric throttle bodies found on the new motors and making an electric exhaust cutout? Aluminum has a melting point above 1200 degrees and I doubt it will ever get that hot a good distance past the converter. So far my EGT gauge hasn't registered 1000 deg at the exhaust manifold from what I have seen. I run two EGT sensors about 3 ft apart and they usually read about 150 deg different although some of that may be due to the sensors being different. One signals the gauge and the other is for datalogging.

I noticed the units sold for this task are mostly aluminum.

The throttlebody motors are two wire units as can easily be seen once the cover is removed from the throttlebody

[IsaacHayes]

Aren't the 3500 TB's/etc stepper motors.. But yeah I've thought of it.

[Joseph Upson]

Aren't the 3500 TB's/etc stepper motors.. But yeah I've thought of it.

Stepper by way of varrying resistance electronics, I just tested the motor itself with a 1.5 volt AA battery and it runs like a typical electric motor although slow due to the low power input.

[IsaacHayes]

Really...... Hmmm Then yeah why not? I haven't opened my LX9 3500 TB yet.

The heat may get to the motor eventually. You'd need some sort of way of knowing then it was open/closed so it doesn't load up the motor.

[Superdave]

the heat will kill the motor.. also it'll leak all the time.. lol

[Joseph Upson]

the heat will kill the motor.. also it'll leak all the time.. lol

Not sure about that one Superdave, unlike what I've seen in specialty kits made for this, the motor is a pretty heavy duty unit to start with and considering it is designed for direct connection to the engine which will subject it to very high temperatures certainly higher than boiling water temps I believe it will survive without a problem considering the exhaust heat would travel past it instead of directly over it and it would only be subject to the most heat when it is open and exhaust is allowed to pass through it.

A case in point for durability would be the electrically operated EGR valve, same magnetic electromotive principle, different function, if those solenoid coil windings can last behind the heat they are subjected to then most certainly the design of this motor will.

I could be wrong but I believe this unit was designed with great heat resistance in mind especially given the heat it will generate from being prevented from full revolution in its normal use.

It would only leak if it were damaged, I have the throttlebody from my burnt 3900 and it is disfigured giving some idea of the temps reached under the hood, the throttle blade didn't look bad if I recall correctly. I would have to look at it again.

[geldartb]

hold it up to a light and you will see it doesnt seal 100% like a cutout does.

for the money and time spent on this you could just buy an electric cutout. FYI stay away from the Quick Time Electric Exhaust Cutout there junk.

[Joseph Upson]

hold it up to a light and you will see it doesnt seal 100% like a cutout does.

for the money and time spent on this you could just buy an electric cutout. FYI stay away from the Quick Time Electric Exhaust Cutout there junk.

Actually cost wise there's no comparison to purchasing them. I have the throttlebodies as left overs along with exhaust tubing, a welder and plasma cutter. This is enginuity driven. The easy way would be the cast iron manual cuts from JC Whitney for $40 ea. If you are referring to the stock stop that prevents the electric TBs from closing I've modified one to allow it to close completely.

[IsaacHayes]

Yeah but even at idle there is air going through with the TB closed. I don't think the leak would bet that big of a deal to worry about though.

[Superdave]

well.. there is one good way to find out if it'll work.. :P


If you need another one let me know, i've got mine laying around somewhere.

[Chris88CL]

I've been considering this also and happen to have a 3500 TB specifically for this purpose.

How did you get past the stock partially opening issue? What modifications were made? I havent cracked mine open yet. It's still got the stock harness on it with all 10-15 wires still.

[Joseph Upson]

I've been considering this also and happen to have a 3500 TB specifically for this purpose.

How did you get past the stock partially opening issue? What modifications were made? I havent cracked mine open yet. It's still got the stock harness on it with all 10-15 wires still.

Grind away the area with blue coloring indicated by the pin cap and it will allow the throttle to close completely, note once the cover is removed there are only two terminals to power the motor.

[Chris88CL]

Very nice. I think I might go to do that tonight. I wish the welder wasnt out of gas.

[TurboProject]

I believe most if not all of the drive-by-wire throttle bodies are servo motors and not stepper motors. And since there's only two wires going to that motor then that should mean that it is a servo motor. Steppers have 4 to 6 wires.
But servo motors are really just motors and it's the control circuitry that controls their position. So if you just connect a switch like some of the exhaust cutout ones have that allows you to reverse the polarity then it should work by just connecting to those two wires you're seeing.

Another big difference with those electric exhaust cutout motors is that they use gear motors which produce a lot of torque. This helps them stay closed as well as open against exhaust pressure. You really can't force them open by hand very easially. The drive-by-wire TB on our altima can be forced open pretty easially.

[Joseph Upson]

I believe most if not all of the drive-by-wire throttle bodies are servo motors and not stepper motors. And since there's only two wires going to that motor then that should mean that it is a servo motor. Steppers have 4 to 6 wires.
But servo motors are really just motors and it's the control circuitry that controls their position. So if you just connect a switch like some of the exhaust cutout ones have that allows you to reverse the polarity then it should work by just connecting to those two wires you're seeing.

Another big difference with those electric exhaust cutout motors is that they use gear motors which produce a lot of torque. This helps them stay closed as well as open against exhaust pressure. You really can't force them open by hand very easially. The drive-by-wire TB on our altima can be forced open pretty easially.

I don't have the throttlebody here with me but if it allows the blade to stand straight up there should not be a problem with it being blown open since the throttle blade is centered on an axis allowing for equal pressure pushing on both halves at the same time in the same direction, wanting to fold it rather than open it. I would imagine this is the reason it is not sucked open by engine vacuum either.

If it were off center the story would be different in favor of the larger of the two surface areas. That throttlebody spring is pretty strong and you only need the polarity to work in one direction since it will automatically close without power. In order to reduce heat from electricity the minimal amount of voltage necessary to open it fully would have to be applied instead of the full 12 v from the battery which I'm sure would burn it up pretty quick. If some how it is blown open then a small reverse polarity voltage should do the trick since it is also gear reduced favoring the motor.