Unhooked my double throttle the other day and man do i ever get boost faster now. car feels really smooth and just drives so much better.

 

When you say "unhooked" did you just unhook the vacuum lines from the solenoid and plug the nipple on the intake?

 

Yeap unhooked the vacuum line and plugged the solenoid nipple. The vacccum is still attached on the other side.

 

Did you have a boost gauge to show what your before/after boost was?

FYI, the double throttle is designed to reduce boost when the engine is cold.

 

no its not, its designed to reduce airflow (sorry to nitpick)

 

And the reduced airflow reduces boost and engine load. It's the same thing, isn't it?

Dave

 

You guys are freaking funny...

 

i have heard this is a good mod. anyone know more about it?

 

so is it a bad thing or good thing to do?

 

What's good about this is that you can now remove all associated plumbing for the vacuum controlled secondary throttle. This removes one hose from the throttle body area. Must leave the solenoid attached so that the ECU does not give an error code unless you want to replace it with a resistor. The second benefit is less air flow turbulence after the first double throttle which does not open up 100%. The first (mechanical) is at an angle to the second (vacuum)one. This should give a wee bit more hp, but how much has not been qualified. At least it makes the system simpler and frees up space.

 

any links or write-ups for this?. Is this safe to do for a non-sequential PFC equipped FD?

 

is it safe for a sequential with a pfc?

 

Its function is primarily to protect against the idiot factor. The valves stay shut until the car is warmed up. This doesn't allow too much air into the cold motor. When I say idiot factor I am talking about people that would start the car up cold and immediately floor it. So, its safe with whatever setup you may have.

 

It's not ECU controlled, it's controlled by a solenoid on the rack.

It's never "safe" to do, but it's also never harmful to do. It's something Mazda put in there to help prevent idiot owners from popping their motors. This may be news to you, but the owners are the number 1 enemy of this car.

here's the link on how to delete it.

http://www.rx7.org/Robinette/double_throttle.htm

Also, if you just want to disable it, all you have to do is pull the hose off the actuator and zip tie it shut.

 

So, are you saying that there are no benefits to doing this mod?

 

the only benefits would be if the actuator or solenoid got stuck closed(which I've never heard of happening) or if you're building your car up and you really want that extra 2-3hp you get from the flow increase of not having the butterflies in there. Or if you're doing a DIY rebuild and you want to make it that much easier to take off the UIM next time. Other than that, you're just putting your motor at risk.

 

The DT solenoid is ECU controlled, and the PFC doesn't activate it. If you have a PFC, you know what it's like to have it disabled, but not removed.

 

no, reduced airflow at the same boost. The DTC works by closing 2 of the three intake butterflies. flow @ 10psi through 3x area is greater than flow @10psi through 1xarea.

So in short, you still run 10psi, but because there is less of a gap to force the air through, the flow is less. Same principle as to why removing the cat causes the car to lean out - you run the same boost but the car leans out because resistance is reduced and thus flow is increased.




p.s your car might run much better because of a leaky DTC solenoid partially closing the valve all the time.

 

With the DT closed, my friends FD sees a max of 7PSI. With DT open, he sees 11.5.

I'm with Dave on this one.

And Bob, your theory on the midpipe is long outdated. It's been shown that running a midpipe at stock boost does not cause the car to lean out. It's because the wastegate gets overwhelmed and causes overboosting that causes the lean conditions associated with installing a midpipe, not the incresed flow itself.

 

Having the DT closed reduces boost (measured after the throttle body), and airflow. Removing the DT is not a "mod". It simply allows more flow to a cold engine. The loss of weight is virtually zero. The amount of space saved is virtually zero. So why would anyone do this?? The only reason must be so that they can boost higher on a cold engine.

The DT is there for a good reason. Leave it alone!!!

 

Well, if DigDug is correct, then those of us running PowerFCs don't have it anyway.

 

If its working fine it's best left alone.

 

Having a power FC has nothing to do with having a DT. The power FC may control it (I don't know), but it certainly doesn't eliminate it.

 

I removed mine purely for the extra 1 horsepower,, i swear i can feel it LOL,,, No really i removed mine because it cleans up the upper intake its 1 less solenoid on the rack and if you get giddy like me and completely cut out the double throttle divider ect maybe just maybe it really does make the car a little faster. (I want my car to be simple) :-)

 

An FD will never be simple.