Well, I disconnected the Secdonary Throttle Body Ports From the primary TB port just to see if I would get any more low end HP and Torque. And The answer is Yes. Not very much. Its not enough to jump up and down about but there was an increase between 1000 and 2300 Rpm then the power pretty much died after that.
I did a couple test runs. I also dropped the clutch at idle and hit the gas at the same time. I got a little wheel spin and it bogged down a little bit but it kept on going. I also did this before I tried this mod and the engine almost boged out complety even on dirt.
After 2300 rpm the power dies out pretty quick. Im going to use a VDI port actuator and with an RPM switch and an electronic air pump to actuate the secondary ports. I just need to weld up a bracket for the actuator.

So..

The Engine reved quicker
Had better throttle responce
And added some Torque and HP between 1000 and 2300 RPM.

Justin

 

You need to explain what you did better, because the primary and secondary TB ports aren't "connected" in the first place.

 

I think he means that he made it so the 2ndary butterflies do not open at all.....and that he is using a VDI actuator to open them at a later RPM..instead of them opening while the primaries are opening like they are supposed to...

I think....

 

I think he ment he disconnected the secondary plates from opening in TB..

But on my 90 GTU secondary and primary plates don't open at the same time.. at about 2000rpms the secondary plates open.. done to improve low end... so disconnecting it woult be pointless.

 

Double-post due to 502 proxy error...
Horray for new servers..

 

If you didn't use a dyno, you didn't "test" anything.

 

I have one question, why the hell is this a poll?

 

Then that would be a truely silly thing to do, since the motor would be completely strangled most of the time.
It's not governed by revs, only pedal position. You can actually feel the pedal stiffen slightly as the secondary throttles start to open. You'd be amazed how much driving you do with only the primary throttle just cracked open.

 

NZConvertible is on the money today
IIRC, it's upto about 15% throttle before the secondary's start to open? and yes you can definatly feel the pedal stiffen.

 

so then i guess what hes doing is forcing the secondary throttle plates to stay closed all the time under 2300 rpm, even at WOT (which would essentialy then be WOT of the primary throttle plate, and closed secondary plates), in an attempt to reduce overall throttle diameter helping with the low end torque.... seems like it could be an interesting idea

 

Sure, if you like having maybe 50hp tops...

 

well yeah, but then you open them up at 2300 rpm... seems like it wouldnt change high end at all, and may give a bit more in the low end...

 

A 13b is never going to have a great deal of torque under 2300rpm.....
It seems like an awefully overly complex way to get a poofteenth more torque under 2300...

However, if this guy feels that he needs that extra poofteenth of a HP under 2300 and he doesn't mind fabbing up this stuff to get it work right, then I applaud him for his efforts!

I however would not do this

 

We can pretend we have low end

Just grab a nice heavy flywheel and some 4.30 gears out of a GTUs . . .

And get hard-rubber donut-spare tires for both the rear wheels so you'll break free more often.

And bleach. Lots of bleach.

 

Hey Viperdude, nice work and ignore these clowns. Come over to the other RX7 forum on the net if you want a little more supportive and *constructive* criticism for your work than this garbage. I for one believe that the secondaries must stay shut under about 2500 rpm to keep the primary ports as the only intake path into the engine until that rpm range. The benefit of this is intake port velocity and an enhancement of the "tournament effect", aka. inertial supercharging and pressure wave tuning that the Mazda ENGINEERS designed into the manifold. So why didn't these engineers design viperdude's system in the first place? Easy. It would cost a lot more to put an rpm switch in there and implement a rpm governed throttle butterfly opening system. I applaud you for your efforts and creative thinking to have seen this flaw in the stock throttle system.

Get a life you haters!

 

Far be it for me to express my own views and thoughts on this public forum, however, I thought the 'inertial supercharging' effect was only designed into the secondary runners?

While your doing this though you might aswell take it to the next step and have varible inlet runner lengths aswell, I mean if your going to go to all the trouble of doing this you may aswell keep going and make a really excellent inlet manifold.

But just out of sheer curiosity how are you going to 'activate' the secondary throttle butterflys with an electric air pump?
Just interested, because getting the trasition to work even close to smooth would require alot more than just having the two secondary runners completly shut at 2299rpm yet totally open at 2301rpm....

Not a totally bad idea by any means, just needs some more thought I think

 

Exactly, which is why this is basically a poor application of good theory. It would require a lot of effort and smarts for very little gain.

88IntegraLS, what's you're problem all of a sudden? Haters? Jeez, I think you must take all this a bit too seriously. You carry on being supportive, I stick to being realistic.

 

"so then i guess what hes doing is forcing the secondary throttle plates to stay closed all the time under 2300 rpm, even at WOT (which would essentialy then be WOT of the primary throttle plate, and closed secondary plates), in an attempt to reduce overall throttle diameter helping with the low end torque.... seems like it could be an interesting idea" Posted by 88IntegraLS.

- Yup thats exactly it. Thank you. And I know about 5 other rx7 forums.. which one are you talkin about? lol

"so then i guess what hes doing is forcing the secondary throttle plates to stay closed all the time under 2300 rpm, even at WOT (which would essentialy then be WOT of the primary throttle plate, and closed secondary plates), in an attempt to reduce overall throttle diameter helping with the low end torque.... seems like it could be an interesting idea"

- You have it down in your head exactly

"well yeah, but then you open them up at 2300 rpm... seems like it wouldnt change high end at all, and may give a bit more in the low end..."

- Exactly, High end will remain the same and the low end would increase a little.

"But just out of sheer curiosity how are you going to 'activate' the secondary throttle butterflys with an electric air pump?
Just interested, because getting the trasition to work even close to smooth would require alot more than just having the two secondary runners completly shut at 2299rpm yet totally open at 2301rpm..."

- I want to actuate them by a small 12v electric air pump. The one I want is a diaphram style so its very quiet. It puts out a constant 10 Psi so I can have it run the 5/6th ports, the VDI port and the secondary TB plates. All i have to do is have an RPM switch turn on the air pump at a low rpm around 2300 for the TB ports and then have another rpm switch open up one of those EGR, relife or switching solenoid valves to alow PSI to the 5/6th ports and then another rpm switch to open up another electronic solenoid switch for the VDI port. Sounds confusing but it can be done.

"because getting the trasition to work even close to smooth would require alot more than just having the two secondary runners completly shut at 2299rpm yet totally open at 2301rpm... "

- The Air pump will open up the valves fairly quickly since it takes very little PSI to operate the actuator. I did say this is an IDEA. its not operational yet. All i have done was disconnect the secodnary TB plates to see if I could get more low end power/torque. And I did feel some, Not a lot, but some.

Justin

 

Point being you don't want the throttle butterflys opening too quickly....
It'd be like having your foot at 15% throttle then as soon as you hit 2300 it'd be like slamming it to 100%........

Good idea, would take alot of plumbing, switches, wiring, thinking, practice, dyno runs, trial and error testing just to get the transition point right let alone the speed at which to open up the butterflys...
Might want to have a close look at some vacume secondary carbs to get an idea of at what speed you should be aiming for to open them up at... You MIGHT find that they openup proportionatly to vacume..

If you want this hugely complex system to get about 1 poofteenth of a HP more below 2300 then go for it, i'd like to see the results from your tests aswell, would be interesting....

 

You are basically trying to emulate the Renesis intake. Although the engine only has 1 throttle plate, it does have valves that open different runners in series as rpm's rise. Only the primary ports receive air up until 3750 rpm. Only 2 runners have any air running down them. The other runners have valves that are closed so no air gets down them regardless of throttle position. At 3750 rpm the secondary runners kick in. Now we have 4 ports getting air. At 6250 rpm the auxillary ports open. At 7250 rpm the VDI kicks in and a secondary intake tract to the air filter also opens. Each of the intake runners also has a fuel injector as well for a total of 6. All of them also come in sequence with the runner openings. The Renesis does suffer a little from the valves not opening terribly quickly due to the fact that they like the aux ports of the 2nd gen are operated from air pressure and not electrically. Look at the dyno charts. You can tell when each set open by looking at where the dips in the power curve are. This theory does work though and is in practice in the newest rotary powered car on the market! Just a little better executed by Mazda

 

"You are basically trying to emulate the Renesis intake. Although the engine only has 1 throttle plate, it does have valves that open different runners in series as rpm's rise. Only the primary ports receive air up until 3750 rpm. Only 2 runners have any air running down them. The other runners have valves that are closed so no air gets down them regardless of throttle position. At 3750 rpm the secondary runners kick in. Now we have 4 ports getting air. At 6250 rpm the auxillary ports open. At 7250 rpm the VDI kicks in and a secondary intake tract to the air filter also opens. Each of the intake runners also has a fuel injector as well for a total of 6. All of them also come in sequence with the runner openings. The Renesis does suffer a little from the valves not opening terribly quickly due to the fact that they like the aux ports of the 2nd gen are operated from air pressure and not electrically. Look at the dyno charts. You can tell when each set open by looking at where the dips in the power curve are. This theory does work though and is in practice in the newest rotary powered car on the market! Just a little better executed by Mazda"

- Yup, thats basically where i got the idea.

"Point being you don't want the throttle butterflys opening too quickly....
It'd be like having your foot at 15% throttle then as soon as you hit 2300 it'd be like slamming it to 100%........"

- Yup i know, I ust dont know how i would make them open slowly.

Justin

 

How about using the front set of throttle plates that most people just take off. Modify it to accept a vacuum actuator like the VDI system on the '89-'91's have. Set it up off of the air pump to open at a certain rpm. You wouldn't even need to change anything else. I'm not sure how this would work but it would be the easiest way to try it in your case. This way it isn't determined by throttle position but rather rpm.

 

I don't get it. Why not just mash your foot halfway to the floor, instead of the whole way, if you think you're getting more power at low rpm with a partially open throttle?

It never ceases to amaze me the lengths na gen2 owners will go to for a poofteenth more power

 

Because you can't get the primary throttle plate all the way open without opening the others too. With the way he is talking about doing it you can.

 

This would make more sense if the upper & lower throttles were on different length runners, but they are not. The distance to the dynamic chamber is the same.
The VDI is a different story - the lengths are different.