JyRO

iTrader: (3)

Guys,

I've been thinking about this for a while, and searched to see if I had ever posted about it. It doesn't appear that I ever did.

I'm smart enough to consider the idea, but not smart enough to figure out how to complete the project. Since I've owned the Power FC, this is even more on my mind, because the Power FC holds both turbos activated for longer times.

____________________

On a stock twin turbo system, if the ECU controls when the 2nd turbo comes online via controlling the actuator for the 2nd turbo, then why couldn't the signal from the ECU to control that actuator be manipulated?

For example, let's say normal single turbo driving, the signal to the solenoid that controls airflow to the actuator is 0 volts. But the signal to the solenoid that causes actuator movement (and in turn both turbos to work) is 5 volts.

Question: Why couldn't we put a switch in our vehicle that would allow us to throw the switch and put 5 volts to the solenoid? Thereby overriding the ECU signal, and pulling in both turbos?

Disclaimer: I don't understand nearly enough about the turbos. At one point I understood more than I do now, and I realize I'm leaving details out above about how the turbos work (because of my lack of knowledge). But in my thinking, I don't think the details matter as long as the ECU signal could be manipulated.

The reasoning: There are many times I would like to ride down the road, or sit in traffic with both turbos online. ITS MUCH LOUDER, and I like it. But at the same time, there are times that I'd like only the primary turbo to work, it reacts quickly in traffic.


So, in my thinking, with a switch inside:

Last thing: It might be a challenge to create 5 volts simply, but would it hurt the solenoid to activate it with 12 volts? That would be easier.


JyRO

RENESISFD

iTrader: (13)

So you want to make your car non sequential in traffic so it is louder? That is the only reason?

I believe you need three solenoids activated the turbo control Pressure and vacuum and the charge control.

As far as 12V vs. 5V I do not know how much of an effect it will reduce the life of the solenoids. Seems like too much work just to make the car a bit louder in traffic.


John

JyRO

iTrader: (3)

Mine is significantly louder with both turbos online. The PowerFC has brought that to my attention.

But aside from just the LOUDNESS, the SOUND QUALITY is better. But yes, just for noise, I can't see it making any performance improvement. At least not on my FD. There might be some advantage on other guys FDs, dunno. My turbos are otherwise stock. I'm used to LOUD *** motorcycles. And you know the saying, LOUD motorcycles save lives. That's got to cross over to cars as well. So, uhhh, yeah, I'm trying to save lives too!

arghx

iTrader: (3)

The whole system is controlled by three standard 12 volt 3 port ON/OFF solenoids and two duty controlled 2 port solenoids.

What you are proposing is mostly possible, but it would be a little more complicated than you think. Look carefully at this



Notice that all three of the main solenoids are controlled differently.

JyRO

iTrader: (3)

Kind of what I figured. I'm digging around now to find a thread that clarifies all this turbo actuation. Not an easy thread to find.

arghx

iTrader: (3)

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/why-engine-so-damn-complicated-part-1-sequential-turbos-demystified-841821/

and

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/comparison-rx-7-13b-rew-supra-2jz-gte-sequential-turbos-960727/

Speed of light

iTrader: (8)

Yes it can be done and it works. It takes a 3-pole double throw switch to accomplish. There is a how-to for this on an old web site, IIRC. (Max Cooper's old site maybe?)

I never understood why more people didn't do this as it's so easy--perhaps most rather do a mechanical mod than an electrical one. functionally, it is the equivalent of the poor mans' sequential.

JyRO

iTrader: (3)

Thanks for the info. I'm gonna have to hunt that how-to down. I like the idea of having it completely reversable (no part permanently modified), and having the vehicle operate either way (sequential or non-sequential) with the flip of a switch.


Is this the place to find the 'how-to'? http://www.fd3s.net/turbos.html

RENESISFD

iTrader: (13)

I think it is because what OP wants to do will only work if the solenoids are finctioning properly. If you have one of the three solenoids sticking it will cause a whole different set of problems. Most go non sequential because they are having problems with the rats nest.



John

DaleClark

iTrader: (55)

FYI, with the Datalogit, you can change the turbo transition point to whatever you want. You can also set it to zero RPM so it's always in twin turbo mode. I've done that to play around, but unfortunately you have to have a laptop fired up to change those settings back and forth.

It's also a good trick if you want to see how your car would sound non-sequential with zero work.

Dale

Tem120

iTrader: (5)

is there any performance advantage to going none sequential ?

DaleClark

iTrader: (55)

You'll get a "SEARCH!" statement here quickly, but basically sequential = broader powerband but more complexity, non-sequential (when done right) = less low end power, more top-end power, less complexity.

Dale

RENESISFD

iTrader: (13)

Isn't it 4 solenoids? The turbo control actuator has two solenoids; 1 for vacuum and 1 for pressure to improve the response of the actuator.

I think for OP's purposes only 3 solenoids would be involved, both turbo control solenoids and the charge control solenoid. If OP decides to drive around and rev the car past the transition point then something would have to be done about the CRV opening. So I guess all 4 solenoids would need to be controlled with one or more switches.


John

arghx

iTrader: (3)

I'm sorry, three outputs from the ECU controlling four 3-way solenoids. Both turbo control solenoids are run off a single output, pin 4R.

You are forgetting about the precontrol and wastegate... it depends what you are doing for boost control.

RENESISFD

iTrader: (13)

^ Why would you need to mess with the precontrol and wastegate solenoids for what the OP wants to do? I do not see why

"I'm sorry, three outputs from the ECU controlling four 3-way solenoids. Both turbo control solenoids are run off a single output, pin 4R."

^Got it.



John

JyRO

iTrader: (3)

I've got a lot of reading to do. You guys are over this old dog's head. I like the dataloggit approach, except that it's not as switcheable as I would like. Woudn't want to have to fire up a laptop to change a setting vs. flipping a switch.

Mine is such a sound difference, it would be like having an e-cutout in my exhaust.


My mind is most in tune with what RENESISFD has asked. I'm wondering: Could I not just activate the turbo control actuator, and that be the only change?

arghx

iTrader: (3)

Yes, I agree that busting out a laptop is not convenient and would to a large extent defeat what you are trying to do.

It's definitely noticeable, I'll agree with that.

With both turbos running in parallel on the stock system, the actuators are in the following positions:

1) Turbo control is OPEN
2) Charge control is OPEN:
3) Precontrol is fully OPEN:
4) Charge relief is CLOSED
5) Wastegate is duty controlled--it opens and closes to various positions in order to control boost



The solenoids and actuators work differently though. The Charge control valve itself is normally open, but the solenoid engages at idle (closing the valve) and turns off at the transition point. The turbo control valve is normally closed, and the solenoid turns ON at the transition point to open the valve. The charge relief valve is normally closed and opens during a narrow rpm window when the charge control solenoid is engaged. The wastegate and precontrol have their own somewhat complicated logic.

JyRO

iTrader: (3)

By this you mean, both turbos are ONLINE? On a stock system, this would typically be like at full throttle and high rpm. That's what you mean, right?

Are my RED additions correct? I'm not being picky on your wording, I'm sure you understand what you're saying. I'm trying to ensure I understand everything correctly.

Mahjik

iTrader: (1)

Send a PM to "gfelber" (Gene) to see if he still has the instructions on the mod:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/electronic-non-sequential-switch-227896/

He seems to still be semi-active here on the forum.

arghx

iTrader: (3)

Yes. "fully online" as in not in some kind of prespool or transition mode.

correct, that's what I meant by "actuators"

Now for the actual solenoids it's like this...

1) Turbo control (both of them) are ON, receiving ground signal
2) Charge control solenoid is OFF, normally having 12V on it
3) Precontrol solenoid is at 0% duty, so it is effectively OFF
4) Charge relief solenoid is OFF, normally having 12V on it
5) Wastegate solenoid is duty controlled, with the duty cycle changing in order to keep boost under control

reverus

i thought that the actuator needed to see 8 psi of boost in order to properly bring the secondary online not just as a programing function but as a mechanical nessesity to have enough pressure to equilize the pressure in the actuator itself

arghx

iTrader: (3)

The charge control, charge relief, and turbo control solenoids have vacuum and pressure chambers to supply whatever is required. Recall that the charge control valve is a butterfly valve in the Y pipe that joins the two compressor outlets. The turbo control valve is a swing valve in the exhaust manifold to supply a large amount of exhaust to the secondary turbo after the transition point has been reached.

The precontrol valve supplies a smaller amount of exhaust to the secondary turbo during the prespool phase. It works like a wastegate actuator; spring pressure must be overcome for it to open. The precontrol actuator is supplied with air from the primary compressor outlet, and the precontrol solenoid bleeds pressure out of that actuator in order to control boost when only the primary turbo is online.

So if you flip a switch to disable the precontrol solenoid, you are right that the actuator will still need to see enough pressure to overcome the spring. I suspect that isn't a big deal considering that the turbo control valve will still be open and thus plenty of exhaust can still flow through the hotside of the secondary turbo.

reverus

aaah yes. i understand now