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Discussion Starter #1
I have a question on the variable intake system, it opens the second set of runners at 4800 to 5000 and with the 6250 redlineits kinda short. isnt there a way to make it open sooner? I used to have a 86 toyota carolla gt-s with (tvis tuned variable intake system) thats where honda got the idea on the integra gsr and now nissans qr25 motor. I found that by putting a smaller vacuume pot on it it opend quicker and sooner, but i havent been able to get much info on nissans variable intake system. to see if this same method would work to get the second set of runners to open a tad sooner getting more air into the engine. thus more power...

on the toyota it orriganally opened at 6 with a redline of 8 after i swapped the dashpot for a smaller one it opened at 4600 and really made a difference.

hopefully there will be a way to do this with the qr25 cause once the second runners opens it just really comes to life!
 

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INTAKE RUNNERS

you can make the second set of intake runners stay open all the time by zip tying the butterfly valve open. Its on the drivers side look down the fire wall and you will see a rod with a pivoting clamp on on side. push the clamp forward until it hits the stopper then zip tie. :eek:
 

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you should note that my doing that you would be keeping your short runners open all the time, thus killing your low-end. I would say that as with honda motors, there will be after market valve controlers soon that you can hook to the motor/ECU and manualy change the setting based on driving condition. With the revlimiter at a weak 6100 rpm you want to have all the low-end you can get.
 
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Dude, i just wanted to say that hachi roku's kick ass!!!!!! long live the 86!

Jason


Initial D style
 

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Discussion Starter #6
i loved that car i put the wide body kit on it from trd after market cams, forged crank rods and pistons, total seal rings, garrett t3/t4 hybrid turbo @ 12psi with intercooler, boost controller, custom exhaust system, mallory ignition, eibach sportline springs and koni shocks and struts. superchips ecu upgrade with the rev limiter reset to 10K. And the best part it was the coupe version rear wheel drive with a 5 speed :D so it loooooved to do donuts
 

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INTAKE RUNNERS

The intake runners are controled by pressure not by the ecu. If look at the actuator you will see it is mechanical, thus no wirers and no ecu mod. As for losses I know several people who have done this the only down side is bad gas milage because both runners are open at the same time. It does help acceleration one person running a 50 shot ran a 13.9x on the stock tires:p :eek:

search: b15sentra.net
 

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BlackoutSpecV said:
yea, wow...
thats what a long day of work will do to you, i was off on valve timing.... BLAH

Okay so no more mid-day work postings.
sorry I though you wanted to know about the intake itself.
Yes the car could benefit from some ecu tuning and some new cams and valve springs. JWT has prototype cams and I would not be surprised if they were working on the ecu;)
 

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Re: INTAKE RUNNERS

cortrim1 said:
The intake runners are controled by pressure not by the ecu. If look at the actuator you will see it is mechanical, thus no wirers and no ecu mod. As for losses I know several people who have done this the only down side is bad gas milage because both runners are open at the same time. It does help acceleration one person running a 50 shot ran a 13.9x on the stock tires:p :eek:

search: b15sentra.net
Whoa....I gotta correct you on this. They *ARE* controlled by the ECU. The ECU has one wire that goes to the intake runners. The Runners are mechanical, however, they are controlled electronically. The ECU sends a 12V signal to the intake runners at all times when the RPM is under 5000. At 5000rpm, the ECU cuts the 12 V signal to the intake runners, which allows the system to apply vacuum to the solenoid, which in turn moves the plunger and changes the runners.

I am currently working on a setup to have the runners switch at a different rpm using a switch. I can get it to work but can't get the RPM right. The switch seems to have a mind of it's own. But I'm working on it, and will post results when I get it figured out.

Torry
 
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unfortunately i dont think that will matter man....the intake manifold is coming out soon, it will eliminate that shit...
 

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Re: Re: INTAKE RUNNERS

ezcheese15 said:


Whoa....I gotta correct you on this. They *ARE* controlled by the ECU. The ECU has one wire that goes to the intake runners. The Runners are mechanical, however, they are controlled electronically. The ECU sends a 12V signal to the intake runners at all times when the RPM is under 5000. At 5000rpm, the ECU cuts the 12 V signal to the intake runners, which allows the system to apply vacuum to the solenoid, which in turn moves the plunger and changes the runners.

I am currently working on a setup to have the runners switch at a different rpm using a switch. I can get it to work but can't get the RPM right. The switch seems to have a mind of it's own. But I'm working on it, and will post results when I get it figured out.

Torry
thanx for the info torry:p
 

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A note about the butterfly valves: Yes, you can make the manifold run at max volume all the time by zip tying the cable to the actuator open, however you won't notice any performance gains (realistically you should get less low end torque).

It's meant to be there for a reason. If you disconnect it, the intake will function more like a regular multi-valve intake. Your basically creating a fixed geometry intake manifold by doing this mod. If the butterfly valves are tied to be left open partially or all the way, your creating a slower charge motion, which means the flame spreads slower, resulting in sluggish burn rates and lower engine output.

And since the actuator is controlled by vacuum pressure and ECU, wouldn't you think that by modifiying it to stay partically or fully open, that it may send a different signal back to the ECU causing you some problems?

As for the switch idea, I don't think it'd be beneficial personally, not very practical for a daily driver. If your in the middle of a race, you need to be focusing on the road. Not to mention human error, I mean if you don't flip the switch at the correct time, your forcing your engine to breath through a restricted intake setup at high RPM's. That spells lower engine output.

This of course is just my 2 cents...
 

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KSipmann said:
A note about the butterfly valves: Yes, you can make the manifold run at max volume all the time by zip tying the cable to the actuator open, however you won't notice any performance gains (realistically you should get less low end torque).

It's meant to be there for a reason. If you disconnect it, the intake will function more like a regular multi-valve intake. Your basically creating a fixed geometry intake manifold by doing this mod. If the butterfly valves are tied to be left open partially or all the way, your creating a slower charge motion, which means the flame spreads slower, resulting in sluggish burn rates and lower engine output.

And since the actuator is controlled by vacuum pressure and ECU, wouldn't you think that by modifiying it to stay partically or fully open, that it may send a different signal back to the ECU causing you some problems?

As for the switch idea, I don't think it'd be beneficial personally, not very practical for a daily driver. If your in the middle of a race, you need to be focusing on the road. Not to mention human error, I mean if you don't flip the switch at the correct time, your forcing your engine to breath through a restricted intake setup at high RPM's. That spells lower engine output.

This of course is just my 2 cents...
The switch I had installed was electronically actuated by a signal off the crankshaft position sensor. You can select the RPM you want it to activate at beforehand. You don't "flip" the switch when you want it on. It is completely automated. All it is doing is changing the switch point on the car. Stock it switches at 5000 rpm. The switch will make it switch at any RPM that you select. So let's say you put in 4000 RPM. Then the switch switches at 4000 RPM automatically. You don't have to "think" about anything.

The idea of the switch is not to gain more peak HP or Torque. It is to gain more HP lower in the curve. Between 4000 RPM and 5000 RPM, if the secondaries were open, you would make more HP between those points, and roughly the same torque. I don't know exact numbers until I dyno. But the point is, down low you are not changing the torque or HP, and up top you are not either. This is middle range stuff you are changing. And it *is* an increase, I swear. I guess I'll have to dyno to show actual numbers. But I swear it will work they way I picture. Right now I have to wait to get a new switch though, one that is not defective ;)
 

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Ok, well let us know what you find out then. An actual dyno chart will put alot of the doubt to rest hopefully. Good luck!
 

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dyno

KSipmann said:
Ok, well let us know what you find out then. An actual dyno chart will put alot of the doubt to rest hopefully. Good luck!
I dynoed my friends car with the intake zip tied open and it lost power from 3000rpm to 5000 rpm roughly 10hp and 14lbft of torque. the ecu will have to be reprogrammed to make the most of the intake runners opening sooner (just my $.02);) the dyno chart is on b15sentra.net(deathfrombelow)search please
 

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Interesting....
how was it between 4000 and 5000?

Also, I doubt the ECU will need to be reprogrammed, there is nothing to reprogram. The ECU simply supplies the right amount of fuel for the amount of air coming in. And as far as the flame front goes, and the pressure wave going back through the intake, that is all physics, the ecu has nothing to do with it. If you think otherwise, please explain. I'm all ears.
 

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ezcheese15 said:
Interesting....
how was it between 4000 and 5000?

Also, I doubt the ECU will need to be reprogrammed, there is nothing to reprogram. The ECU simply supplies the right amount of fuel for the amount of air coming in. And as far as the flame front goes, and the pressure wave going back through the intake, that is all physics, the ecu has nothing to do with it. If you think otherwise, please explain. I'm all ears.

look at the dyno chart it clearly shows a loss in hp and tq between
3000-5000rpm due to 2nd intake runners being open all the time. Opening them sooner may have no ill effects, but I would bet a reprogrammed ecu would help. I have done multiple tests for throttle postion and timing and found that nissan did a good job detuning the car. For example the throttle body and timing starts to back off after 5000 rpm even at WOT. Also I would think that to take full advantage of the extra air flow you would have to reprogram the ctvc which is controlled by the ecu and does have a factory preset program. but this Is totally theoretical and I am sure someone other than me has the facts. Torry good luck with the rpm switch I hope you can make it work:p
 

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Discussion Starter #20
ezcheese15 said:


The switch I had installed was electronically actuated by a signal off the crankshaft position sensor. You can select the RPM you want it to activate at beforehand. You don't "flip" the switch when you want it on. It is completely automated. All it is doing is changing the switch point on the car. Stock it switches at 5000 rpm. The switch will make it switch at any RPM that you select. So let's say you put in 4000 RPM. Then the switch switches at 4000 RPM automatically. You don't have to "think" about anything.

The idea of the switch is not to gain more peak HP or Torque. It is to gain more HP lower in the curve. Between 4000 RPM and 5000 RPM, if the secondaries were open, you would make more HP between those points, and roughly the same torque. I don't know exact numbers until I dyno. But the point is, down low you are not changing the torque or HP, and up top you are not either. This is middle range stuff you are changing. And it *is* an increase, I swear. I guess I'll have to dyno to show actual numbers. But I swear it will work they way I picture. Right now I have to wait to get a new switch though, one that is not defective ;)

im curious where you got the switch what you hooked it up to etc. i was wondering if you could give say a step by step like you did with the balance shafts removal. :D

thanks btw it helped on removing the balance shafts
 
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