No butterflies on SOHC

[slakker]

Tell me I am wrong. they do not exist on the sohc. Does the dohc have a 2nd set of runners or what

[navysnail]

sohc has no butterflys, only throttle plate.

[slakker]

I erspect ya but where were ya 2 days ago. I was fed some null**** about it and tried it. It is bogus.

[WAbernethy]

My sohc had butterflys.

[slakker]

Where the hell would they be. There is no way. They would have to be against the intake ports. They cant possible be designed to let in any extra air, becasue there is only one set of runners. no extra place to pull the air from. I pulled the top part of the manifold off and can put my fingers into the engine ports. No 2nd butterflies. Please tell me I am worng and how you removed them. I am curious

[WAbernethy]

They are right at the end of the runners b4 going into the head. They do not allow extra air to enter your engine, they close down to increase the velocity of air going into the head. Supposed to help low end. I took mine off knowing that with the turbo, they would just get in the way. I didn't bother removing the shaft, just the plates. Looked like too much work.

[slakker]

You would ahhave tio drain the coolant or atleast lower the amount of fluid to get that part of the intake off. Did they give you any benefit. I swear I dont think they have them, but I am willing to believe you because you are not a smuck. Any gain was it worth the effort

[WAbernethy]

I did run N/A for a while after the change. I did it when I did my timing and top end last spring. I'd say that there was no noticeable difference. It would be more trouble than it's worth for you imo.

[navysnail]

i thought dohc had butterflys, sohc has none that i can find and none shown in the fsm that i have. i know mine doesn't have them.

[slakker]

I dint think mine did eitherr but I am not going to jump on abernathy. I tried.

[WAbernethy]

From my FSM:

1990 ENGINE PERFORMANCETheory & OperationNissan; 240SXINTRODUCTIONThis article covers basic description and operation of engineperformance-related systems and components. Read this article beforediagnosing vehicles or systems with which you are not completelyfamiliar.AIR INDUCTION SYSTEMSWIRL COMBUSTION VALVE (SCV) SYSTEMNOTE: For location and identification of ECU terminals, seeappropriate L - WIRING DIAGRAMS article.The SCV system is designed to improve engine torque and powerproduction by increasing or decreasing intake manifold inductionvolume under different driving conditions. A limited induction volumeis desirable at low or medium speed under heavy load. This willincrease intake velocity and improve atomizing of fuel and combustionefficiency. An increased induction volume is desirable under heavyload and high speed condition.SCV system consists of swirl control valve (built into intakemanifold), diaphragm type swirl control valve actuator and swirlcontrol valve solenoid.SWIRL CONTROL VALVEValve is used to modify the induction passage of the SCVsystem. It is set in the fully closed or fully open position by theswirl control valve actuator. Valve actuator is regulated by the ECU-controlledswirl control valve solenoid.SWIRL CONTROL VALVE SOLENOIDSwirl control valve solenoid receives power from a 10-ampfuse in the relay box. Solenoid is energized when ECU provides aground for solenoid through ECU terminal No. 12. When ECU activatessolenoid, manifold vacuum passes through solenoid to swirl controlvalve actuator, pulling swirl control valve closed.

The shaft sticks out of the back of the manifold, somewhere near the egr and it should have a little actuator attached to it. Why would I make this stuff up?

[navysnail]

i thought that the buterflys and swirl valve were different things. my 1990 240 has a swirl valve, and i would leave it on because the only thing it may do is decrease fuel milage and, as abernethy said, no noticeable difference is noticed. sorry for the confusion.

[randybunctious]

of course it has secondary butter flies.....morons.....they are hard to miss when you take your intake off. same here, it wasnt really worth the trouble of taking them out. I cut the rod to the manifold and left it in, then made a plate to fit where the actuator was. i didnt notice a difference.

[slakker]

I did take my intake off and they dont exist. My hands still have grease imbedded in them from the wark, wanna come smell my azz. Your FSM quoting was that the 90 dohc or sohc. What is the big softball sized attachement on the back of the manifold/ There is no shaft, but where the attachment is there are the screw in fillersAny more ideas

[randybunctious]

it is probabky the vaccum actuator that opened the butterflies, same basic part as a choke pulloff.but apparently the butterflies were takin out of your manifold if there are screws in there. i promise it came with them.

[slakker]

They arent just screw though. The are about .5 inch with 3/8 inch squares in them. There is a something attached to it but there is no way I can tough the underside....Nevertheless if it is pointless to do then why are we argueing about it anyway. No harm no foul thanks guys.

[randybunctious]

werd