iamtheyi

I just had some guy come up to me and ask me if i took of the "butterfly" system in my intake manifold. I am completely oblivious to WTF he's talking about. Can someone explain what it does and where it's located?

Pandapants

What kind of motor do you have? They're like "secondary throttle bodies" on the lower intake manifold for emission purposes.

iamtheyi

I have a KA24DE. so they're just another throttle body? and you have to get them removed if you're going KA-T?

SoloSilvia

These "butterfly valves" did not come on the S14 Intakes. They only came on the S13's. They are like what he explained above kinda...They are located actually in the top runners right before the head, and all 4 runners have a what you could say looks like a "throttle body plate" inside, they open and close with a vacuum source to 1 valve bolted on the back of the intake, almost works like a turbo wastegate...kinda...lol

So if you have an S14... No need to worry about these pesky things, as you do not even have them!

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iamtheyi

lol. Thanks a lot for the info guys :]. Helped clear up stuff. I thought there was a huge part of my engine that I didn't have a clue existed ><. Thanks again.

Pandapants

lol. I have a single cam, so the runners are on the bottom manifold. Doh

GSXRJJordan

A little background:

At low RPM/load, you want a small diameter, long runner to efficiently flow small quantities of air into the combustion chamber at reasonable velocity. At high RPM/load, you want a huge, short runner to let as much air in as possible while maintaining high velocity. Obviously, you can't have both.

Unless you put a set of butterfly valves in the intake tract, to simulate long runners at low rpm (butterflies closed) and short runners at high rpm (butterflies open). Modern literbikes use two sets of these for good partial throttle response, as well as traction control.

So yeah, butterfly valves... they exist!

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DALAZ_68

F the mess...i told Luis to get rid of that shit out of the CA...lol

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iamtheyi

so, the s14 not having them is false? or still fact and butterfly valves have nothing to do with me.

sliptones629

the s14 does NOT have them. Nor do you HAVE to get rid of them if you go turbo w/ a s13 manifold. Im using my s13 lower and a s14 upper for turbo purposes. Mix and match bag type deal. All DE's but some little differences and some easily interchangeable.

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pidass

are they worth getting rid of on a s13? We talking about 1-2hp gain or a good bit?

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iamtheyi

^ from what I've read so far(online so be wary), getting rid of it when you're non-turbo makes you lose a lot of lower end power but will gain some top end. For a turbo, you need it for increased air flow. But if you're turbo, it's better to get another intake mani cause the stock one sucks.

modulation

About 6 months ago I got a s14 manifold and switched over to it from my normal S13 manifold. (I went from butterflys to no butterflys.)
Nissan calls them SCV's or swirl control valves. They aren't just for emissions, they help to increase the velocity of the air in the intake manifold at lower rpms which helps the fuel "aerosol" better and thus low end torque.

90% of the time it honestly sucks. The butterflys really helped low-end torque and below like 3,500rpm's my engine feels like a 1.4L 4 cylinder.

Above 3,500rpm though there is a difference, and above 5k rpms it's night and day. The car actually has power all the way to redline and yeah it drops off a bit, but way less then without butterflys.

If you have a daily-driver or autox car I'd keep them, but if your car is suppose to be a track car then get rid of them

If you have a turbo, get rid of them.

Walperstyle

to get rid of them you have to remove the intake (believe it or not, people think you can do it without removing)

You then need to weld up all the holes inbetween each plenum.

www.240SXTECHDVDS.org Home Page has a complete emissions removal dvd that helps big time with understanding what everything does.

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modulation

I'd just get a S14 manifold if possible. Makes it a simple swap.

sliptones629

just remember when you swap the whole thing that the throttle bodies are different from s13 to s14. Either swap just the upper or get the whole setup from a s14

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D.Adams

think these are what you are talking about

NOT MY PIC

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doomviillain

whats the result if you dont weld the holes shut?

stinky_180

I've read that there isn't enough turbulence to cause any problems. I can't confirm this as I welded mine. The post is on zilvia...

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brndck

its just like the tvis system on toyota 4age engines, helps streamline the airflow across the entire rpm range.

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projectRDM

Completely false.

The holes between the runners are not open to atmosphere, you don't have to weld anything there. The only two holes that are an issue are the center one that the set screw goes into the secure the rod, and the end hole where the rod goes into the intake.

You can put the set screw back in and fix the first issue, and you can either leave the rod in place, tap/thread a bolt in, or weld the other hole where the rod goes in.

The SCVs are only found on 1991-mid 1993 KAs, when the cams were changed out for the S14 style 232/232 degree units the SCVs were removed. So, most S13s have them, but not all. 1994 convertible models for example don't have them.

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SHIFTrl240

Edit: guess I'm wrong ^^^^^^^^^^^^^^^^^

Massive boost/vac leak I'd imagine.

When I put my KA-T together, I simply unscrewed the plates from the bar and left the bar in it. That way I didn't need to weld up all the holes, and I had removed 90% of the restriction.

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Frank_Jaeger

This thread always comes up when searching about butterfly valves. I'm bumping this old ass thread to corroborate what this guy said. I might take off my manifold again to put them back in.