butterfly removal from ka24e

[sliders]

I am removing the damn butterfly contraption in the intake runners on my ka24e intake manifold and am just wondering if anyone knows the purpose of this thing besides im thinking of it making a better idle when engine is cold if this is so I dont care about the idle.If you have any info on this let me know before i weld the side hole up for good.Also if you know of taking all the vacuum lines off the back of the head adn doing away with them let me know I found this site where the guy did a swap and left them off with no problems but now i cant find it again to see wich ones he plugged.....thanx for the info

[deviousKA]

Its actually called the SCV swirl control valve, so i would guess it helps to swirl the air. I have read it increases velocity into the ports at lower rpm. You wont regret removing them.

Just plug any vacuum lines that you take off. Im not sure if removing the two vacuum switches on the back will throw a code, i highly doubt it will on sohc s13.

[lovemysan2]

Devious, whats the pros and cons of removing the SCV systems

[deviousKA]

Well, personally i still have mine installed and working. I dont feel there is a "major" airflow restriction, but no doubt there is some. Many people have removed them with good results, and if was planning on keeping my stock intake manifold for long i would remove them as well. As far as pros/cons? Its all basically opinion. Some may argue loss of low end torque with them removed, but the KA has plenty of room to work in that department. I would say its a good trade off for less top end restriction.

For anyone wondering, heres a picture of the SCV

[steppinsx]

If you want to know how removal will affect performance, disconnect the harness connector to the SCV solenoid behind the rocker cover near the firewall. There are two there. The one closest to the driver side (LHD) is for the SCV. Disconnecting it will force the valves to stay open.

I leave mine disconnected except for the emmision test.

[Calesta]

Ok another question... if I'm putting one of these intake manifolds onto a Hardbody's KA24E, I can just remove all the SCV stuff and be fine, right?

[deviousKA]

Yes Calesta you will be fine.

[Calesta]

Ok- thanks for the info. I'll write up a step-by-step DIY on the IM swap when I get around to it.

[niznos]

steppinsx, I read some where else that doing the disconnect will force them to stay closed. When I read the FSM about it, it seems it implied it would stay open too, but since reading that other post, I was hesitant to do this.

[andrave]

I unbolted the butterflies, unscrewed the ends, and pulled the rod out of mine with vicegrips. I cut off a section of the rod and used JB weld to plug the hole. No restrictions at all! and less clutter, which is what I want.

[Nismo1182]

I did it on my E and I did it to my DE. I removed all vaccumm crap on the back of the head. It does not throw any codes and it improves top end flow just a tad and low end decreases a tad.

[steppinsx]

steppinsx, I read some where else that doing the disconnect will force them to stay closed. When I read the FSM about it, it seems it implied it would stay open too, but since reading that other post, I was hesitant to do this.

I couldn't actually tell that they were open with it disconnected but by alternating between connected and disconnected, I experienced the behavior that Nismo1182 is discribing. I also assumed that since when the butterflies are closed, about 90% of the flow is blocked, that the top end would definately drop off if they were closed.

[niznos]

Thanks steppinsx, I may get around to doing this sometime soon. I have the R4 cam and it really sacreficed my low end as it is, but I guess it's worth a try.

[Nismo1182]

They stay open when you disconnect the solenoid or vaccumm source.

[tiger]

i took my butterflies out and had to cut the metal rod... thing is... I forgot to seal the holes on 3 and 4.. **** what will this do?

[InsanityInc]

i took my butterflies out and had to cut the metal rod... thing is... I forgot to seal the holes on 3 and 4.. **** what will this do?

You'll have a MASSIVE vacuum leak. If you still have those holes and it's on the same car as the one you're having problems with, that's your problem right there.

[tiger]

::slams head on desk::: well I guess I'd better go fix that. JB Weld should do the trick. I also gota plug the hole where I cut the EGR pipe off of my exhaust manifold too.. it makes the car sound worse than it really is when I try and start it up. That might explain the stalling? wow. ok. thanks.

[InsanityInc]

considering you have 4 holes half an inch across in your intake manifold, I'm rather surprised your car starts at all.

[vvaffle]

An alternative to this on a DOHC s13 is just using the s14 manifold right? Or does it have to be an OBDII manifold and therefore early 95 manifolds are the same as DOHC s13 manifolds?

[InsanityInc]

An alternative to this on a DOHC s13 is just using the s14 manifold right? Or does it have to be an OBDII manifold and therefore early 95 manifolds are the same as DOHC s13 manifolds?

Well, conventional wisdom is that you must use the s13 lower and s14 upper manifold, due to differences in the idle valves and such. I can confirm that works as it's how my car is set up. The s14 lower manifold has some vacuum line and coolant line differences. Definitely less of a pain than removing the butterfly valves.

[vvaffle]

so you could do that without ever taking out the lower part of the manifold?

[tiger]

yea the metal parts were broken off in most of them so i put filler in them anyway... I also discovered that i had some vaccum hoses not connecte.d... AIV vaccum hose... OOPS. Well I got her running and i'm happy... I accidentally plugged a hose that coolant is supposed to go through (it's a small one) so now i gota take the mani off again and find a way to route it back in.. thanks for you help guys.

[InsanityInc]

so you could do that without ever taking out the lower part of the manifold?

No. You have to jump through quite a few hoops to get the manifold off, and you have to remove the lower part in order to remove the upper part.

[tiger]

i fixed it... I filled those holes and I saw my AIC valve vaccum hose wasn't on, Crap.. so everything's good except for some small things i have to do on the car tomorrow. thank u!!!

[Kaikias]

Got this from Nissan Preformance Mag

We came across some interesting tech information while researching the factory service manual on the installation process. As you can see from the pictures,the 2000-2001 QG18DE has a butterfly system in the intake manifold at the flange where it bolts to the cylinder head. This is called a Swirl Control valve. We call it a flow hindrance. The Swirl Control valve was basically a contraption used to help boost low end torque and fuel economy, and would open completely on full throttle. Interestingly enough, Nissan must have figured out that this did not help much and actually robbed the engine of airflow, because the 2002+ QG18DE engines do not have the Swirl Control valve. The intake manifold we sent to Extrude Hone was a 2002+ intake manifold, so the valve was not present.

http://www.nissanperformancemag.com/june05/qg/

[tiger]

I drove mine the other day and I can definately feel the torque is not all there in the lower rpm's... now that i have taken the butterflies out.

[Kaikias]

Is it better in the upper range?

[tiger]

the reason i'm not driving it right now is... you know the coolant hose that attaches to the fitting on the block?? Well I took the fitting off of my other block and put it on the 98 block and when I was tightening it... a tiny crack happened... so I thought if I put some jb weld or something it wouldn't leak but I was wrong.. anyway.. I have a tiny hole in another coolant hose and it started getting hot when I was driving it back to the house.. I just took it down the road but I did notice that it didn't feel the same (torque wise) as before. I have to take the intake mani off for the 3rd time and have someone come over and weld it.

[Kaikias]

Look on the bright side you should have it down to an art form by now.