intake butterflies?

[XTCshri2222]

I've read some people who've taken them off, what benfits dose that provide?

[dattodude]

My dyno experience says that taking them off is a lot of effort for minimal probable benefit over 7000rpm.

I have left my butterflies on, and I'm playing with the opening RPM threshold using an on/off output on my Autronic SMC.

I too was initially blinded by the search for ultimate 'flow', as many forum conversations recommend.

But the evidence on the dyno, we tested:

1. leaving them open2. having them closed until 4000rpm

We found up to 20% more torque below 4000rpm, by using the butterflies as the factory intended. Which if you want a daily driver..this is significant.

Cheers.

[rexhunta]

**** Dattodude, thats a hellva difference.. wow, and i alwasy got told to remove them, think i'll leave the ****ers in there heh

[tyrannix]

if you head over to mototuneusa, and read all his articles, it would suggest that the smaller port would provide gains everywhere (as seen with toyota 4age engines, a power gain can be had just from switching from the big port, to the small port head)

have you tried a dyno run keeping the butterflies closed even longer?

CJ

My dyno experience says that taking them off is a lot of effort for minimal probable benefit over 7000rpm.

I have left my butterflies on, and I'm playing with the opening RPM threshold using an on/off output on my Autronic SMC.

I too was initially blinded by the search for ultimate 'flow', as many forum conversations recommend.

But the evidence on the dyno, we tested:

1. leaving them open2. having them closed until 4000rpm

We found up to 20% more torque below 4000rpm, by using the butterflies as the factory intended. Which if you want a daily driver..this is significant.

Cheers.

[XTCshri2222]

reason i posted this was, removing the butterfies didn't make much sence. But by keeping them closed longer whats the principle behind the power gain?

[TurboFortysx]

I do not agree. I removed the butterflys and did some massive port work on my manifold. I did not see any performance loss below 4000 rpm and the turbo spooled the same. On my engine at the same boost level I made 20 more WHP with the butterflys taken out.

[tyrannix]

if you go over to that link ( mototuneusa.com )its the venturi effect, as teh size of your pipe decreases, so does pressure, and velocity increasesby having a smaller port, the air/fuel mixture is entering teh cylinder at an increased velocity, both keeping the fuel from collecting anywhere (staying particulated in teh air mix) but it also makes less any reversion effect (less mix can escape back into the intake if the hole is smaller)

but this guy got 5-8 WHP gains on a dyno on a bike, so that gives some gumption to the theory

and im going to try it (reducing intake port size) on an extra head on my 4age

CJ

reason i posted this was, removing the butterfies didn't make much sence. But by keeping them closed longer whats the principle behind the power gain?

[biosehnsucht]

you would only want them to open when the amount of boost pushing past them is more than can flow with them closed, really..

if you lost nothing down low taking them off, you didn't have them working right to begin with, or you just think you lost nothing..

[ragenasian]

I hope this doesn't come out sounding too stupid but what is the advantage of these butterflies? I have a 4 port head on my 200sx and I have sold three of these heads in the past couple of months to people who prefer the 4 port over the 8 port. Is there an advantage to these butterflies that the 4 port head users are missing out on??

[dattodude]

Before big boost and before big revs, you need to keep the intake speed up to help fill the cylinder with as much air/fuel as possible before the intake valve closes. It also helps keep the injector fuel mist atomised.

For drag racing?..sure pull 'em out. But don't do it thinking it's a good idea for the street.

As for my tests, we did move the RPM level up and down at which the butterflies opened up, but didn't find much extra "area under the curve" to be found at 7psi. I also had a large 4500rpm "on-boost" GT28, which also made a difference on the time the butterflies should open. It was left at the 4000rpm as per factory spec.

I used the standard restrictors/valves to make them flap shut quickly on off throttle, and open slowly after 4000rpm.

I've recently put in some big cams and smaller exhaust housing, so I'll be doing more tests in the next couple of months. I'll be sure to let you all know how it goes.

So I can tell you that there is a difference in torque/power when using them, versus holding them open all of the time. I just can't comment on the top end power.

Cheers

[Not_a_sr]

what are you using to control them? the stock silenoid? i should beable to program this as an output in megasquirt which is what ive been thinking about doing.

[MegasquirtCA]

Indeed you can Not_a_SR all you need is a solenoid and have a wire attached to it.

You go into megatune pick out a port setting you want, theirs over 200 port settings. You punch in the information such as rpm based switch meaning when you want to solenoid to click at which rpm.

Same way you would use megasquirt to control VTEC

[dash]

I never just dicard an item without thought. Always made sense to me that closed butterflys + boost at lower rpm would yield strong torque.Then I happened accross an interesting post on club4ag where a turbo corolla owner 'experimented' with his TVIS (same butterfly concept). Megasquirt tuned, opening the flaps at various rpm, coupled with his small turbo.Results was "v8 like tq, very unnatural produced from a tiny 1.6L" he described it, in addition to spooling his turbo significantly earlier.Made a tremendous difference in the driving characteristics.

Same guy actually posted lots of comparisons vs his smallport 4age, which couldn't match the TVIS 'experience'.

I'm driving the euro 4port ca18 now, but will definitely play with the butterflys on my japanese 8 port to compare.

[Swedish Mike]

Tell me more about these 8 intake port heads, same exhaust port diameter? Same valves?

The Euro intake ports are actually too big, all the expensive built CA engines here got welded ports. A bit smaller and better shape gives more power/torque at all revs.I´ve seen both bondo and welded ports, both work but welding better cause some guys got problem with bondo pieces in the cylinders.

/Mike

[boost_boy]

There have been countless posts about this subject and everyone is entitled to their opinions and experiences and I'll definitely share my experiences on the matter. Back in 1997 when I was running a CA16DE in my sentra, I didn't have the vacuum hoses hooked-up correctly , so power valve did not operate when it was supposed to resulting in good performance, but not the best (very lazy below 4000rpm). The CA16DE bored me, so later on that year, I moved-up to the CA18DE leaving the vacuum hoses the exact same way I had them with the CA16DE set-up resulting in even better performance, but still lazy below 4000rpm.

I finally got the vacuum scheme perfected and with the power valve connected properly, the car/engine was more responsive coming into it's peak torque which is @ 4800rpm. My point on this subject is, on a N/A engine this system is essentially useful for mild to wild acceleration below a given RPM. Given the fact that the CA is relatively small compared to most performance engines being built for today's enthusiast cars (ie Sti,Evo,SRT-4, even the mazda speed), you still can't compare it to any other engine besides itself. I didn't mention the hondas because they are not turbo'd from factory and they use a totally different approach that makes a honda a premiere 4 cylinder builder in the car industry.

Bigger bore, longer stroke, small cylinder head ports, are some of the things that gives 4 cylinder engines good torque down low. A 4AGE or CA DOHC series engine rely heavily upon their butterfly valve system to put back some the low-end grunt that is missing due to their relatively small bore and stroke. On atmospherically driven engines, this system is ideal and have been proven to assist in producing low rpm torque not present in small displacement engines.

But now, on force inducted or turbocharged engines, the butterfly valve system's presence, especially becomes questionable in smaller displacement engines. Case-in-point "Toyota" and their amazing 1.6l 4AGZE (supercharged) power-puppy. Guess what guys, unlike it's N/A 4AGE brethren, it has good grunt from 1200rpm on and amazingly "No TVIS". Now why did they do that when the TVIS was a big hit with the N/A engines? Hmmm, we'll have to ask the engineers themselves, but my hypothesis is the fact that because they were using a blower that gave near instant power in the lower rpms, and since the fact that the engine is designed to rev pretty high and produce power in the upper rpms as well, why waste the money incorporating this system along side a blower.

My CA18DET engine have all revved pretty good and produced wonderful power on the stock engines, minus the activation of the butterfly valve system. I honestly think they are worthless on the CA unless you plan on driving around off boost. I agree that for a track-based platform, they should be X-filed. But once again, beauty is in the eyes of the beholder and one should do what they want to do to make their machine function the way they want it to. With the proper cams or even the stock cams, I can personally and honestly say that the butterfly valves can be removed or left open. They cause a carbon and sludge build-up that is totally unacceptable for me and most people don't talk about that down-fall. At or around 4000rpm, my car is seeing full bost and is producing better than 300whp with a good size, but properly spec'd turbocharger and is producing over 277lb/ft of torque which is more than enough for a street car. Just my snott on the subject !

Dee

Without butterfly valves functioning, 20psi on a T3/T04E with a .48 rear housing and .60 front housing and an internally stock CA18DET as well as conservative tuning.

Without butterfly valves connected, 14psi on a T3/T04E with a .48 rear housing and .60 front housing, an semi-stock CA18DET (HKS 264 cams with a 8.5mm lift) mild programming.

[float_6969]

I left my butterflies in and, am switching them at the same 4000rpm switchpoint via the SDS that Dattodude suggested. I haven't been to the dyno yet, but as I've stated many times before, the difference is noticable.

+1 for leaving them in and hooking them up so they'll work properly.

[tyrannix]

do you have a dyno of those hks cams @20 PSI (to compare with the stock cams @20 ) ?

CJ

[boost_boy]

do you have a dyno of those hks cams @20 PSI (to compare with the stock cams @20 ) ?

CJ

I don't have a graph because it was never printed. With the HKS bump sticks, the car put out 327.5whp and 266.2 ft/lb of torque (IIRC) @18psi when I wasn't the hottest tuner (still am not), but I knew what I was doing. Also was using MSD 50lb/hr injectors in which the injector duty cycle was 109% and about a year later, I found out my Nismo FPR was failing miserably. See the dates and the power curve between them.

Dee

[tyrannix]

is that the difference on the <5000 curves, the fuel having a rough time, or the cam specs (or butterflies even) ?

when i dyno the s13 for the first time, im going to do a few butterfly on/off runs during the tuning without changing anything. ill post up what happens

(want to see for myself before i decide wether to use the 4 port head before i dump cash into machine work)

i was planning on making the ports smaller on teh 4 port too (almost replicating the difference between the TVIS and GZE on the toyota)

CJ

[boost_boy]

is that the difference on the <5000 curves, the fuel having a rough time, or the cam specs (or butterflies even) ?

when i dyno the s13 for the first time, im going to do a few butterfly on/off runs during the tuning without changing anything. ill post up what happens

(want to see for myself before i decide wether to use the 4 port head before i dump cash into machine work)

i was planning on making the ports smaller on teh 4 port too (almost replicating the difference between the TVIS and GZE on the toyota)

CJ

I think different size injectors between the two as well as the MSD DIS-2 help makes difference. If I need torque to get around town, I'll just throw in some extra timing in the lower rpm. But I live in Miami, either you got a long stretch of road or just stay off the throttle because you'll kill somebody or sombody will cause you to kill them and/or hurt yourself.

Dee

[tyrannix]

i seem to remember reading in one of the old stickies or something that CAs dont like to have their timing advanced much, are you talking just a couple of degrees, or what?

CJ

I think different size injectors between the two as well as the MSD DIS-2 help makes difference. If I need torque to get around town, I'll just throw in some extra timing in the lower rpm. But I live in Miami, either you got a long stretch of road or just stay off the throttle because you'll kill somebody or sombody will cause you to kill them and/or hurt yourself.

Dee

[Not_a_sr]

mine loved 20deg advance as base timing when i first got it running, it hates anything more retarded then 15-16

[boost_boy]

i seem to remember reading in one of the old stickies or something that CAs dont like to have their timing advanced much, are you talking just a couple of degrees, or what?

CJ

Base timing in most cases should be at 15 degrees. But up in the power band, the CA, RB, VG, and even the KA is extremely fussy about high timing. The SR seem to love 30+ degree of timing. The head design and quench/squish areas play a heavy role in what these will accept. I won't go into #s, but my engines don't see 30 degree of timing either (I've learned my lesson).

Dee

[datsunboy]

I thought there was a section in the stickies on how to route the vacume lines properly....but I cant find it.

I just bought a SSS attessa U12 Bluebird with a CA18DE for $50.and I robbed the vacume stuff for the intake butterflies from it for my car.Just wanted to make sure that the way they are hooked up on the DE is the same way I should hook it up on the DET.....I assume so?

[dattodude]

Yep. ECU determines when they open by opening the solenoid valve. The characteristics of how they open and close is based on the restrictors (or one way valve/restrictors) that are plumbed in.

DET and DE = Same-o.

Chris

[tyrannix]

its strange now, i seem to remember both ca18s that i disassembled had a straight vaccuum line from the plenum to the butterfly solenoid, i dont remember having any restrictors or extra things on there

CJ

[float_6969]

Referencing the the butterflies to the manifold isn't going to do you much good. If you're familiar with port dynamics, the butterflies should be strictly RPM based. The idea of the butterfly is to increase port velocity and swirl in the combustion chamber. This would only be needed in the lower RPMS.

EX: RPM=2K, TP+100% Referenced to manifold:butterflies open and not increasing port velocities in the lower RPMS, which is needed to increase torque. Operated via RPM based solenoid:butterflies closed, increase port velocity and swirl in the combustion chamber. Torque is increased until the flow required by the engine is greater than what the ports can flow. At that point, the butterflies would be opened and more flow, and horsepower, would be gained.

In a perfect world we could have infinitly variable length intake ports, cams, and cam timing.

[tyrannix]

In a perfect world we could have infinitly variable length intake ports, cams, and cam timing.

what? yours didnt come with those?

CJ

[float_6969]

Yea, I got screwed on my clip. Thanks for re-hashing an old arse thread for that worthless post! You are my new best friend, sorry C-rad...

[tyrannix]

Yea, I got screwed on my clip. Thanks for re-hashing an old arse thread for that worthless post! You are my new best friend, sorry C-rad...

I WIN

but seriously, yeah, i was searching for the 'correct' way to connect the butterflies. because with both the CAs that i disassembled in japan, i dont remember any extra restrictors or valves or anything, just a vaccuum line going to the butterfly switch (solenoid) itself

which also brings me to the point that for my CA20 build, i am 95% that i am going to use an 8 port head, even tho i have a 4 port one (that will be saved for a possible future project) and with the CPC plenum, i am going to try and squeeze teh GSXR ITBs between the 8 port runner and the plenum. my first real test of fabrication skills (which im not so sure i actually have any (?) but the GSXR ITB unit was *dirt* cheap, so i can screw around with my welder and try )

the reasoning is> I cant fight logic, and logic tells me to do it. Even tho people have told me for the application i should not use it. ... ... with the turbo probably getting full spool around 3500-4000, i would still need that low down help for torque, and getting the turbo spooled up, Unlike the 4AGZE, which the supercharger has available boost down low and needs the flow because its under boost at such low revs.

and for anyone interested, i am having machine work done right now and will be rebuilding the 4age for my ae86. for 1. so i can just get it running (moving to a new house soon) 2. so i can use it in stock class racing for a bit while i get my skills back up so i dont wreck my s13 on the track.

CJ