JDM Cyclone Intake Manifold

This is a rough VFAQ for installation of a JDM Cyclone dual-runner intake manifold on the Galant VR-4. The manifold and coil pack I received are 90-style electronics, so some tweaking is needed to make the 91 coil setup fit. The tach interface is a bit different between the years and need swapped out. Also, the Power Transistor units are slightly different and need to be changed.

[Cyclone Pics] [Coil Pack Mod] [Power TR Mod] [On-Vehicle Install] [Butterfly Control]

So why go to the trouble? What are the disadvantages & advantages of going to the JDM Cyclone dual runner manifold vs. the stock US manifold? Here are answers to some common questions and misconceptions.

Cyclone Advantages


Q: Is any Mitsu manifold with "Cyclone" on it dual runner?
A: No. There are a number of "Cyclone" manifolds on Mitsus, not all of which have dual runners. Be sure you are getting the 8-runner manifold before you commit to that unnamed "Cyclone."

Q: What is the little white cylinder that came with my intake? What do I do with it?
A: It is a vacuum reservoir for use in conjunction with an ECU controlled solenoid to control the butterfly opening. The US ECUs don't have this functionality so you can just plumb the butterfly straight to the manifold if you don't want to build a secondary butterfly controller. Also see http://www.dsm.org/archives/1999/01/19990122.txt/47.html. However, the Cyclone manifold performs much better with some form of secondary butterfly control. See the butterfly control section of this FAQ.

Q: What all parts are needed to make this swap?
A: Cyclone manifold, coil pack & power transistor brackets, manifold support bracket.

Q: Will the Cyclone clear the stock A/C compressor?
A: Barely. With a little careful bending of the A/C lines and/or grinding of the manifold support bracket it will be a tight fit but will work. I had good luck, Ken didn't. YMMV.

Q: Will the stock spark plug wires fit now that the coil has been relocated?
A: No. But the US 1G DSM NGK replacement wires will supposedly fit if the 1-4 coils and 2-3 coils are switched in the bracket. Some people have reported better fitment by swapping the #3 & 4 plug wires. That was not my experience, all of my wires fit only when keeping them on the correct plug when using the stock wire routing. It is an extremely tight fit that I was uncomfortable with, so I ordered a set of Cyclone-specific wires from Magnecor [part# 43485?]. Expensive? Yes. But they are a direct fit and have plenty of slack. Also Ken mentions that Kingsborne wire [ph# 800 643 0375] makes an inexpensive set for the cyclone, part# 11-571 cyclone.

Manifold Flow Data

Manifold flow at 28" H2O, 0.400" [10.2mm] lift, manifold bolted to stock head:
Manifold Flow (cfm)
Cyclone 201
US stock 203
US EH* 210

*Extrude Honed. Flow bench data is courtesy of S. Evans and vacuum / spool data is courtesy of N. Pharr.

A 1.0% difference in flow between the Cyclone and US intakes is hardly significant. Even Extrude Honing the US intake only nets 4.4% more airflow than the stock Cyclone. The stock head is obviously a limitation. Extrude Honing hardly seems worth the cost unless bolted to a ported head. When bolted to a ported head, the Cyclone does begin to fall behind the stock manifold by 5-10% at maximum valve lift.

Cyclone Pics

Coil Pack Mod

The cyclone coil packs can be retained, just change the wiring to the later 91+ style.

Power TR Mod

power TR units

As you can see, the brackets are very different, as are the bolt sizes. I simply drilled and tapped new holes for the 91 Power Transistor unit. Not a big deal, took me about 10 minutes.

On-Vehicle Install
by Ken Inn

Stock Manifold Removal

One of the difficulties is the removal of the stock intake. I used a 1/4" ratchet, a couple of short extensions, and the real secret is a 12mm flex socket. The most difficult bolt to get at is underneath, driver's side. After removing the coils and the transistor, you can just crack it loose with the flex socket, and about a 4" extension, BUT you CANNOT back it all the way out, and it is really difficult to reach with your hand. This goes for all of the bolts underneath the manifold, with the flex socket, you cannot back them all the way out, just break them loose, and back them off about 1 turn, then you can loosen them all the way with your hand. The easiest way to get at three of the bolts underneath, is from the passenger side of the car. You will be able to get the three underneath off, then, take off all of the rest up top, except two. Back them off almost all the way out, then tilt the manifold up, and you can then get that last bolt underneath. If you take off all of the bolts up top. you will have to support the manifold with your other hand, and it is quite heavy. The support bracket is in the way, there are 2 top bolts, and one bolt to the block, I believe they are all 14mm wrench size. Be careful, because the knock sensor lead goes thru this bracket, and you will have to disconnect it first, or you will pull the wire off of the knock sensor, about a 100$ part. Also, this bracket has the vacuum line nest, which I have long since bypassed or removed. I unbolted the bracket, but could not get it out until I took off the manifold, BUT it did then allow better access to the bolts underneath.

Cyclone Manifold Installation

The ONLY way to bolt up the cyclone manifold is to first take it apart, and bolt up the first piece that has the butterflies. This is a piece of cake. However, the second part, which makes the 180 deg turn, is tricky. there are 2 studs for guidance, and you cannot get them in because of the obstruction of the a/c line. The stud nearest the water pump is the problem. I yanked it and used a long bolt instead, which worked perfectly. Now I can disassemble the manifold on the car. Some say to bend the a/c line [I had no problem with this and used the stock mounting points. - Kyle]. Well, on my car I would have to bend it at least an inch and when I tried, freon started to leak. This line is held on with only a 6mm bolt, on a flange, and you will end up bending the flange, too, and you will get a leak. If you notice, it is hitting one of the raised bosses that hold on the coil pack. I cut off that one boss, and it cleared nicely, but now the coil pack was obstructed. If you bolt down the coil pack with the bolt nearest the water pump, you can then rotate the coil pack slightly, and redrill a new mounting hole, then you can use 2 of the 3 mounting bosses, which I think is plenty.

Butterfly Control

The JDM Cyclone ECU has functionality installed to control the secondaries that is not present in the US ECU. The simple option is to plumb the butterflies straight to manifold vacuum so that they open proportional to the throttle opening. While this does work, it doesn't exploit the benefit of keeping the secondaries closed and keep the intake velocity up until the turbo is making significant airflow, maximizing bottom and lower midrange power. So at what point should the secondaries open? Rumors say that the JDM ECU opens the secondaries at ~8psi boost. Ken is sure that it has to be much higher than 3000 rpm. In either case, the optimal switch point will vary a bit depending on turbo and exhaust size and overall engine volumetric efficiency. The setup described here is an adjustable boost-pressure based system that will allow the user to tweak the system to best operation for their engine.

Parts Needed

So what do we need to assemble this Cyclone controller?


The white vacuum canister is a reservoir with a one way valve. This is absolutely essential to operation since the reservoir damps the butterfly responses to the variable engine vacuum, greatly smoothing their response. This way the butterflies open slowly, not snapping open. This smooths the transition from single to dual runner operation and avoids "hiccups" in the airflow. It seems like the system needs about 6-8in vacuum to keep the butterflies closed. Plumbing the diaphragm directly to the manifold seems to cause surging at times. The Hobbs pressure switch is adjustable, so you can play with the boost pressure level needed to open the secondaries. The Hobbs switch specified above is set for 4psi, but can be adjusted from ~3-10psi.

In a pure sense, here is what the control system diagram looks like.

And plumbed using the purge control solenoid. The purge solenoid is a two way solenoid. When unpowered, the air flows from the top to the rear nipple under the electrical connector. When powered, the air flows from the top to the front nipple where the vent cover is. Please note that the direction of the purge solenoid does matter.

NOTE: If there is a power connection problem the above diagram will default to direct manifold control of the secondaries. It is possible to reduce the cost of the system by switching the Hobbs type from NC to NO and reversing the purge solenoid direction which will switch the two solenoids - NO on the vacuum reservoir line, and NC on the direct butterfly line. Either setup will have equivalent performance and operation when working correctly. However, in a situation where the Hobbs switch is an NO-type, if the power connection is lost the default operation will be primary runners only since the vacuum reservoir will pull the secondaries closed. This will cause a flow restriction at higher boost/rpm since the secondaries will never open. The only advantage of the Hobbs NO setup is cost, as the NC Hobbs switch is ~$15 more than the NO version.

Kyle's Custom GVR4 Installation

My installation was a bit custom on my GVR4, so your actual mounting will vary depending on your car type and available space. I have way too many vacuum lines [purge solenoid + Hobbs, MAP sensor, boost gauge], so I built a custom air distribution manifold to bolt underneath the solenoid rack and clean up the plumbing a bit. In addition, my Cyclone did not come with the manifold support bracket or vacuum reservoir, so I had to find a home for a different vacuum canister [from a 90-93 Isuzu Impulse 1.6 DOHC w/ a similar setup].

The most useful part I found was the solenoid rack from a 1G turbo DSM. The one right above the brake booster that contains the fuel pressure and purge control solenoids. The entire assembly comes off with the removal of the two 10mm head bolts in the fire wall. If you cut the wiring harness and retain the stock power connector, you now have a pre-wired rack that requires only a little work to become a Cyclone controller. Find a mount location for the Hobbs switch as you are in business.

Performance - Ken

What I have noticed, is the lower and mid range driveability is GREATLY improved. The car will pull cleanly from 1500-2000 rpm in any gear, and just putting around town is really easy. I find myself always in a higher gear, and if I want to go faster, I just step on it. I have a vacuum/boost gauge installed into the actuator line, so I can see when it starts to open. Right next to it, I have a green lite that comes on when the water injection sprays, I have it set to about 8 lbs boost. Most of the time, the lite comes on just as the vacuum is reading about 2-4 inches, and I know that the butterflies are just starting to open. During cold start, the performance is greatly improved. The car is very smooth, and part throttle acceleration seems more brisk. The car acts like it wants to pull a lot better. You cannot tell when the car is cold or completely warmed up, the throttle response is the same. I have only had one opportunity to take the car on a long drive, I went to austin, 225 miles each way. I had the cruise set to 75, and at times I had it up to 85 mph, a/c on all the time, and I stopped twice, once was to meet one of my customers, and I took him to dinner. My mpg was 28, the best I have ever gotten in this car.

Ken's Comments

When I first hooked this thing up, I just tapped the intake vacuum, and I was not impressed. I did see some sparks of life in stop and go traffic, where you either gotta be wound out in first, or lugging second. I noticed that as long as the butterflies were closed, I could start off in second, and stay in second, and it made it a bit easier. That's when I started thinking about a way to keep the butterflies closed longer.

It is very smooth. From what I can tell, when in cruise mode the mpg is really good. I think now I can get 30 mpg. City driving was a slight improvement, about 2 mpg, but the driveability was greatly improved. I think this is a great mod for people who are not into racing the car, and use it for a daily driver. before I had it hooked up like this, I told everyone it was not worth the effort. now, I recommend it highly. hope this helps.

Kyle's Comments

I got the Cyclone controller up and running this weekend and had a chance to do a little testing today using the Pocketlogger. I mainly looked at RPM & airflow under load in 4th gear, accelerating from 1500-4500rpm WOT with the controller on and off. The controller is setup to not open the secondary runners until 4psi of boost.

The data is very limited (two data sets) so take this with a big grain of salt. Under ~3300rpm the Cyclone controller flows a little more air, anywhere from 0% to 7% more as with the controller off, with an average of 2% greater. Above 3300 rpm with the controller off the flow is slightly better, with a max of +3% and average of +0.6%. So the Cyclone controller does seem to do a little at lower rpm, but a higher rpm it is too close to say.

While I couldn't log it, the 16G turbo spools noticeably earlier, making >5psi boost below 2500rpm. Subjectively, the engine does seem to accelerate more smoothly and surge less with the controller on, but that may be the placebo effect. More to come as I continue to play with it.

Big thanks to Ken Inn for all of his help, the basic controller design and permission to use excerpts from our correspondence

Feel free to reprint this document for your own or mechanic(s) personal, non-profit use only. Do not repost this document on any other website without my prior WRITTEN consent. Any use of this document for profit/resale/redistribution of ANY type is forbidden. You may link to the main page, but I advise not linking directly to this document since the site structure does ocassionally reorganize and links will move.

Kyle Zingg 2002-5

Further info on manifold and related to cyclone
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