Last Update - March 06, 2001
RMS Intake
Custom intake pipe with K&N cone filter
$175US including shipping. Rebel MotorsportsThis intake is made up of a "K&N-type" (oiled cotton cloth) cone air filter, and a nice big intake pipe of a shape and length that positions the cone filter right up close to the inside of the driver's side air vent (those wonderful "scoops" in the body, just behind the doors on each side of the car).
The greatest advantage of this, or any custom intake, is that it replaces the complicated stock intake system. The stock system includes an air box that is baffled to absorb noise from the engine and turbo, and it includes a great big air bladder called a "resonator box", which also absorbs noise and vibration in the airstream. The resonator box acts as a capacitor to smooth out the airflow before it passes through the Air Flow Meter (AFM). The AFM can measure smoothly flowing air more accurately. Theory aside, there is a demonstrable performance gain in removing the stock airbox and resonator.
With the stock intake system removed, the engine and turbo are free to make all the lusty grunts and sensuous machine-sounds they want to, and the turbo is free to spool up in about half the time! Yes, removing the stock intake system cuts turbo-lag in half (from about 1 second to about a half-second, at 3000RPM). With the RMS intake, the car suddenly felt much livelier than before, with improved throttle response, turbo response, and overall power.
The RMS intake, when installed per the instructions, puts the filter, pipe, AFM and turbo inlet pipes all in a straight line with the turbo. The cone filter is positioned up against the driver's side air vent, maximizing the amount of cool, outside air that the engine will breathe (instead of hot engine-compartment air; remember, cool air makes more power). Rebel Motorsports claims a horsepower increase of about 10hp on an otherwise-stock MR2 Turbo. I'd say this claim is valid, although the increase is mostly due to a ~1psi higher maximum boost, which in turn is a result of having a less restrictive intake.
All other connections to the intake remain intact, such as PCV and BOV.
Evaluation
I experienced all the promised benefits of the custom intake, including less turbo lag, more power, and more high-performance-like sounds from the engine-room (cool). C'mon, this is why we all buy "high-performance" exhausts, right? ;-) The intake pipe is nice and wide, and points the filter right at the cool air vent. I favour the kit's oiled-cotton filter over the foam filters that are commonly available. However, the RMS kit's black-painted mild-steel pipe isn't much to look at compared with some anodized-aluminum options available. And, I did have a lot of trouble installing the RMS intake.
The installation instructions that Jeff Bihn e-mails out to customers are insufficient. See Marc Summers' article on Installing The HKS Super Power Flow Filter System for hints on removing the stock air intake. There are some bolts to be removed that are not visible from above the car, but you can find them with your hands if you know where to feel. The following notes will also help to explain what should be a simple installation.
Be sure to keep all removed parts (bolts, brackets, washers, gaskets, etc.), until you are completely finished with the installation, because you will have to re-use some of these parts. If you are one of those clever MR2 owners with their own BGB, you will have noticed that the intake gasket in front of the AFM is a non-reuseable part. I went and bought a new gasket from Toyota before starting the installation, but I need not have. The original gasket was still quite resiliant and undamaged, I could have re-used it as RMS recommends, and saved $5 and a trip to the dealership. Be sure, when assembling everything, that the gasket does not block any of the little secondary air passages.
Before installing the new intake, loosen all the hose clamps between the AFM and the turbo, and twist the joints to loosen them. You'll need to re-align these pipes slightly to get the intake to fit parallel with the firewall. I also had to temporarily disconnect the BOV return line and the PCV line from the intake. Don't forget to tighten all clamps and re-connecct everything when it's all in.
I found it easiest to remove the AFM from the car, bolt the RMS intake to the AFM, and install the whole ensemble together. Look into the driver's side fender-well where the air-vent is, and identify the big (>1") metal gasoline filler-pipe and small (<1/2") metal overfill pipe that come down together from the gas cap, and angle to the right, towards the front of the car, making two nested "L"-shapes. The cone filter should slide into the crook of these two bending pipes, to reach towards the air-vent, so that the filter is, in fact, resting in the elbow of the gas pipes and pointed at the vent. (The first time I tried to install the intake, i was pushing the filter against the gas pipes, and couldn't figure out how it was all supposed to fit in there!).
The cone filter should be just perched on the end of the intake pipe, not pushed all the way on. You want the pipe to breathe through the whole filter.
I found that the AFM now bonked against a body tab unless I bent a slight "S"-shape into the mounting brace that came with the RMS intake.
After driving a while with the RMS intake installed, I became concerned about some bonking and rubbing noises I was hearing (apart from the mechanical symphony put out by the free-breathing engine and turbo). I removed the intake and noted that the wire mesh of the cotton filter was slightly crushed and damaged from rubbing against the metal gas pipes. I solved this problem by making a helical cut in some 1/2"-ID heater hose, and wrapping the hose around the overfill pipe (and securing it with plastic-sheathed metal twist-ties). The filter now had a perch padded with foam-rubber. Also I noted that the AFM was still bonking against the body tab just above it. I solved this problem by bending the mounting brace (as mentioned above), and by spacing the AFM down from the mounting brace with a couple of plastic washers. Finally, I was satisfied with the fitment of the intake.
Throughout my installation pains, Jeff Bihn at Rebel Motorsports was more than reasonably helpful. He admits that writing instruction manuals is not his strong suit. After we exchanged several e-mails and digital photos, he phoned me from MS (Missouri? Mississippi?) to talk me through the installation. He was also generous with his knowledge concerning other issues of turbo hot-rodding.
Recommendation
Despite the bumpy installation and the imperfect fit, I like the RMS custom intake. It gets the engine breathing cool, outside air without the hydrolock risk that some cold-air intake systems present. The "K&N-type" oiled cotton cloth filter is, in my opinion, better than the many foam filters that are marketted with "high-performance" intake kits. The price seems a little high considering the simplicity of the kit, but it is still some of the cheapest horsepower you will ever make, and a great first performance mod. With the sharper response and lustier sounds, the change in the car's character is all-good.
HKS 45mm Boost Gauge
-760mm/Hg to +2.0 bar vacuum & boost gauge, installed in place of stock boost "gauge".
$470 CDN including installation by Yoshio.The stock boost "gauge" is not designed to do anything except to reasure unsavvy MR2 owners that their turbo is, in fact, working. With the extreme damping and ungraduated gauge face, it is useless for performance tuning. Before attempting to modify the boost limit of an MR2, it is imperative that one installs a proper boost gauge.
Many options are available, from the built-in boost displays integral to some electronic boost controllers (EBCs), to electronic "analog" gauges (which read pressure via an electric transducer) and with features like peak-hold and overboost warning. I went the cheap and simple route, installing a mechanical analog gauge with a vacuum line that runs all the way from the gauge cluster to the engine compartment. Well, "cheap" is a relative thing. The HKS boost gauge costs a lot more than equivalent gauges from Autometer, VDO and others. The attraction of the HKS product is that their 45mm gauge is almost a drop-in replacement for the stock gauge (which is right in the centre of the gauge cluster, between the speedo and tach). I like this installation much better than the various other mounting options (A-piller pods being the most popular alternative). It looks stock to all but the most cognizant passengers.
There is an excellent VFAQ on www.MR2.com, on how to complete the installation of this gauge into the stock location (see: HKS 46mm Boost Gauge Install by Dean M. Fujita). I printed out this article, studied it, then decided to let Yoshio at Japanese Automotive install it for me instead. I wasn't feeling up to pulling my whole interior apart. Yoshio also sourced the gauge for me. I paid $210 for the gauge and $260 for installation (Canadian dollars).
Evaluation
Over $500 (with tax) for a boost gauge?? Yes, I could have put a better gauge into the A-piller, with an installation simple enough to do myself, for less than half that price. Yes, a stock appearance is very important to me. You know those kids that spend $thousands on body kits, stickers and foglights, and whose only "performance" mods are a chrome exhaust tip and color-matching ignition wires? I am their opposite. I get a kick out of "stealthy" performance upgrades.I am totally pleased with the outcome of this mod. A real boost gauge is essential to performance-tuning a turbocharged engine, especially if you will be disabling the ECU's boost controls and safeguards (the T-VSV, the Fuel Cut). And, the boost gauge should be installed within easy view of the driver. An electronic gauge with peak-hold and overboost warning would have been nice, but I'm sure by the time I need them, I'll be installing an EBC with those features. At the time of this installation, my upgrade plans included a manual boost controller (see below), and leaving the Fuel Cut enabled.
Yoshio's installation was very good, as expected. I asked him to clamp or zip-tie all vacuum connections, because a leak in the line to the gauge could spell disaster through misinformation. The vacuum run from the manifold to the gauge is quite long, and there are several points where the line could be pinched or kinked, so it is important to use the right type of hose (hard plastic, rubber/silicone) at the right points along the way. The hose runs from the engine room through an existing grommet in the firewall behind the driver's seat, under the centre tunnel trim, up behind the dashboard and into the back of the gauge. Unfortunately the gauge ended up slightly off-centre, but more importantly the interior was re-assembled perfectly.
The gauge is lit, and is easy to read at a glance despite it's small size (once you get to "know" it). If you lived with the stock gauge for any length of time, you'll be amazed by the quick responses of a real gauge: the needle snaps back and forth through the "vacuum" range faster than you can move your foot on the accelerator pedal. And, when you get into the boost, the needle sweeps through the positive pressure range exactly in step with the increasing push felt in your back.
Recommendation
Get a boost gauge. For a seriously stealth installation, get a 45mm HKS boost gauge and replace the useless stock gauge with it. For a cheaper alternative, get an A-piller pod and an Autometer (cheap!), or an Omori electronic one with the two above-mentioned cool features. But for goodness sake get a real boost gauge!
Joe P. MBC
Manual Boost Controller (MBC) made by Joe Pampena.
$50US ($60US shipped to Canada) Joe P. MBC.There are basically two families of boost controllers. The electronic boost controllers (EBCs) are user-friendly, very effective, and relatively expensive ($300+ US). Their manual cousins (MBCs) range from relatively to extremely cheap, and from good to dangerously imprecise. Briefly, a boost controller affects the boost signal seen by the wastegate, thus changing the maximum boost which the turbo will produce. Since too much boost can destroy an engine in seconds, one should not monkey with this parameter until one knows what one is doing, and one should choose once's boost control method with care.
EBCs are clever boost-control computers that can employ sophisticated algorithms to dynamically set your boost to maximize performance and safety. They generally consist of the brain/display/interface 1/4-DIN unit that installs into the cockpit, a solenoid-switched boost control module, a manifold pressure sensor (I guess), and a lot of wires. An EBC is a must-have for monstrous power production, where sloppy boost control will certainly kill a "million-dollar" engine. They are also just really cool, if you have the means.
MBCs are simple, manually-adjusted valves that interrupt the vacuum line going from the turbo outlet (or the intake manifold) to the turbo wastegate. There are many home-made MBCs out there, including those constructed from $7 worth of aquarium parts, and welder's tips of a certain nozzle size forced into the vacuum line. The Joe P. MBC is not among these dirt-cheap (and in my opinion cavalier, though creative) options.
Most MBCs work by either bleeding off some of the pressure in the line ("bleeder-type"), or by restricting the boost signal ("restrictor-type"). You could say that Joe P.'s design is a "non-linear restrictor-type". It is a variation on the successful and respected ball-and-spring design, whereby the wastegate sees no boost signal until the desired maximum boost is reached, at which point the pressure in the line is enough to push the sprung ball past an opening in the valve body, allowing the wastegate to see the full boost signal. This has the advantage (over bleeder- and vanilla restrictor-type designs) of holding the wastegate completely closed, allowing boost to build more quickly, until max boost is reached, at which point the wastegate quickly opens. See Joe's web page, above, for more technical information.
Joe sells the MBC and installation kit for $50US, including delivery ($60US delivered to Canada).
