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April 2014 Question IT

Fixing what you broke

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Got a burning question or simply need some advice with problems you've encountered while wrenching on your current/future projects? Ask our automotive guru Eric Hsu anything—literally, he's going to answer every single question, as long as it's automotive related.

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Mazda RX-8 20B Swap

I own a '04 RX-8 and the car has given me some hiccups from the start (the thing wouldn't start after a week out from the dealership because of fouled spark plugs), but I love the car especially after reading the possibilities of the rotary. With all these dreams of rotaries dancing in my head I had the epiphany many rotary heads have with a 13B. What about a three-rotor? Enter the 20B. How feasible is this in my car without it becoming a garage queen? How much of a budget do I need to do it right? Who or where can I look to find info on this swap? Can the original six-speed transmission be used? I know it's been done before. Enter your May '11 issue with one of the best examples of an RX-8 with a 20B built to perfection that I still drool over. Now I know a little in my scouring of the Internet and forums, but there's a lot of crazy stuff being thrown around so trying to sort through it is a bit of a headache, to say the least. Hence why I come to you. If you could help me figure out fact from fiction and any answers I would be ever grateful.

-Carlos Keller, TX

The 20B is a pretty expensive engine. The costs of the parts alone to install a 20B into your RX-8 will probably be triple the value of your RX-8. That's fine if you're down with dropping that kind of cash, but then you'll either need to figure out how to install it and get it running, or fork out the same amount of cash to have an experienced shop install it for you. Try contacting Ron Bergenholtz down in Houston, TX, at JTran Motorsports. Ron built the Bergenholtz Racing RX-8 that successfully ran in Formula D. He's been building street and race cars for a long time now.

You can run the RX-8 six-speed transmission, but that's about it. Just about everything forward of the transmission will need to be replaced. Engine mounts, cooling system, induction, engine harness, turbos, intercooler, and more will all need to be custom fabricated. Then you'll need a stand-alone ECU and fuel system as well. All in all, it'll be a very costly swap and will take a good deal of time to get it all done right.

Integra DB8 EVAP Valve Issues

I just finished my '95 Integra GSR four-door build after six long months. The engine has been blueprinted with Type-R pistons, but at low rpm the car is misfiring. The car still has plenty of power that you can feel. My initial diagnosis, although it could be wrong, is that it is related to a vacuum problem. The engine is currently running the stock GSR intake. I like the way it looks and want to keep it, but here is the problem: Intake Air Bypass Solenoid - IAB (36163-PT2-004) and Purge Cut Solenoid Valve Assembly (36162-PT3-Q01). I have no idea if they are working or not, but what I can tell you is that they both look very similar and have some type of round little cap that is cracked. The IAB, as you probably know, goes on top of the intake manifold and the Purge Cut Solenoid goes under the manifold connected to this vacuum tank thing. So, if I wanted to get rid of those bad boys, is it possible? If it is, what do I need to do? Is it a good or bad idea? Please point me in the right direction. I have been working on it for almost six months getting this thing done and when I think it's finally done, this problem comes up. I can't wait to drive this car.

-Julian P., via

The intake air bypass solenoid is necessary for a street car because it controls idle speed. Of course you could also just adjust the throttle stop screw to hold the throttle plate open for idle, but you'd lose the functionality of idle speed under different conditions (A/C, cold start) and deceleration fuel cut (good for fuel economy). I recommend keeping the Intake Air Bypass Solenoid, but you could ditch the Purge Cut Solenoid, especially if you've removed the charcoal canister. The purge solenoid exists to purge the charcoal canister and dump the buildup into the intake manifold during high vacuum situations. With a '95 OBD-I ECU, you can remove the Purge Cut Solenoid without any ill effects. If you wanted to be extra sure, you could just leave the solenoid plugged in without any hoses attached to it. Or you could also measure the electrical resistance of the solenoid with a voltmeter and simply plug in a resistor of similar value and remove the purge solenoid.

Catch Cans

There are so many different variations of catch cans sold on the market today, but do they really work? The typical unit only has a two-port (inlet and outlet) fitting to run from the valve cover to the intake, but it's hard to imagine it actually working correctly. Can you set the rumors straight and tell me if this is indeed a good investment as I am looking to install a Cusco-type catch can on my '08 WRX 2.5-liter. I was just wondering about the hose routing, because there are no input or output marks on the nozzles or anywhere on the can and I need to know which line to use from the engine and intake.

-John S., via

If you bought a genuine Cusco catch can for a WRX, it should be application specific. If you bought a universal unit, you should return it and get the application-specific part number because it does make the installation a lot easier and includes instructions. There are a lot of fake parts out there, but you can visit Cusco's website on how to identify fake Cusco parts.

Different catch cans are better for different situations. Some of the more complex units with multiple cans and a bunch of hoses are better suited for cars that spend a lot of time on tracks whereas the simpler single-canister catch cans are better suited to street cars. The Subaru flat-four engines suffer from a lot of oil getting blown out of the valve covers during heavy acceleration because of the position of the cylinder heads. They are very low and close to the oil pan so the oil doesn't always drain back into the crankcase as well as inline-four engines, where gravity plays a big role in draining the head of oil. During heavy acceleration, blow-by gases pressurize the crankcase and cause some of this built-up oil in the cylinder heads to get blown out. In a stock car, this oil gets blown out directly into the turbo inlet. After the addition of a catch can, the oil will collect in the catch can and "catch" the oil in the can. In theory, only the residual gases go back into the turbo inlet.

A catch can is a nice addition and can keep liquid oil from building up in the charge system. For race cars that spend a lot of time on tracks, the necessity of a catch can is critical since there are a lot of high-g situations, a lot of time spent at full throttle, and a lot of blow-by gases flowing through the crankcase. Catch can systems for track cars commonly have multiple canisters for higher oil capacity, better air/oil separation, and have drain-back hoses to allow collected oil to drain back into the crankcase. This way the engine will still have enough oil in the crankcase to keep oil pressure where it needs to be.

All properly designed catch cans are baffled inside to help separate the liquid oil and the air. For a Subaru, both valve covers connect to the catch can via the factory crossover pipe, and this enters the catch can. Inside of the catch can, there is usually a wall that acts as a baffle. The liquid oil that enters the catch hits this baffle and drips to the bottom of the catch can. The residual blow-by gases then exit the catch can and enter the engine from the inlet of the turbocharger. This keeps oil from building up in the charge system (turbo, intercooler plumbing, intercooler, throttle body, and intake manifold) and prevents liquid oil from entering the combustion chambers and causing poor combustion (e.g. knock, misfire).

Ignition Upgrade?

I recently built my turbo H22 Honda 2.2L motor with plans for a coil-on-plug conversion. I've been told that they are good for use in high-boost, high-rpm, or high-compression applications; the increase in spark energy can be seen over factory smart coils. I know some of the older-model cars use MSD 6AL-type boxes or high-output external coils, but what do you think is the best bang for the buck ignition system upgrade?

-Mike, Santa Rosa, CA

Bang for the buck would highly depend on the level of necessity. If you have a simple 6 psi of boost street car engine, a good set of plugs, ignition wires, and a multi-spark box will probably do the trick. If you've built a 40 psi of boost 900hp drag engine, then high current, coil-on-plug coils are probably a necessity. Without any information, it's hard for me to tell you what I recommend. I'm guessing you've built a mild street car engine so I'd recommend running a new distributor cap and rotor, hot external ignition coil, a set of high-performance ignition wires, some NGK Iridium spark plugs (gapped accordingly), and an MSD Digital 6 ignition box (this is 2014, so let's stick to digital). MSD has distributor caps that already have provisions for an external ignition coil. In fact, you could just run all MSD ignition components except for the NGK Iridium spark plugs for an almost one-stop ignition solution. This ignition setup should be fine for over 500 whp. Going to a coil-on-plug solution requires custom wiring, four coils, and an ECU that can control individual coils.

Spark plug gap can vary according to cylinder pressures and air/fuel mixture, but you'll probably want to start off at 0.032 inch and then start gapping them down .003 inch at a time if there's any misfire. It's not uncommon to gap the plugs all the way down to .020 inch for a high boost engine.

Nitrous & Tequila

Being a child of the Internet I've seen Nissan 350Z cars using 150 hp of nitrous to defeat mighty 12-second quarter-mile cars (my main goal is to hit at least low 13 seconds). How safe is that and what would it take to hook all this power down on the tarmac, straight slicks or street tires would still hold up on Second gear? Is it a one-time deal before you blow that sweet VQ35 to pieces, or is 75 or 100 hp a decent daily driven option for a good 375hp cheap build considering I've got a few bolt-ons like a Skunk2 plenum spacer, JWT pop charger, UR lightweight pulley kit, and custom catback exhaust. Or would you rather suggest saving money and go for a blown VQ, maybe a Stillen supercharger?

-Jay, Rimouski, Quebec, Canada

Nitrous is a wonderful thing and is definitely the quickest and cheapest way to get some horsepower out of your engine. I like to think that nitrous and tequila are pretty similar in that they both give your more power, but in both cases, too much can result in disaster. Considering the VQ35 doesn't have the strongest pistons or connecting rods, I'd keep the nitrous under 100 hp with a single fogger nozzle. Add a good clutch, steel flywheel, good gas, and a pair of slicks in the mix and you should be able to run 12s in the quarter-mile. Getting 11s might take a bit more nitrous, but proceed with caution (much like tequila). Be sure to run a colder spark plug too. The stock VQ plugs have a heat range of 5. I recommend running a colder heat range 7 NGK Iridium spark plug.

Beyond 100 hp, I'd recommend a wet direct port setup, which can be conveniently plumbed onto the lower intake manifold. Ideally, you should also log your air/fuel ratio (add a wideband if necessary) to make sure the engine is running safely and run some race fuel if you do not have ignition timing control. Also a bottle heater and blanket will keep your engine running consistently when on nitrous. Hit up the guys at UpRev for their data logging and ECU tuning software if you don't already have it. Of course, a set of forged pistons and rods would increase engine longevity also.

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