Question It July 2013 - Import Tuner Magazine

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.

Got a tech question? Send it to questionit@importtuner.com

Turbo Tech

I’ve been researching aftermarket turbos and came across various manufacturers who use billet, Inconel, titanium, or stainless steel material compressor wheels. There’s also the element of extruded compressor wheels or CNC type, which is information that’s foreign to me. Can you offer some insight into what the advantages of purchasing a turbo with a specific wheel material or design can help in improving overall boost response on a drag car, road race, or autocross vehicle?
-John Barret,
via importtuner.com

Chances are you won’t find Inconel or stainless steel compressor wheels. Inconel is a high-temperature material typically used in high-performance turbine wheels (that’s the wheel on the exhaust side). Stainless steel compressor wheels are only found in extreme use compressors and are not typically found in automotive applications since stainless is more difficult to machine and cast. Aluminum is the most common compressor wheel material, because it can handle the temperature range of the compressor section and results in a wheel that is lighter in weight, which reduces inertia. The lower the inertia is the better the response because the wheel assembly accelerates easier, which results in reduced turbo lag. Using billet or extruded and machined aluminum compressor wheels can make for a stronger compressor wheel compared to a cast wheel, which, when properly designed, makes for a lighter compressor wheel again lowering inertia.

On the turbine wheel side, inertia also plays a large roll since the turbine wheel is typically the heavier wheel. BorgWarner has reduced inertia to their EFR series by using Titanium Aluminide and Garrett will be releasing a new generation of turbine wheels, which promises much improved aerodynamics in the near future.

Typically only the larger turbocharger manufacturers (e.g. Garrett, BorgWarner, etc.) have the lab equipment required to measure flow properly, test for wheel durability, and housing burst containment so I keep that in mind when specifying a turbo for any application. Properly designed turbos from the large turbo companies result in greater service life and better performance over that service life. There’s a slight premium, but it’s well worth the extra cost in my book.

Transmission Upgrade?

I own a ’00 Honda Civic Si coupe, with the B16A engine, and I’m planning on rebuilding the entire engine and installing a TO4E turbo, aftermarket camshafts, valvetrain, forged pistons, and billet crankshaft. While I’m keeping it all amateur/tuner level, should I change the stock transmission? Or will a race clutch/race flywheel get the job done, considering I’m looking to obtain between 350 and 450 bhp?
-Victor Castillo,
via importtuner.com

Amateur or pro, at over 200-300 percent increase in horsepower output, the stock clutch isn’t going to live very long, if it lives at all. I’d recommend you get a high-performance clutch kit from a supplier like Advanced Clutch Technology (ACT), which has been in the high-performance clutch business for many years. ACT offers plenty of clutch options for the B-Series engines to suit your preference: lighter pedal, different disc materials, and more. As for the flywheel, it would depend on the car’s intended purpose. If you plan to drag race on slicks, then you may want to use a heavier flywheel to improve the launch. If you are going to road race, then a lighter flywheel would be the way to go to help the engine accelerate faster. A heavier flywheel can improve a drag launch on sticky tires since it has greater inertia. A lighter flywheel provides better acceleration where there are a lot of throttle transients as in road racing. If it’s a street car and you don’t live in a hilly area, then a lighter flywheel is probably the way to go. Keep in mind that if you are going to drag race, some tracks require that you use an SFI-certified flywheel to prevent the potential of a cast flywheel from bursting into pieces during an 8,000-rpm clutch drop. ACT’s lineup of steel flywheels is SFI certified so you won’t have any issues during tech at any track.

Subaru Impreza Hunting

I’m looking into purchasing a ’93-01 Subaru Impreza as my first car. I will have to pay for the majority of it, and would like to do a lot of the work myself for any repairs or modifications. Later, I would like to get a turbo, but for now I can’t because it has to be insured under my name, and, at my age, a turbocharged, two-door would be very pricey with insurance companies. However, when I shop around on forums and such, a lot of the cars have already had an engine swap done to add a turbo. I also noticed that I could buy a non-turbo version (L or LX) for very cheap. The 2.5RS version would be ideal, but they are very hard to find stock. Is it more cost effective to buy the cheap car and do an engine swap at a shop so I know it’s done right, or should I buy an already swapped car and run the risk of it nickel-and-diming me to death with perpetual repairs? Or, as a third option, should I buy the 2.5RS and somehow add a turbo to this? I have not researched the third option much, but it seems expensive.
-David Dipple,
Team Driver for Xcel Cuts

If you want to make sure it’s done right, then I’d recommend you buy a stock car and build it yourself. You get to pick the parts yourself and how they’re installed. JDM GC8 turbo engine swaps can be found at a pretty reasonable cost these days, so personally, I’d probably go this route. On the other hand, finding an already turbocharged car that has been properly built can save you a bundle of money. The reality is that owners aren’t going to ever get back their investment so this is probably the cheaper way to go. The key here is finding a properly built car. If you don’t think you know enough to figure that out, then pay a shop you trust to do an in-depth inspection. A couple hundred dollars can save you a couple thousand dollars in this instance. The 2.5RS responds well to turbocharging and the added displacement of a 2.5L engine also helps performance too. But as you said, it’s a more expensive option so this is something that your budget will have to decide.

Rotary Update

Thank you for your response, advice, and information in regards to my email on supercharging an RE. I did my research and the kit from Mariah is kind of expensive. However, later on down the line I will build a supercharged RE. Since my email, I lucked out on finding an S4 13B turbo in great condition, removed from a wrecked and running Turbo 2. I am in the process of pulling my six-port now. While the engine is out I plan to clean the engine bay and install a new brake master cylinder. I will also be replacing the trans cover/gasket, seal, shift fork, fork pivot, pilot bearing/seal, throwout bearing, and clutch.

I hope to have everything done and my FC back up and running within a few days. There are a few hard parts I need like the accelerator cable and knock sensor. I will keep you posted on my build, but for now I have attached a few pictures.
-Desmond Marshall

Awesome, glad your project is moving along. Best of luck and let us know how it goes!

’89 CRX B18C Swap CEL (WTF)?!

The check engine light on sensor in downpipe 4 wire were so the wires hook up and also what is the valve called that goes on block to provide oil to turbo as well as what else something goes there already but need splitter valve for turbo?
-First-Time Car Owner,
via importtuner.com

Dude, your question certainly sounds like you just hit the pipe when you were writing the “question”. At least send the question in legible English next time. You didn’t mention what year ECU you were running or even which CEL you are getting so I’m not entirely sure which CEL you’re experiencing. Whatever the case, get yourself a factory service manual for the ECU and harness you’re running and then connect the oxygen sensor’s wires accordingly. As for the “valve” for the oil supply on the turbo, it isn’t a valve at all. Actually it’s a T-shaped fitting that threads into the block where the factory oil pressure sender goes. The oil pressure sender goes to one leg of the “T”. One leg of the “T” threads directly into the block and the third leg of the “T” is where the oil supply line for the turbo connects. As for the splitter valve for the turbo, I’m not sure what you mean. If you are talking about a MAP sensor bypass so the ECU doesn’t throw a CEL for seeing boost, then you’ll want to get a Synapse Missing Link or Blox MAP sensor bypass. Hopefully this answers your questions, but lay off the pipe next time before sending another question please.

Honda Brake Tech

I just bought a ’00 Honda Prelude non SH. I wanted to know how to improve my car’s performance and looks without spending a lot of money. Right now the car needs new brake pads and rotor/discs. I prefer drilled instead of slotted but is there a big difference between the two, and which type would help the car brake better? Also, with Hondas stolen on a regular basis, what would be a great car alarm for the car? I’ve looked at Viper alarms, but those are really too expensive for me.
-Brandon Laforteza,
Bay Area, CA

As for the rotors, slotted rotors will have a longer life for both the rotor and pad. Drilled rotors look cool, but do tend to develop hairline cracks under heavy use and will wear brake pads a little quicker. As for cheap performance and appearance mods, you can stick to the exhaust system, intake, lowering springs, and some wheels. I’d recommend trying to find good quality parts used rather than buying cheap knockoff junk on eBay. You said it yourself: If Hondas are always stolen then perhaps it would be wise to invest in an alarm system. I’ve seen Viper alarms installed for under $200. Look around at the local stereo and alarm shops, and I bet you can find something for even less. It might be a little old school, but you can always get an antitheft device like “The Club” too. I’m sure you can find these things for cheap online.

Mazda RX-8 Boost

I am planning to purchase an RX-8, but heard about the reliability problems of the motors. Can you tell me about the things I should look for, being sure the RX-8 I buy will work well? Also what is the best aftermarket forced induction system available for the RX-8? I looked at the Blitz supercharger and the Greddy bolt-on turbo kit. What’s your opinion on either of them?
(PS. Hope my English isn’t too bad, because I am from France.)
-Yann R.,
France

Your English is better than the guy above with the Honda! The RX-8’s rotary engine is not unreliable, especially when it’s stock. It does suffer from mediocre power output and gas mileage, and does consume more oil than a piston engine however. When modified with forced induction, rotary engines can still have a long healthy life as long as it is tuned properly and maintained well. Rotary engines are sensitive to detonation so the ECU tuning and intercooler is critical to the life of the engine when adding boost. Proper oil and water-cooling is also critical to a rotary’s life so keeping tabs on those items is also important. In many ways, a turbo rotary is like a high-maintenance chick. She needs makeup, clothes, and a gym membership to keep herself looking good. A turbo rotary needs the right parts, to be built properly, and good tuning to keep it running flawlessly. Pretty similar, huh?