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May 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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Higher Learning

I recently became interested in performance cars and decided to get into the import tuner scene, but I don't really know all of the different assembled parts of a vehicle. How did you get into cars and learn about the different parts and what they do to become, as they say, a guru?

-Ryan Huey, via

I got into cars from watching a lot of racing on TV when I was a kid. Back then Formula 1, USAC/CART, and IMSA ruled the airwaves. Also, my elementary school doubled as a park so we had a clear open view of the street. I'd see all of the high school guys drive by in their Corollas, Celicas, Supras, RX-2/3/4/7, 240/260/280Zs, etc.; they all had wheels and exhausts, and I remembered staring at every car that cruised by. It was a much simpler time (early '80s) of course, but it inspired me to start getting interested in cars long before I was of legal driving age.

To learn about cars, I started taking them apart when I was 14. I didn't start putting them back together until I was 16. As with any complex assembly, it's a lot harder to put them back together than to take apart. When I didn't know how to put something together, I tried to read about the topic (e.g. how to rebuild a power steering pump). If that didn't work out, then I'd ask my dad if he knew. I tried not to ask him because he always thought I should have been studying instead of messing around with cars so I'd have to deal with a potential lecture. As a last resort, I'd ask my uncle, but that would always involve some sweeping, mopping, and lunch deliveries before I got an answer. I learned a lot taking apart and building my own cars, then I got jobs part time working on cars, and then I started going to school for mechanical engineering. In the end, I learned the most by reading and just doing. So I'd recommend by starting with some reading (books, not forums!) and doing, followed with some formal training or schooling. From there, you can decide how much of a guru you'd like to be yourself.

Fuel Injection Delivery

I recently picked up a Mazsport Interceptor-X for my Mazda RX-8. The rotary engine is upgraded with a GT3582R, FMIC, Atkin seals, Rotary Aviation components and other upgrades. I want to use the secondary 1,000cc injectors as my primaries to be able to maintain 400 whp at low boost (15 pounds or less). Should I use the current GT3582R or switch to a GT3572R? Which one would achieve my goal with quicker response under 15 pounds of boost?

-J Bravo, via

I think you mean GTX3576R, correct? If so then, yes, the GTX3576R will be able to generate quicker boost response. The GT3582R will probably make a little bit more peak power, but the newer aerodynamics of the GTX series' compressor stages make them spool considerably quicker.

Compound vs. Twin Turbo Advantage?

Are there any advantages to running a compound turbo setup versus a twin turbo or single stage turbo setup? I was made to believe that the compound turbo setup offers minimal turbo boost lag like a twin turbo setup while maintaining top end power similar to a single turbo. Is there any proof to these claims, or does it sound too good to be true?


Compound turbos are typically only used in ultrahigh boost applications such as a tractor puller. The complexity and the amount of hardware required for a compound system is what make them so rare and limited. You'd need two turbos, two intercoolers (one between the turbos and another after), two wastegates (one to bleed into the second turbo to get it pre-spooled and one to bleed exhaust pressure), two compressor bypass valves (one to allow the second turbo to pre-spool and one as a bypass valve) and a myriad of control solenoids to control the wastegates and bypass valves. Even if you were by some miracle able to fit everything into your engine bay, you'd then still have the trick of getting the controls all figured out. It would be tricky to get the two turbos to provide a flat, seamless boost curve without any dips in the torque curve either. All in all, there's a reason why you don't see compound turbo setups in anything but tractor pulling contests.

Diamond In The Rough

I found your magazine by happening to stumble across the Import Tuner website. I wanted to give you guys a shout-out and offer a photo of my most recent project. I am in the process of a restoration and engine conversion in a '73 Mazda 808 sedan with a rotary engine. A lot of people don't know that the 808 came with a piston and not a rotary engine.


Awesome project! I always liked the RX-3's front end a lot better than the 808 though. If you can find the parts that is . . .

Engine Building

To The Great and Powerful Mr. Hsu,

A buddy and I are trying to swap a turbo VG30DETT into his factory non-turbo Z32, and we have encountered some issues with the donor engine. The guy he purchased the engine from claimed it had good compression and was 80 percent through a rebuild before he injured himself and was no longer able to continue, so we are checking all the previous work to make sure that everything necessary was done and done proper. Good thing we did, as my buddy found a razor blade in the intake runner of cylinder No. 6. Coincidentally that cylinder also shows low compression (while turning over the engine by hand via a wrench on the crank-I know this is not going to give true readings, but all the others were grouped close and No. 6 was significantly lower), and we can hear air escaping through the intake manifold.

While we had it apart, we started measuring the block to determine if it was still within the factory spec. This is where we think we have the problem, and where we need some advice. Based on the factory service manual detailing measurements of the engine, it looks like we need to measure the taper and roundness of each bore. How strict are the limits? Cylinder No. 6 actually looks fine, but No. 3 and No. 4 (the one in the middle of each bank) show more wear. No. 4 is out of taper and round, while No. 3 is out of round only. If the limit for taper is 0.0006 inch and we are at 0.00075 inch will that cause major problems? Same question if the roundness is out by about that much with the same limits. My buddy doesn't plan on racing the car; he is looking for a fun and reliable street cruiser, possibly pushing around 400 whp when it's said and done.

The other thought I had was about a torque plate. I've read that a machine shop should use a torque plate while honing the bores to simulate the stresses and strains that the head and studs will put onto the block to have a better finished product. Should we be using a torque plate when taking the bore measurements? Any other advice you could provide would be greatly appreciated, as this is the first engine build either of us has taken on.

-Ryan and Stan, via

First of all, if you are measuring to the 10 thousandths of an inch, then you'll need to concern yourself with the quality of your measurement instruments. You'll need to be using a name-brand dial bore gauge that was made in the United States, Western Europe, or Japan (e.g. Mitutoyo, Sunnen, Starrett, etc.) and setting them up with name-brand micrometers. You should also be using a micrometer stand or a vise with soft jaws to hold the micrometers during setup too. If you hold the micrometer for too long, your body temperature will heat it up and can throw off the setup. Anything else isn't going to offer you the accuracy you'll need to make a measurement this small.

Secondly, yes, you should be taking these bore measurements with a torque plate in place. A torque plate allows the head bolts/studs to be tightened in place, which typically distorts the cylinder block some. Since this is the way the engine is run, this is the way the block should be measured. However, if you are using a stock piston then you can generally follow the factory service manual's recommendation because they have already taken into account the block distortion in their clearance values.

The most critical measurement when it comes to piston-to-cylinder wall is going to be the minimum piston-to-cylinder wall clearance. If the piston manufacturer recommends a minimum of .004-inch piston-to-wall clearance, then you'll want to make sure that there is no less than .004 inch of clearance anywhere. I've seen an engine run a taper of more than .002 inch. I don't recommend it by any means, but I've seen it. If you have the time and budget, I'd recommend you get the block honed to where it should be. I think that as long as the minimum clearance is met and that your taper is within .001 inch, you should be in good shape.

Engine Swap?

I own a '93 Mazda Miata that I am trying to search for a legal swap to make some power. What's a good legal swap?

-Richard; National City, CA

The simplest and easiest legal swap for you is going to be a swap from the '04-05 Mazdaspeed MX-5. The parts are still available from any Mazda dealership, and it all bolts right in. Then, of course, there's the old-school "Monster Miata" swap, which uses a Ford Mustang 5.0 drivetrain. Here's a short list of what you'll need to legalize your car with a swap in California (see California Code of Regulations for exact law):

  • The donor drivetrain is from a California legal car.
  • The donor drivetrain is from the same model year as your car or newer.
  • You must retain all of the emissions devices from the donor car. This includes charcoal canisters, fuel tank pressure sensors, etc.
  • You must retain all catalytic converters from the donor car.
  • You can convince the guy at the California referee station that you didn't hack it all together.
  • It passes the California visual and tailpipe emissions test.

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OK. so I have a 2003 Eclipse gt. I'm wanting to give it up to 6-700 whp what would you suggest? I was thinking about going wit a evo 8 motor making it awd putting twin turbo with a 50 shot of nos... I know that's a lot of work.. But is their any other way?

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