Q This is more of a technical question. Which of the three SR20DET engines - S13, S14 or S15 - are best for upgrading and potential power output. I was gearing toward buying the S15 black-top engine when I get back from Iraq, but I wasn't sure if it was the best choice.
A It's easiest to break up the SR20DETs this way: first there's the red-top S13 engines; then the black-top ones; but you've also got black-top S14s and S15s, which are entirely different from the older black-top S13s and are exactly what makes distinguishing all of these from one another somewhat confusing. Red or black, any of these SR20DET engines are good candidates for a buildup. In terms of which is the best performer in stock form, the answer is either of the black-top S14 or S15 Silvia engines. The main difference here is the Garrett T28 turbos they use instead of the smaller T25 units bolted onto previous SR20DETs. Some of these later model SR20DETs also come with more sophisticated ball-bearing center sections and all late-model S15 engines feature an improved impeller wheel on the compressor side. These later model engines also feature Nissan's VCT (Variable Camshaft Timing), which offers the driveability benefits of switching between low- and high-intake camshaft profiles; but that makes little difference if all you care about is top-end power production. S15 engines also feature fairly large 480cc/min fuel injectors in comparison to the other engines' 370cc/min ones. If you really have your heart set on a black-top S14 or S15 engine, be careful not to get mixed up and end up with a black-top S13 engine by mistake. The newer engines can be distinguished by a large bump on the intake side of the valve cover courtesy of the VTC system and a higher mounted intake manifold plenum. Overall, if you plan on swapping turbos and upgrading the fuel system, any of the SR20DETs will work for you; about the only thing you'll be missing by going with an older, less expensive one is the VCT.
Q Hi, I have a Ford Zetec 2.0 and am going to turbocharge it. How can I make the oil return?
A There are a few things to keep in mind when designing a turbocharger oil return line, regardless of the type of engine or turbo you're working with. Use heat-resistant materials, minimize bends and lengths, and use materials no smaller in diameter than the turbo's oil drain orifice. Also, keep in mind that there's relatively little oil pressure on the exit side of the turbo's center cartridge; gravity's about the only thing you've got going for you here, so route your line accordingly. Skimp on any of these steps and turbo failure will be in your future. It's important to allow oil to drain out of the center section as freely as possible. If it can't, it'll build up and pressurize inside and potentially blow seals, allowing oil to dump into the exhaust stream. This makes for oily, black clouds of smoke and ultimately a useless turbo. Since gravity only works one way, make sure the turbo's drain outlet is oriented as close to downward as possible and is a good few inches higher than the top of your oil pan - of course, this is mostly determined by the manifold you have. Depending on the turbo you're using, there should be some type of bolt-on oil drain flange with either a female or male adapter integrated into it; most of these flanges feature NPT (National Pipe Thread) dimensions. Constructing a steel-braided line with NPT-to-AN adapter fittings is usually the best route to take. You'll need to weld a fitting to your oil pan to thread the line's hose-end to. It sounds like a lot of work but this setup will make for the easiest should you ever need to remove it. Make sure the fitting is positioned as high up as possible on the pan to avoid drainback. Typically, -10 (51/48-inch) diameter hose allows for suitable drainage; expect to pay about $100 for the whole setup. There are cheaper alternatives that involve hard lines, pieces of cooling hose and several worm-gear clamps, but nothing beats a flexible steel-braided hose in terms of longevity, heat resistance, and fit and finish. This is one of those places where being cheap doesn't pay.
Q Is it possible to cryo-treat automotive transmission ball bearings and, if so, will the dimensions remain the same? Under extreme rpms, my modified Honda's countershaft bearing balls break free from their riveted retainer couplings (the other bearings hold up because they use a serpentine retainer that weaves through the balls). The bearing continues to function, but the balls slap into each other. Very annoying! I've replaced four of them with no other signs of failure.
A You can cryo-treat most metals. But the real question should be whether or not that will solve your problem. Cryo-treating is a heat cycling process in which temperatures drop to minus a few hundred degrees Fahrenheit. The process realigns the molecular structure of the metal and increases its overall strength. A popular process for strengthening parts like axles, U-joints and engine internals. It's not uncommon to cryo-treat various transmission pieces like planetary gears - the results make for stronger pieces and a transmission that can run up to 50 degrees cooler. But I'm not so sure how that'll fix your current situation, regardless of whether or not cryo-treating will expand the ball bearings in size, which, by the way, it shouldn't. You've still got a problem with the bearings breaking free. The problem isn't the actual balls but rather the retainer. You might look into having the retainer coupling treated to prevent self-expansion and allowing the balls to break free. But we suspect there might be something else wrong; without knowing how much torque your engine's making, it's a little difficult to diagnose though. If you were in the 400-lb-ft range on, say, a Honda B-series gearbox, we'd expect you to be complaining about more than just a countershaft bearing. And if you're producing just a bit more than stock power levels, we'd suggest you make sure you're using the proper viscosity and type of manual transmission fluid - it's possible tranny temps could be getting just high enough to wipe out those bearings of yours.
Q What's the skinny on these "Pulse Plugs?" They claim to produce 1,000,000 watts as opposed to 50 watts produced by regular spark plugs, therefore burning more fuel, which increases cylinder pressure, which produces up to a 10-percent increase in torque and horsepower.Thanks,
A We haven't tested these yet, but claims like these bother us for a couple of reasons. First, where the heck is all this additional energy coming from and how does it all of the sudden appear? A typical ignition coil converts battery current into higher voltage, low-amperage power, but this will maybe get you to around 500,000 watts, maybe. Is it magic? A typical automotive electrical system just doesn't have the means to create much more. Second, an engine's power rating is a product of how much air and fuel is available to be compressed; of course, spark is a factor, but it typically isn't going to make too big a difference on an unmodified engine with presumably adequate spark to begin with. The idea with these plugs is that the spark happens about twice as fast. In theory, this would be a good thing since; at the very least, disregarding the 1,000,000-watt claim, the same amount of energy could be used over a smaller timeframe. This would mean every last bit of spark energy could be used during combustion. Sounds plausible. We've wanted to test these for a while so look for something along these lines in the near future.
Q Hello, I subscribe to your magazine and find it blatantly informative and enjoyable to read. To the point, I'm wondering if you guys can shed any light upon the subject of engine swaps, particularly about swapping the 7M-GTE out of my '88 A70 Supra. I want to replace the 7M for a 2JZ-GTE. Does it fit? What needs to be replaced or modified? Can I keep it twin turbo?
A million thanks for your time,
A It fits. But swaps like these are only for the die-hard. Are you die-hard? Consider this: a complete 2JZ swap will likely cost you more than what your MKIII's worth - perhaps several times more depending on the condition of your third-generation Supra. But those are just details. Besides the engine, since you've got an '88, you'll also need a set of custom engine mounts to make the 2JZ sit right, or you could just source a front crossmember from any '90-'92 Supra and the 2JZ will bolt right in with 1JZ-GTE engine mounts. Add to that a 1JZ-GTE flywheel and bellhousing and you're well on your way to getting things to work. The JDM market is an affordable place to go looking for your twin-turbo 2JZ, but there are a couple of things you'll need to address if you go this route. For one, you'll need to extend the wiring harness so it will reach (made for righthand drive) and you also might need to swap the oil pan and sump for Supra pieces so it'll clear the crossmember (2JZ Aristo engines only). And don't forget to get the ECU and engine wiring harness that goes along with the 2JZ. Keep in mind, there's quite a bit of wiring involved here, come to think of it, there's also not a lot of room for those two turbos. There is two ways you can avoid cutting your firewall open though: either downsize and go with the single-turbo 2.5L, 1JZ-GTE or convert the 3.0-liter to a single turbo setup.
There's no question too hard for Aaron, so if you're stumped, send your question(s) to email@example.com