500HP Stock-Block B16A - Tuned To Perfection - Wrenchin'

The Engine
Behold, the test engine: a well-used B16A originally purchased from a local Japanese engine distributor. According to Internet sources-and arguably less than savvy tuners-the B16A block itself is notoriously weak, requiring, at a minimum, a block guard or even a full sleeve treatment. Often times, the measures taken to outfit the average street-bound B16A are nothing short of overkill. While dedicated race engines can be pushed to stratospheric power levels once sleeved, decked and stuffed with all manner of custom reciprocating components, the majority of these steps are unnecessary for typical street use. Combined with poor tuning, any block, sleeved or otherwise, can be easily damaged. Steel crankshafts, forged rods and top-of-the-line forged pistons are not spared when it comes to an improper tune. When appropriately tuned, the factory cylinders, connecting rods and crankshaft can withstand more power than most are likely to utilize in, say, your typical turbocharged EG street car. Just how much is too much? How about 500 hp paired with more stock components than any sane person would otherwise dare?

With a goal of 500 hp, forged pistons become mandatory. While B-series pistons are by no means inferior, cast metal is what it is and just can't put up with the cylinder pressures associated with 500 hp-despite the tuning. Placing confidence in the remainder of the factory components is easy but previous testing has shown that the factory cast P30 pistons tend to fail well before the 500hp mark. A set of Arias pistons were employed and tied to the factory B16A connecting rods. The Arias pistons feature a flat-top design that lowers the compression ratio to 9.0:1. Naturally, this drop in compression reduces the power output in normally aspirated trim but allows for higher boost levels, especially on the street. Avoiding detonation is critical when it comes to street use and the power lost from compression can easily be compensated for with boost. Were this a race-only engine we'd opt for higher compression, but for street use the drop in static compression is nothing short of a blessing.

It should be noted that confidence in the factory connecting rods' strength should not run short (the author has posted a number of record-setting, stock-rod Bonneville runs utilizing a turbocharger, nitrous, even a blower, not to mention countless miles of road racing in naturally aspirated trim). In truth though, most enthusiasts will opt for forged rods when using forged pistons but this exercise points out that it's possible to get by with the factory rods for those with tight finances. While most builders might sleeve the block, install a block guard to minimize the horrors of cylinder distortion or at least re-machine it, we didn't. Out came the factory B16A pistons and in went the new Arias slugs and rings-even the old rod bearings were reused. Remaining true to form, the idea to use aftermarket head studs was tossed aside and, instead, the factory head bolts that had been through countless torque cycles were used, along with a factory head gasket. Obviously, this is not the way to properly build a serious turbo engine but it goes a long way toward demonstrating just how strong the stock stuff really is and what a good tune can yield. The long-block was finished off with such exotic performance hardware as the stock P30 intake manifold and throttle body-you can't make this stuff up.

The Turbo
Attaining 500 hp requires a healthy turbo, not to mention a suitable intercooler. A Turbonetics T66 was selected to help get there. According to the supplied compressor maps, 500 hp should be realized at a calculated pressure ratio of 2.70, that's 25 psi assuming a peak normally aspirated power output near 175 hp. This would yield an efficiency of 76 percent. As it turned out, the normally aspirated engine didn't quite make that much, however the turbo combination bettered the power/boost formula allowing the goal to be met with less than 25 psi of boost. Things were looking good.