Dart B-series Engine Block Build - Pound For Pound

HT: Is the block prepped at this point? What about the water passages inside the block? Dart says they're enlarged.
LW: When sand cast parts are created, the casting has to be thick. It was necessary for Dart to make the outer walls and the water-jacketing farther outboard so they could get more water around the cylinders. They may not have as much water around the cylinders as a stock block, but there's enough.

The best thing about Dart blocks is that their cylinders stay round. While the sleeves themselves are thin [relative to most aftermarket sleeves], the robust aluminum structure around them provides plenty of support. The fact that the thickness of the sleeves is the same all the way around also means that they expand evenly as temperatures increase, keeping the bores round for ring seal.

HT: What about the bottom side of the block? Do you use the oil squirters?
LW: There isn't sufficient space for the squirters with the stroke combination we're building here. However, the factory squirters are great in applications where stock-style cast pistons are in use. And while properly engineered forged pistons are capable of operating at higher temperatures and loads, assuming there's room for them, we still incorporate the squirters in engines we build that operate for long periods of time at high RPM in the upper gears (like road-racing applications). In drag racing engines we build, I never use oil squirters because we want to limit the amount of oil that finds its way to the cylinder walls and ultimately to the combustion event where it invites detonation.

HT: Looking at the Crower 92mm crank, it seems ready. Do you do anything like knife edging, balancing, or some other kind of prep for the crank?
LW: No, the cranks are pretty good. We do check the balance on all the cranks we use, and Crower's are usually pretty close as we receive them. If we were building for drag racing or something where we're searching for 2 or 3 additional horsepower we'll remove some weight, but for this application it's not worth fooling with.

All in all, the Crower cranks are very nice pieces when it comes to straightness and journal consistency, but one thing you definitely have to check is the thread-depth on the flywheel boltholes. As received from Crower, these holes are not all tapped to the same depth, and they're also not all tapped to the same depth as a stock Honda crank. I also recommend using new bolts and torquing them 5 foot pounds more than Honda's spec. A drop of red Loctite on there is also a good idea, especially if you're running an aluminum flywheel.

HT: What about these custom-length Crower rods you had made?
LW: The rod I had made for this thing is 5.885 inches (149.5 mm) long. It's not one of Crower's super light rods, so that if you want to switch to forced induction down the road you can keep these. These give a rod ratio of 1.62:1.

HT: On top of that rod we have an Endyn Rollerwave piston. What's Rollerwave?
LW: Roller-Wave describes the mixture and pressure motion our pistons create in the combustion space. "Combustion space" is defined as the area between the combustion chamber and the top of the piston. The quench pad of our piston on the intake side is three-thousandths (0.003) of an inch higher than on the exhaust side. When the piston reaches Top Dead Center (TDC), the pressure wave created by that difference pushes the mixture to the exhaust side. Also, at TDC, the rod changes directions and that causes the exhaust side of the piston to flip up ever so slightly.

We have a slot in the top of the piston that basically connects the two exhaust valve reliefs, and that slot lines up exactly with the edge of the chamber on the exhaust side so when the piston does the flip, it creates a wall causing the pressure wave to be reflected and rolled over to the exhaust side. The fact that the exhaust valves are a latent heat source causes mixture ionization, making the exhaust side the ideal area to place the combustion process. If you light there, you light more of the mixture than you would if the mix is spread out.

We shape the entire area, from the piston top to the quench pads to the bottom of the head, to mechanically force this to happen. It causes the burn to be much more rapid and complete with less tendency for detonation. That's also what I call soft-head technology, something I started doing in the mid '80s.