T: Let's move to the top end. What modifications do you perform on the head?
DH: We start with a stock B16A head and then port and polish the cylinder head. The factory head flows extremely well and we only perform small amounts of porting, especially around the fin area and valve pocket seat. The fin area that separates the runner into the two valve faces needs to be narrowed, and the valve pockets need to be ported for better flow. The rest of the area needs to be polished for smoother flow.
We also mill the crap out of the cylinder head to reduce the combustion chamber volume. We mill the B16A head about .080 inch, which transforms the original B16A circular combustion chamber into one similar to a GS-R, a squared combustion chamber. That's why it's important to fly-cut the pistons so the valves don't hit the pistons.
The most important part of the cylinder head is a good valve job. It goes back to cylinder sealing. The more pressure you can seal within the combustion chamber in the compression stroke, the more power is generated when the mixture is ignited. The head is obviously outfitted with all Skunk2 vavletrain hardware that includes stainless-steel valves, high-tension dual-valve springs, titanium retainers, Stage 3 camshafts and adjustable cam gears.
T: We notice you didn't mention cutting the portion of the valve guide that sticks out of the head. What's your take on that?
DH: We do see better flow with cutting the guides, but reliability issues are also of concern. The guides are so short that oil leaks are more common through the guides, so we choose not to cut them.
T: Any work done on the induction end?DH: We use a Type R manifold that's extrude-honed and mated to a 66mm Skunk2 throttle body.
T: With all the information you told us, anyone can build a 252-hp B16?
DH: I wouldn't say anyone. The combination has been good on the engine dyno for 252 hp and on the chassis dyno for 210 hp. The engine is at about 12.0:1 compression, so race gas is a must. It's not your ordinary street engine.
T: Moving on to your B-series drag engine that you used in Project Beta (DC2 Integra): What was done on the bottom end?
DH: First, we started with a B18C bottom end because of its structural integrity compared to the LS. The block was bored to 86mm while using a 95mm crankshaft from a 2.0-liter Prelude engine. The combination computes to a 2.207-liter engine.
We even experimented with an 87mm with a 99mm stroke engine. The problem we found with the combination was that piston speeds were too fast and the piston was outrunning the flame, causing poor power output. We eventually went with a 1/2-inch deck plate with a rod length of 155mm, giving a fairly decent rod-to-stroke ratio of 1.63.
T: What type of pistons do you run?
DH: The factory pistons were out due to the large bore. We opted for a set of forged pistons with an extremely flat dome. There has been much improvement over the years with forged pistons for sport compacts, and you can run much tighter piston-to-wall clearances today than three to four years ago. They're also much lighter. A forged piston is much stronger than a factory piece. Similar to the B16A engine, we outsource all coarse machine work and perform all the final machining in-house. We balance and blueprint the entire engine to our standards.
T: Anything else special about the bottom end?
DH: For the drag engine we run an electric water pump to reduce drag and run the smaller water pump gear. Also, we had to change the tensioner placement due to the deck plate.
T: Anything different on the top end compared to the B16A?
DH: The B18C head we use is a blend of the B16A and B18C design. We added material to the intake runners to raise the short turn of the port. That way the intake charge has better direct flow into the combustion chamber instead of having to make a 90-degree turn into the chamber. Again, we concentrate on the fin area and valve pockets for better flow. The rest of the port is polished for smoother flow. The head is also milled to reduce combustion chamber volume.
T: What did you use of the valvetrain?
DH: We tried a couple of different combinations. First, the head is fitted with our springs, retainer and adjustable cam gears. The first combination we ran was a two-lobe design, eliminating the middle lobe. But we found that running only the third lobe to operate both valves was much better.
T: So on the induction end, you weren't limited to the factory manifold we noticed you had on the TWM setup. Any trick things there?
DH: We started with a TWM manifold, but we tuned the manifold on an engine dyno. We played with manifold length for best overall power.
T: Thank you, Dave, for your time and information. We're sure the B-series guys also thank you for your knowledge and wish you the best in 2004 with Project Delta. Any last words?
DH: You're welcome. It was my pleasure. When we came out with the Project Beta, we raised the bar of what's possible in front-wheel-drive drag racing. We plan to raise the bar again with Project Delta (RSX), and we're confident the information we gained with the development of the K-series engine will make a statement. Our first race is at NHRA Moroso, so be on the lookout.