The porting of the head is pretty straightforward with good, clean ports; nothing too radical, just solid, basic headwork. Ferrera stainless-steel 1mm oversize valves featuring swirl-polished heads and turned-down, flow-improving stems. Ferrera titanium valve spring retainers and dual valve springs control valve motion.
We noticed some unusual aspects of the valve job. The 45-degree seat seems slightly on the wide side; witness marks from the hand lapping job show the valve contacts high on the 45. Normally, the 45 would be narrowed by the 70-degree cut right to the edge of the seating surface, but for some mysterious reason, Lee left the 45 on the wide side towards the port side of the cut. What is going on? Perhaps this was done to create a venturi effect at partial valve openings? No one is talking.
An AEBS camshaft moves the valves to the tune of about 345 degrees of duration and around .500-inch of lift. AEBS is a little secretive of the exact numbers here. Since the duration numbers sound pretty large, we figure that this is SAE duration. This would put the 0.050-inch lift duration at a still mind-boggling 320 degrees or so. No wonder it revs to 10,000 rpm. Lee was vague about where he sets the cams, but he mumbled something about the tightest lobe center possible. We also noticed the two low-rpm VTEC lobes were radically different in size and shape, probably to impart some swirl on the mixture at low rpm. We know the stock low rpm lobes are like this, but on the AEBS cam, they are radically so.
The intake manifold bristles with innovation. The large, hand-fabricated plenum has non-parallel walls to avoid resonance. The short, straight intake runners have velocity stacks that extend inside the plenum to help reduce the side effects of reversion at high rpm. The manifold features two sets of injectors. The 300cc/min RC Engineering primary injectors are mounted on the bottom of the intake runners. This is done to place them out of the area of highest flow activity, which is usually the top of a port or intake runner. By placing the injector at the bottom, the injector tip causes less turbulence and thus improves flow. Atomization is improved as well. These primary injectors operate all the time.
A second set of 300cc/min injectors spray from the back wall of the plenum, directly at the bells of the velocity stacks. Lee told us these injectors operate at high rpm to provide additional fuel. Their placement is to provide additional evaporative cooling, much like what is done with Indy cars. Since the primary injectors are used to ensure good throttle response, the secondary injectors can be placed way back like this with no detrimental effects on throttle response.
The injectors are batch-fired by an SDS stand-alone ECU. The difficult part of the program, switching between primary and secondary injectors, is one of Lee's secrets. Dual BK throttle bodies grace the top of the manifold. Although they are too big for this engine on paper, their placement helps assure equal air distribution through the manifold and helps keep the plenum non-resonant, to one degree of freedom. Finally, to help reduce heat soak, the manifold is given a coat of ceramic thermal barrier coating from Polymer Dynamics.
The exhaust features an AEBS header. Lee got his start in making headers and this one bristles with ideas that are far from typical. The header is constructed of 321 stainless, with the primaries stepping through three increasing diameters. This is to keep the exhaust gas velocity high and reduce reversion on overlap. The header terminates into one of AEBS' signature collectors. Cylinders 1 and 4 and cylinders 2 and 3 are paired, but the two pairs are separated by a large fin within part of the collector. The length of the fin is critical-and secret. This provides a significant increase in torque with no other penalties.
Even the valve cover on this engine is unique. There are large diameter vents on top of the valve cover, which, according to Lee, are there to allow air circulation within the engine to reduce high-rpm pumping losses and maintain high-rpm ring seal.
What are the magic numbers? The wonder engine pumps out about 260 hp to the wheels at 9000 rpm, with the powerband almost flat across to 10,000 rpm. The engine cranks out 166 lb-ft of torque, peaking at about 7200 rpm.
Predictably, the AEBS engine has a bit of an edge in the horsepower department, by about 10 hp more than the R&D engine. However, the R&D engine puts out almost 20 lb-ft more torque over a much broader powerband. Other than the fuel requirements, the R&D engine's powerband would make it a great engine to kick some ass with on the street! In direct contrast, the AEBS screamer does not come alive until 6500 rpm.
These two engine builders are diametrically opposed in their approaches to extracting power from Honda engines. You are probably wondering what all this information boils down to. Which one is faster? Surprisingly, it is almost a toss-up. In practice, Lookofsky's car is the faster of the two, but Lookofsky runs mostly in IDRC, where his car can be 100 lbs. lighter. Scalise runs solely in NIRA and must carry 1,700 lbs. If both cars weighed the same, we'd have some interesting competition.
We would think the torque of the R&D car would be less affected by ballast and its ultra-high-compression engine would fare better at high altitudes. Its broad powerband may be more forgiving to driver error while traveling down the 1320. However, the lower torque of the AEBS car may make it easier on the driver to launch. In either case, the race would be a close one.
Impossible Compression + Impossible Displacement + Impossible RevsAn armchair engineering analysis of R&D's impossible enginesThe unfathomable displacement, unreasonable revs, and absolutely unbelievable compression of R&D's record-breaking engines contradict what years of racing experience suggest should be possible.
Doing an armchair engineering analysis, we think we might have figured out why this engine works so well. Because this engine has a very long stroke and a low stroke to rod length ratio, volumetric efficiency and power should fall off at high rpm due to the limited flow capacity of the intake and exhaust ports. The dyno defies our predictions, however. The powerband is broad and flat and the downward power trend does not start until over 9000 rpm. This kind of rev limit is unheard of for the bore/stroke/rod length combo R&D must be running. We also know that combustion stability is hard to maintain at the ultra high cylinder pressures that these astronomical compression ratios can produce.
A little known fact of engine dynamics is that volumetric efficiency (VE) increases with gains in compression ratio to a small but predictable extent. This engine has an ultra-high compression ratio and a piston speed that should not tolerate high engine rpm, but ironically, as far as we can tell, these two factors are working together in R&D's favor. As the piston speed goes up with engine revs, the cylinder pressure starts to drop due to the falling of VE. This is due to the limitations of the cylinder head's ports and bottom end configuration. When this downward trend in VE occurs, two things must happen. First, the high compression helps keeps VE reasonable, and second, the high piston speed and the dropping of VE keeps the cylinder pressures to the point where combustion stability remains manageable with super-high compression. Because of the super-high compression ratio the pressure remains high enough for good thermal efficiency and power production even with the falling VE. Is R&D on to something here? Could they have found a sweet spot in the engine's dynamics juggling VE and cylinder pressure? SanAngelo is not talking.
Ultra-high compression ratios are one of the ways that NASCAR engine builders have been able to find power in their super speedway engines despite being forced to run restrictor plates. It seems that the R&D engines are similarly restricted by the piston speeds and ports that were not designed for the flow demands of big displacement and high piston speeds. Perhaps they were studying what's going on in NASCAR and other intake restricted forms of racing.
Either way, by brute force or by really clever engineering, the engines are sweet. Flat torque curves and broad useable powerbands are the signatures of R&D's monster engines. These are admirable results, and it is results that count, right?
The Crystal BallOur predictions for an all-motor futureWith the season at an end, let's make our predictions of where naturally aspirated racing may go in the next few years.
First, we predict that more attention will be made to the engine's stroke-to-rod length ratio and bore-to-stroke ratio in an attempt to reduce piston speed in Hondas. Bigger displacement, higher revving engines will result.
The Nissan SR20DE has a strong potential in this class, with fully developed variants being highly competitive in Europe's touring car classes. The SR20 found in a top touring car puts out more power than either of these engines-with less displacement. And, the parts to do it are available from European racing suppliers.
Careful study of the control valvetrain harmonics and an increased use of lightweight titanium will allow higher revs, perhaps in to the 11,000- to 12,000-rpm range. A major domestic aftermarket company will come out with an improved cylinder head with high velocity and good flowing ports for the workhorse Honda B-series engine.
Roller cam followers will debut for B-series engines. These will free up horsepower by reducing valvetrain friction. The roller itself will allow a more radical cam profile for more area under the cam's lift curve. These sorts of cams will allow a broader, higher power curve.
More attention will be given to crankcase pumping losses. In Formula 1 racing, much research has been applied in this area, with significant gains to be had. We predict that a partitioned crankcase divided between cylinders 2 and 3 will help considerably at high rpm.
Dry sump oil systems from road racing will increase power by 5 to 10 hp, due to better ring seal and less windage losses. (Dry sumps will be needed to ensure good oiling at more than 10,000 rpm, anyway.) If no one invests in dry sumps, a stronger oil pump will be needed as many of the higher revving, naturally aspirated Hondas break oil pump gears due to crank harmonics.
Special gasoline-based fuels will help stabilize combustion and speed the flame front travel without detonation. European F1 fuel supplier, Elf is reportedly considering bringing some of its super fuels to the U.S. market.
Sequentially shifted, straight cut gear, and constant mesh transaxles with selected ratios will help engine builders by allowing them to build more powerful, higher revving engines without worrying about gear spacing. Straight cut gears will soak up less power in the transaxle. The issue is, who will be able to afford this technology?
Incremental gains will take place in exhaust design, reciprocating weight reduction and suspension tuning. With these developments, we should be seeing low 10s pretty soon; perhaps times will be knocking on the 9s if the constant mesh transmission is embraced.
Those are our predictions for now, let's come back to this subject in a few years to see if they have come true or not!