First the chassis work for 'Bisi's all-motor Honda Insight; now the engine. Last month we followed along as 'Bisi Ezerioha brought his all-motor Honda Insight up to NHRA safety standards by installing a comprehensive roll cage and subframe. Next up; under-hood motivation.
If you follow the happenings of the Honda world, you know DOHC Honda powerplants are regularly discarded from JDM machines and shipped to the States for would-be engine swappers. And for every one of those more powerful JDM engines given new life, there's almost always a lowly SOHC relative sent off to the boneyard.
That's where Ezerioha comes in. Even though a trip to the wrecking yard may yield DOHC Honda muscle as far as the eye can see, Ezerioha is searching for what many are hoping to lose: SOHC power. Rescuing single-cam Honda engines from the scrapper and squeezing loads of horsepower and torque out of them is what he does best.
It began as a cost effective and simplified way for Ezerioha to compete, but has since proven to be more than just a means for saving a few bucks. Already producing power figures comparable to those seen in twin-cam mills with the Civic's SOHC D series, Ezerioha has since stepped up to the bigger-and-better-in-every-way F series. The F22A1 from the '94 Honda Accord DX is his engine of choice. Relative to D-series mills, it boasts a larger bore, a longer stroke, bigger ports and valve diameters and plenty of room for more valve lift.
Machining the BlockWinning drag races almost always boils down to making more power than the guy in the other lane. And it's not just about power production; it's about reliable power production. Reliable power production begins with the engine block; in this case, machined by the experts at RS Machine in Gardena, Calif. The process begins by stripping away the guts of the F22A1 and hot-tanking the parts in a bath of solvent.
Upsizing engine displacement by enlarging the bore diameter is a sure-fire way to step up power output. Increasing the bore diameter not only adds cubic inches, but also ups the compression ratio and increases "quench area." The quench area is the portion of the chamber where the deck of the head matches up to the flat portion of the piston at top dead center. Quench increases turbulence in the chamber and improves the combustion process.
Unfortunately, the F22A1's cylinders are too thin to support additional bore. Instead, 90mm Darton, ductile iron sleeves are installed after removing the 85mm factory cylinders with a boring bar. With the boring complete, the Darton sleeves are spec'd for trueness and run on a lathe before being installed.
With a special blend of epoxy setting up inside the engine block, the Darton sleeves are hydraulically pressed into place as a single unit. Once in position, the block is decked and the cylinders are honed.
Decking trues the block's surface for a tight seal against the head and squares it with the cylinders. Decking also establishes the deck height, which directly affects compression ratios and piston-to-head clearances. Piston-to-head measurements as close to zero as possible are ideal; however, the elasticity of rods and piston pins at the proposed 9400-rpm redline requires larger tolerances.
Assembling The BlockThere are two schools of thought concerning the bottom end. One relies on maximizing engine displacement while sacrificing high-rpm performance, the other on maximizing high-rpm performance while sacrificing displacement. For Ezerioha, the latter has proven more reliable.
Displacement increases relative to bore and stroke. When displacement is increased via stroke, rod ratio is sacrificed, resulting in increased piston speeds and substantial piston-to-wall side loads. Both result in premature piston and piston ring failure. The rod ratio is determined by dividing the rod length by the stroke. The higher the rod ratio, the lower the piston speed. Lower piston speeds generally translate into greater durability and allow higher rpm.
The solution: The F22A1 crankshaft is ditched and stroke is decreased from 95mm to 90.7mm with an H22A crank swap. An additional 2mm of stroke is removed through the offset grinding process performed by Lopez Crankshafts.
Offset grinding relocates the crank's rod journals inward or outward in relation to the crank's centerline. The journals are ground to smaller diameters, as their centerlines are offset further from the crank's centerline for more stroke, or closer to the crank's centerline for less stroke.
The stock F22A1 rod ratio is a mere 1.49. For perspective, the high-revving B16A's rod ratio is 1.74. Ezerioha's rod ratio is a high-rpm-friendlier 1.80 after the offset grind, longer 6-inch connecting rods and upwardly relocated piston pins.
Last, the H crank is heat-treated and nitride-hardened for added durability. The guys at RS Machine finish off the crank by knife-edging and polishing it. Knife-edging streamlines the contour of the crank's counterweights for reduced drag as the crank spins through the oil mist. Polishing cleans up any imperfections on the crank's journals in preparation for the bearings.
A combination of forged Arias pistons and a set of Howard's connecting rods rotate off the crank. 'Bisi's planned 17:1 compression ratio requires special pistons. Constructed of 2618 billet aluminum, they're sized for the 90mm bore and their skirts receive an antifriction moly coating courtesy of TurboHot.
Ezerioha tells us the pistons weigh about 260 grams each-an impressive number considering the bore size. Piston dome width, rather than height, is increased to achieve the high compression ratio without negatively affecting flame travel. As piston domes rise, the flame travel becomes obstructed, making it difficult to ignite and maintain a stable burn during combustion.
Aluminum rods, which absorb pressure from the combustion chamber more effectively than chrome-moly, are used for their light weight and shock-absorbing capabilities. ARP rod bolts securely clamp the rods around the crank journals.
Crank and rod bearing clearances are critical and determine the longevity of the engine. Too small a gap between the bearings and crank and the oil supply is restricted. Too large a gap and the oil washes across the bearings. Both result in metal-to-metal contact and a seized engine.
The rod journals are ground to B-series diameters to allow the use of easy-to-find B-series rod bearings. OEM rod bearings from the B18C1 are employed along with standard F22A1 bearings on the mains. The B18C1 rod bearings were selected because of their special friction-reducing coating applied by Honda.
Ezerioha begins the rod and main bearing sizing process by measuring the crank journals' outside diameters. An arbitrary bearing size is installed all the way across and the caps are torqued. Inside clearances are then checked with a dial bore gauge and the differences are calculated. Smaller or larger bearings shells are set in place and rechecked. Upsizing both the upper and lower bearing shells on a single journal will decrease the bore diameter by .002 inches. For even smaller adjustments, a single upper or lower bearing shell may be swapped in place, resulting in a bore difference of only .001 inches.
To eliminate power loss as the crank swings through a pan full of oil, a Barnes three-stage dry sump oil pump, along with a Z10 aluminum oil pan, are utilized. The dry sump stores oil in an external container, allowing the crank to spin unimpeded above the pan. The pump's first stage draws oil from the tank. Stages two and three are scavenging sections that pull oil from the pan.
The faster the oil is evacuated from the pan, the more a vacuum effect is created, allowing the pistons easier travel down the bore. The result: more power. This vacuum effect, in combination with a good ring seal, is responsible for the F22A1's superb 2-percent leak down results.
Machining The HeadThe F22A1 top-end was chosen not just for its cost effectiveness, but also for its excellent port configuration. Its design also allows room for a more ideal valve angle. The perfect port configuration places the port at a right angle relative to the valve seat. This isn't possible since there must be a valve in the center of the port, so the ports are reworked. Headwork is also a joint effort between RS Machine and Ezerioha.
Ports are reshaped beginning with the intake side. The F22A1's intake ports flow well in stock form, but Ezerioha enhances them further through his proprietary square-port reshaping process. Square porting removes the radius where the port walls meet the port floor. The process also allows more airflow into the smaller ports and helps keep airflow at an equal velocity. Aluminum is removed and added in order to achieve the desired shape. The polishing step is skipped here, as Ezerioha explains that the rough intake ports will further aid in keeping the fuel in suspension.
Aluminum is welded to the combustion chambers to achieve the desired compression ratio and increase quench area. RS Machine decks the head, just enough to clean it up. Similar to the block, decking the head trues the surface for a positive head gasket seal.
Assembling The HeadOversized, Black Diamond valves from Kibblewhite are the first step in putting the head together. The valves are a one-piece design with hardened tips and are constructed of a proprietary friction-reducing material. Kibblewhite nickel aluminum valve seats are used because of their heat transfer capabilities and ability to tolerate high-rpm abuse. Bisimoto single valve springs and RS Machine titanium retainers with OEM keepers hold the valves in place.
A Web Cam camshaft controls the valvetrain, but despite our prodding, Ezerioha remains tight-lipped about the lift and duration. In fact, all he would tell us is that the lobe separation angle is 109 degrees. The lobe separation angle is the distance measured in degrees between the intake centerline and exhaust centerline of the cam or cams. DOHC cylinder heads have the luxury of adjusting the lobe separation angle and overlap using cam gears; SOHC top-ends do not.
The rocker arm's pad area is increased to take full advantage of the cam's radically large lobes. With a stock-size pad, the camshaft lobe would roll off the rocker too soon, not allowing for maximum valve lift. An AEM adjustable cam gear allows fine-tuning.
Sandwiched between the head and the block is a .043-inch-thick SCE head gasket. A new set of factory bolts fasten the head to the block.
The TransaxleThe gearbox is not what you'd expect. In keeping with Ezerioha's cost effective/simplicity mantra, the D16A1 transaxle from the '87 Integra is selected. Although the H- and F-series gearboxes will work, their weight and the availability of upgraded gears makes them a poor choice. Compared to other D-series trannies, the Integra box is much more stout. It utilizes larger bearings on the main and input shafts and uses steel shift forks.
As power and rpm increase, gear engagement becomes a problem. The solution is to replace the factory synchro system with a dog engagement gear set. The D-series gearbox has been completely overhauled by Jamie Houseman of Houseman Autosport. Since Ezerioha's transaxle won't need the ability to downshift, the deceleration side of the gears is back cut to assist in power shifting. This treatment also allows for quicker shifting. The transaxle houses a helical 5.00:1 final drive for improved acceleration.
The D-series tranny doesn't bolt directly to the F22 so an aluminum adaptor plate marries the incompatible tranny and block.
This creates another problem: the transmission's input shaft doesn't reach the clutch disc. To solve the dilemma, a custom 8-pound aluminum flywheel designed by Ezerioha is installed, spacing the clutch away from the block and closer to the shaft. The unique flywheel bolts to the Prelude crankshaft and is compatible with the D-series clutch, which is an off-the-shelf unit supplied by Action Clutch. The dual diaphragm pressure plate clamps a four-puck, semimetallic disc.
So far, preliminary dyno pulls on an experimental version of Ezerioha's F22A1 have produced 341.6 hp and 247.6 lb-ft of torque to the ground. Never mind the fact that this is a single cam, these are impressive numbers for any four-cylinder, minus the aid of a turbo or laughing gas.
Check back next time for the engine install, suspension, brakes, paint and testing.
Previous InstallmentsMay 2005Part 1: The chassis