Build Series: Old School Labs – SR20VE/SR20DET Hybrid Engine Build, Part 2
When I wrapped the first installment of this SR20VE/SR20DET Hybrid engine build destined for use in my Old School Datsun 510, the bottom end was assembled using Eagle ESP connecting rods sourced from a Honda H22, JE Pistons’ Asymmetrical slugs with an 11.5:1 compression ratio, and an SR20VE high pressure/volume oil pump. Prior to mating the soon-to-be-installed Port Flow-prepped cylinder head atop the Tomei multi-layer steel head gasket, the entire rotating assembly was sent to Revco Precision, for a full balance and blueprint process. From buttoning up the bottom end using some key components to strengthen our engine to modifying our SR20VE cylinder head to work with the SR20DET S14 bottom end, I’ve got a Frankenstein build that’s sure to pique your interest. Follow along as this hybrid engine build continues and I address the all-important engine oiling system, transmission upgrades and street/strip worthy clutch setup.
Due to the nature of the naturally-aspirated engine build, I’m determined to extract every ounce of horsepower feasible from this setup. Initially, the decision was made to knife-edge the crankshaft to reduce rotating mass and windage, but after careful consideration, I ultimately decided against this modification as the OEM crankshaft was balanced with numerous holes drilled into the counterweights. I was concerned that knife-edging the crankshaft might affect the crankshaft’s integrity, especially since I plan to spin this little engine well past the 8,000 rpm mark. As an alternative, I decided to integrate a crank scraper and windage tray from Ishihara-Johnson.
Oil viscosity (the fluid’s resistance to flow) determines the length of time it takes the oil to flow when cold and when the engine is hot. Regardless of the type of oil used, engine oils do not share the same properties as a fluid as thin as water, which would easily fly off a rotating crankshaft and return to the pan. When running at high rpm, the oil is under more pressure and is pumping faster; these two conditions create windage, the oil foaming condition which causes parasitic drag on the crankshaft. Windage occurs when oil splashes out of the pan’s sump as the engine spins, which can cause the oil supply to leave the sump area and induce surge at the pump. In some cases, windage can starve the oil pump and lead to internal engine damage. A significant amount of oil wraps itself around the crank like a rope, robbing horsepower and efficiency.
“It is not unusual for a quart or more of oil to be suspended in the cloud at high rpms in many engines,” says Ishihara –Johnson owner Kevin Johnson. “This impacted and entrained oil eats up horsepower your engine is making by increasing the rotating mass and also creating parasitic drag.”
At low rpm levels, and in extreme conditions where the rotating assembly is flooded by sump oil, a crank scraper mechanically strips off excess oil much like a knife would peel off a potato or apple peel. The scraper removes oil directly only from portions of the surface of the crankshaft and the rod big ends, neither of which depend upon lubrication of any sort. These components, as well as the pistons, do depend upon a flow of oil to cool them. By constantly removing oil that has contacted these hot surfaces and allowing fresh oil to re-wet and cool them the thermal efficiency of the engine is enhanced.
The steel scraper designed for wide block (fully counterweighted crankshaft version) mounts between the main bearing girdle and attaches to the existing mounting points for the factory louvered pan baffles. The layer closest to the rotating assembly has two scraper louvers for each of the piston bays. They are chisel-edged with a relief cut into the second, larger louvers, so they follow the contour of the connecting rods and counterweights. The louvers can be bent down or up to close the tolerance to the engine components. Ishihara-Johnson recommends to clearance the louvers using the thickness diameter of a paper clip for best performance.
Ishihara-Johnson also offers an optional expansion of their original scraper and windage tray. The expansion pieces extend both the scraper and windage tray. Using these optional pieces requires modifying the cylindrical indentation in the stock sump which was designed by the factory to allow access to the torque converter bolts. For manual transmission vehicles, I highly suggest removing this indentation as it causes obstruction to the flow of air in the fourth piston bay.
Modifying this inward-facing bulge requires cutting and welding on a precut piece of aluminum that is provided with the kit. After using Dykem’s red dye to scribe an outline of the bracket, I drilled and cut out the remaining section for a perfect fit. Design Craft Fabrication helped to TIG-weld the aluminum into place.
Windage Tray Upgrade
The Ishihara-Johnson windage tray features numerous advantages over the OEM piece, including a closed rear section to prevent oil from sloshing into the crank under hard acceleration and aggressive shifts. It’s also designed to minimize oil aeration, permit rapid oil return, and protect the crankshaft from oil splash-back.
Along with the windage tray, we installed the optional Teflon-bladed scraper. These can safely contact rotating engine components without damage, and is more efficient as it gets closer to the crankshaft. The rotating assembly will bed or seat in the soft Teflon and develop a running clearance of .001 to .005-inch.
To check for proper clearances, I applied Prussian blue to the crankshaft counterweights. Prussian blue is a dark blue pigment that engine builders rely on to aid in precision fitting of machined surfaces; it helps to locate high spots on bearings, valves, or gears. I used this removable dye to determine exactly how much of the Teflon blade was coming in contact with the rod bolts and crankshaft. The Teflon insert was trimmed back until it just barely made contact with the rotating surface, leaving only minimal bedding needed.
With the Teflon adjusted to its proper location, I used blue threadlocker and fastened each bolt to 30 inch-pounds. The last thing I need is for any nuts or bolts to come loose and cause havoc inside the rotating assembly.
When it came time to bolt up the upper oil pan section to the block, I discovered clearance concerns that prevented the piece from sitting flush. A combination of the newly installed girdle scraper, windage tray and ARP main studs were all coming into contact with the upper oil pan.
Looking back at the situation now, I should have designed an elevated spacer between the block and upper pan as a quick remedy to address the problem. But at the time, I took the more painstaking process of drilling each hole while adding additional clearance. Gary Castillo of Design Craft Fabrication was once again enlisted to weld our newly-clearanced holes to properly seal the oil pan girdle.
Whenever you’re building an engine, it’s a good idea to clean everything, then clean it again, then inspect it, and if necessary, clean it a third time. Cleanliness is critical to an engine’s long-term durability. For a head gasket to seal properly, the head and engine deck surfaces must be clean. Any foreign material such as dirt, old gasket material or grease will hinder the cylinder head and gasket’s ability to properly seal which will ultimately lead to blown head gaskets or worse. To avoid these kinds of problems, make sure both head and block surfaces are properly surfaced at a qualified machine shop, then cleaned once again using Acetone, brake cleaner or degreaser before installing the head gasket. Never use a wire brush or abrasive on the mating surface of the cylinder head or block as it can leave an uneven surface.
For those hard-to-reach areas like the oil galleys or journals on the crankshaft or block, I recommend using a gun cleaner kit sold at many sporting goods stores. The kit can be used to degrease, clean and remove any metal shavings that might be left hiding within the block or cylinder head casting.
Think all thread chasers and thread cutting taps and dies are the same? Guess again. With a chaser, you will simply be moving metal around and straightening the threads while a thread cutting tap or die will usually do just that – cut new threads. If you are not extremely careful, you can easily remove threads instead of straightening them. Dirty or damaged threads can give false torque readings as well as decrease a bolt’s clamping force, so it’s always a good idea to clean the threads throughout the engine prior to assembly. I prepped this block using Metric ARP Thread Cleaning Chasers prior to installing the ARP head studs.
I decided to mate this engine to a 6-speed manual transmission from a Nissan Silvia S15. This transmission was never offered in the US and was specifically for the Japanese and overseas market. Another interesting fact is that the 6MT synchromesh was designed by Borg Warner.
The Nissan 6-speed transmission was designed to use a dual-mass flywheel and unsprung disc plate. The dual-mass flywheel is basically two flywheels with springs in the middle to act as a dampener. The two flywheel halves are able to move independently of each other within a limited range. The springs help absorb engine vibration which reduces wear on the transmission and the rest of the drivetrain. The benefits of a dual-mass flywheel are smooth operation and dampening of noise, vibration, and harshness (NVH). But as with any dual-mass flywheel, a major drawback is the total weight.
Lightweight Spec Clutch
To combat this challenge, I decided to use an aluminum flywheel and standard-style clutch assembly from SPEC Clutch. The dual-mass flywheel alone was scaled at 26.6 pounds, while the new SPEC flywheel weighed in at a scant 10.1 pounds. The significant weight reduction will allow the engine to rev quicker, exert less drag on the engine, and provide quicker throttle response. Interestingly enough, the combined weight of the entire SPEC clutch assembly which included the flywheel, pressure plate and clutch plate weighed 26.8 pounds, merely .2 pounds heavier than the OEM dual-mass flywheel alone. I also swapped out the 6th gear with a Nismo reinforced cross gear, which brought the gearing much closer to the 5th gear ratio, and changed the ratio of the 6th cog from 0.764 to 0.8624 to provide less RPM drop when shifting into 6th gear.
The SPEC Stage 2 Plus Clutch Kit features a multi-friction disc in a full-faced configuration, with carbon semi-metallic material on one side and Kevlar on the other. The Spec Stage 2 Plus clutch offers good daily drivability and very good wear characteristics but provides 15-20 percent higher torque capacity than Stage 2. The hub is double sprung with spring cover reliefs for flexibility and heat-treated components for strength and durability, making it ideal for street, drag, autocross, road racing, and drifting – exactly how I plan to use this car.
Taarks V2 Oil Block Adapter
The SR20DET factory oil filter adapter has been known to crack or break due to the weak oil filter sensor screw, so I looked into a solution, eventually settling on the Taarks V2 oil block adapter which allowed me to fit both an oil filter relocation kit and oil cooler. The Australian-based Nissan specialists at Taarks offer all the necessary items to build a SR20VE conversion, and all of their components are rigorously tested both on and off the track. The adapter, CNC machined from 6061-T6 billet aluminum, has also been designed with SR20VE conversions in mind and comes with an extra -6AN ORB (O-Ring Boss) port at the top to feed the VVL solenoids, and dual 1/8-inch NPT ports to feed gauges or other needs. This adapter is also machined with a receiving groove for use with a Viton or rubber O-ring for sealing that can be easily replaced should you have an issue.
Here’s a side-by-side comparison of the Taarks adapter versus the Tomei unit. The pieces have a similar appearance, but the Taarks adapter has the additional port for the VVL and is machined to accept the ORB fittings, which I prefer for optimal leakage control in medium and high pressure lines.
Keeping It Cool
Selecting an oil cooler that would work within the Datsun’s modest sized engine bay was a difficult task but with some creative thinking, I was able to shoehorn a Koyorad 25-row cooler into place. It measures 11.25-inch x 7.5-inch x 2-inches thick, with a volume capacity of one-half quart. This cooler is designed to be highly efficient and strong, able to resist deformation up to 10 Bar/145 psi. The cooler incorporates -10AN ORB ports for both inlet and outlet.
The Setrab remote oil filter relocation kit allowed me to relocate the oil filter for convenient access; it’s designed to allow multiple orientations to give plenty of installation flexibility. A set of AN fitting plugs were tapped to accept the oil pressure and temperature gauge sensors. I then plumbed the oil cooler using -10AN Earls Performance Pro-Lite 350 hose and kept things nice and tidy using Vibrant Performance billet line separators. Earl’s Swivel-Seal hose ends in black were used throughout the cooling system to maintain a stealth appearance.
Fittings and More Fittings
Five Ten Automotive, another Australia-based company, also played an integral part in getting this engine up and running. Five Ten Automotive offers an array of motorsports products ranging from hose fittings to hard lines and adapters. They set me up with a number of their 100 series braided hose AN fittings to plumb the fuel lines along with their billet aluminum Pro Series fuel filter.
Mazworx VE/RWD Conversion Oil Pickup & Other Hard Parts
Mazworx offers a modified oil pickup that’s a key component when performing the SR20VE hybrid conversion. Mazworx dissects and combines a Nissan S14 blacktop main pickup to a VE pickup tube. The modification allows the larger VE inlet tube to sufficiently deliver oil when using the bigger VVL oil pump in comparison to the original SR20DET oil pump and pickup.
There is always that uncertainty when it comes to purchasing a used engine. Will the thermostat fail after a few hundred miles? How about that clutch slave cylinder? Because I wasn’t willing to take any chances, I purchased some key quality components from Nismo including a low temp thermostat, clutch slave cylinder which works well with aftermarket clutches using a stiffer pressure plate, a steel braided clutch line, and a new clutch fork pivot ball, which is an upgrade over the factory unit. The OEM pivot ball lacks the necessary support and has been known to break, rendering the clutch fork dangling in your bell housing.
Tomei Powered High Capacity Oil Pan
Lateral and longitudinal forces from turns, acceleration, and braking, especially in drifting and road race vehicles, could push oil around the floor and up the side of the pan, starving the pickup under high-rpm/high-lateral g conditions. This is a common problem for high-performance engines. The SR20 engines are notorious for oiling problems. From spun rod/crank bearings to occasional faulty oil pickup units, this engine has been begging for an aftermarket fix to prevent such mishaps from occurring. To remedy the problem before ever encountering it, I contacted Tomei Powered to purchase their larger-capacity oil pan.
The factory SR oil pan has a built-in baffle, but it does not provide enough flow control by itself to prevent oil starvation in high g-force turns. Tomei’s large- capacity oil pan prevents oil starvation under extreme driving conditions with integrated baffle plates and a two-piece partition swing plate design to reduce oil slosh. This highly durable, steel constructed oil pan also allows a 15 percent oil capacity gain over the factory unit to make sure the engine gets the oil it needs. Combined with the crankshaft scraper and other oiling system modifications selected for this engine, I’m confident it will perform under pressure.
Follow along for our third and final installment coming soon as I pull the wraps off the stuff you’ve been most waiting for. In store yet to come: I have the cylinder head massaged for improved performance, then implement a set of Honda S2000 individual throttle bodies. This is turning into one crazy build!