by Chuck Johnson of Moto-IQ
In our last story, we covered the basic design of our land speed record breaking engine we’ve dubbed the SR15VET 20V. This time around, we’ll take a deep look inside the engine and detail its build with none other than our resident Nissan guru, Nick Hunter of 5523 Motorsports.
We like to call him the zombie vampire because we’re ass clowns who find the need to humor ourselves at the expense of others. Put all the ass-clownery aside though, take a deep look into Nick Hunter’s track record of building Nissans, and you’ll quickly understand how he earned his real nick name “the 23 Doctor.” (Translating 2-3 into Japanese you get ni-san.) Nick’s nickname (no pun intended), was initially earned through his experience repairing thousands of Nissans as a master tech at a local Nissan dealer. However, the nickname was quickly solidified through the multiple VQ35DE race engine builds he executed for Grand Am race teams as well as the likes of Dai Yoshihara and his Abu Dhabi drift car. Throw in the slew of SR20DET, RB26DETT and VR38DETT street car builds he has executed over the years and there’s no need to justify the nickname any further. Let’s take a look at the Nissan Doctor in action.
It just so happens that Nick Hunter was one of the first in the US to figure out how to install a SR20VE head on a SR20DET block. Although most everything lines up, there are a few things that need to be addressed to make the SR20VE head swap happen. Since the VVL head doesn’t line up exactly with the RWD SR20DET block, plugging this drain hole in the block is one of the modifications that needs to be made.
To accomplish this, Nick Hunter drilled out one of the factory oil drain holes in the block with a 45/64 drill bit and then used a ½-14 tap to thread the hole. Nick then threaded a stainless steel plug in place.
Upon receiving the engine block back from the machine shop, amongst some of the many things that Nick Hunter measures and verifies, is the flatness of the block’s deck along with the bore diameter and cylindricity.
After completing his pre-assembly routine, Nick then turned his attention to sizing and specing the engine bearings. Since this was going to be an all out racecar engine build, Nick Hunter opted to go with main bearings from Nissan’s hopped up version of the SR20DET, the 54C. The main bearings from the 54C variant of the SR20DET engine feature five oiling holes of varying diameter intersecting an annular groove. In comparison, a standard SR20DET main bearing only has two oiling holes intersecting the annular groove.
To take full advantage of the 54C main bearings though, a complimenting annular oiling groove had to be cut into the block. The 54C has this from the factory whereas the other variants of the SR20 only have an oil hole drilled into the main bearing housing which aligns with the larger hole in the standard SR20DET main bearing. To cut the annular groove in place, Nick built this fixture using an old main bearing cap, angle grinder, and cutting wheel. Want 54C main bearings done right? 5523 Motorsports is one of the few places that can do it.
This fixture might look a bit medieval giving the impression of questionable accuracy, but rest assured that it is complete with a Z-axis adjustment screw to control the cut depth to a couple thousandths of an inch.
Once the main bearing housings were altered, Nick bolted the main bearing caps and crankshaft girdle in place. Using a bore gauge, he then measured each of the main bearing housings for diameters and roundness.
Knowing the unique diameter of each main bearing housing bore is one of the things that allows Nick to control the main bearing housing tolerances to .0001″.
Nick has a whole stash of different grade Nissan bearings, which vary in shell thickness. This is what allows the bearing clearances to be optimized and matched for each of the crankshaft journals. Check out the uber rare OEM Pulsar GTI-R main bearings. Good luck ever finding a full set of these anymore.
The good thing about choosing an engine shop like 5523 Motorsports that specializes in building Nissan engines is the wide inventory of parts specific to Nissans that they carry. In many cases, an engine builder will just order oversized ACL bearings with .001″ extra clearance, slap them in, and call it a day. Excessive bearing clearances often result in low engine oil pressure and shit bearing life. Nick prefers to take his time optimizing bearing clearance to OEM spec. There’s no short cutting here. This detail is just one of the things that separates 5523 Motorsports from your average engine shop.
While Nick worked on gapping the rings, I measured the diameter on the crank journals in an attempt to make myself somewhat useful. (Although I probably just got in his way more than anything else.) The crankshaft journal diameters were the last piece of the equation that Nick Hunter needed to select bearing grades and fine tune clearances. Put simply, clearances are calculated using the following basic equation:
Main bearing clearance= Main bearing housing – (top + bottom shelf thickness) – journal diameter.
Once the bearings were sized, Nick Hunter cleaned out each of the oil passageways in our 63.5mm stroke crankshaft. Any debris left over from the de-stroking or nitdriding process could easily destroy a main or rod bearing… and that would suck.
Next, Nick Hunter gapped each pair of compression rings for a specific cylinder in the engine. Much like bearing clearances, ring gap has the potential to make or break a race engine. An oversized ring gap can lead to excessive blow-by, poor oil control, and power loss. While on the other hand, too tight of a ring clearance can cause cause the ring ends to butt, grab a cylinder wall and potentially lead to piston land failure. From years of experience, Nick Hunter has dialed in the ideal ring gaps suited for specific ring materials and dimensions as well as engine power and application. This is one of those types of secrets that engine builders take to their grave.
The oil squirters were cleaned, inspected, and reinstalled before the crankshaft. With our short stroke and long rod, we had plenty of piston to oil squirter clearance. Insufficient squirter clearance can be a problem with many aftermarket pistons for stroker and even sometimes factory stroke applications. Be sure to check for this if you’re building an engine.
Once each of the oil squirters were fastened, Nick Hunter installed the thrust and main bearings in place and then lowered our de-stroked SR15 crankshaft into position.
One of the things that makes the SR20DET bottom end so stout is the crankshaft girdle, which ties all of the main cap housings together better stabilizing the crankshaft and bearings. Also, note the use of factory main bolts versus aftermarket studs.
Whenever possible Nick Hunter prefers to stay with the OEM main bolts as there is some concern that the high clamping loads associated with main stud kits can cause distortion of the main bores. Of course the main bores could be line honed with the studs in place, but since the SR20DET main caps are floating and non-doweled, there isn’t a guarantee that the concentricity across the main bores will be preserved. Combined with tight factory bearing clearances of less than .001″, the distortion could cause the crankshaft to bind against the bearing.
Note the oil under the main bolt washer, since torque is really only a measure of friction, it’s important to lubricate the washer faces and bolt threads. Chasing the threads of each bolt hole is also a good idea. One improperly installed bolt can lead to a main bearing failure and a dreaded game of connecting rod peek-a-boo.
After the main bolts were torqued, Nick Hunter first checked the crankshaft to ensure it wasn’t binding and spun freely. Then, he checked the crankshaft for adequate thrust bearing clearance by placing a dial indicator on the end of the crankshaft and gently prying it forward.
With such a short stroke, our pistons had to be designed with dome tops to yield a compression ratio of 9:1. The combination of very low 14.5 degree valve angles and the need for deep valve reliefs made anything higher than 9:1 impossible to achieve.
Nick Hunter then joined our asymmetrical, forged JE Pistons to our set of longer, K1 Technologies connecting rods which were originally destined for a Honda H22 engine. Likewise, the connecting rod bearings from a Honda H22 engine were installed between the H22 K1 rods and the de-stroked SR15 crankshaft. Although Honda bearings were used, Nick still stayed tight, aiming for nominal factory bearing clearances.
After Nick Hunter installed each set of rings on to their corresponding piston, he compressed them with a ring compressor and then installed each piston and rod combo into their respective bore.
A connecting rod experiences high loads, which distorts and ovalizes the connecting rod’s big end bore. This distortion causes the connecting rod bolt to undergo bending, tensile, and sheer stresses making the connecting rod bolt among the most highly stressed fasteners in an engine. Due to the high levels of stress, K1 Technologies connecting rods are equipped with ARP 2000 connecting rod bolts for their high tensile strength and excellent notch toughness.
The correct way to measure a connecting rod bolt is by measuring its length both before and after its installation. This difference is called stretch. Since the crank girdle kept us from being able to measure the stretch of the connecting rod bolt, we placed the connecting rod in a vice and used the “torque and angle” method to install the ARP connecting rod bolts.
In this method, the connecting rod bolt is first cleaned and then lubricated with specific ARP bolt lubricant. It’s important to use the specific lubricant supplied with the bolts as different lubricants can reduce or increase friction and alter the amount of torque that the bolt requires to overcome that friction. Once the bolt is lubed, it is torqued to the amount specified by ARP and afterwards, rotated a certain increment of degrees. After installing the connecting rod bolt using the “torque and angle” method, we used a stretch gauge to ensure that the bolt was installed with the correct amount of preload. Once we verified that a specific torque and angle yielded a specific amount of stretch, the K1 connecting rod was installed on the crankshaft and then fastened in place using the same torque and angle method.
Once all four pistons and rods were attached to the crankshaft Nick Hunter turned his attention towards assembling the outer extremities of the engine block.
Not wanting to take any chances, a new OEM timing chain and guides were ordered and installed. Any small issue can easily result in a useless heap of aluminum mildly resembling that of an engine.
Another necessity to complete the SR20VE VVL head swap is a FWD oil pump housing. The reason for this is the two bolts holes on top of the oil pump housing which the FWD SR20VE VVL head bolts to. On a RWD SR20DET, these two bolts are inside of the timing chain galley, whereas on a FWD head they can be accessed from outside the engine.
Our friend from Japan, Big Tom, was kind enough to send us a new SR16VE N1 oil pump for our SR15VET. We chose the SR16VE N1 oil pump because of its flow and pressure characteristics. In terms of performance, it’s apparently only trumped by the SR20VET oil pump.
The crank pulley is another one of the modifications that needed to be made to make a FWD oil pump work on a RWD block. This billet aluminum pulley kit from G Spec Performance is one of the few off the shelf options on the market.
One of the other parts that is required to allow the N1 oil pump to work on the RWD block is an oil pump drive collar from a front wheel drive SR20. The RWD version differs in length from the FWD unit. Used in tandem with the billet spacer that comes with the G-Spec Performance kit, the new crank pulley will clear the FWD oil pump housing.
Supposedly there are a few different solutions in terms of oil pump pickups that’ll work when using the N1 oil pump on a RWD block, but we really didn’t want to take any chances. A factory oil pump pick up modified by Mazworx ensured that the pickup was located at the right depth and on center with the opening in the oil pan’s baffle plate.
With the bottom end assembly complete, we arranged to meet with a representative from the SCTA to have our engine verified and the bottom end “sealed”. Before an engine is sealed, a representative from the SCTA measures the bore and stroke to verify the engine’s displacement.
Having the engine sealed by the SCTA beforehand, would prevent us from having to go through less accurate methods of measuring displacement which might result in us having to tear the motor down after a record run. Needless to say, tearing down an engine on the salt would absolutely suck.
In the next article, we’ll finish up the build of our SR15VET 20V engine with a detailed walk through of the head work and assembly executed by 5523 Motorsport’s Nick Hunter.
Article by Moto-IQ