The Nissan VQ series engine has proven its potency for decades on the road and in tuning shops. It appears in everything from the Nissan Cefiro to the Renault Samsung in some form or another. Available in displacements from 2.0 liters all the way up to 4.0 liters, it’s most common in the United States as a 3.5-liter. Here, Stateside, we mostly got them in Maximas, 350Zs, and G35s. The engine also underwent a few changes over the years from the intake cam variable VQ35DE, to the VQ35DE RevUp. 2007 brought about a redesign of the entire block resulting in the VQ35HR. But for all intents and purposes, we’ll be discussing the first generation VQ35DE out of a 2004 350Z.
These motors boast an all-aluminum block and head design, iron main bearing caps, forged connecting rods, and a forged crankshaft from the factory. With some minor bolt-ons, they can really wake up, and typically put down mid 260s at the wheels. But let’s say that isn’t enough. Ready to go turbo? The stock motor can only support so much, so it’s best to download the factory service manual (FSM), crack it open, throw your checkbook into the wind, and get building. Here’s our top 10 tips on building this venerable motor.
#1 Always Have The Rotating Assembly Professionally Balanced
Sure, the pistons weigh the same, right? And the rods? Mostly, yes. But that crankshaft was half way balanced from the factory for the OEM piston and rod combo. Not to mention that you’ll no doubt be replacing that tired dual-mass flywheel. So when you drop off the block, pistons, and rods with your machinist, make sure you give him your flywheel, bolts, and bearings while you’re at it. In the long run, you’ll be glad you did.
The pistons and rods will come numbered from the machine shop so you know where they go after balancing.
Freshly cleaned and precision balanced, this crankshaft is ready and waiting for installation.
#2 Bearing Selection
Nissans are pretty finicky with their bearings and tolerances; especially with the VQ. The intended usage of the engine you’re building will determine your bearing choice. Will this be your daily driver? Will it be a dedicated race car? Frankly, we never use any bearing other than OEM Nissan, if you ask five different engine builders, you’ll get five different opinions. We tend to go with OEM because we know they will last and they’re available in every size necessary to get that proper fit you’re looking for. In many cases you just can’t get that with an off the shelf box of aftermarket brand bearings when all they sell is a “standard” size set. It is possible, though, to use that “standard” size bearing set and have your machinist micro-polish the crankshaft to achieve the tolerance you’re aiming for. That, of course, is given that they’re already tighter than what you want.
For this motor, we’re using an OEM crankshaft. Nissan stamps each crankshaft and each block with their corresponding alpha-numeric code for their respective journal size. Simply match up the codes, use the bearing size chart provided to you in the factory service manual, and select the proper bearings. Want to go a little more loose? Just go down a size (thinner). We tend to prefer close to OEM tolerances with a good, 10W-30 oil for moderate horsepower engines. For those looking for serious power, go a little closer to the loose end of the spectrum (yet still within specs) and then alter the oil weight in order to set the oil pressure where you would like it to be. Don’t forget to use plenty of quality assembly lube after installing the bearings. We also like to put a few dabs of assembly lube on the back side of the thrust bearings in order to hold them in place on the main caps while setting the crankshaft into place.
The crank is labeled YSLJM and 111111 at the oil pump end for bearing selection.
Left: A little dab will do ya to keep the thrust bearings in place while installing your crankshaft. Right: The block is also labeled at the top of the rear.
#3 Oil Squirters And Piston Notches
These motors are also equipped with delicate little sprayers that coat the underside of the pistons with flowing oil in an effort to cool the piston tops and reduce detonation. Do not forget to install them! They should be the first thing you install on your block. If you already installed your crankshaft, go ahead and take it back out as you’ll need the room. Be very careful when installing the sprayers as they are pretty fragile.
Once it’s time to install the pistons, note which direction is forward. Most aftermarket piston manufacturers will machine a small dot on the edge of the piston that should face the front of the motor. Also, pay attention to the piston skirt. The skirts extend into the crankcase when reaching Bottom Dead Center and will easily shear off the leg of the oil squirter. To remedy this, manufacturers machine out a small notch in the base of the skirt. Double check to make sure everything lines up properly at that point.
Oil squirters installed in the block galley before the crankshaft.
#4 Piston Ring End Gaps
If this is your first time building an engine on your own, stop now and go purchase a piston ring end filer and a quality set of feeler gauges. Piston rings right out of the package aren’t ready to be installed; they require some finishing first. Determine your ideal ring end gap by using the sizing chart included with your piston set. We used Wiseco pistons on this build, and went with their recommended gap specs. You need to first convert your bore size into inches. Typically, the spec sheet will have the bore in inches already, but if it isn’t, take the metric bore and multiply it by 25.4.
Now that you have the bore size in inches, use the chart to determine which gap spec you need. For this motor, we’re going with the forced induction spec. Take the bore size and multiply it by the amount recommended for each ring. Set your ring into the bore and use a piston to slide it down into the cylinder about an inch or so. The piston helps to square up the ring in order to get a true gap reading. Measure your gap and determine how much needs to come off in order to get the spec you are trying to achieve.
Remember to take off just a little bit at a time. If you go too far, you’ll have to buy more rings and try again.
The top rings are much harder to grind, but the second rings take very little grinding to take off a lot of material. Use caution and grind tiny amounts at a time. It’s better to take off a little each time than it is to take off too much and have to order a replacement set. Also, be sure to set your gaps with the rings being tested in their respective cylinders (i.e. test rings for the #1 cylinder in cylinder #1, and so on). Also, make sure you use proper piston ring installer pliers. It’s very easy to snap or distort a ring by trying to install it by hand.
Once all your rings are filed and you’ve made sure to debur the edges of the ends so they don’t snag in the ring land, go about setting the rings onto the pistons. Included in your paperwork with the pistons will also be a diagram as to where to set the ring end gaps. Note, not only do they need to be a certain width depending on your application, but they also need to be arranged or staggered a specific way in order to retain proper leak down and compression.
Left: Once the rings are gapped and crankshaft installed, you can assemble the short block. Right: Make sure you keep each set of rings with their specific piston.
#5 Always Use ARP L-19 Head Studs
ARP makes some amazing hardware options for a multitude of engines and we use them as often as possible. In this case we’re using them for the main bearing caps and obviously for the headstuds. But, they have two options for the VQ35 engine. Given the choice, shell out the extra few bucks and go for the L-19s; They are much stronger and a superior product. We have personally witnessed a few 500+hp VQ motors lift the heads with standard ARP headstuds. In fact, some performance shops won’t even sell the normal studs; they exclusively sell the L-19s. They don’t come in a fancy ARP box, nor do they come with instructions. But they are the clear choice.
ARP L-19s are the best head studs for the VQ.
They do come with ARP lube, though. Use it. Now, a common misconception is that you have to lube both ends of the stud. This is actually incorrect. Thread lube is designed to allow you to smoothly apply the proper amount of torque to the hardware in order to achieve the desired amount of pull. Motor oil reacts differently to pressure, so it would require a different amount of torque to achieve the same hardware pull. We typically put a very small amount of motor oil on the threads that go into the block only to help them go in. No rotational torque is applied to these threads, so it really doesn’t matter. The studs are hand tightened into their holes, anyway.
Before you go throwing studs into the block, put the heads on first. Trust us. We tend to copper spray the head gaskets first just for that extra bit of sealing, and then lay the heads onto the block. Once your cylinder head is resting in its dowels, go ahead and remove the cam caps and cams and set them aside in the order you took them off. Now, take a headstud and put a generous coat of lube on the upper portion of the threads. Rub some lube onto a washer and slide the washer on. Then, take a nut and thread it onto the stud one or two turns. Dip the lower threads of the stud into some oil, or even just wipe the threads down with an oil soaked rag. Wipe off your excess, and drop the stud into the mounting hole of the head. Repeat this step for all eight of your studs. By pre-assembling the studs in this manner, you don’t have to worry about accidentally dropping a washer sideways down into the galley where the stud lies, or the nut.
Prepped head studs waiting to be threaded into the block and torqued down.
Once all eight studs are in place, thread them into the block with the proper Allen wrench. Remember: Hand tight only. That doesn’t mean you crank it down, it means you thread them in until they stop spinning. Now that they’re all set into the block, you can torque the studs to the required 90-95lb/ft. Do it in three stages, typically 35 ft-lb, 65 ft-lb, then 95 ft-lb. Pro Tip: Stand on the back legs of the engine stand when torquing the nuts down, and the engine stand won’t be able to rotate under heavy loads since you’re not acting against it.
#6 Cam Cap Organizing
Now that your first cylinder head is torqued down, you’re ready to install the cams and cam caps. Unfortunately, though, someone else in the shop messed up your work space and everything is now disorganized. What do you do?! Luckily, Nissan labeled the cam caps for you. They also used letters that cannot be confused for being upside-down or backwards. Refer to your FSM for the proper locations.
Easy way to keep your cam caps and cams organized on your bench.
#7 Timing Cover O-rings
These guys are tiny and easy to forget about, so that means they’re super important. They help supply oil from the head to the front covers that supply oil to the VTC gears. They do not get an RTV on them, either. That’s a sure fire way to clog up the oil passages. Each cylinder head gets two tiny ones and the block gets two larger ones. Wait until you’re ready to install the inner timing cover before placing them into their homes. They sometimes like to pop out of place when installed and left unattended.
Left: These are the main oil o-rings. Right: These tiny o-rings are easy to overlook. There are two per head.
#8 RTV Cleaning & Placement
This is the part that really sucks when it comes to these engines. Chances are, you’re rebuilding a previously used motor. The factory sealant is made from a combination of liquid nails and magic, but it needs to get cleaned out of the grooves as thoroughly as possible. Don’t use anything abrasive like wire wheels, drills, or sanding discs because you will cause the mating surface to become uneven and inevitably cause oil leaks. We like to use a razor blade in a holder to get the used silicone off of any flat surfaces. We then take a small flathead screwdriver with a fat handle (for comfort; you’re going to be doing this for a while) and actually gouge out each channel. Angle the flathead against one side of the channel and slide it with some force. Then, angle it the other direction and slide it again. This will basically trowel out a long string of silicone. Scrape around the ends and remove as much as possible.
Be sure to thoroughly clean out all of these crevices before applying new RTV.
The FSM also shows a pretty specific way to reapply the RTV. We recommend following it. The factory gasket kit from Nissan comes with a tube of Nissan brand red RTV, but we always use RTV Ultra Grey. You can get a caulk gun sized tube of it at any popular auto parts store. We find this has more than enough to do several motors and it gives us a lot more control over the size and placement of the bead. Once your cover is all cleaned, RTV is applied, and your oil control O-rings from step #7 are in place, slide the inner cover onto the dowel pins and firmly press onto the motor. Watch to make sure the O-rings don’t migrate during the process.
Inner timing cover installed and ready for timing chains. Note: oil & water pumps are also installed. There are two bolt lengths used in the engine. Keep them straight.
Pay attention to your bolt sizes when preparing to torque down the inner plate. The majority of the M6x1.0 bolts are 16mm long, while a small amount are 20mm. The FSM will show you precisely where those 20mm long bolts need to go. If you mix them up, not only will you strip the threads out of the holes that required a longer bolt, you’ll also pop out the backside of the holes that required the shorter one. Then you’ll be tearing it all back down and doing some major thread repairs.
#9 Timing Chain Marks
Now that your inner cover is in place and torqued down, it’s time for the timing chain. First and foremost, set the motor to TDC on cylinder #1. Install the oil pump and crankshaft timing gear. Double check that the marks are lined up for cylinder #1 TDC. The cams get their chains and gears put on first. Since the cam gears aren’t side-specific, Nissan machined both left and right side timing marks onto each gear. Follow the FSM for each side and line up the marks accordingly. The main tip here is that the chain links are painted orange, and the gear has a dimple machined into the side for quick viewing to ensure that the chain is still lined up.
Once the intake gear is held in position for installation, the marks aren’t visible. Look to the side of the gear and you can view that it’s all still in time. The chains don’t flex a whole lot, so both gears need to be slid onto the cam end in unison. Once they’re both slid onto the cam, rotate them as a group and line up the dowel pin for the intake cam first. It’s the only one you have to go by feel, so it’s best to go with that one initially.
Then, using a crescent wrench on the cams, rotate the cams as necessary to install the exhaust gear onto its dowel. This rotation should only consist of a couple degrees of movement. Torque your cam gear bolts by hand. Do not use an impact gun which can crack the cam ends and your gears will eventually shatter the cam. We find that you can put a crescent wrench onto the cam and brace the handle against the casting of the cylinder head to hold the cam in place while applying torque. Install your main chain according to the marks described in the FSM, bolt in your guides, your water pump, and tensioners. Rotate the motor to ensure everything is working properly and smoothly. Pop in your two remaining small O-rings at the top, and follow Tip #8 for the outer cover. Now you can finish tossing everything back onto the motor!
Crescent wrenches make this part easy if you don’t own large wrench sets.
You should install your cams with the pin orientation very close to this. You will need to rock them slightly to fit the gears. (Right side head shown).
Here we see the chain, guides, and tensioner installed.
#10 Oil Passage Plug
So you’ve got the engine all wrapped up and in the car. It’s time for your first start-up, and oil is just spraying all over the engine bay and your shop floor. What could have possibly been overlooked? Oh, only this damn oil plug that every machine shop removes from the block to clean everything out after they’ve done their job. Of course, they didn’t tell you about it. And of course, you saw it in the box of random hardware they returned to you and you just assumed it was something they thought was yours. Nope. It belongs on the block. Up front; right hand side. Hidden from sight. Make sure the crush washer is on this bad boy and tighten it down. Next time, this plug will be the #1 thing you think about; not #10.
Forget to put this in once and I guarantee you’ll never forget again.
While we are talking about Nissan’s venerable V6 in this article, a lot of the concepts are applicable to most engine builds. The biggest takeaway is focus on the smallest of details because sometimes getting them wrong can have the biggest of impacts on the power output and longevity of your engine. Happy building.