Project Pathfinder Part 10, How to Build the Nissan VG30E
We are getting quite excited as Project Pathfinders motor is now up and running. We are out to show that a solid and reliable naturally aspirated VG30E can be just as strong or stronger in the power department as the VG33R supercharged motor in the Frontiers with vastly superior fuel economy. We also want to show that we can get the pulling power of a small V8 out of the VG. Last month we covered some tricks that Dan Paramore of DPR used to make our heads flow. This month we will dive into the shortblock of our super Pathfinder.
Perhaps the hottest combo for older vehicles like ours equipped with the VG30 is using the block from the bigger bored VG33. This is especially good for a post 87 engines with the better cylinder heads although the VG33 heads feature 10 mm exhaust manifold studs, which is good as the older engines 8mm studs, are very prone towards breakage. The donor motor for Project Pathfinder was pulled from some poor bastards rolled and very totaled Xterra with only 1800 miles on the odometer.
When the heads were sent to DPR, we stripped down the shortblock and deburred it internally to remove casting sand and stress riser causing flash from the interior of the block. After this prep we obtained a set of pistons from a first generation Infiniti Q45 (1990-1994) VH45DE engine. These pistons give 3.4 liters of displacement and the flat top dome gives a compression ratio to 9.6:1, up from the stock 9:1 of the dished standard piston. The piston feature low friction coating on the skirts to boot and are cheap.
|This close up shows the additional notches cut in the top of the Q45 piston to clear the VG’s valves. Any automotive machine shop can do this easily and cheaply.|
|The black stuff on the skirt of the Q45 piston is a Teflon like anti friction coating, very similar to Swain coating and other similar products. Nissan applies this at the factory.|
|Here is the Q45 piston when compared to the dished lower compression stock piston. The Q pistons are 1mm bigger to give a new displacement of 3.4 liters.|
|Nissan rings need a smooth surface. This is a 600-grit plateau finished bore; it is as smooth as glass. Don’t let an old school machine shop talk you into getting a rough bore. Nissans have chrome rings that require a smooth bore.|
The Q piston domes must be slightly modified with notches for valve clearance. We had a local machine shop duplicate the VG’s valve notches on the Q pistons. The piston pin diameter for these pistons is 0.866” up from the VG33E’s 0.822”. This happens to be the same size as the 300ZX’s VG30DE rods so these rods can be used or the stock rods can be easily and cheaply rebushed for the larger pin. The VG30DE rods are stronger so it is advantageous to use them although the stock E rods are definitely not weak.
VG30DE or DETT rods are easy to find as many Twin Turbo Z owners have upgraded to racing rods. The advantages of the DE and DETT rods are stronger bolts, which are torqued to 43-48 ft/lbs vs 28-33 for the E rods and a bigger piston pin and more beef in the big end of the rod. We happened to have the rods and crank from a VG30DETT lying around so we used them. The stronger crank and rods from the twin turbo Z are not really necessary since the stock parts are beefy as well but since we had them, we might as well use them.
After this cleanup, we bored the VG33 block to 93 mm using a torque plate to assure that the bores would stay round when a cylinder head was bolted on. We fine honed the cylinder walls to a 600-grit finish and plateau hone the surface to make it even smoother. The Plateau honing speeds break in, reduces friction, gives the parts a longer life and reduces oil consumption.
If you are thinking of building a similar motor to ours, since there are many variations of oil pump, crank snout, balancer and drive pulley on these motors, you are probably best off installing the crank, balancer, oil pump, oil pan and water pump from your vehicle into the VG33 engine. Fortunately all of the bolt bosses for the accessory drives and motor mounts are exactly the same Between the VG30 and the VG33. This saves time and money for the big bore conversion.
If you are putting early VG heads on the VG33 block there are a few things you have to consider. In 1987 the coolant flow through the heads was modified to improve cooling. If you have the earlier heads, it’s easy to incorporate these changes by simply laying a 1987 and later head gasket on the head deck to locate where holes should be drilled for the additional coolant flow.
If you put a VG33 block on VG30 heads the water passages between the head and block have a slight misalignment. Simply lay the VG33 head gasket on the VG30 heads and scribe where the passages are misaligned. You can then grind away the scribed areas with a die grinder or dremel tool to fix the water flow. The misalignment is slight and you will only literally have to grind away about 1/8” of material to get the passages to match.
|This is where the mismatch of the style pre 87 old head to new block is.|
|This is the mismatch of the water passages between the VG33 and VG30 is, simply slightly grind the hole so the block holes match up.|
|To fit a pre 87 head on a new block, you must drill the two holes so more cooling water can flow.|
Next we polished the stress risers off of the cranks parting line and the rod beams and had the parts shotpeened. This is not entirely necessary as the stock parts are really strong, but since we were in there, shotpeening and polishing are cheap insurance items. After this work, the crank, rods and pistons were sent out to be balanced. After balancing, we micropolished the cranks journals.
We thoroughly cleaned our block with Motul Moto Wash, a great clean due to its anti rust properties, If you have ever prepped an engine before, you know how it’s a struggle to keep the barely new machined iron surfaces of the bore from rusting and Moto Wash works like no other here. We used a Summit Racing engine cleaning brush set to clean all the passages in the block. It’s amazing how much crap ends up in there! After blow-drying off the engine with compressed air, we used Motul Contact Cleaner to clean the bores perfectly. It’s amazing how much grit and slurry from machining gets caught in the bores as well.
We assembled our engine using genuine Nissan bearings to the tighter end of the stock clearances. We also used the oil pump from a VG30ET motor for its 25% larger capacity. Our Dan Paramore heads were bolted in place with our Nissan Motorsports cams and we were ready to rock.
We have been taking it easy while breaking in our motor but its apparent that we have plenty of power for once. Now there is enough acceleration to push you back in the seat and the increase in low-end torque is really noticeable. It’s possible to even break our big off road tires loose sometimes, even with our limited slip diff. We think that this motor is probably great for everything from off-roading to towing.
The motor even had enough power to edge out a ricey GS Integra after it was obnoxiously tailgating us. The Integra driver looked amazed when he could not pass a SUV with raised suspension and big tires. When the SUV edged away he looked even more surprised.
We have noticed a few things that we have to do; our motor now slightly detonates on cheap 87-octane gas that we used to feed it due to the higher compression. We will probably do a multimap ECU so we can take advantage of 91-octane fuel and still run around on crappy 87 when we have to. Our tranny now shifts sluggishly and slips from all the new found power as well. We have to do some research on what to do about that as well. If any readers have suggestions for what to do with the tranny, please contact us with your suggestions.
We are really happy with our motor setup. It might make our old warhorse actually pleasant to tow with. Stay tuned, in the next editions of Project Pathfinder, we tackle the steering issues, which are coming up again fixing them once and for all and make vast improvements on the brakes.