Project 350Z: Buidling a New Engine - Part 2

by Mike Kojima

When we last left off on Project 350Z, we were in the process of assembling a group of parts to enhance the durability of our project car.  As we stated before we were not looking at building the ultimate naturally aspirated VQ35DE but simply a more durable one that could hold up to a life of track days, drift days and stunt driving practice days. If we could get a little more power out of the engine while we were in there, all the better.

While in there we focused mainly on several early VQ weak points, mainly the weak oil pump, weak connecting rods, poor cooling and bearing issues. Because our Z is an old track beater, (although a well equipped one!) our goal was to accomplish this on a budget with minimal expense on parts and labor. Our goal was also to minimize downtime to return our car to fun use as fast as possible. This is what ruled out a swap to a stronger and much more potent HR engine, exotic headwork and large displacement stroker hybrids. 

For this segment, check out how we put the bottom end of our engine together!


One of the parts that was in the process of being shipped when our last segment was being put together was a Fluidampr harmonic balancer and front pulley.  We like to use this part on engines that will see a lot of continuous high rpm hard use.  What makes the Fluidampr unique is that it uses an inertia ring that is suspended in a viscous silicone fluid. The damper is tuned by the mass of the inertia ring and to a degree by the viscosity of the fluid.  What we like is that the damper is both vibration frequency and amplitude dependent since the inertial ring isn't constrained within the housing.  We have found these dampers to work exceedingly well and have had good engine life while using them.  Fluidampr claims that there dampers can also free up power lost to vibration and although this may be true on some engine combinations we have not been able to verify this yet on our dyno. We can tell you that vibrations are obviously reduced on any of the engines we have tried them on. 
Perhaps the biggest weak point on the early VQ35DE engines is the oil pump.  The oil pump gears are fragile and will break during extended use of much more than 7000 rpm.  We cured this issue by replacing the gears with the later parts from a rev up version of the VQ.  The rev up gears are made of stronger material and are safe up to 7700 rpm.  To further increase their fatigue strength we had them WPC treated and had the oil pressure relief valve WPC treated as well as we have had a few Nissan oil pumps fail when this valve has stuck.
After carefully deburring the oil relief port to reduce the chances of the valve hanging up in that area, we reinstalled it.
Oil was applied to the inner pump rotor.
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Sunday, August 09, 2015 11:17 PM
Curious, is the coolant flow through the cylinder head different on the Revup motors?
Mike Kojima
Mike Kojimalink
Sunday, August 09, 2015 11:20 PM
No just the HR as far as I know.
Monday, August 10, 2015 7:42 AM
I'm curious, why did you choose the factory headgasket as opposed to say, a Cosworth or other aftermarket gasket?
Mike Kojima
Mike Kojimalink
Monday, August 10, 2015 8:04 AM
The factory headgasket is as good or better than an aftermarket one. Plus we could get the improved HR waterflow.
Monday, August 10, 2015 8:43 AM
With new pistons and rods added to a new OEM crank, did you rebalance this rotating assembly?
I imagine it's internally balanced and would require some mallory. I'm curious due to your general thoroughness.
Monday, August 10, 2015 8:45 AM
Pathfinder mod ?
Monday, August 10, 2015 9:04 AM
You measured the rod bearings in 3 spots to check for roundness. Were those 3 spots fairly close together? I know the area where the edges of the rod caps meet up are supposed to be looser. I've never had the tools to do it this way but always wished I did. Fortunately I haven't personally built a high effort engine and the plastigage method has been sufficient.
Mike Kojima
Mike Kojimalink
Monday, August 10, 2015 9:34 AM
As far apart as possible.
Mike Kojima
Mike Kojimalink
Monday, August 10, 2015 9:44 AM
The pistons and rods were within one gram of each other. The crank was balanced as was noted in the story. Generally, you only need mallory metal when converting a crank from external to internal balance which usually is an old school domestic V8 thing.
Monday, August 10, 2015 12:39 PM
Loving this build. How many RPM's would you say a stock HR is good for if tuning with UpRev?
Mike Kojima
Mike Kojimalink
Monday, August 10, 2015 12:41 PM
about 7700 rpm is super safe although some have reved to 8k with few issues with the right valvetrain.
Tuesday, August 11, 2015 1:18 PM
Coming from "old school V8's" where a change in rotating mass is rectified as needed I was curious. Thanks for the response. I'm enjoying broadening my knowledge through this site, and look forward to some new experiences because of it. Keep up the good work.
Sunday, August 16, 2015 8:50 AM
+1 on the Pathfinder mod.... if that meant using the 90mm Pathfinder crank. Lot of people want to know if those are usable in 3.5L VQs with custom rods. That would be a game changer, especially with 100mm+ pistons in sleeved cylinders. 4.3L by my calculations....
Sunday, August 16, 2015 9:28 AM
not the crank... its a the pathfinder cooling mod.
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