New VG35E High Compression Build

Interesting, I guess that the cylinder wall thickness was actually checked. Details such as what head gaskets should be useful to others as my VG days are past but will follow for sure.

Very cool. I'm always interested in N/A builds,
What are the pistons from?
Are you doing anything to the heads?
Doing anything different with the oil pump?
If this works out for you I might try and duplicate it!
Keep up the good work!

Nice work, did you just put the piston at tdc and manually open the valves to required height? Or did you hook up all the timing gear and rotate it all?
Maybe the 3.4 notches are for a non interference fit?
Do you have a part # for the pistons? Do you think that if you used "DE" rods they could have been bushed?
Thanks!

Thanks - I absolutely love building motors. There's not many things more entertaining, in my opinion Anyway, yes, I did assemble the motor with the heads (cams included) and solid lifters. This is how I got accurate measurements off the plasticine i.e., that's how the yellow stuff in the previously-posted picture was smashed by the valves -- by solid lifters set to zero lash, off the 0.420/208 camshaft…properly phased using the factory markings and timing belt. If I had to guess, I think people cut the valve reliefs in Q45 pistons because they see the reliefs on the OEM VG33 pistons. And I think those reliefs are present on the OEM pistons simply to avoid annoyed owners who: 1.) don't replace their timing belt as per factory recommendation or 2.) take their vehicle to mechanic who installs the belt incorrectly… i.e., in either case, creating a condition where the pistons could hit the valves. In other words, having those reliefs allows the pistons to reach TDC with the valves at max lift, and there's no contact.

Note that this build *will* result in bent valves if the belt is installed improperly, or if the belt breaks -- it would be ugly.

I don't know what "DE rods" are…but, of course I could drop $1,000+ on some custom rods with bushings but, frankly…I don't think it's necessary. There's factory motors and racing engines that run steel-on-steel, and I've never seen or even heard of a credible account of a problem with such a setup.

Sorry, I assumed you knew about DE's.: VG30de is the twin cam engine in the z32 300zx ( and other cars). They have stronger rods ( and crank ) that bold right into other vg's.
I've never had a DE rod in my hand so I was just conjecturing (sp?) if it would be able to be bushed.

Piston part #?

Anyone heard of any updates on this project?

Nice!! Glad to hear the positive results! Looking forward to the dyno readings.
Were you able to find a part # for those pistons?
Thanks!

Great! what aftermarket cruise control system did you use?

Finally..here's the post-build dyno results (in red, below). Regardless…I gotta say > the truck is waaaay better to drive now - I love it! It doesn't feel sluggish anymore…doesn't drag and slow down on long inclines like it did before…and it accelerates sufficiently while getting on the freeway. I'm super happy with the results, as felt through the pedal and driver's seat

Oh..and the cruise system came from a company called Rostra. They're easy to find on the Web.

Before we look at dyno results, we'll remember that Nissan says the stock VG33E produces 180HP @ 4,800RPM and 202 ft-lbs. @ 2,800 RPM. These are crankshaft specs, not rear-wheel specs. I increased displacement by 5.6% so, all else equal, it's crystal clear that we should expect to see 5.6% increase in power (factor of 1.056) since the motor is now burning 5.6% more air+fuel. So all else equal, the increased displacement from this project contributed about 10HP: 180 * 1.056 = 190HP at the crank.

Estimating increases in power from increased compression is more tricky. The 16.7% increase in compression increased thermodynamic efficiency - by producing more expansion over the piston's stroke length, and by compressing the now-hotter air+fuel mixture into a smaller space, improving fuel/air mixing. But how much additional power do we get? This is tricky to estimate because "…over the load and speed range, the relative impact on power and thermal efficiency varies." To keep things simple, I'll based my estimate on somebody else's lab work Based on the paper (pdf) referenced below, I'm comfortable with assuming another 2% (3.6HP in this case) increase in power i.e., 180 * 1.02 = 183.6

ABRM.jpg

So far, the above suggests we should expect to get another 13.6HP at the crank, from increased displacement and compression alone. But we didn't…at least not according to three more runs on the dyno.

The camshafts I installed increased valve lift by 18.6%, and duration by about 12%. The actual dyno-result following *all* the work done showed an increase to ~192 HP @ 3,900 RPM at the crank (extrapolated from 146HP measured at the rear wheels, using OEM spec of 180 as a base) occurring at 300-900 RPM sooner, and torque increased by to ~207 ft-lbs at 3,900 RPM at the crank (extrapolated from 182 ft-lbs measured at the rear wheels, using OEM spec of 202 as a base) occurring at 1100 RPM later.

The port work and increased cam lift and duration are supposed to help the cylinders, to help fill them closer to their maximum efficiency. But if Nissan engineers already did good a job with their design and manufacturing, there might not be room for improvement. In fact, it's possible changes could negatively impact all their super-intelligent work. All I did to the castings is remove bumps and smooth the interior port and chamber surfaces. Based on results from this project, it appears to me that Nissan engineers did a great job on the heads and camshafts. And I don't think the head work or cams did anything of any significance to increase power (I think it's possible the cams reduced potential gains). Would results be significantly different if I changed the factory exhaust manifolds and rest of the exhaust systems? Perhaps… (maybe next time).

Here's some good reading on the technical aspects of this project.
http://www.imedpub.com/articles/infl…ion-engine.pdf
https://www.khanacademy.org/science/…-carnot-engine

I put a lot of time, effort and money in this thing. After coming this far, I consider this an R&D project – I’m not going to provide a piston part number. What I’ll share is generally how I went about this: I sifted through publicly-available piston manufacturer's parts-books, and I picked a piston that has specs that interested me. You can put just about any piston in any hole if you measure first. Of course, I could’ve just ordered a custom piston set with whatever specs I fancy…but I wasn't willing to spend $1,000. As a reminder: the pistons I installed use a larger, heavier wrist pin, which requires removing the factory rod bushing and enlarging the small end. The wrist pin bosses don't have an accommodation for oiling like the factory pistons do, and; the oil-control ring groove doesn't allow the oil to flow back to under-side of the piston, like the Nissan pistons do. Having said all that, I'm working with a professional mechanical engineer/machine designer and a piston manufacturer to make a modified version of the 94mm piston, to incorporate features from the Nissan factory piston, including the smaller pin. My objective is to create a quality hypereutectic piston - for half (or less) of what custom pistons cost - that incorporates factory-designed oiling features, and that allows anyone to build a 3.5L, 10.4:1 motor, using their old VG33 without having to modify anything but the bores.