We have heard for a while now that the internals on the high rev motor were supposed to be upgraded,but have not yet had the chance to take an 05 motor apart. Well thanks to Jimmy,aka Paranormal,we got our chance. He managed to spin main bearing #6 due to lack of oil. As you can see from the pictures,the rod on the right side is dicolored from the heat and the rod is elongated and egg shaped.A few more seconds and this rod would have snapped and went through the block. Now the rod on the left is out of an 03 model with the 287 hp motor and the rod on the right is from the 05 high rev motor.We can not visually tell the difference in the rods or pistons,so unless Nissan changed the material they used to produce it,the rumor that the 300hp motor is sporting stronger internals is false. We will not make a claim like this without backing it up,that is why I plan on having my engineer take measurments of both rods and give a comparison in the next few days.However upon initial inspections the internals seem to be exactly the same..




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I'd have to say your fears are unfounded for now untill they are tensile tested etc...

 

What about the other internal parts? Like the valve springs. Maybe Nissan only upgraded certain internal parts.

 

Thanks for the info MRC - I doubt that tensile strength has increased if the mold hasn't changed at all.

 

As far as I've read, the only thing that was beefed up were the connecting rod bolts. That's it.

BTW, what was he doing when the bearing spun? I'm a firm believer that the VQ35 is not happy operating at higher rpms (6500+rpms) for extended periods. Rod/bearing failures are fairly common with the VQ35 motors where as I've never read of one single rod/bearing failure on an NA VQ30. Even ones that have seen 7500rpm duty.

 

he was only at about 3500rpms when it went.We found the car to be about 3 qts of oil low,although we do not know if that was a cause or effect situation.At any rate he thrashed his crank shaft in the process.The rods and the rod bolts appear to be exactly the same.

 

Correct,that is why I did point out that unless they changed the material used on the rods, the rods "appeared" to be exactly the same.

 

I would not think the mold would change unless it was necessary. New molds are very expensive, whereas a change in material could yield stronger rods. Any way, not flamming, just saying it aint over till it's over.

 

Another theory, if the pistons are lighter, then the rods would in effect be stronger...

 

I seriously doubt Nissan would release the changes to the 05 motor if they didn't do them.

Can't remember where... but I'm about 98% sure there was a press release/official information released about what the changes were.

edit: from here

"- The engine is the new higher performance version of the standard 350Z VQ engine
- Modifications made to achieve 300 horsepower include:
- strengthened connecting rods and bolts
- double-mass crank pulley
- revised shape of the piston head
- new camshaft profile, remapped ECM and more"

Seems like there was more info out there... really don't have time or effort to argue.

 

The modifications for the 05 motor only apply to the anaversary motor
The conrods do not now have bolts, but studs & nuts

 

The con rods have different # designations on them. the Left one says 35 and the other one says 14. Just to put on the new numbers, new molds had to have been made for 05+. They could use a different alloy to make them stronger while still maintaining the shape. The 03 vs. 05 rods should weigh the same even if the alloy is different, since steel alloys will generally have the same density.

 

And people are running UDPs on these motors? Scary. The upgraded pulley is there to protect the engine (bearings, rods, crank) from the higher operating rpms. Clearly Nissan felt this was necessary protection and only confirms my argument that the stock pulley is in fact a damper.

This guy wasn't running UDPs was he?

 

The connecting rods still use the bolts as you can see.The motor is from an 05 6 speed G35 that is the high rev motor.

 

I can not recall,I will ask my mechanic tommorow..good point to bring up.