http://www.turbo6.net/vqtech/Images/VQ/VQ35HR/


I took these with my camera phone and they don't look that good. But here you go.


I can't get it to show up on the camera, but it has 'Hitachi' in it.

 

What other piston is it being compared to in those pics?

 

you can see where it says hitachi in pic 0206071919c, on the inner side of the skirt. at least it looks like it says hitachi.

 

That is a standard VQ35DE piston on the right.

 

Oh yeah. Part# A2010-JK21B

 

some areas of the vq 30 ,vq 35 pistons to me actually look thicker.

and also i dont really see the height difference the HR piston is suppose to have over the 3.5 ?

 

The location for the top compression ring and the oil control rings are the same but the location for the second compression ring is slightly lower. And the best I can tell for now, before I get my calipers to measure, the pin height appears to be the same.

 

I need to put this thing on a scale. I am betting it is lighter because of the way they designed the skirt.

 

Where did you get HR pistons from?

 

I didn't .

 

So how are you planning on measuring the pistons and components? Or are you refering to measuring the VQ35DE pistons?

 

I'll just measure the one I have with my calipers.

 

Im confused

 

yeah me too, do you have an HR piston or not? if not, how are you going to measure it?

 

Yeah I was just being a smarta$$. He asked me where I got the pistonS from. But I only ordered and bought one piston from Nissan.

 

How much did a single piston run you?

 

IIRC the OTC price was <$50. That means you can buy a set for <$300. Not bad for small upgrade to an older VQ35.

 

how you you rate this HR piston compared to a CP piston.

 

Yeah those combined with 440$ eagle rods, ARP rod bolts and JWT valve springs would make a good 8000 RPM engine!

 

OK sounds great but ..........will these HR pistons go in a VQ35DE as is?

 

hmm, is it worth the upgrade to these vs the CP's, taking into account the cost, etc, i would say these are a great upgrade for the money... 300 vs 800.

 

Well if youre opening your engine anyway it would be worth it. These combined with the eagle rods would be good for high reving NA or boost. Both ways IMO. Just cause we have the ''old'' VQ35 doesnt mean we have to dump it lol. Junkyard VQs are so ******* cheap anyway.

 

Now the questions is, $300 is only for the pistons? or does it include the rings and wrist pins? I figure its just the pistons alone...

 

Anyone know what's the compression on them? still 10.3:1?

 

That brings up a good point! All this excitement about the stronger piston design, we forgot about the C/R factor. NA would not be a problem but the c/r is 10.6:1... def not good for boost. Hmm it would be an awesome alternative to getting a new set of pricey aftermarket pistons but that would only be good if this would can sustain FI.

 

True true, as this may be somewhat off topic justin, but i talked to cort, and he runs 40 lbs of boost with 12:1 comp pistons.... ??? I know what your thinking.... crazy *** cort.


With an awesome tune, i don't reckon that this piston would pop...

 

Are these pistons forged or hypereutectic cast? Do the HR combustion chambers have the same volume as the DE? Is the small end diameter the same between the HR and DE rods? Since the HR apparently has smaller valves, would milling the valve reliefs a bit be necessary? Is the compression height on the HR pistons the same? Does nissan offer them in an oversize (service)? Anxiously awaiting the answers from SR20.

 

what kind of tune would be necessary to run these efficiently besides higher octane? Timing advance?

 

The compression ratio wouldn't necessarily be 10.6:1. We don't know for sure yet if the HR combustion chamber volume is the same or if the HR pistons have the same compression height (distance from wrist pin bore centerline to crown deck). Even if the resulting compression ratio is in fact 10.6:1, .3 compression points isn't a big deal considering the pistons strength.

 

.......

 

true but you really can't compare a built 4 banger (not really even a honda motor anymore, I think he runs a Dart block? or some insane race setup) but its more than just tune to handle that much boost.

 

Learning something new everyday. Especially something about internals of a engine and the process of building one.

 

I suppose I should have worded it: "Is there anything you'd need to do differently to run these in a regular VQ35DE so that the slightly higher compression doesn't cause problems?" assuming the compression height and combustion chamber volume are the same.

 

They are cast. Look at the inside detail.

 

Something to keep in mind. The reciprocating assembly comes from the factory at a certain balance weight. Replacing the DE pistons with the HR pistons (if they are of different weights) would require a rebalance of the whole reciprocating assembly. The assembly consists of the pistons, rings, pins, bearings, rods and bolts. This is reardless of whatever problems the CR creates or valve relief diameters in the pistons are.

 

Well if you plan on tearing the motor down to take such an endeavor as replacing the internals, balance and blueprint, micropolishing the crank, redecking the block are just some of the things one should do since they are in there already. The main concern right now is the fitment.

 

You almost sound like you're saying potential fitment issues or the resulting compression ratio isn't important... The balancing is secondary and besides the point. We need to determine what the physical differences between the DE and HR pistons are first.

 

I'm very curious to know why one skirt is wider than the other? What is the theory behind this?

 

Less friction. The wider skirt portion is on the thrust side where it's needed and more narrow on the opposite side where the extra skirt area is unnecessary.

 

Copy and paste straight out of nissanperformancemag.com:
"The pistons have some interesting features, mainly an asymmetric shape with a larger skirt area on the thrust side for good support and a cut down skirt on the non-thrust side for less friction and less weight"

Basically what Nismology said.

linky here: http://www.nissanperformancemag.com/september06/vq35hr/