Nippon NPR pistons.

[gixxer750]

Come on, thats a bit of stretch! Youd have to get lucky to hit the frequency the knock sensors are looking for with piston slap. Not to mention if it doesnt go away once warmed up... somebody built it to loose.

A properly rebuilt motor should last just as long as stock, how does stronger parts = shorter life span?

How many forged vs stock engines have you built and ran at high power levels?


I've built many many properly, and I am offering up my opinion on the matter.

I will say this. Some of the best/longest lasting/quietest pistons I've seen for an M series are wiseco. I prefer a stock engine all day long if it can withstand the requirements for the horsepower goal. ANY 2jz I build for someone I would highly recommend them to stay with stock internals at anything under an ultimate power goal of 700 or less. Anything over that I would recommend aftermarket rods. The stock pistons are fine to over 1000 whp. The rods are the weak link above 800. The 7m has a similar situation. You will most like bend or break a connecting rod in a properly tuned engine at 600+ horsepower before you hurt a piston.

 

[grimreaper]

You really think because its forged it wont last as long? I think its in the build and the builder.. All pistons have SOME amount of slap on start up...

I personally have not built any forged motors but have had three built for me. All forged, all different trucks, all different setups and ALL ran 100% as they did stock after the N2o or boost that was put through them. One was my DD and my work truck for 100K... not one issue with it when i sold it. Only reason that one was rebuilt was the stock ring lands and piston crown were known for cracking and breaking under extreme psi...

 

[gixxer750]

Yes, a forged motor REALLY won't last as long as a stock setup, as long as the power stays within the reliable power window for the stock parts.

 

[grimreaper]

fair enough... you have had motors torn apart because of piston slap an bore wear?

 

[Hmong_1G]

I going with NPR piston set from Driftmotion. I would like to run chrom moly rings though. Hum... o well. I will be getting the necessary parts from Driftmotion.

 

[gixxer750]

I going with NPR piston set from Driftmotion. I would like to run chrom moly rings though. Hum... o well. I will be getting the necessary parts from Driftmotion.

You will be much better off with a mild steel ring.

It is VERY hard to get a chrome ring to seat in a toyota block. It has to have a very aggressive hone and a VERY aggressive break in. If you let it idle for a while on first start, or it is running very rich, you can kiss ring seal goodbye. A chrome ring will last longer, but chances are against you seating it correctly on the rediculously hard cylinder walls of the 7m.

 

[williamb82]

stock 7mgte rings are chromoly.

 

[Hmong_1G]

stock 7mgte rings are chromoly.

HUM....they are?

 

[IJ.]

Seems to be some misunderstanding/confusion of the various ring materials...

CroMoly is a steel.

Chrome is a plating process and is very hard and as mentioned has a hard time seating in a 7M unless it's been honed with an agressive finish.

Moly is another surface prep that uses a ring with a groove in it's face that's filled with molybdenum and is prone to flaking/failure on engines that see detonation.

 

[CyFi6]

So what rings are the best choice for a BPU build? OEM? Are the prices rediculous for OEM? Are there any aftermarkets that make a similar ring to OEM?

 

[CajunKenny]

^Good question that I would like to see answered also.

As far as the Forged NPR Piston, my buddy just pulled his 7MGTE engine apart because of run-ability issues and four of the six pistons had failed. If I remember right...Two were cracked between the rings and the other two were cracked/broken toward the top. I'm pretty sure this is within 1k miles; but, don't know the mileage for sure. I 'think' he got them off ebay.

I know that there are a LOT of factors that determine piston/engine life and I'm not necessarily knocking NPR's. I'm just stating an instance...

 

[gixxer750]

So what rings are the best choice for a BPU build? OEM? Are the prices rediculous for OEM? Are there any aftermarkets that make a similar ring to OEM?

I would say an oem build would be best.

I personally believe that the OEM piston "quality" is better than that of many aftermarket forged "quality".

Note in above, I am not saying the oem pistons are "better", but the quality is most likely better than the forged and more thought put into the design. Many aftermarket ones are either a clone of the stock piston top with other revisions to reduce weight, or a generic piston top that they use throughout most of their import lineup. Probe however seems to be an exception to this, as they were actually "designed" mostly by members here on the board that know WTF is up, and know far more than I do. A few of them should chime in on this thread.

Side note - probe industries 2jz pistons are crap. They are not NEARLY as strong as the stock pistons.

 

[BrandonW]

what are the rings that come with the real npr pistions made of?

 

[CyFi6]

OEM Pistons also cost about $50-$60 a piece... And a piston ring set costs around $200

 

[CyFi6]

Cajun can you please get more info on these and pictures? Im doing a build right now and want to go with stock internals, but i also dont want to pay $400+ Just for stock pistons/rings when thats costs just the same as forged almost. I dont want to use NPR's if they are cheap and shitty either though.

 

[CajunKenny]

He's on this forum and his handle is JMBSupra. I would suggest sending him a PM. He's a machinist so he knows metal!

He said that after a closer comparison between the NPR's and the Stock pistons, he feels that the stock ones are better. He based this on the fact that the casts are better and better material used. He also found that the stock ones have thicker side skirts over the NPR's. Again...he's a machinist and knows metal.

He's rebuilding using stock pistons.

I'm sure he'd be glad to relay his experience and thoughts.

Good luck!

 

[Hmong_1G]

He's on this forum and his handle is JMBSupra. I would suggest sending him a PM. He's a machinist so he knows metal!

He said that after a closer comparison between the NPR's and the Stock pistons, he feels that the stock ones are better. He based this on the fact that the casts are better and better material used. He also found that the stock ones have thicker side skirts over the NPR's. Again...he's a machinist and knows metal.

He's rebuilding using stock pistons.

I'm sure he'd be glad to relay his experience and thoughts.

Good luck!

This could be a bit concerning.....:aigo:

 

[BrandonW]

is it a bad idea to use the rings that come with the npr's?

 

[7thousandpiecesMGTE]

I would say an oem build would be best.

I personally believe that the OEM piston "quality" is better than that of many aftermarket forged "quality".

Note in above, I am not saying the oem pistons are "better", but the quality is most likely better than the forged and more thought put into the design. Many aftermarket ones are either a clone of the stock piston top with other revisions to reduce weight, or a generic piston top that they use throughout most of their import lineup. Probe however seems to be an exception to this, as they were actually "designed" mostly by members here on the board that know WTF is up, and know far more than I do. A few of them should chime in on this thread.
Side note - probe industries 2jz pistons are crap. They are not NEARLY as strong as the stock pistons.

I'd like to hear more on this, I wasnt aware of that.

How good are the probes compared to stock as far as quality and design?

 

[gixxer750]

The "design" of the probe piston was a joint effort between probe and some HIGHLY technical supra owners. They designed what they believed to be the best piston design wise for the 7m. Search around, find the old probe group buy thread.