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1G 6 bolt piston options

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dwb

Proven Member
813
560
Sep 9, 2021
Broomfield, Colorado
I'm looking for some replacement piston options for my 6 bolt 4g63 turbo engine. Not looking for forged (unless the price is right) or anything with higher compression. Basically I'm going with a stock-ish rebuild. My current stock pistons have valve marks on them and I've considered fixing them up and running them, but still weighing my options.

Are there any aftermarket pistons that are compatible with 1g rods with stock compression that won't break the bank? I've read up on 2g pistons, but I'm shying away from them for a few reasons - higher compression, requires machining 1g rods, oil squirter interference, and availability.
 
Stupid question, but ive seen it before. You sure they arent the normal indentions they have for the valves?
 
I'm looking for some replacement piston options for my 6 bolt 4g63 turbo engine. Not looking for forged (unless the price is right) or anything with higher compression. Basically I'm going with a stock-ish rebuild. My current stock pistons have valve marks on them and I've considered fixing them up and running them, but still weighing my options.

Are there any aftermarket pistons that are compatible with 1g rods with stock compression that won't break the bank? I've read up on 2g pistons, but I'm shying away from them for a few reasons - higher compression, requires machining 1g rods, oil squirter interference, and availability.


I didn’t have a single issue with oil squirter interference on my 6 bolt w/ 2G pistons. Any decent machine shop should be able to bore the wrist pin hole 1mm over to fit the 2G wrist pins and honestly the bump in compression is super nice for a street car. Even on a stock 1G map.

As far as availability goes, the NPR pistons are a proven performer and still readily available. Here’s one in 0.040” over for $160 from eBay.


Here’s some 0.020” overs. Same price.

 
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I didn’t have a single issue with oil squirter interference on my 6 bolt w/ 2G pistons. Any decent machine shop should be able to bore the wrist pin hole 1mm over to fit the 2G wrist pins and honestly the bump in compression is super nice for a street car. Even on a stock 1G map.

As far as availability goes, the NPR pistons are a proven performer and still readily available. Here’s one in 0.040” over for $160 from eBay.


Here’s some 0.020” overs. Same price.

Good to know! I guess I didn't look hard enough. ROFL

That doesnt look bad. Smooth it out and send it.
Right? I'm on the fence about this one. It's getting a rebuild anyway...
 
Right? I'm on the fence about this one. It's getting a rebuild anyway...


Honestly those don’t look too bad. Just deburr/sand those spots smooth and send it. I wouldn’t bother with replacement pistons unless you specifically wanted a bump in compression or were going forged.


Work smarter not harder.
 
Seems kind of academic as you haven't torn it down yet. You may find you have to get new pistons given your mileage. You wont know until the machinist looks at the block. If it can be cleaned up and those pistons are good (on the side also) then it's your choice.
 
Seems kind of academic as you haven't torn it down yet.
Sure I have, but I'll be the first one to tell you I have no idea what I'm doing ROFL

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:D

Just for fun, here's what 270k miles looks like (yes, #2 has a broken ring)
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As we have already mentioned in your other post, when the pistons contact valves, generally the contact marks on piston top is not the most concerned part. Damages on wrist pin boss and ring lands etc are, and which we can not see it without disassembling. Usually it's fine, but in some cases it's not. I have reused the pistons by smoothing contact marks without any issues but I have also seen some pistons got slightly deformed or cracked in wrist pin boss by hitting valves.
To fully inspect wrist pin boss, you should remove the wrist pin. And you have to ask a machine ship to do that if you don't have proper tools for that since OEM pistons/rods have a press fit wrist pin. They would probably charge for removing/re-installing pins and inspecting pistons. So if you don't do it by yourself, I would use that money to buy a new piston kit.
 
This is great information. Thank you everyone for your valuable input. I seem to have some possible mis-information about 2g pistons, so I'm going to be digging into that some more. Furthermore, I will be getting the block/crank to a machine shop so I know what I'm working with and what parts I need to throw at it. I'm beginning to lean more towards a new set of pistons and rods, if for no other reason but piece of mind.
I apologize for so many questions and seemingly repeat topics, but your advice is not falling on deaf ears. Much appreciated!
 
I'm guessing you're thinking about 2g pistons. They don't fit. It required custom machining to the rods you have. Years ago it was a "budget" solution. There are lots of piston options available now. Rather than incur the machining costs just buy better pistons that fit.
 
I'm guessing you're thinking about 2g pistons. They don't fit. It required custom machining to the rods you have. Years ago it was a "budget" solution. There are lots of piston options available now. Rather than incur the machining costs just buy better pistons that fit.
Thinking, yes, but not without due diligence. If we're talking budget solution for a ~stock setup, what would be today's choice for piston/rod combo? Something like this? https://www.ebay.com/itm/161974975522?hash=item25b675fc22:g:SaoAAOxyni9TCZ4h
 
I have a motor with a set like these in it on one of my stands. Its built and ready to go into a car and they were not a junky set. This set is a standard bore and you would have to have any machine shop "hot rod" the small ends to put them on. It is something machine shops do all the time, or used to. The Hi Performance pistons and rods use full floating wrist pins with locks on both sides of the piston.
 
My experience with NPR pistons has been...less than positive. I chose to do the 2g pistons on 1g rods to keep it cheap. They lasted maybe 300 miles or so. Decided to go with a Wiseco set for the re-rebuild 2.3 upgrade. Was pushing maybe 25psi on these. But longevity all depends on your power goals.
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I'm guessing you're thinking about 2g pistons. They don't fit. It required custom machining to the rods you have. Years ago it was a "budget" solution. There are lots of piston options available now. Rather than incur the machining costs just buy better pistons that fit.

I kind of disagree. NPR pistons are $160 shipped, you’re going to need the block machined one way or another even if you get forged pistons instead so I’m not including that cost, $150 max for the rods to be machined out 1mm and the pistons put on the rods(local guy quoted me this today). You cannot put a full floating wrist pin on a stock dsm rod without machine work(at least to my knowledge. Someone will correct me if I’m wrong) so either you’ll need to machine the stock rods for a forged piston, or go with a set of aftermarket h beams.


Cost vs cost it’s $310 for brand new 2G pistons on 1G rods with machine work included and ready to drop in and go.

Forged pistons and rods are gonna be $850-$900 minimum combined for eagle/wiseco if you can find a screaming deal. Extreme psi has a package deal for $940 shipped for them but that’s the cheapest “quality” forged piston and rod combo I could find.


Way cheaper to go NPR 2G pistons on 1g rods.

Or just grab a set of brand new engine tech 1G pistons for $130 and just have a machine shop put them on.
 
My experience with NPR pistons has been...less than positive. I chose to do the 2g pistons on 2g rods to keep it cheap. They lasted maybe 300 miles or so. Decided to go with a Wiseco set for the re-rebuild 2.3 upgrade. Was pushing maybe 25psi on these. But longevity all depends on your power goals.
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Why haven't you posted that in the Carnage thread.....man that suks!!!
I did a short list of rebuild costs and this is what I came up with, I didn't include machine shop work but the pricing was just pulled off of one if our vendors parts.
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My experience with NPR pistons has been...less than positive. I chose to do the 2g pistons on 1g rods to keep it cheap. They lasted maybe 300 miles or so. Decided to go with a Wiseco set for the re-rebuild 2.3 upgrade. Was pushing maybe 25psi on these. But longevity all depends on your power goals.
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That is clearly not the pistons fault. Either had a fueling failure/ran lean or was poorly tuned to a lean condition. More than enough evidence there showing a lean condition. No piston would have survived that.
 
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