Engine Internals Dilemma

[Seouljer]

Ohh my goodness.
Ive owned a DSM project since october and have been running into issues . Ive made some really stupid mistakes and have had to ask several questions. You have all been great so im reaching out again for some advice. The motor that came with my car was just a bottom end. It had dropped valve and tore up a piston. I dissasembled the block to take a look at the cylinders and see where to go from there. Everything looked great because the bottom end had a fresh rebuild when it dropped the valve and everything was fresh and new. I looked up the code on the pistons and found out that the 6 bolt bottom end I owned had modified 6bolt rods and 2g pistons. So since i needed new pistons and everything in the block looked good i found a set of used evo 8 pistons to put on my already modified 6bolt rods. I also purchased new bearings and rings and other parts to put the motor back together of course. Well i dropped off my block and head at the machine shop to get worked on and they called me back and informed me that the blocked needed bored......CRAP!!!!! Like an idiot i spent money on parts i cant even use!! Stupid mistake. Im still a little mad about it but have mostly gotten over it. Whats done is done and i have to move on to get this car running. My problem is, is that im a little lost about what route to take. My car is a 91 TSI fwd and i would like to make about 400 whp. Options:

NPR 2g pistons on my current rods
EVO 9 pistons on my current rods
Forged aftermarked like a wiseco on my current Rods
Forged rods and Pistons

Sorry to be so long winded. I just want to do this right. The machineshop said the block had to be bored 20 over. Opinions please. Im totally fine with over building the motor but dont want to overdue it unless i have to i guess.

Thanks And sorry again about the long post
Seouljer

 

[WES_393]

Why not swap out the current pistons for NPR .5mm over pistons? It would be cheap and effective.

 

[Seouljer]

Why not swap out the current pistons for NPR .5mm over pistons? It would be cheap and effective.

Definitely the cheapest option . Should I be good to 400whp with NPR's And if i want to go past 400whp then i would have to go another route right? Sorry im kind of being a spaz. Im just worked up because im getting tired of all the bumps in the road to getting this built

 

[reddragon1]

I would use an oem piston and not a cheap copy.

 

[BogusSVO]

I would use an oem piston and not a cheap copy.

You know the oe pistons are NPR?

 

[bastarddsm]

I would use an oem piston and not a cheap copy.

The consensus is that NPR pistons are OEM pistons. Lots of people run them with no issues.

Op, I would just use stock type stuff. Stock 1g style pistons are good for more than 400whp. You just have to not be to aggressive with the tune.

You could run a set of forged pistons on stock rods, but then you have rods that are weaker than the pistons.

Also before you decide make sure your rods are in good shape. If they need to be resized, you might consider buying rods too.

 

[WES_393]

You know the oe pistons are NPR?

That is correct. Nippon, Denso, Mitsubishi: All very closely related.

So with with NPR pistons and 6-bolt rods, you should be good for MUCH more than 400hp. If I'm not mistaken, the record for the stock 6-bolt is around 750hp right now. Not saying everyone can get to that much power safely, but it shows just how strong they are.

 

[greekgodchaos]

OP, this is what is happening to me LITERALLY word for word except for the valve dropping and piston damage, I have the Evo 8 pistons right now mounted to my 6-bolt rods but I am ordering NPR .50mm oversize 2g pistons since NPR is the same company that made the OEM pistons in the first place; same compression ratio increase to 8.5:1 but they are not as light as the Evo 8 pistons, however there is that important factor to note that the NPR 2g pistons are brand new with rings included! If you are like me, you would know it to be the better choice to go with new 2g pistons rather than used Evo 8 pistons...now just have to figure out what to do with them haha Here is where I just bought my new set 2 hours ago. So in the meantime I am taking a dremel to the rough spots in my block to make it as smooth as possible so no bits of dirt or metal find their way into some rough bits.

 

[reddragon1]

I did not know that good info thou.

 

[Seouljer]

Thanks for all the input!!

OP, this is what is happening to me LITERALLY word for word except for the valve dropping and piston damage, I have the Evo 8 pistons right now mounted to my 6-bolt rods but I am ordering NPR .50mm oversize 2g pistons since NPR is the same company that made the OEM pistons in the first place; same compression ratio increase to 8.5:1 but they are not as light as the Evo 8 pistons, however there is that important factor to note that the NPR 2g pistons are brand new with rings included! If you are like me, you would know it to be the better choice to go with new 2g pistons rather than used Evo 8 pistons...now just have to figure out what to do with them haha Here is where I just bought my new set 2 hours ago. So in the meantime I am taking a dremel to the rough spots in my block to make it as smooth as possible so no bits of dirt or metal find their way into some rough bits.

And thanks for the link! I can't believe someone ran into almost the exact same issue as myself! Good luck with your build. I just ordered the npr pistons in the link .020 over same as you.

 

[greekgodchaos]

Thanks for all the input!!





And thanks for the link! I can't believe someone ran into almost the exact same issue as myself! Good luck with your build. I just ordered the npr pistons in the link .020 over same as you.

I am interested since our builds are going down very similar tracks to see how your s and mine turn out. Keep me/us posted on the progress man, I am very interested!