Using non-turbo pistons in a TSI? Passable, Bad, or Very Bad?

[madcows]

Ok, I know this probably sounds ridiculous, and in reality probably is, but I'm going to ask it anyway in the hopes I get an informative reply instead of just being called an idiot. Here it goes..


So I just got my block back from the machine shop where it was bored over (from .5mm over to .75). I was initially going to buy some NPR pistons, but decided to just let the shop order some aftermarkets, and have them swap over the connecting rods. I know I sound like a horrible person for having no idea what brand they bought (there looks to be a logo on the inside of the piston skirt that is a sort of S inside a circle), but that's the sad reality. As far as I know, the old pistons were from a 2G turbo - the stampings on them were 63DT-F1 - whereas the current ones just say 63D. So from what I've gathered on my own, these are 1G NT pistons (or did 2G NT also have this stamping?), and therefore 9:1 CR. Since I was planning on having 2G T pistons anyways, is an additional .5 in CR a huge deal? My intention is to have a mostly stock daily driver, but maybe push it up to 250hp some time down the road. This project has already been one hassle after another, and I just want to put the damn thing back together already, but of course, I also don't want to have to go through all this crap again in a couple months. So what I want to know is, is using NT pistons a bad idea, or should it be safe with the stock tune, and maybe reduced boost? What about down the road if I want to get ~250hp? I don't really want to have to go back to the machine shop, but if using these pistons is just asking for trouble, then I certainly will.

Cheers

 

[VetoJuice]

If they are in fact NT pistons they will have weak ring lands which will not hold up to the power, at least not for very long.

 

[FearlessNick]

I don't know much on turbos. But I'm pretty sure you need to run low compression and the N/A pistons are high compression. I couldn't tell you what would happen. But I know running a set up that's not right can cost you money in the long run.

Basically what I'm saying is do it right. Save you time, hassle, and money.

 

[99ECLIPSEGSXDSM]

NA Pistons will not be able to handle much boost. 6-8 psi maybe

 

[jayson427]

even if you went over 250hp i think you would be fine on the pistons. its the rods if anything that would be an issue. if your bore matches the tolenences then you should be alright. i think the stock ecu would adjust for the little bit of CR that your going up to. i would read around a little bit more tho, im not up to par on 1g's like i am 2g's. just from reading around i dont think you would be in trouble. i would find out what kind of rings they are using for the piston tho then post back.

 

[Cdc1221]

Without someway to tune, youll just kill the rods. 1gs run an aggressive tune factory because its 7.8:1 CR. Read this...

http://www.dsmtuners.com/forums/art...s-need-timing-control-h20-meth-injection.html

Keep in mind this is for 8.5:1 CR 2g TURBO pistons

 

[RamenPride]

The ring lands on NT pistons is higher up than those on a turbo piston. The rings will crack, break, etc. at the first sign of knock.

 

[donniekak]

NA Pistons will not be able to handle much boost. 6-8 psi maybe

They handle boost fine. What they don't handle is any detonation at all. Unless you have a way to adjust the factory timing table, which is almost to aggressive for 7.8:1, the 9:1 pistons will shatter quickly.

 

[cmfd]

i ran a stock 6 bolt nt i pulled out of a junk yard at 19-20 psi on my 16g for about 6 months. ended up spinning main bearings. i do have bigger injectors and link tho.

 

[DROPthatCLUTCH]

People around here will do for some cheap power.
If you want the thing to run good for years, build it right. If you always wrench on your dsm and it's not a dd then throw some NT pistons in that bi*** and run it hard man!

 

[goldeninja20]

I broke 2 ring lands on 1 piston running 12 psi for about 150 miles )': So please do not do it. The ring lands are indeed very weak.

 

[awdtalon4451]

Can you do it? Yes, would I do it? Hell no!!... I cant emphasize that enough . Why chance it on a fresh rebuild? Seems like wasted money if you ask me. If I were you I'd chalk my loss and buy the right pistons.

 

[clipto]

Hence why there in non turbo cars.

 

[Mischif]

I've always been under the assumption that the n/a pistons can handle up to around 15psi of boost. It all comes down to your tune though.

 

[Arthris]

2G turbo maps are very conservative. 1Gs are aggressive. Justin beat me too it . I would look into some sort of tuning.

 

[madcows]

Thanks for all the replies..


As far as I know, the rods are from a 1G, but they had 2G pistons on them before, which from my understanding would have necessitated the small end of the rods to be bored out to accept the larger wrist pins. Yet, these pistons just have a 64D stamping - can anyone confirm whether the 2G NTs also used the same stamping? If these are indeed 1G pistons, it doesn't look like they have been bored out to accept the larger pins... Hmmmmm..

I'm really trying to avoid having to tune it at the moment, but this is putting me in an uncomfortable position. Would I like to just be able to throw in 1G turbo pistons? Yeah. But what do I do with these rods if the small end has been bored out? I should probably just go back to the machine shop and have them get the right pistons (I told them it was a turbo), but now I'm feeling a slight bit of discomfort going back there, as they have caused expensive mistakes on one of my dad's car before too. Is it ok to bore our the pistons to accept larger wrist pins?

I probably shouldn't have got a DSM if I wanted to avoid some of this:

 

[boost97gst]

Yup, NT rods would be the weakpoint. Far more than the pistons would.

Dont beat up on yourself so much, bud. It will all work out. These cars kick everyones ass at some point or another

 

[donniekak]

Yup, NT rods would be the weakpoint. Far more than the pistons would.

Dont beat up on yourself so much, bud. It will all work out. These cars kick everyones ass at some point or another

Nt, and turbo rods are the same in a 6 bolt.

To the op. if they already messed up something for a family members car, why take your stuff there?

 

[pauleyman]

I should probably just go back to the machine shop and have them get the right pistons (I told them it was a turbo)

Why are you even asking? It's their mistake, make them fix it. It's nothing to measure the rod ends to see if they've been modified. If they are stock order 1g turbo pistons. If they're modified to accept the 2g wrist pin then order 2g turbo pistons.

 

[1gslotsi]

1g rods are the same or they not na pistons are 9:1 and i thought 91and 92 were the big rods?

 

[pauleyman]

6 bolt rods are 6 bolt rods whether it's turbo or not. 7 bolt rods are the same whether 1g or 2g. Obviously there was no 2g 4g63 NT so NT 7 bolts are limited to years 93-94. Spyder may count but it isn't a point of this discussion.

 

[madcows]

@donniekak

They supplied my dad with the wrong crank and rod bearing set before, though it seemed like a honest mistake. Now that this happened, they seem a lot more questionable. I don't intend on giving them my business in the future.


@pauleyman

I'm not so sure that I even want to go the 2G piston route, as I don't intend on having the car tuned any time soon. So that's why I was wondering what the consensus around here is concerning having 1G pistons bored out to accept 22mm wrist pins.


As far as the current rods are concerned, they were the ones that were originally from the car - 1990 TSI

Ok, just checked - the wrist pins are indeed 22mm.. Now to decide whether I should buy 2G turbo pistons, or 1G and have them bored (if possible).

 

[pauleyman]

1G and have them bored (if possible).

No.
You do know 7 bolt 1g pistons are the same as 2g pistons except for compression ratio. This why its very easy for 1g 7bolt guys to use 2g pistons. If you are 100% positive these rods have been modified you can use 93-94 1g pistons.

 

[brownie956]

If you're using NT pistons, you're just asking for trouble. You may be able to run a few lbs of boost at the very most..NA internals do not see and aren't designed to withstand the heat and pressure that turbo internals do. Get yourself some turbo specific pistons.

 

[madcows]

@pauleyman

I have verified that the rods have been modified. So what you're saying is that the 1G pistons from a 7 bolt have the 22mm wrist pins, but their compression ratio is the same as the ones used on the 6 bolt?