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NA Pistons Found in 6 bolt, Head Question, Parts Find

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Artofschiffy

Proven Member
70
6
Mar 12, 2017
SFV, California
After blowing my head gasket and learning more about my 90 TSi AWD, I have found a cluster of red flags and have some other questions I am looking to find answers to.

The bottom end of this motor was recently rebuilt by one of the previous owners. This is the original block from my 90 TSi AWD. Balance shaft has been deleted and I just discovered "63D" NA pistons while taking of the head. The notches on the intake/exhaust are different sized and from what I've read these are less durable and have a 9:1 compression ratio. No wonder why my compression was 178-180 throughout the 4 cylinders.. Am I going to be okay running with this bottom end setup?

The top end was a 2g head and a 1g intake manifold. No port matching or oil mods were done to it so I ended up buying a 1g head. I purchased the 1g head to replace the 2g head with and the only info I received was "ported, ss valves, aftermarket springs, and ti retainers". Well after doing research and taking measurements the head has dual valve springs and +1mm oversized ss nitride intake and exhaust valves. I believe the aftermarket parts are all from supertech. Head thickness is close to spec (5.2) and the surface is flat. Should I check for valve clearance and is this head okay to use with the NA pistons? Also something looks like it dropped where the head bolt washers go and has made a gash. Is this okay or do I need to take it to a machine shop? (pic below) Going to be installed with ARP head studs and felpro composite.

I purchased a bundle of parts pretty cheap from some guys that mainly sell used domestic parts. This is what I ended up getting: Quaife QDH8B front differential for dsm awd, new whiteline GVR4 racing springs, one camshaft, and 2x 1G heads (one fully assembled for probably a decade and the other was recently rebuilt but has no cam caps, crower springs, stock valves, but the surface appears do have been dragged on asphault aka paper weight). I may end up trying to sell everything but the heads but does anyone have this quaife front diff and would you recommend it? The camshafts are pretty rusted, could I even clean them up to have them running again? Don't appear to be stock, but I can't even get the cam gears off to see if anything was engraved by the dowel pins.

Biggest concern are the NA pistons and the built 1g head with oversized valves. What should I do about the pistons? Run it until it needs a rebuild?

Any info would be greatly appreciated, I just want my 1g up and running!!
 

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As for the NA pistons im sure they will be fine. I personally don't have any experience with them but as long as your cams are not excessively huge I don't see any issues, but @bastarddsm would know, he's ran them.

Now with the gash in the stud hole, the only thing I would do is just re round the hole with a Dremel where it appears to be slightly smooshed and call it good, as long as the washer isn't going to pull through, looks good to me!
 
^ all OEM DSM pistons are cast. I've not really had many problems with running boost with n/t pistons. I went 107mph with them, and probably could have done more. I wouldn't worry about them on a stockish setup, just keep the tune on the mild side and you'll be fine. My beater GGSX has a n/t engine in it. Turbo and E85 on it. Valve releifs are probably too small for big valves.
 
As for the NA pistons im sure they will be fine. I personally don't have any experience with them but as long as your cams are not excessively huge I don't see any issues, but @bastarddsm would know, he's ran them.

Now with the gash in the stud hole, the only thing I would do is just re round the hole with a Dremel where it appears to be slightly smooshed and call it good, as long as the washer isn't going to pull through, looks good to me!

After figuring out the different pistons with smaller reliefs and having oversized valves I was probably going to run stock cams. Do you think I'll be okay?

^ all OEM DSM pistons are cast. I've not really had many problems with running boost with n/t pistons. I went 107mph with them, and probably could have done more. I wouldn't worry about them on a stockish setup, just keep the tune on the mild side and you'll be fine. My beater GGSX has a n/t engine in it. Turbo and E85 on it. Valve releifs are probably too small for big valves.

I plan on using stock cams with the oversized valves. Do you still think they will be too big for the smaller reliefs on the NA pistons? I don't plan on going running my 1g very hard
 
As long as you're running close to stock like Bastarddsm says, you wont have any problems with those pistons. I've done 4k miles with 10:1 N/A pistons and a T25 on stock tune without issue, although I'm sure with a good tune you can extract more from the higher compression and fix the AFRs. Between the turbo and N/A blocks, I am 99.9% sure the deck height and compression heights are the same. The only real difference is the flat top on the N/A and the indented turbo pistons. Valves are all the same between engines (correct me if I'm wrong?) so the reliefs will match in any case. And by that logic, your oversized valves should be fine with the N/A pistons.
 
As long as you're running close to stock like Bastarddsm says, you wont have any problems with those pistons. I've done 4k miles with 10:1 N/A pistons and a T25 on stock tune without issue, although I'm sure with a good tune you can extract more from the higher compression and fix the AFRs. Between the turbo and N/A blocks, I am 99.9% sure the deck height and compression heights are the same. The only real difference is the flat top on the N/A and the indented turbo pistons. Valves are all the same between engines (correct me if I'm wrong?) so the reliefs will match in any case. And by that logic, your oversized valves should be fine with the N/A pistons.

Awesome! That's what I wanted to hear. I'm going to be running stock cams just to be safe so I don't think I'll have issues with clearance. Thanks!
 
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