blackeg

soooo, i am contemplating a little bit of boost through an lsvtec with the nippon cast "turbo pistons" . power will be relatively low, 300-350 absolute most. what kind of ptw should be the target here?

the hp goal says it should have a few thou, but with the casting/aluminum used would they not expand much and risk cracking a skirt or slapping around and trashing the crosshatch? this is a longevity build id like at least 50k miles out of it daily driven, but i wont continually boost or drive the **** out of it just some more pep to get around traffic if needed

the original ls motor is already apart, it had 230k miles, sheared the keyway on the underdrive pulley and i was not going to just boost it cuz stock motor can handle 300hp.

TheShodan

iTrader: (14)

So, for that goal, tell me again as I may have missed it, but...what was wrong with stock again?

boosted94gsr

I'm running Nippon pistons with stock LS rods and ARP rod bolts in my setup. Straight LS with about 315whp. I don't know my exact ptw clearance but I just told the machine shop to set it on the loose side of OEM spec but stay within OEM specs. I had the head off after around 300 miles and the cylinder walls still looked good with perfect cross hatching.

IMO Nippon pistons are perfect for your goal. There is a guy on YouTube (I think he is a member here too) with a "how to turbo you civic over a weekend" video, he ran Nippon pistons in his gsr at 420whp for a few years without issues. He eventually made his hatch awd and upped the power to over 500whp. These pistons seem to be pretty tough for how cheap they are.

boosted94gsr

I don't think there is anything wrong with a stock setup for around 300whp, but it is nice to have the thicker ringlands that the Nippon pistons have. I was going to just re-ring my stock LS block, but the cylinder walls needed to be bored to 81.5 so I just bought Nippon piston instead of new OEM. They were only $180 shipped off of eBay. It was a easy choice considering my block needing over boring and the inexpensive cost of the Nippon pistons. Ok enough rambling from me lol.

blackeg

230k miles, gummed up oil control rings, underdrive pulley keyway slot rounded off the crankshaft. (beware the new craftsman tq wrenches they are some new made in china **** ive had a few times where my 20-150ftlb wrench had bolts come loose.) it was coming apart. i know to build it right when it is apart ive been there many times before. this motor would get a fresh stock rebuild as i would have left it stock if it had say like 100k miles no issues. instead of oem pr4 pistons why should i not use the nippons?...

i was doing some searching and found a post were you said the arp replacement studs were good for all motor not for boost. do they have a history of failing on boost? id still have power levels around where stock would be good, just have another 1000 at most rpms

boosted - we would have the same block and power, i would just be running a b16 head with gsr cams, rev limit would be low probably around 8200. i think the oem maximum spec for ptw is .002.

about 5 years ago i had a vitara motor. i set the ptw to .0035 at 75.5mm. i know the motor ran for 12k of my miles and then another year getting its *** kicked by the guy i sold it to before the turbo blew. would that be a good number to shoot for? id like to keep it tight if possible

Runnerdown

No need to set so loose for a mild kick around dd. The oe type cast pistons either break the ring lands or melt from the top down under extreme conditions. Avoiding slap and wear, and having a long life similar to a stock motor is very achievable with someone like you who can tune and evaluate things well.

However, the nippon material vs oem is something to question. My only experience is with RS and oem pistons which are very comparable if not identical. I'm assuming nippon is similar but not 100% sure... especially if they claim to have a "turbo" piston available.

h2.4

when we do vitara's we set p2w at .0022"-.0025. on a b series, I think .0025" would be fine, but we haven't done any cast b turbo pistons, usually forged.

TheShodan

iTrader: (14)

I guess I don't really have a specific answer for that.. I just don't feel that if the pistons are still in good condition despite the rings, I'd just "throw them away." I would have just had the OEM pistons professionally cleaned, checked and used Hastings piston rings and been done with it. With 9.3:1 compression, you can't go wrong. No compression guesswork, nothing.

As for me stating that ARPs were only good for NA and not turbocharging, I don't believe that I would make such a statement, as I don't believe that at all. If you have something on the record (basically on the forum) you want to present to me as evidence, by all means , please let me know, and I can either interpret or fill you in on the context... But as a matter of general principle, ARP studs are just fine for turbocharging.

blackeg

honestly, i was searching around for a few hours pretty late the other night and i thought i recall seeing it. i must have looked through a hundred threads i dunno if i could find it offhand. its all good though, if the alternative is stock ls rod studs ill use the arp its probably the best option for stock rods.


as for the material, i thought they used the same aluminum as the vitaras, which i understood to be "stronger" than what honda uses..

TheShodan

iTrader: (14)

Ah, you mean ARP rod bolts, that replace the OEM ones when doing an NA build.
Not studs, which imply the use of the term head studs. that's completely different.

The use of ARP replacement rod bolts don't do much more for you than the OEM for this particular power level and purpose, as you would have to have the machine shop round the big ends of the rod and hang the piston/rod combination so that they are within balance. For 300-350whp, again, not the best use of machining dollars, unless you really plan to use a bit of VERY high rpms for this engine. Otherwise, I don't think you'd gain any advantage in the build by doing so, but if it makes you feel any better at night, then all means.

That's different than me saying that it is flat out "no good" for turbocharger use vs. NA.

I see where you're coming from now.

boosted94gsr

They state in there discription on eBay that with an LS block and LS head your compression will be 9.2-1.

This is also quoted from thier discription about the alloy they used.

"Nippon Racing has redisigned these pistons to share the alloy of the far superior Mitsubishi OEM Turbo castings"

TheShodan

iTrader: (14)

Its called a "marketing description".. We all deal with this. My statement was merely around the fact that "if it ain't broke, don't fix it" type of thing.

Again, I'm just too old.

blackeg

ahhh, yeah sorry for the confusion. arp headstuds are used in all the motors i build. if nothing else for their re-usability.

im going to hone the block lightly today and check out how big the bore is once cleaned up. ill go from there for what pistons i get and if they are 81 or 81.5mm.

boosted - yeah they yield the same compression as ls pistons, which according to zeal with a b16 head are 9.98:1

ill be honest the winter here was so bad last year and im getting awfully old and lazy i might take the turbo kit off through the dead winter and run a stock ecu of some sort. i can get it inspected at that time too. i didnt think it would be this hard to find a used inline pro manifold but thats another issue

blackeg

well this build is over before it began really. found this #3 cyl after i started honing. caught me by surprise this motor was never beat on. it came from my friends wife's car. she had it for like 10 years and was the 2nd owner. old lady before her. i never had more than bolt ons on it and it only saw above 6000 rpm a couple times.


just to stay on topic, so far ive gathered that there is no need for excessive or even forged piston to wall specs. keep it around .002-.003....agree? disagree?

EsotericImage

iTrader: (8)

Wow, thats where the B20's crack


I also know the feeling of gathering parts, get ready for a build adn take off the head to be greeted with a cracked sleeve..

Good luck to you!

blackeg

i know right lol!

anyhow, i just got a head back from my machine shop so im gonna toss together this 82x89mm 11:1 lsvtec for the car which was the original plan over the winter.

i will try those nippon pistons one day tho

Runnerdown

Wow talk about a surprise. That's sucks.

I'm also working on an 82mm build right now with RS itr pistons.

blackeg

nice! 82mm seems to have good results just thinking of slowsleeper's build off the top of my head. im just going a basic build about 11:1 and itr cams. just want some more pep to pass slow rednecks on my commute. im still gonna have to hit the valley with it just once to see how it does lol.

still cant believe it was cracked. i have another block if i wanted but that has to go to 81.5mm and i was hoping to just be able to rehone and go from there since my machinist has been getting real slow lately

DC_Legacy

Go to NAPA, I bought one from them years ago and it was made in America and can be recalibrated if you have them send it in for servicing......If you buy one at Autozone or Advanced Auto, or other places I know those outfits sell the Chinese knock-off of that torque wrench......its a shame, not a tool you really wanna go cheap on if you ask me but for Craftsman to do that..WTH

blackeg

good to know. i still have my old craftsman 10-80ftlb wrench that works great, this is my newer one 20-150ftlbs that blows. ill have to check napa next time im there