forged vs. stock 95 pistons

[BryanK]

Hey I've been doing some research into forged pistons vs. stock '95 pistons, and I was wondering what the general consensus was about each? I've heard that the forged pistons tend to slap... the forged metal doesn't expand as quickly as the stock hyperutechnic (sp?) ones and tend to slap around in the cylinders a bit. Anyone have any confirmations of the problems, or experiences to the contrary? Anyone forsee any other problems with the forged over the stockers? I'm really just aiming for ~400 hp, and I realize that forged pistons (on 1g rods in this case) may be a bit much, but I may be able to get a good deal. I'm not looking to raise compression any... sticking with the 8.5, just wondering if there are any other adverse effects of forged pistons. How common is the slapping phenomenon? Can't I eliminate this simply by adding a nice set of rings? Or maybe just let the car warm up for ~10 minutes before driving?
Thanks,
Bryan

 

[larryd]

as far as Ive heard slapping is common on all forged pistons, worse on some brands then others.

You can NOT drive your car until its fully warmed up or youll do damage.

And I heard today that the life of Forged pistons isnt nearly as good as 95 pistons..

just a few reasons I have 91 rods and 95 pistons in my car

 

[flowfx]

ive seen guys here with 9:01+ compression, that must seriously spool a big turbo.

but isnt it dangerous at the same time?

 

[larryd]

just means you should run lower boost.

 

[Thalomos]

I plan on going with 9.0:1 Waiting to spool sux... and making the same power, spooling faster, and runing lower boost (so you hit max boost even FASTER) just seems like a good idea to me

 

[BryanK]

Thats basically the same way I was thinking. I guess I'll just stick with the '95 pistons, and maybe mill the head a lil to up compression some. Is that safe to do? How accurate can you get the compression ratio by doing that?
Thanks,
Bryan

 

[Formz]

I got Ross forged pistons with rings and pins for about $20 more then 95 pistons, so I said why not?

 

[BryanK]

For me, the why not is drivability and durability. Yeah, forged pistons are nice if you're running 25 psi + nitrous, but I'm not planning on going over 20 so I think the '95s will do nicely. I just don't want to deal with pistons slapping around be worrying all the time about 'em. Thats just me.
Is it necessary to let an entirely stock engine warm up before driving? I usually make a practice of letting her warm up for a while, but sometimes I'm just in a damn hurry. I don't let it rev above 3,500 before she's warmed up... could I have caused damage, or where you saying that as pertaining to forged internal motors.
Thank,
Bryan

 

[Copper 95 GSX]

I would go with the 95 pistons. No need to get stuff that your application doesnt call for. By the way, i saw the front bumper... i have my old side markers if you want them. Later,
Cale

 

[BryanK]

Yeah I definately want your sidemarkers.... whatdya want for 'em?

 

[GreenGVR4]

You must let the car warm up fully with forged pistons...also if you go with forged pistons they useually come with Moly rings which start burning up after about 20,000 miles(depending how you treat the car), but they will last longer if you dont run the car hard..and let it warm up completly before driving.

 

[Copper 95 GSX]

Come get em...they're yours. Later, Cale

 

[cmc]

As long as you warm the car up well, you shouldn't have issues. I run forged, but have a spare block w/ 1grods and 95 pistons.

 

[BryanK]

alright thats good to know. Larry, you said if I don't let the care warm up I'll cause damage... what kind of damage? I'm figuring if I can get a good deal on this, I'll just use the the forged pistons, knowing I'll have my '95 stockers if I need 'em. Say I'm running late and don't let the car warm up, will it cause damage to the pistons, or to the entire engine? If it'll screw up my whole engine than I'll just replace them immediately with my '95s and sell the forged ones. If I'll just run the risk of messing up just the pistons, I'll keep the forged until I feel the need to put the '95s in (or possibly just sell them). Whatdya guys think... I might have the opportunity to get a JDM (I know, its just the shortblock so it doesn't even matter) shortblock with Ross 8.5 compression w/ ross rings and 1G rods. Turned and polished crank, knife edged as well (should that be a concern?... on our already crankwalk susceptible cars to remove material on the crank). So yeah, thats basically it. What would you pay? Sound like a decent deal? Here's a link to the add. Whatdya think? What would you pay?
http://www.gopartstrader.com/cgi-bi...gi?request=detail&website=default&ad_id=61724
Thanks,
Bryan

 

[larryd]

im honestly not sure on that.. I know it has to do with the pistons slapping around which would lead me to belive the cylinder walls would get scored up pretty bad

 

[BryanK]

yeah thats sort of the way I was leaning as well. After all, it can't be good on your cylinder walls to have your pistons slapping around like that. Would if matter if I got a good set of rings? Maybe keep the pistons a little more supported?
What do you think of the deal though? Sound decent or what?
Thanks,
Bryan

 

[98TsiAWD]

Are 95 pistons different from 96+?

 

[nothing stock]

If you've never measured a bore, then I propose your talking out your ass.

Forged is good, pistons slap isn't important if it's not slapping when your reving the engine.

 

[Formz]

Originally posted by nothing stock
If you've never measured a bore, then I propose your talking out your ass.

Forged is good, pistons slap isn't important if it's not slapping when your reving the engine.

but if you start driving the car before that slap goes away... you could be running into some trouble. correct?

 

[candela]

Yes 95 pistons have a smaller clearabce compared to 96 plus pistons, only meaning that they might burn a little more oil. That is the onl;y difference that Ive ever heard of. And personally Im doing the same thing, but Im goint with forged 9:1 pistons instead of the 2g pistons, but i do have a big rod 2g setup right now that I will keep for spare if needed.

 

[GreenGVR4]

the reason you have to let the car warm up is because the piston gets hot it expands, thats when the slapping stops... also i have a knifed crank and have had no problems.

 

[UndergroundR32]

Ask Jeff Hill and he'll tell you that as long as the cylinders are bored/honed correctly you wont get slap. That's not to say that you can hop in and drive, but he gave me the impression that your machinist has a huge effect on the long term reliability of your pistons.

 

[BryanK]

I see. And yes, nothing stock, I have measured bore. I personally built an 11:1 compression chevy 402 big block that pushed 624hp/720lb ft. of torque, at 17 years of age (that was last year, but granted I did have an experienced mechanic looking over my shoulder). I have measured bore clearance, and I realize that yes, there is VERY small clearance between the piston and cylinder wall, but I also realize that I know jack sh*t about import engines so I figured I'd get some other opinions. Furthermore, I have no doubt that Larryd has much more personal experience concerning this issue than I, so I had no problems accepting his notion that slapping pistons *might* have the *possibility* of scoring the cylinder walls. And yes, the possibility of having a slapping piston ruin my entire engine is very important to me. I gotta have this car get me through college, some of us aren't fortunate enough to have our mommies and daddies buy us $8K vehicles or put out $2K to buy a new engine. I want this done right the first time. Seeing as how *I* am paying for my college tuition, I can't afford to have this done twice. I'm not saying that you're mom/dad bought you your car, I'm just jealous of those rich sons of b*tches whos parents do, and then have the nerve to tell you how your car sucks.... but thats a different topic. Sorry 'bout the rant.
Anyone take a look at that add? Any thoughts?
Thanks for the help so far.
Bryan

*edit* Nothing Stock, looking back at your mods reveals that you also probably know much more about this topic than I. I know a good deal about domestics, but jack sh*t about turbocharged applications. I'm talking real world experience, not knowledge gained from reading a bunch of online sources. Sorry about the rant, not so much directed towards you as to the entire world. Thanks for your input.