TunerMax

iTrader: (2)

Well I'll leave this wide open for now, in the hopes of gaining some good input.

I'm building an engine to put into my DAILY DRIVER, that sees weekend race duties once in a while (Road courses). I don't want to just thoughtlessly slap whatever-everyone-else-uses forged pistons in it and end up disappointed.

My primary concerns/wants:

- STOCK noise level (as possible). I do not want piston noise from these
- STOCK reliability (as possible). They should not wear out faster than a stock 350's pistons would
- Minimal/no blowby when cold. I will be starting this car and literally driving away immediately, regularly. I cannot be forced to let the car idle and warm up for 5 minutes before being able to drive it.


The car is Vortech supercharged, Si Trim. Currently 400 WHP (detuned). Goals are another 50-100 WHP out of the kit. I'm still running stock intake, exhaust and cams, etc with the old (stock) engine and making 400 WHP detuned, so I can't see another 50-100 WHP being out of reach from this kit with supporting mods.

I want the pistons designed to easily handle 12-15 PSI of linear SC boost, 7000~ RPM, and 600~ WHP. Obviously I won't be putting 600 WHP to them, but I want them capable of handling it.


Soooo, hypereutectic? Forged? I do have a budget but it's flexible as long as I'm getting what I want. my biggest concern is noise, reliability, and oil consumption/blow by. Searching led me to expected 'forum answers' of just "put this in, that's what I did". I would like to have a lot more information before deciding, so if anyone has any links to good threads or good reads that are VQ35 specific about pistons/brands I would absolutely love that!


Thanks for any/all input gents!!!

-Matt

djamps

iTrader: (1)

Clearances are by far most important for your requirements than piston (anything other than stock is 10x better and probably more than you need). Why are you so focused on piston type anyways?

RudeG_v2.0

iTrader: (1)

I don't see the point of the time, labor, and expense to tear apart the motor to upgrade the rods only. Stock pistons have had their fair share of blow by/OC issues too. I'm also skeptical that about your noise concerns as well, especially above the noise level of the Vortech SC. I'd go with CP 9.5:1 pistons for a built block Vortech setup. Just advise your engine builder of your concerns and it's intended use primarily as a daily driven street car.

jerryd87

iTrader: (4)

dude seriously you need to spend some time on google and learn how these things actually work ill help out because this honestly isnt something that is asked very often, i can tell you right now your list of demands are exactly why this platform has a **** reputation for reliability they want stock type noise, smell, huge power but then get pissy when the engine blows because it is built so tight to meet there noise requirements.

im sure you have heard "cheap, fast, reliable pick two" well heres another one that is equally true "power, reliability, comfort pick two" where noise, smell, and other things people dont seem to like fall into comfort.

first thing is first, you want stock noise level, leave it where it is, a higher power engine generates more heat cooling system eliminates alot of it but it dosnt do **** for the rods, pistons and crank journals getting hotter thats oil and fuels job, you can cool the oil but it dosnt cool till after it has already ran through the engine. the ENTIRE reason race engines are noisy is because you cannot bypass thermodynamics more power is more heat plain and simple, the only way to stop from blowing a engine from additional heat is larger clearances to account for the increased expansion, increased clearances make a looser engine which results in more noise.

second reliability dont touch the engine more power means less reliability plain and simple you cannot bypass physics with parts.

minimal/ no blowby, again see number one your making more heat which means larger clearances you can have your stock power level and little blow by or more power and more blow by. no blow by on a higher power level means under high heat track conditions your going to butt the ring ends togeather and snap your piston lands off. blow by has 100% absolutely nothing to do with pistons it is merely a result of ring gaps, ring quality, and ring seat im a very big fan of the "aggressive" ring break in.

finally on to the piston choice, i have searched high and low and done extensive research into vq pistons, no one makes hypers for the car. IF they did or if someone is now offering them since its been a couple years since i did my research then hypers are technically much stronger then forged pistons, by alot actually. they have two major downsides though, they are extremely brittle meaning the tune has to be absolutely spot on right from the start, any det under load is going to shatter them, and they have a greater amount of expansion leading back to that whole looser engine and more noise thing.

forged are used because they are weaker but they have more flex to them absorbing things that cast and hypers would normally shatter with but technically there different strength limits are lower(perfect tune the hypers will handle more good luck with a perfect tune) as well as lower expansion.


people need to get the whole high hp and stock levels of noise, smell, maintenance out of there heads. ask any engine shop, ask anyone with a high power car, its not possible when you start putting bigger power per rod like that, a street car could mayby get away with what you want, absolutely not a track car even the street car wouldnt be able to be pushed hard.

TunerMax

iTrader: (2)

Thanks for the responses so far!

Yah I don't plan on doing only rods

Thanks! Yes the Vortech is currently loud, I hope to quiet it down quite a bit soon as well, most of the noise is from the BPV once you raise idle RPM. But you're right, noise is subjective, and everyone's opinion of what is 'loud' is different. I'm not dilusional lol.
I like to be able to pull up to the house at midnight and not wake the neighbours or tenants. I also want to be able to start the car at 530 AM for work in the morning without it rattling and screaming away, which is something I can't currently do.



I'm building the engine, but I will be sending it out to have the crank checked out and have the block honed/bored obviously. I will be the one doing the research about which pistons and clearances I require, which, I though, were set by the piston? Don't pistons come with a working clearance specification because they all expand differently?
Sorry if my ignorance is showing here

TunerMax

iTrader: (2)

1st, thanks for the reply and all the great information!! I am obviously new to this, it's my first engine build, and I appreciate it!

2nd, sorry I struck a nerve, but relax, I never posted a "list of demands", I actually said WANTS and AS POSSIBLE. I'm not dilusional, whatever the engine needs to be safe and still put the power down, it will get. Which is the entire purpose of this thread and my research. I don't plan on selecting or installing anything until I fully understand my options and the reasons why I should/shouldn't do it different ways.

I guess I should be more specific, I would PREFER a sleeper, something that doesn't sound broken when idling, and something that only makes a bunch of noise when I step on it. I'm not expecting miracles, reliability and function are more important. I don't want the engine to blow.



Well I have been looking briefly and so far I haven't found then either, so I would assume that you are correct. I haven't put a full list together of options, perhaps I should do that first, I guess, apologies that I'm still learning order of operations here, I"m kind of jumping around, lol

My thought was the hyper's don't expand as much so I don't need massive clearances. Similar is the difference between 4032 and 2618. I want very much to use 4032 here, if possible, for the same reasons. It sounds like this will give me the best of both worlds, low expansion, while retaining high strength and reliability.

As far as CR is concerned, I'd really prefer to keep it around stock. 10:1 or close there-abouts. Again I need to research my options some more clearly and post back findings.

Triji

iTrader: (2)

LOL.... 1st, you got a Vortech bro, get used to the sound... The blower sounds like a rattle can at lower RPM's and at higher you will get the blower quieter but have more engine / bypass noise... Just the way she is... At least mine anyway...

2nd, the 9.5 seems to be the best CR for a Vortech and a balance of safety / power... Lower than that she feels doggy and above that you need to make sure you have a spot on tune to be safe... Or good gas / E85

djamps

iTrader: (1)

The exhaust should be your main concern if you are worried about neighbors. Only bass will go thru closed doors/windows/walls. Loose clearance engine rattles are nothing compared to your blower and/or exhaust.

Resmarted

iTrader: (2)

There are going to be limitations on how tight you can run it.

But for your piston question, stay away from a high aluminum content piston. A wiseco for example is a high aluminum content piston, which requires more piston/wall clearance which means more piston slap on cold start. A je or cp piston has a higher silicone content allowing for a tighter piston wall clearance, as silicone actually expands less under heat. My wiseco pistons for example have a 4 thou piston to wall clearance, which is quite loose and will slap plenty. The reverse side to this is that a higher aluminum content piston is going to be 'stronger'. BUT the CP/JE's etc pistons can handle more power than you'll make so don't worry about it.

jerryd87

iTrader: (4)

didnt strike a nerve i was being nice, ask the regulars on the forum thats about as nice as i get lol.

broken sound when idling is perfect because no one really suspects i know the sleeper look very well my car looks like ****. the conversation usually goes "dude you just put a shitty hood on your car and some wheels nothing special" me "$500 minimum race" other person "ok" other persons buddy "dude you really dont wanna do that, just look inside the interior in the car" other guy "oh ****........ nm" my car is loud as **** too between the increased tick from the cams, 4 inch exhaust, and other things and people still buy into the sleeper thing just because the car isnt pretty, heck even flat paint goes a long way.

the hypers expand more because all they are at the end of the day is cast pistons with additional silicone, more silicone means more expansion but higher strength, the fact they are cast still of sorts is why they are brittle(instead of being put under pressure after casting like forged) guys are running HR at 500 whp so stock should be fine but you will likely need a meth kit since you supercharged, 500 hp on a supercharger and turbo is different if you are making 500 on the blower plan for 560-600 because while you will only see 500 at the wheels the engine is making alot more due to parasitic losses on the supercharger(blower is also a misnomer that refers specifically to roots style chargers since they compress by moving the air vs centrifugal and whipple types which actually compress inside the supercharger and are true compressors) so a supercharged engine will be under greater stresses

the reason everyone uses pistons like cp or arias extreme are because they are a top quality product, one of the best you can buy in the united states, if you buy outside the country there is wossner which offer more compression options and what i run but any of those top tier manufacturers will be a good choice which is why everyone runs them.

jerryd87

iTrader: (4)

ok nm i had it backwards on silicon but not really high or low aluminum content all pistons are made of aluminum there is no "low" content. just adding other stuff changes its characteristics. ill keep my 4032 wossners myself they work excellent and you shouldnt be driving a high power car without warmup first

DaveJackson

iTrader: (5)

I know what the eutectic point is from a course I took, but I have never heard of this "hyper-eutectic" term. Interested to find out if it's a gimmick, misused term, or what.

Resmarted

iTrader: (2)

You're right, it's not "high" or "low"... wikipedia can explain this: "Hypereutectic pistons are made of an aluminum alloy which has much more silicon present than is soluble in aluminum at the operating temperature. Hypereutectic aluminum has a lower coefficient of thermal expansion, which allows engine designers to specify much tighter tolerances"