00" Altima ka pistons stronger than 240 ka ones? True?

[twofortyrida1388]

I wish I could find the site again but they said only the 00" Altima pistons were strengthened by being shot peened and some other shit. I was wondering if this was true because then I could focus on mainly those rods and save a crap load on pistons.

[Walperstyle]

bump, i am also curious. I have heard SOHC pistons are better then DOHC.

[panama DRIFT]

^^ as far as i heard sohc pistons just increase compression on the dohc to somthing like 11.6:1, not sure bout the exact number :)

[TheWolf]

what are you going to do... build an engine with used altima pistons out of a junk yard? new ones are going to be the same price as forged units so what's the point?

[twofortyrida1388]

Not exactly. I can get a new piston set from advanced(place of work) for about 220. 20% discount rocks.

[projectRDM]

98-01 Altima pistons have slightly stronger ringlands. There was a design change to help prevent oil blowby which was common on the 93-97 models as they approached higher mileage. I would expect though that any auto parts retailer will carry OTC no name pistons for all 93-01 models and they will not be any better than the older OE units would be. In other words, buy the newer OE pistons from the dealer or go big.

[TheWolf]

amen russ.. advanced will likely just carry rebranded topline pistons which is bottom of the barrel stuff. Step back here at look at the picture. New OE dealer pistons will be more than forged unless you get dealer pricing on pistons. do it right and do it once. don't skimp.

I'm starting to get flashbacks of mustang guys building 600HP nitroused engines on used junkyard 1990 cobra pistons because they're "Factory forged".

[WILDACEX187]

is forging that much more expensive that manufacturers dont make their performance engines with them? i heard that jdm sti's have forged pistons but the ones we get here have cast :(

[S14DB]

is forging that much more expensive that manufacturers dont make their performance engines with them? i heard that jdm sti's have forged pistons but the ones we get here have cast :(

yep, dimes turn into dollars.

[TheWolf]

it's just an extra step. instead of pouring in the aluminum. You have a machine that heats a slug up and them stamps it into it's shape. Cast pistons also have a more reliable expansion and can be controlled with expansion bands. This is more important on bigger engines such as 6L + but it's an issue. A good example of small engine expansion controlled is the STI. One can look at the .0005" (not a misprint) pistons to wall clearance and the hypereutectic cast piston it runs vs a forged pistons .003-5" to see the difference in those issues of expansion.

[twofortyrida1388]

Thanks for advice. With replacing rods and keeping stock pistons will it hold up to about 300hp and max of 7000rpm? I want about 250-300hp and keep a good curve to at least 6500 and hopefully 7.

[98koukile]

All STi's have forged pistons, the stock wrx has cast, they don't use forged pistons on most engines because its not necessary until you add boost into the equation

[TheWolf]

you mean.... All STI's made internationally before 02 have forged pistons.. which is mostly true.. most of the later ones have hypereutectic pistons.
all STI's made for the USA have these. http://axispowerracing.net/25sti/20stivsforged2.JPG

it's not that I make shit up to illustrate a point. I love people who spout nonsense that some how boost on a WRX is different than boost on an STI. God.

http://forums.nasioc.com/forums/showthread.php?t=465249

http://www.airpowersystems.com.au/us_spec/subaru/sti/pistons/pistons.htm

Clevite catalog today showed one piston for all altimas through these years so doubtfull any better ringlands are inplace.


Again Cast vs Forged lesson for people who don't understand.

There's nothing the same between them

What is the difference between a forged piston and a cast piston?
A cast piston is liquid molten aluminum poured or injected into a mold. A forged piston is made from a solid ingot and pressed or extruded into shape before machining.

Forging is a manufacturing process where metal is pressed, pounded or squeezed under great pressure into high strength parts known as forgings. This is usually done by heating the metal, but some forgings are produced without heating.

http://www.aluminum.org/Images/aaluminum_industry_images/aluminum_products/forgings/ForgingPress2.jpg

Generally, forged components are shaped by either a hammer or a press. Forging on the hammer is carried out in a succession of die impressions using repeated blows. In a press, the component is usually hit only once in each die impression.

The Forging Process

The three basic types of aluminum alloy forgings are: open-die forgings, closed-die forgings, and rolled rings.

In open die forging, the work component is not completely confined as it is being shaped by the dies. This process is commonly associated with large parts such as shafts, sleeves, and disks, but the part’s weight can range from 5 to 500,000 lbs.

Most open die forgings are produced on flat sides. Round swaging dies and V dies are also used in pairs or with a flat die.

As the forging workpiece is hammered or pressed, it is repeatedly manipulated between the dies until it reaches final forged dimensions. Because the process is inexact and requires a skilled forging operator, substantial workpiece stock allowances are retained to accommodate forging irregularities. The forged part is rough machined and then finished machined to final dimensions.

In open die forging, metals are worked above their recrystallization temperatures. Since the process requires repeated changes in workpiece positioning, the workpiece cools during open die forging below its hot-working or recrystallization temperature. It then must be reheated before forging can continue.

Impression die forging is the most basic example of impression die forging and accounts for the majority of forging production. In impression die forging, two dies are brought together and the workpiece undergoes plastic deformation until its enlarged sides touch the die side walls.

Some material flows outside the die impression, forming flash. The flash cools rapidly and presents increased resistance to deformation, effectively becoming part of the tool. This builds pressure inside the bulk of the workpiece, aiding material flow into unfilled impressions.

Ring rolling has evolved from an art into a strictly controlled engineering process. In the ring rolling process, a preform is heated to forging temperature and placed over the internal roll of the rolling machine. Pressure is applied to the wall by the main roll as the ring rotates. The cross-sectional area is reduced as the inner and outer diameters are expanded.

Rings can be rolled into numerous sizes, ranging from rollerbearing sleeves to rings of 25 ft in diameter with face heights of more than 80 in.



This is why it costs more than cast. Inject metal or do above.

[projectRDM]

Thanks for advice. With replacing rods and keeping stock pistons will it hold up to about 300hp and max of 7000rpm? I want about 250-300hp and keep a good curve to at least 6500 and hopefully 7.

Stock rods really are fine unless you're breaking 450-500hp, you're thinking too far ahead.

As for your goals, KAs run out of steam before redline, you're not going to get much more out of it no matter how high you rev.

[twofortyrida1388]

So basically to keep power that high it would need some serious cams and headwork?

[Iceman00]

So basically to keep power that high it would need some serious cams and headwork?
Nah, JWT cams, and cam Sprokets. You'll be Set.

[twofortyrida1388]

Are there any cams that would be semi aggressive that I can run n/a until it is turbo?

[S14DB]

BW stage 2

[twofortyrida1388]

What is that like 264/264? That is what I had planned on running in the first place.

[Iceman00]

What is that like 264/264? That is what I had planned on running in the first place.

JWT's are Almost the Most aggressive (unless you count BC V3's..and thats a tough call) and JWT cams cam be used with Turbo motors with the Adjustable Cam sprokets.

[twofortyrida1388]

That makes things alittle easier.

[Ruby240]

I'm starting to get flashbacks of mustang guys building 600HP nitroused engines on used junkyard 1990 cobra pistons because they're "Factory forged".

Cobras were only in 1993, unless in Canada, they then had one in 88 (was identical to a GT except for the "cobra" lettering). And to top that off ALL 1987-1992 5.0's had forged pistons. 93 5.0's used Hyper pistons, and the 93 Cobra & Cobra R had forged slugs.

And FWIW, the OEM 5.0 block splits around ~500-550hp through the lifter valley, down the front behind the timing cover and down the back of the block to the rear crank seal.

I've seen too many. Any that made 500+ Hp on a stock block didn't last very long at all, or if they did last, it was because the car wasn't taken to redline and granny shifted always.

[twofortyrida1388]

So for the money what would be the best pistons (cp, wiseco, je, etc). The rods I now know are good for around 400 horse. I know the seam line on the sides of the rods can be smoothed down to reduce stress and drag. The rods can put on the crank and a special machine will measure rotating force so that the rods can be balanced better. So what are the weak points for revving minus the cranks (4 counterweights).

[BigVinnie]

As for your goals, KAs run out of steam before redline, you're not going to get much more out of it no matter how high you rev.

KA's run out of steam from using a half weighted crank. I'm willing to guarantee that Brian Crower 91mm stroker kit will make a KA a 8000RPM redlinin' son of a bitch......
The GT3 cranks are drilled clear through to journal 1 and the bolt is applied all the way through with the harmonic dampener in order to exceed the normal redline conditions.

The bottom end just needs to be modified pretty much, to more of a AERO standard as well.

To stay on topic there is no difference in strength between a altima and240sx piston. The rings are just positioned differently.

So for the money what would be the best pistons (cp, wiseco, je, etc). The rods I now know are good for around 400 horse. I know the seam line on the sides of the rods can be smoothed down to reduce stress and drag. The rods can put on the crank and a special machine will measure rotating force so that the rods can be balanced better. So what are the weak points for revving minus the cranks (4 counterweights).

Super tech pistons by far for price and strength would be the way to go.

[twofortyrida1388]

Thanks for clearing that up. I wish I could find that site...(giving me damn false info)....those bastards.