Will it survive?

[Damein17]

ok, I was curious if the block I have will survive a build I'm thinking about.

Block info:

KB Hypo Pistons
Total Seal Rings
Clevite Rods/Bearings
New, refinished, 0 miles.
bored to a 306.

Build info:

Vortech S trim (8-10psi)
TF twisted Wedge Heads
TF upper/lower intake
Headers, usual exhuast stuff.
Various supporting mods like high output fuel pump, better FPR, etc.

Essentially, going by Summit's little "output" ratings, the S/C puts you at 331/356 and the H/C/I put you at 350/370. Now, I wouldnt be using the cam, I'm just using the numbers as a baseline. Its my understanding that the charactistics of a boosted cam and N/A cam differ heavily and a larger, stronger N/A cam would seek only to harm me in a boosted application. So, I'll likely be sticking with a stock cam, or search one out thats designed for a boosted motor.

Thing is, the S trim claims up to about 50% more power, now, on a H/C motor making close to, or at 300, thats looking to be 450, + whatever gains are seen from exhuast, good CAI, better MAF and other assoted support mods. Also, the ECU till be dyno tuned by a competent local shop.

So, could this build see crank numbers in excess of 500hp? Its been my understanding that the stock block gets a little squirrely around there. I know I've been vague as to the extent of the mods and such, and there are compression issues to look into with switching to the Twisted Wedge heads and then running boost, but this is all sort of a shadow of a plan right now, I'm just curious, before I get real gung-ho about anything if I'm gonna crack the block into more than once peice and kill a school bus full of 3rd graders with the shrapnel.

Thanks kindly!

 

[giddyup306]

I could only guess what the output of that combo would be. Even if I assume a perfect tune...

It looks like your at the point where I'd seriously concider an aftermarket block. Oh and I'd get some forged pistons. You don't want hypers for a boosted application. I got a set of forged pistons from CHP for my 347 for like $250. Very reasonable compared to other manufactures but less money. Your also gonna want some better rods with nice ARP bolts.

 

[Damein17]

Hypers are bad with boost? Didnt know that, what exactly makes them ill suited?

Looks like I'll be toning down the build a little bit. I'm wanting to avoid having to re-do the internals and especially go with a completely new block, since I have a 0 mile short sitting at the house, hehe.

I wonder about an S-trim with a different upper and lower intake and just call it a day, lol. Supporting mods included of course.. hehe.

 

[giddyup306]

Hypers are bad with boost? Didnt know that, what exactly makes them ill suited?

Looks like I'll be toning down the build a little bit. I'm wanting to avoid having to re-do the internals and especially go with a completely new block, since I have a 0 mile short sitting at the house, hehe.

I wonder about an S-trim with a different upper and lower intake and just call it a day, lol. Supporting mods included of course.. hehe.

Well I'm not exactlly a metallurgy expert but they are just made of stronger metals and during the forgeing process the forged pistons are stronger because of the way the flow of the piston is when it's forged. Cast pistons start life as a liquid and forged are still a solid and seqeezed into the shape via thousands of punnds of pressure. I'd have to do a little diggin on what exactlly the metals are in the hyp. pistons but I know they are far inferior to forged.

Also don't bother with a forged crank. A nice cast steel crank will do fine. Just make sure that you go through a lot of heat cycles because it will get stronger when you do so. I bought a Scat crank for cheap a few years ago and it really is a quality piece. However, they moved there plant to I think Tiawan and you can physically see a difference in the way they make their cranks. I have a good friend of mine that owns a reputable machine shop and does a lot of performance engines and is active in IMCA. He claims that the new Scat cranks just don't hold up. Then again in IMCA you beat a motor a lot more than in 1/4 mile racing. I'd suggest the Eagle brand cranks.

 

[jgfiveoh]

the hyperuetectic (or however u spell it) pistons have a little bit of silicone (i think) added to them. they warm up faster and make less noise during a cold start and are ok for daily drivers. as soon as u add boost or nitrous your asking for trouble.definitely go w/forged. as far as a cam, u could use the stocker and 1.7 rockers, or an E303 and 1.6 rockers. the idle isn't crazy but u can still tell u got a cam. it will take u farther than the stock cam and definitely go great w/boost. u may have to get a higher stall converter if ur using an automatic with it though. i found out the hard way. good luck!

 

[giddyup306]

the hyperuetectic (or however u spell it) pistons have a little bit of silicone (i think) added to them.

I believe you are correct. However, cast pistons also have silicone in them hypers just have more. I'll have to get the exact numbers after work because now I'm curious.

 

[Damein17]

thanks for the info. so you think my best bet would be to geta set of forged pistons? any one know ewhere to get set for for a decent price?

also i posted again about this becasue for some reason the computer im on wasnt showing the replys or this post.

 

[352Ford2]

The metals used to make forged and hypereutectic/cast pistons are pretty similar alloys of aluminum. They both start off as a cast slug, the difference is in the manufacturing process, and a forged piston is forged into its shape using tooling, and machined a touch to its final dimtions. The shaping of the piston this way gives better grain structure and grain flow.

Cast pistons are cast close to their size and machined to exact dimetions without the middle step of forging. Cast pistons have a lower coefficient of thermal expansion so you can run tighter piston to bore clearances, and hence less piston slap on startup (although the forged pistons we have today are pretty dam good) All a hypereutectic piston is a cast piston that has a special heat treatment (to put it simply). This heat treatment allows more silicon to enter the crystal lattice. In a phase diagram there is a line of equilibrium where everything is happy and in the lowest energy state (that is where everything likes to be think of a ball rolling down a hill), Hypereutectic means it is to the right of equilibrium (in this case more silicon in the Al) and eutectoid means it is to the left of the equilibrium (in this case less than normal amounts of silicon).

While this makes the material properties much harder than std cast AL, it also makes it more brittle (think about that with detonation, pieces flying everywhere).

Hope this clears up some confusion.

 

[srothfuss]

Very good!

The switch to hypers on the OEM side was two fold:

1) Lower cost
2) Better smog properties from the more thermally stable casting

 

[jgfiveoh]

how about that? we all learn something! thanks.

 

[86bluecobra]

not all forged pistons are good either. for instance some TRW forged pistons have silicon added aswell. You have to look into what your getting. that being said i have run nitrous on trw forged pistons which i was told were as good as hyper pistons for 6 years now. i just took my heads off this morning. the pistons look great. I don't always buy the you need the most expensive of everything to make combo's work.