Manley pistons / rods

[belize1334]

This is a 2 part question.

1 - I've heard a lot of people say that aftermarket pistons and rods tend to run tight on pin bores as well as big end bores. This is supposedly done to allow people to run tighter specs if they choose to... I'm planning to run manley pistons with h-beam manley rods in my g4cs build. My question is, should I anticipate needing to resize these or will they come true to spec?

2 - I talked to Ian at MAP who suggested that h-beam rods are only good to about 500 HP. I've also heard many a wise man say that OEM rods are a bad idea on a stroker and that you should step up to h-beam even for low HP builds. But OEM rods are good for 400+ HP... So is h-beam really even a step up? I'm planning on running some form of tdo5 turbo. This build is about spool, not big power. Is there a significant advantage to h-beam rods over OEM?

 

[diambo4life]

That's quite the opposite. Aftermarket pistons run looser than OEM pistons and that's due to the forged material they are made of. The rate of expansion is different. For 500HP...you really can stick with the stock shortblock. No need to build it with that HP goal. Just tune the car correctly.

 

[belize1334]

If you'll recall, I'm building a G4CS 2.4L engine so there's no such thing as an OEM short block -- at least not one with turbo pistons. But, 1G big rods are an option. I'd need to have them resized for ARP hardware though so I may as well get aftermarket rods too -- unless they will also need resized -- which brings us back to 1). Should I expect to have to resize aftermarket rods? And, again, is there a distinct advantage to h-beam over OEM? Are they 10% stronger? 20% stronger? 50% stronger? Or is it ONLY the fact that they come with and are sized for ARP hardware?

 

[prove_it]

Good questions. I can say that one advantage to running aftermarket rods is that they are lighter, balanced and are a bit stronger. How much stronger? Tough to say. Your going to be making considerably more torque than the average build. Personally I'd go with the H beams. When I built my 2.0L it was overkill to run eagle rods. Now the reason I did was this:

I needed new pistons. I could have reconditioned my stock turbo rods and had the small hole enlarged to fit the wisecos, have them balanced, and have arp studs installed and have the large end bored to correct for the ARPs. Now when I built the estimate for all this, I found the eagles were only about 100 bucks more. Well geesz, not a tough call. So I bought eagles and sold my turbo rods for 50 bucks, which made the difference around 50 bucks. So 50 bucks got me stronger and lighter rods without the risk of a machinists error.

Food for thought.

 

[BogusSVO]

No, you will not have to resize the H beam rods, the high to low spec on the housing bore is .0007 no wiggle room there.

Who ever gave you that tidbit of info has not resized a set of rods.

If you loosen the housing bore, then you will not have proper crush on the rod bearing to hold it in place. go any tighter and you loose oil clearance.

Pi works both ways.

Look into the Brian Crower H beams, Balanced several different brand sets of rods and the BC were the closest in being matched weight than other brands .7g from low to high.

The BC rods also have a slight taper in the beam, you can get them with the 22mm wrist pin, and are rated 50hp per rod more than Scat, Manley, Eagle (150 hp)

 

[prove_it]

Quoting diambo4life:
That's quite the opposite. Aftermarket pistons run looser than OEM pistons and that's due to the forged material they are made of. The rate of expansion is different. For 500HP...you really can stick with the stock shortblock. No need to build it with that HP goal. Just tune the car correctly.



This is true to an a degree. Not all aftermarket pistons are forged the same. You can buy high and low silicone composition pistons. In fact every brand is different. You can't just buy them and expect them to do what you think they will. Verification with the manufacture is important when buying pistons and giving the machinist this info is critical.

and yes, you can have a short block run those power levels for a while, like Marks car, but that isn't a rule. I've seen many many failures on stock engines. Mostly due to higher mileage and unknown conditions in the block.

Not trying to burn you, just making sure the newbies listening get all the right info.