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Alright, I just bought some new Eagle Forged H-beam Rods, stock specs, and I was curious as to what I should do next regarding pistons. I am looking to start saving because i have my heart set on the new KB supercharger. The goal is 500 rwhp, and close numbers for torque

I want my compression to be as low as possible so i can try to run street gas, so I was looking at a set of forged probe srs pistons with a -18.1cc dish. I don't know how many cc's the heads are stock, or how thick the gasket, so i have no idea how low the compression would be. I want 8.5:1 or less and any brand/dish/ring setup recommendations would really help me as I want to start getting this buildup under way.

The rods are Eagle p/n CRS5933F3D
Scroll down on this link to read about them
The crank is a Cobra crank that will need to be turned.
The block is a new stock iron Romeo block, unused, excellent shape
I need tips on what brand/size/type rings to run, and about pistons. I know nothing about rings other that the first is 1.5, the second is 1.5 and the last is 3.0 whatever that means. This is my first engine buildup so i need as many tips as possible to get this (eventually)blown daily driver moving.

Thanks
Jad
 

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15.5cc dish and NPI heads will give almost exactly 8.5:1 compression which I think is a good choice. 18.5cc dish (which are what PI engines get stock) comes out to approx. 8.3:1 I wouldn't go below that. you'll lose streetability.

rings: http://www.modularperformance.com/rings1.asp
Check out Mike's other stuff too.
 

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This is along the lines of something I was planning on asking later, so I'll ask it here.

I've always tried to build my forced induction motors (roots supercharger or turbocharged) motors with 8.5 to 9.2 CR's. But it seems that more and more people are saying they are running 9.5 to 10.2 CR’s on some of these SOHC and DOHC motors and then pumping in 15 to 18 lbs of boost.

How is that possible on premium gas? I know if I build a 10.2:1 engine and put a roots blower on top, I’ll be quickly picking piston pieces out of the oil pan?

Are the boost numbers deceptive and just what they are seeing in the manifold or are the SOHC and DOHC able to handle a lot more boost without detonation?

And just so I don’t completely highjack this thread, when determining pistons, I ALWAYS cc the heads and do the math to calculate the exact CR that I need. Then go hunting for pre-made (i.e. not custom) pistons that will get closest to the CR along with the dimensions that I need.

Forced induction piston recommendations from B&M, Weiand, etc.(mainly for roots superchargers):
Forged
Large ring lands
Tight Clearances
Shallow ring grooves (some of the newer pistons are using some pretty deep grooves and that weakens the ring lands)
Thick rings (again, some of the newer pistons have pretty narrow (1.5 mm) for less drag and longer life)

Just my recommendations. :thumbsup:
 

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Then go hunting for pre-made (i.e. not custom) pistons that will get closest to the CR along with the dimensions that I need.

I am pretty sure that all of the 4.6 pistons are custom made. I would run 8.5 to 9.0 compression on a supercharged motor. There are quite a few good pistons on the market. You might want to talk to KB about piston choices. Mod motors are setup different from their pushrod cousins.
 

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When I said custom pistons, I was talking about pistons from Venolia, Ross, etc. where you give them the specs and they give you the piston. Lots and lots of money!! :eek:

I think any piston (or any item for that matter) that has a part number that you can order is not a custom part. :D

But that's just me. :thumbsup:
 

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Ah. Ok yeah I see what your saying. A truely custom/unique piston.
 

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Discussion Starter #7
i was looking for something off the shelf to minimize costs. there's nothing on the market of which i've heard that is near 15.5cc so i'd have to go to 18cc. How would the engine run minus the blower because it'll be awhile before i can afford the SC? i don't know what brand of rings would work with what pistons.
 
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