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<blockquote data-quote="swampratt" data-source="post: 3101125" data-attributes="member: 15054"><p>You need to go for a ride in my old school built 57 chevy.</p><p>It has about everything you want I would bet.</p><p></p><p>The octane thing is not as critical as you would think with the right combo of parts.</p><p>The hypereutectic cast piston is advertised as being stronger than regular cast piston ..they add more silicone to the alloy and that makes it harder.</p><p>Harder is not stronger in certain applications.</p><p>If you get into detonation with a harder piston it will shatter like tempered safety glass.</p><p>Yea you can live fore a while maybe in that situation.. but it is not like old school cast where you can actually beat the bearings out from detonation with the old cast piston and the piston lives..</p><p>A hypereutectic piston normally has more than 12% silicone some up to 20% that makes it very hard and not very resistant to impact loads.</p><p>Yes it is more scuff resistant.. but keep the air filter sealed up and oil clean and scuff resistant is a non issue.</p><p></p><p>It expands less than the cast piston and you can run tighter cylinder wall to piston clearances but this tight clearance is a bad thing in my book..as things heat up clearances get tighter.. you can allow the clearance with more expanding pistons and end up the same.</p><p>Hypereutectic piston tops run much hotter than cast or forged Downside is you need to gap the rings wider.</p><p>As you can come into a situation of butted rings.</p><p></p><p>More heat in the combustion chamber is good to a point.. but too much of it being generated and you get in trouble.</p><p>The cast iron head SBC gets along fine without the added heat.</p><p>You can find heads with very efficient chambers and you can turn old school heads chambers into a modern chamber that works very well. Talking old double hump or some 305 heads.. the 76cc and 70cc heads are too square to get there. </p><p></p><p>Reading on pistons.</p><p><a href="http://blog.jepistons.com/2618-vs.-4032-material-differences" target="_blank">http://blog.jepistons.com/2618-vs.-4032-material-differences</a></p><p></p><p>then this.</p><p><a href="http://blog.wiseco.com/-what-makes-a-racing-piston" target="_blank">http://blog.wiseco.com/-what-makes-a-racing-piston</a></p><p></p><p>Smaller chambers are less detonation prone..I have tested than a few times in my builds.</p><p>Less surface area in the chamber because it is smaller and that is the key.</p><p>That is how I can run higher compression with pump gas.</p><p></p><p>Then you have rod to stroke ratio.. this also helps out in the compression department..Longer rod dwells piston at TDC longer and this makes the engine less detonation prone.</p><p>Rod to stroke ratio on the 350 is good. I have ran 12:1 on 91 octane with smallish cams 270H to be exact 224@ .050.. it had 245 psi cranking pressure. happy camper..I shifted it at 6900rpm daily.</p><p>In less than 2 years i put 75,000 miles on it.</p><p>Yes i drove a lot years ago.. wife would log over 70,000 a year and I would also. Lots of time for testing things out.</p><p>Get this I changed oil in cars every 2 weeks. 3000 miles.</p><p>Line your wallet.</p><p></p><p>I used to run Oldsmobiles and tossed stones at the Chevy.</p><p>I got a 78 nova handed down to me ..Finally it was mine and It was going to get a 455 olds.</p><p>But I had researched the small block chevy for about 2 years and decided to try my hand at a 350 chevy build.</p><p></p><p>WOW!!! my first one ran excellent. I could swear it would beat a W30 455 I just built for a buddy.</p><p></p><p>I called him up and told him ..and the race was on.</p><p>It was even steven until 135MPH where I topped out and he went on and ran 152 MPH.</p><p>HHHMMM I had a little 268H comp cam 20.5 MPG if i could keep my foot out of it. Q jet intake and carb and cast iron manifolds.</p><p></p><p>Imagine if i really souped it up. Which i eventually did .. kept tweaking it and swapping cams and heads.</p><p>Finally got it to run 11.50's in the 1/4 with a 370 gear and I could hit 176MPH in 3/4 of a mile.</p><p>Yea in that trim i put another 70,000 miles on that block that started with 100,000 miles and then logged 75,000</p><p>It then went into my 47 dodge truck and 6 years of driving then into the 57 chevy.. each time it entered a new vehicle i would put fresh pistons and rings and bearings in it.</p><p></p><p>Never bored and crank never turned.. cylinder walls never honed except what GM did to them in 1969.</p><p>cast piston and molly rings.. simple stuff.</p></blockquote><p></p>
[QUOTE="swampratt, post: 3101125, member: 15054"] You need to go for a ride in my old school built 57 chevy. It has about everything you want I would bet. The octane thing is not as critical as you would think with the right combo of parts. The hypereutectic cast piston is advertised as being stronger than regular cast piston ..they add more silicone to the alloy and that makes it harder. Harder is not stronger in certain applications. If you get into detonation with a harder piston it will shatter like tempered safety glass. Yea you can live fore a while maybe in that situation.. but it is not like old school cast where you can actually beat the bearings out from detonation with the old cast piston and the piston lives.. A hypereutectic piston normally has more than 12% silicone some up to 20% that makes it very hard and not very resistant to impact loads. Yes it is more scuff resistant.. but keep the air filter sealed up and oil clean and scuff resistant is a non issue. It expands less than the cast piston and you can run tighter cylinder wall to piston clearances but this tight clearance is a bad thing in my book..as things heat up clearances get tighter.. you can allow the clearance with more expanding pistons and end up the same. Hypereutectic piston tops run much hotter than cast or forged Downside is you need to gap the rings wider. As you can come into a situation of butted rings. More heat in the combustion chamber is good to a point.. but too much of it being generated and you get in trouble. The cast iron head SBC gets along fine without the added heat. You can find heads with very efficient chambers and you can turn old school heads chambers into a modern chamber that works very well. Talking old double hump or some 305 heads.. the 76cc and 70cc heads are too square to get there. Reading on pistons. [URL]http://blog.jepistons.com/2618-vs.-4032-material-differences[/URL] then this. [URL]http://blog.wiseco.com/-what-makes-a-racing-piston[/URL] Smaller chambers are less detonation prone..I have tested than a few times in my builds. Less surface area in the chamber because it is smaller and that is the key. That is how I can run higher compression with pump gas. Then you have rod to stroke ratio.. this also helps out in the compression department..Longer rod dwells piston at TDC longer and this makes the engine less detonation prone. Rod to stroke ratio on the 350 is good. I have ran 12:1 on 91 octane with smallish cams 270H to be exact 224@ .050.. it had 245 psi cranking pressure. happy camper..I shifted it at 6900rpm daily. In less than 2 years i put 75,000 miles on it. Yes i drove a lot years ago.. wife would log over 70,000 a year and I would also. Lots of time for testing things out. Get this I changed oil in cars every 2 weeks. 3000 miles. Line your wallet. I used to run Oldsmobiles and tossed stones at the Chevy. I got a 78 nova handed down to me ..Finally it was mine and It was going to get a 455 olds. But I had researched the small block chevy for about 2 years and decided to try my hand at a 350 chevy build. WOW!!! my first one ran excellent. I could swear it would beat a W30 455 I just built for a buddy. I called him up and told him ..and the race was on. It was even steven until 135MPH where I topped out and he went on and ran 152 MPH. HHHMMM I had a little 268H comp cam 20.5 MPG if i could keep my foot out of it. Q jet intake and carb and cast iron manifolds. Imagine if i really souped it up. Which i eventually did .. kept tweaking it and swapping cams and heads. Finally got it to run 11.50's in the 1/4 with a 370 gear and I could hit 176MPH in 3/4 of a mile. Yea in that trim i put another 70,000 miles on that block that started with 100,000 miles and then logged 75,000 It then went into my 47 dodge truck and 6 years of driving then into the 57 chevy.. each time it entered a new vehicle i would put fresh pistons and rings and bearings in it. Never bored and crank never turned.. cylinder walls never honed except what GM did to them in 1969. cast piston and molly rings.. simple stuff. [/QUOTE]
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