which of the 2 is better forged piston
05-01-2008, 09:10 AM
#2
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Depends how they will be used, HP level, etc. Without knowing anything about the engine they are going into, its anybody's guess.
The SRP appears to be a high silicone 4032 alloy (hypereutectic) and the Probe is a 2616-T6 aluminum.... two completely different pistons.
The SRP appears to be a high silicone 4032 alloy (hypereutectic) and the Probe is a 2616-T6 aluminum.... two completely different pistons.
05-01-2008, 10:29 AM
#7
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You are missing the Injuneer's point here. Yes, both pistons are forged, but ...... from different alloys.
Forging is just a process which puts material in some "shape". What material you're putting into that "shape" ultimately determines how much "abuse" the piston can take before "bad" things happen.
Alloy also affects piston to wall clearences, strength, resistance to detonation effects, etc., etc., etc.
Forging is just a process which puts material in some "shape". What material you're putting into that "shape" ultimately determines how much "abuse" the piston can take before "bad" things happen.
Alloy also affects piston to wall clearences, strength, resistance to detonation effects, etc., etc., etc.
Last edited by 97 6SPEED Z; 05-01-2008 at 10:32 AM.
05-01-2008, 10:31 AM
#8
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Yes... the SRP is forge, but to quote from their website:
4032 is not the same as 2616-T6 aluminum.
Additionally, there is a small difference in the valve reliefs (5cc SRP; 4cc Probe) and a major difference in the weight (442G SRP; 351G Probe).
Forged from 4032 low expansion high silicon aluminum alloy heat treated to SRP specifications
Additionally, there is a small difference in the valve reliefs (5cc SRP; 4cc Probe) and a major difference in the weight (442G SRP; 351G Probe).
12-31-2008, 04:48 PM
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12-31-2008, 10:00 PM
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The reference to the Probe should have been 2618-T6. The 4032 will fit tighter, exhibit less piston slap on cold start, and wear longer. But in a nitrous or boost application, the brittleness of the 4032 can be a problem if there is detonation. 2618 is softer, requires a looser fit, will exhibit slap on cold startup, but is not as likely to crack from detonation. I have custom nitrous pistons made by BME. They will only use 2618-T61 alloy for their pistons. Add a Swain moly coating to the skirt, and you have reduced the wear issue with the 2618.
From BME:
From BME:
Piston Tech Briefing
Bill Miller Engineering Forged Aluminum Racing Pistons are made with forged, 2618-T61 aluminum. BME has used 2618 for almost 25 years because Bill Miller believes it to be the best choice when strength and durability are the prime considerations.
Many other piston manufacturers use a silicon-aluminum alloy, such as 4032 or MS75. Pistons made from that have good wear characteristics because the silicon particulate's hardness improves the piston skirt's durability, however silicon is also their downfall because it makes pistons brittle. Through extensive race track testing, BME found that silicon-aluminum alloys, because they are brittle, are prone to fracturing when subjected to extreme loads. The failure rate of silicon alloy pistons in severe-duty, racing applications is fairly high.
This gets worse. With pistons made of brittle, silicon-aluminum alloys, once a crack starts, it doesn’t stop until the piston suffers a catastrophic failure. In the rare case of a crack in a BME, 2618-T61 piston, once the crack reaches an area of lower stress; it stops, making failure less likely.
Bill Miller Engineering Forged Aluminum Racing Pistons are made with forged, 2618-T61 aluminum. BME has used 2618 for almost 25 years because Bill Miller believes it to be the best choice when strength and durability are the prime considerations.
Many other piston manufacturers use a silicon-aluminum alloy, such as 4032 or MS75. Pistons made from that have good wear characteristics because the silicon particulate's hardness improves the piston skirt's durability, however silicon is also their downfall because it makes pistons brittle. Through extensive race track testing, BME found that silicon-aluminum alloys, because they are brittle, are prone to fracturing when subjected to extreme loads. The failure rate of silicon alloy pistons in severe-duty, racing applications is fairly high.
This gets worse. With pistons made of brittle, silicon-aluminum alloys, once a crack starts, it doesn’t stop until the piston suffers a catastrophic failure. In the rare case of a crack in a BME, 2618-T61 piston, once the crack reaches an area of lower stress; it stops, making failure less likely.