Bingo! Don't want to rattle those slugs, they shatter.
Bingo! Don't want to rattle those slugs, they shatter.
No, the S55 uses Mahle 174+ (AlSi12Cu4Ni2Mg), not 2618. It is grafal coated though.As previously noted, eutecticity is a property of the alloy and eutectic alloys melt and solidify at single lower temperatures than any of their individual constituents. This is very helpful in certain applications like soldering; you get a better joint.
BMW S55 and later M engines use Mahle 2618 pistons with Grafal or other Mahle coatings and specify a full SAPS oil in the US. I have never heard of any coating issue with the ZDDP content in normal FS Euro oils.
Yup, Ford migrated the 302HO from TRW forged slugs to hypereutectic ones in like 91 or 92? I can't remember the exact date, but the idea was to tighten up piston-to-wall clearance, reduce blowby and positively impact emissions performance. These engines were more fragile than their predecessors when you added boost.
Nitrous tuneups on hypereutectic pistons are always on the “fat” side with retarded ignition timing to soften the shockwave when the combustion pressure spikes. I’ve run as high as 175 shot on a stock ‘95 5.0 Ford short block with no issues proving that hypereutectics can live like this, so it can be done, but you always have to creep up on the tune. If you go for the gusto without verifying spark, fuel, and nitrous levels things will be disastrous very quickly!
If you keep it safe like this, IMO the limiting factor is only when the piston top and top ring gets so hot that the ring gap closes completely; imagine popping dandelion heads off, but with hot aluminum and disastrous results
I had a "college" Vega and the only reason they didn't last was the sheet metal body which became a rust bucket in short time. Not even the police wanted to stop me; too embarrassing.The Chevrolet Vega used a hypereutectic aluminum block and high zinc oil. I don’t think any of them survived past the 80s.
91 was the last year of the forged pistons in the 5.0HO.Yup, Ford migrated the 302HO from TRW forged slugs to hypereutectic ones in like 91 or 92? I can't remember the exact date, but the idea was to tighten up piston-to-wall clearance, reduce blowby and positively impact emissions performance. These engines were more fragile than their predecessors when you added boost.
Ah yes, it was the aftermarket Motorsport kit that uses the 2618. My bad.No, the S55 uses Mahle 174+ (AlSi12Cu4Ni2Mg), not 2618. It is grafal coated though.
source (bmw): http://s3.bimmerfile.com.s3.amazonaws.com/wp-content/uploads/2015/01/S55-Engine.pdf
Incorrect, the 87-late 92 built H.O. engines had TRW forged pistons. ‘93-95 MY had hypereutectic.91 was the last year of the forged pistons in the 5.0HO.
I should clarify it was the model year 91.
92 was the year of the changeover. Late '92 model years that had the black oil pans (like the '93's) had the cast pistons. Early '92's with the grey oil pan had forged pistons. I used 91 as the last full year of forged piston production.Incorrect, the 87-late 92 built H.O. engines had TRW forged pistons. ‘93-95 MY had hypereutectic.
Yeah, couldn't remember if it was 91 or 92.91 was the last year of the forged pistons in the 5.0HO.
I should clarify it was the model year 91.
Did you name the car " Tetness"?I had a "college" Vega and the only reason they didn't last was the sheet metal body which became a rust bucket in short time. Not even the police wanted to stop me.
I once had a friend tell me the secret to keeping his Vega alive was to "Change 1 plug every month." I did an oil change on it once for him.I had a "college" Vega and the only reason they didn't last was the sheet metal body which became a rust bucket in short time. Not even the police wanted to stop me.
Do you know what motor that is from? Those top rings are waaay down the piston