Okay, time to get things straight. I’m an all motor guy, just recently built a sleeved B18C1 with Endyn 12:1 pistons and GE Sleeves. I was really unhappy with the noise that the Pistons made when the car was cold. It would sound like a deisel for at least 5 minutes after starting.
Anyway, I tore the block back apart after only 100 miles to make sure everything was doing just fine. All clearances (checked by the machine shop while I was helping) were dead on.
Main and Rod Bearing clearances: .0015"
Piston to pin clearance: .0008"
Pin to rod clearance: .0005"
Cylinder to wall clearance: .0027
No scuffing or anything on the sleeves or pistons. Oil looks good. Compression numbers were 270psi across the board before I took it apart. So you know the noise was loud enough for me to think something was wrong.
So now I’m thinking it’s just the design of the Endyn piston that’s causing the noise. I talked with a guy that said he used to use nothing but Endyn in his customers engines he would build, but after having almost all of them return with the deisel motor sound complaint, he switched to a different piston.
After doing a ton of research on forged pistons, I found that there are really only two types of alloys that most manufacturers use.
2618 and 4032 Aluminum.
2618 is a high strength aerospace aluminum alloy. This specially formulated alloy includes elements of nickel, copper, magnesium, iron and 0.25% or less silicon content. The combination of these elements provide for the ultimate in high temperature strength and fatigue properties. Being a very low silicon alloy that has a high coefficient of thermal expansion, 2618 requires greater piston to cylinder wall clearance. This material is ideally suited for high cylinder pressures and skirt loads, as well as elevated combustion chamber temperatures. Applications range from blown, turbo, and nitrous to engines with high mechanical compression ratios. 2618 is 17% stronger than 4032.
4032 is a high strength aluminum alloy with 12% silicon content as the primary alloying agent. These silicon particles are extremely hard and durable and provide a wear resistant surface for the rings, pins and skirt contact areas. Additionally, with the high percentage of silicon, this alloy has a low coefficient of expansion. With 4032, much tighter piston to cylinder wall clearances can be achieved. The end result is a much quieter running engine on cold start-ups’ as well as a more stable piston with less rock over in the cylinder bore. These properties make 4032 an ideal choice for street and many mild racing applications.
JE uses 2618 for JE, and 4032 for SRP.
Arias uses both 2618, and 4032 (depending on what you ask for). If you have a star on the under the piston boss you have 4032. If not you have 2618.
Wiseco uses 4032
Not sure what Ross uses
Not sure what CP pistons use
So now I’m thinking that the design of the piston is most influential on how loud the piston is regardless of material used. Things such as skirt lenght, pin offset, compression height, weight of piston, etc. I guess I’m just looking for answers.
I used a piston that was said to be very quiet, and it’s louder than hell on start up. I’ve used JE pistons before and they were not this loud. Some swear Arias are the quietest pistons. Some say Arias are the loudest. I’ve come to find out that it’s open to interpretation. No one is going to agree on what is loud or quiet, because everyone has a different opinion on what LOUD is. I consider loud to be defined as when it makes enough noise for me to think something is wrong. That’s loud when it comes to pistons.
I would pay for a new set of pistons if it meant I could get rid of even some of the noise. Should I stay with the Endyn piston or switch to something else? Any input you guys have, or things to add would be greatly appreciated. If you have a quiet set of forged pistons, please put what piston and what your piston to wall clearance is set at. Thanks.