I had an RA piston and a regular ej257 piston tested. Chemical analysis and the Brinell test were performed on both.
The chemical analysis determines what the metal is made of and the percentage of each component of the metal.
The Brinell test determines the force required to make an indentation on the metal. It’s one of the commonly used hardness tests for metals.
There are no sponsors involved in this and I don’t work in anything related to automotive industry. I’m just a car nut like most of you out there.
Why am I doing this? I like to work with data. I want to know if the RA’s pistons are in fact different than the regular EJ25 pistons aside from the gross structural differences. Making 500, 600, or whatever record whp on an RA block doesn't imply the pistons will last using that much juice on a regular basis. They are cast pistons in the end. I’m aware that there are videos and articles describing the gross differences between these pistons. However, to my knowledge, no one has confirmed the contents of the alloy used in the RA pistons.
Without further ado, the alloy used for these pistons is essentially the same. The Brinell test is also essentially the same. See the attached picture for the report.
Discussion
For context:
1. When I say a high power engine or build, I’m referring to a modified EJ street car that will see frequent WOT/redline runs for many thousands of miles. I’m not referring to a racing engine that will be rebuilt regularly.
2. Let’s differentiate strength vs longevity. These are sometimes used interchangeably and some also use longevity and reliability interchangeably, but they are different. Parts that have longevity are parts that last a long time. Parts that have strength can resist high levels of stress. Reliability is when something performs it’s intended function relatively trouble free. OEM and motorsport focused parts have a degree of these three things. OEM parts are built for longevity over strength. Motorsport parts are built for strength rather than longevity (Relative to OEM parts. They are built to last within their specific use of course). Both OEM and motorsports parts will have an expected longevity and reliability, but the focus of their design is different as is their performance.
3. Cars making big power on a dyno and doing a few 1/4 mile runs are not what I’m talking about here. See point #1 above. I think most enthusiasts consider the stock block dyno record holders to be dyno queens of sorts. Full disclosure, I see them as dyno queens of sorts. No disrespect, I understand people use their toys for different things, but these are not what I’m talking about here.
Having said that, my two cents on the RA pistons and short block:
Where does the perception that the RA short block withstands more power than previous EJ’s come from (especially the pistons)? It’s probably multifactorial. The idea that they are redesigned (grossly speaking) is a likely contributing factor. I understand they are made by a different manufacturer as well. These two points can make people’s imaginations expand and conclude things. I can see how people come to this conclusion but, in the end, it does not confirm anything. Pair these points with online posts/videos of RA short blocks making a lot of power on a dyno, and voila, some can think the RA short block is the business. There might be more behind the perception of course.
The old perception that EJ pistons are crap. EJ pistons have limitations but, the impact of lingering horror stories of the past is probably immeasurable. Perception is everything. Old stories can brand the future perception of something. It reminds me of stories about the 80’s and 90’s Mustangs. People laughed at the idea of a Mustang braking and turning properly. Current Mustangs are very well rounded performers, but the perception of the crappy handling car lasted a very long time. My point is, perception makes it or breaks it and it can last a long time. EJ’s have a bad rap and it’s not easy to get rid of the reputation. The idea that the RA short block is the answer can be very enticing to many that have a negative perception of EJ’s.
Another issue regarding high power RA’s blocks. Sleeves are another limiting factor. In addition to the limitations of the pistons, EJ sleeves also crack. Even though there is no consensus about a specific power level at which sleeves can crack, EJ sleeves are at risk of cracking above 450-500 whp. I said at risk of cracking. I’m sure some readers have a friend, a cousin, and their dog that ran 600 whp at 35 psi with a TMIC on 91 octane for 85k miles with a DAM of 0.71 on a semi-closed deck without any issues. Unfortunately for the rest of us, sleeves can crack above a certain power level (I’m not going to get into the 702 vs 7xx discussion). The RA block has the same sleeves as any other EJ257. I wouldn’t build a high power car on a semi-closed deck short block.
Not enough RA’s out there. How many are out there? How many of the 500+ whp ones are beat on daily? I think no one knows the answer, I certainly I don’t. Time will answer how well these high power RA blocks will hold. I suspect it will be similar to any other EJ that has been tuned and used similarly.
If what you want is a lot of power, OEM is not best. Subaru’s research and design is done for a ~ 300 hp car that should last beyond it’s warranty period. Their R&D is not meant for the apparatuses that most of us build.
As you can see, in my opinion the legend of the RA short block can be put to rest. If you want a high power EJ, and want it to last, contact an experienced builder and tuner to plan your project.
I’m not more knowledgeable than most Subaruheads. Of course, more knowledgeable people will read this and shed light on some aspects of this.
Now, let the internet create it’s own theories about the above test results.
The chemical analysis determines what the metal is made of and the percentage of each component of the metal.
The Brinell test determines the force required to make an indentation on the metal. It’s one of the commonly used hardness tests for metals.
There are no sponsors involved in this and I don’t work in anything related to automotive industry. I’m just a car nut like most of you out there.
Why am I doing this? I like to work with data. I want to know if the RA’s pistons are in fact different than the regular EJ25 pistons aside from the gross structural differences. Making 500, 600, or whatever record whp on an RA block doesn't imply the pistons will last using that much juice on a regular basis. They are cast pistons in the end. I’m aware that there are videos and articles describing the gross differences between these pistons. However, to my knowledge, no one has confirmed the contents of the alloy used in the RA pistons.
Without further ado, the alloy used for these pistons is essentially the same. The Brinell test is also essentially the same. See the attached picture for the report.
Discussion
For context:
1. When I say a high power engine or build, I’m referring to a modified EJ street car that will see frequent WOT/redline runs for many thousands of miles. I’m not referring to a racing engine that will be rebuilt regularly.
2. Let’s differentiate strength vs longevity. These are sometimes used interchangeably and some also use longevity and reliability interchangeably, but they are different. Parts that have longevity are parts that last a long time. Parts that have strength can resist high levels of stress. Reliability is when something performs it’s intended function relatively trouble free. OEM and motorsport focused parts have a degree of these three things. OEM parts are built for longevity over strength. Motorsport parts are built for strength rather than longevity (Relative to OEM parts. They are built to last within their specific use of course). Both OEM and motorsports parts will have an expected longevity and reliability, but the focus of their design is different as is their performance.
3. Cars making big power on a dyno and doing a few 1/4 mile runs are not what I’m talking about here. See point #1 above. I think most enthusiasts consider the stock block dyno record holders to be dyno queens of sorts. Full disclosure, I see them as dyno queens of sorts. No disrespect, I understand people use their toys for different things, but these are not what I’m talking about here.
Having said that, my two cents on the RA pistons and short block:
Where does the perception that the RA short block withstands more power than previous EJ’s come from (especially the pistons)? It’s probably multifactorial. The idea that they are redesigned (grossly speaking) is a likely contributing factor. I understand they are made by a different manufacturer as well. These two points can make people’s imaginations expand and conclude things. I can see how people come to this conclusion but, in the end, it does not confirm anything. Pair these points with online posts/videos of RA short blocks making a lot of power on a dyno, and voila, some can think the RA short block is the business. There might be more behind the perception of course.
The old perception that EJ pistons are crap. EJ pistons have limitations but, the impact of lingering horror stories of the past is probably immeasurable. Perception is everything. Old stories can brand the future perception of something. It reminds me of stories about the 80’s and 90’s Mustangs. People laughed at the idea of a Mustang braking and turning properly. Current Mustangs are very well rounded performers, but the perception of the crappy handling car lasted a very long time. My point is, perception makes it or breaks it and it can last a long time. EJ’s have a bad rap and it’s not easy to get rid of the reputation. The idea that the RA short block is the answer can be very enticing to many that have a negative perception of EJ’s.
Another issue regarding high power RA’s blocks. Sleeves are another limiting factor. In addition to the limitations of the pistons, EJ sleeves also crack. Even though there is no consensus about a specific power level at which sleeves can crack, EJ sleeves are at risk of cracking above 450-500 whp. I said at risk of cracking. I’m sure some readers have a friend, a cousin, and their dog that ran 600 whp at 35 psi with a TMIC on 91 octane for 85k miles with a DAM of 0.71 on a semi-closed deck without any issues. Unfortunately for the rest of us, sleeves can crack above a certain power level (I’m not going to get into the 702 vs 7xx discussion). The RA block has the same sleeves as any other EJ257. I wouldn’t build a high power car on a semi-closed deck short block.
Not enough RA’s out there. How many are out there? How many of the 500+ whp ones are beat on daily? I think no one knows the answer, I certainly I don’t. Time will answer how well these high power RA blocks will hold. I suspect it will be similar to any other EJ that has been tuned and used similarly.
If what you want is a lot of power, OEM is not best. Subaru’s research and design is done for a ~ 300 hp car that should last beyond it’s warranty period. Their R&D is not meant for the apparatuses that most of us build.
As you can see, in my opinion the legend of the RA short block can be put to rest. If you want a high power EJ, and want it to last, contact an experienced builder and tuner to plan your project.
I’m not more knowledgeable than most Subaruheads. Of course, more knowledgeable people will read this and shed light on some aspects of this.
Now, let the internet create it’s own theories about the above test results.
