My experience with the H22 Mahle "FRM Compatible" Pistons
09-10-2006, 03:53 PM
#1
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Thread Starter
My experience with the Mahle "FRM Compatible" Pistons
Last friday I had a customer come in for a dyno appointment. The customer came with hopes of making around 400whp with his set-up. His build consisted of the following:
Stock h22 Head
Mahle h22 87mm 9.0:1 Pistons
Eagle Rods
Stock Sleeves
Rev-Hard Style Turbo Kit (60a/r 57wheel, t3 .63a/r)
bkr7e plugs gapped to .025
Before the dyno the compression test yielded the following numbers (1-4):
215 215 215 215 (My compression tester reads a little high). The engine had about 780 miles on it with a 'base-map" that was running pretty rich. The fuel pressure was set at 58psi and upon removal of the plugs let me know it was just pig rich, end of story.
Street tuning on the way to the dyno went fine at 13psi and the engine felt pretty strong. I had a nice 11.8:1 air/fuel ratio running conservative timing.
Everything was going well and the engine was making 320whp at around 15-16psi. Air/Fuel was at 11.8:1-11.9:1. Timing was also safe. After the 320whp pull I did one more pull at 15psi to clean up a few spots here and there and the next pull was perfect. I decided to up the boost by 3psi in order to start tuning for the next column over and the boost did not increase, but at 15psi and 6900 rpms the boost pressure dropped and I could hear the engine fell on its ***.
I immediately knew the engine torched... which I had a really strong feeling that this engine would most likely be the first one I have had blow up on me in my history of 3 years tuning becuase I was very skeptical about these pistons. Sure enough... it was the first. The car would not idle worth a **** and it was smoking quite a bit. The compression test (different tester)yielded (1-4): 185 - 185 - 145 - 110.
I very closely inspected the spark plugs and the base of the plug was nice and black, thus ruling out any lean condition (which I already knew was not the case due to the 11.8:1-11.9:1 a/f's). The porcelain insulator tip had a nice light brown tap to it with no speckles, so we know detonation wasn't the problem. On the electrode you could see the color change slightly right at the middle of the bend... which insured that timing was fine.
After the compression test and inspection of the spark plugs I asked the customer several key questions to the build which I asked him prior to the tuning as well. I'll get into this later.
Next thing I did was inspect the cylinder walls using a bore scope to see how the pistons reacted with the FRM lined cylinder walls. I noticed some significant scarring on the walls and down at the bottom of the cylinders which I did not like. You could definetely tell it did not look like a fresh hone job was performed. Also at the bottom of cylinder 3 was very strange. At BDC the cylinder wall almost looked like it had a shiny surface to it. This could have been due to the light reflecting off of the top of the aluminum piston though. The bore scope is a good tool, but I would really like to view these cylinders with the head removed. During the manual rotation of the crankshaft I could also tell the engine was very hard to turn. You know what that means.
Unfortunately I will not be the one doing the tear-down of this engine. I am VERY curious to inspect these pistons as well as cylinder walls to see exactly what happened. I did manage to speak with the guy who assembled the engine and I am also led to believe that the engine failure could also be due to a few other factors.
1) He was not sure how the hone job was done off the top of his head. Again, the FRM cylinders require a 600 grit stone with a 60 degree cross-hatch. Very few people will do this. To the naked eye the hone may look fine, but under microscopic view you will see that during the honing process some of the fibers will rip out causing a crater-like finish.
2) The ring-end gap was not known. The engine builder said he did not remember the ring-end gap but whatever was in the box is what he used.
As you know, with FI you need to gap the rings on the large side due to thermal expansion. If you heat the rings up enough and they butt together, you are asking for big problems.
3) Piston Skirt Clearance was not known.
So with these other 3 factors into play it's hard for me to directly blame the Mahle piston 100%... but the build-up that I noticed on the cylinders as well as the scarring has me a little suspicious. I do know however that JDogg used these pistons for a while in a NA H22 engine and he did not encounter any problems. Turbo is a different ball game. I am almost led to believe that the combustion temperatures that occur with FI could possibly lead to the coating buring away thus allowing the aluminum to come into contact with the FRM cylinder walls.
Again, this is my experience with them and once the engine is broken into I will do my best to further this investigation since very little is known about these pistons.
If one thing is learned, at least maybe some of you can learn from this customer. He saved a measly $800-$1000 because he did not want to sleeve. Now he is forced to either purchase a new engine or spend another $3,000 on a new build which doesn't include labor to do so. If you have an H series engine and want to run a forged piston, SLEEVE YOUR ENGINE.
And yes... you B/k/d series guys are fine with stock sleeves. I've done several set-ups successfully and we all know that they can handle the power
Stock h22 Head
Mahle h22 87mm 9.0:1 Pistons
Eagle Rods
Stock Sleeves
Rev-Hard Style Turbo Kit (60a/r 57wheel, t3 .63a/r)
bkr7e plugs gapped to .025
Before the dyno the compression test yielded the following numbers (1-4):
215 215 215 215 (My compression tester reads a little high). The engine had about 780 miles on it with a 'base-map" that was running pretty rich. The fuel pressure was set at 58psi and upon removal of the plugs let me know it was just pig rich, end of story.
Street tuning on the way to the dyno went fine at 13psi and the engine felt pretty strong. I had a nice 11.8:1 air/fuel ratio running conservative timing.
Everything was going well and the engine was making 320whp at around 15-16psi. Air/Fuel was at 11.8:1-11.9:1. Timing was also safe. After the 320whp pull I did one more pull at 15psi to clean up a few spots here and there and the next pull was perfect. I decided to up the boost by 3psi in order to start tuning for the next column over and the boost did not increase, but at 15psi and 6900 rpms the boost pressure dropped and I could hear the engine fell on its ***.
I immediately knew the engine torched... which I had a really strong feeling that this engine would most likely be the first one I have had blow up on me in my history of 3 years tuning becuase I was very skeptical about these pistons. Sure enough... it was the first. The car would not idle worth a **** and it was smoking quite a bit. The compression test (different tester)yielded (1-4): 185 - 185 - 145 - 110.
I very closely inspected the spark plugs and the base of the plug was nice and black, thus ruling out any lean condition (which I already knew was not the case due to the 11.8:1-11.9:1 a/f's). The porcelain insulator tip had a nice light brown tap to it with no speckles, so we know detonation wasn't the problem. On the electrode you could see the color change slightly right at the middle of the bend... which insured that timing was fine.
After the compression test and inspection of the spark plugs I asked the customer several key questions to the build which I asked him prior to the tuning as well. I'll get into this later.
Next thing I did was inspect the cylinder walls using a bore scope to see how the pistons reacted with the FRM lined cylinder walls. I noticed some significant scarring on the walls and down at the bottom of the cylinders which I did not like. You could definetely tell it did not look like a fresh hone job was performed. Also at the bottom of cylinder 3 was very strange. At BDC the cylinder wall almost looked like it had a shiny surface to it. This could have been due to the light reflecting off of the top of the aluminum piston though. The bore scope is a good tool, but I would really like to view these cylinders with the head removed. During the manual rotation of the crankshaft I could also tell the engine was very hard to turn. You know what that means.
Unfortunately I will not be the one doing the tear-down of this engine. I am VERY curious to inspect these pistons as well as cylinder walls to see exactly what happened. I did manage to speak with the guy who assembled the engine and I am also led to believe that the engine failure could also be due to a few other factors.
1) He was not sure how the hone job was done off the top of his head. Again, the FRM cylinders require a 600 grit stone with a 60 degree cross-hatch. Very few people will do this. To the naked eye the hone may look fine, but under microscopic view you will see that during the honing process some of the fibers will rip out causing a crater-like finish.
2) The ring-end gap was not known. The engine builder said he did not remember the ring-end gap but whatever was in the box is what he used.
As you know, with FI you need to gap the rings on the large side due to thermal expansion. If you heat the rings up enough and they butt together, you are asking for big problems.
3) Piston Skirt Clearance was not known.
So with these other 3 factors into play it's hard for me to directly blame the Mahle piston 100%... but the build-up that I noticed on the cylinders as well as the scarring has me a little suspicious. I do know however that JDogg used these pistons for a while in a NA H22 engine and he did not encounter any problems. Turbo is a different ball game. I am almost led to believe that the combustion temperatures that occur with FI could possibly lead to the coating buring away thus allowing the aluminum to come into contact with the FRM cylinder walls.
Again, this is my experience with them and once the engine is broken into I will do my best to further this investigation since very little is known about these pistons.
If one thing is learned, at least maybe some of you can learn from this customer. He saved a measly $800-$1000 because he did not want to sleeve. Now he is forced to either purchase a new engine or spend another $3,000 on a new build which doesn't include labor to do so. If you have an H series engine and want to run a forged piston, SLEEVE YOUR ENGINE.
And yes... you B/k/d series guys are fine with stock sleeves. I've done several set-ups successfully and we all know that they can handle the power
09-10-2006, 04:03 PM
#2
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Re: My experience with the Mahle "FRM Compatible" Pistons (PrecisionH23a)
I have seen another car do almost the same thing but on N20. pig rich ona 65 shot to start out. IMO not a fan of there pistons just my 2cents
09-10-2006, 04:03 PM
#3
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you say this is forced induction.
Im looking at a NA build and I have the Type S oversized. Stay with what I have, bore the cylinders and go with it, or get the Mahle OEM sized and call it a day?
Would like to see pictures of the teardown
But what I dont get it why he ran an Stock built Head. He spent the money to build the bottom end, but neglected the head? I just dont get that
Im looking at a NA build and I have the Type S oversized. Stay with what I have, bore the cylinders and go with it, or get the Mahle OEM sized and call it a day?
Would like to see pictures of the teardown
But what I dont get it why he ran an Stock built Head. He spent the money to build the bottom end, but neglected the head? I just dont get that
09-10-2006, 04:04 PM
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Re: My experience with the Mahle "FRM Compatible" Pistons (PrecisionH23a)
wow this is what ive been waiting for this kinda news coming from you makes me almost positive i dont wanna dive into those pistons.
09-10-2006, 04:07 PM
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Re: (madcatz)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by madcatz »</TD></TR><TR><TD CLASS="quote">you say this is forced induction.
Im looking at a NA build and I have the Type S oversized. Stay with what I have, bore the cylinders and go with it, or get the Mahle OEM sized and call it a day?
Would like to see pictures of the teardown
But what I dont get it why he ran an Stock built Head. He spent the money to build the bottom end, but neglected the head? I just dont get that</TD></TR></TABLE>
Id stick with the type =S pistons
As far as stock head. You dont to go crazy with the head to make power on boost. A stock head work better then you think under boost
Im looking at a NA build and I have the Type S oversized. Stay with what I have, bore the cylinders and go with it, or get the Mahle OEM sized and call it a day?
Would like to see pictures of the teardown
But what I dont get it why he ran an Stock built Head. He spent the money to build the bottom end, but neglected the head? I just dont get that</TD></TR></TABLE>
Id stick with the type =S pistons
As far as stock head. You dont to go crazy with the head to make power on boost. A stock head work better then you think under boost
09-10-2006, 04:12 PM
#6
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Re: (md23vtec)
Stock h22's head are just fine... but if you have the money then go ahead and go crazy.
This guy was on a budget. He says the car will stay parked until the end of the year until he has enough money to either remove the engine or drop a new longblock into it.
This guy was on a budget. He says the car will stay parked until the end of the year until he has enough money to either remove the engine or drop a new longblock into it.
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09-10-2006, 08:03 PM
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Re: (PrecisionH23a)
Wow, that's some good reading. Thanks for posting that up. I don't think I wouldn have tried these pistons myself until I was 100% sure they were proven. Now I guess they're not. 
09-10-2006, 08:08 PM
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Re: (Hawkze_2.3)
there still 2 new...kinda risky...wait a while maybe they will change a few things...if I remember right they made a change on them already once?
09-10-2006, 08:24 PM
#10
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Re: (ExplicitSpeed360)
Why do you guys always jump on a "new" bandwagon when one comes out. The OP said he had no proof that the problem was the piston themselves but that it may be the build.
09-10-2006, 08:25 PM
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Re: (ExplicitSpeed360)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ExplicitSpeed360 »</TD></TR><TR><TD CLASS="quote">there still 2 new...kinda risky...wait a while maybe they will change a few things...if I remember right they made a change on them already once?</TD></TR></TABLE>
yes, on the valve reliefs.
im in for a somewhat analysis. I'm really interested to hear what else you got to say after getting to look at or getting some info after the tear down. Its a shame that its just going to sit there and not allow anyone to take it apart.
You should contact Mahle anthony. See what they ahve to say about the boost wearing down the skirt and bearing the aluminum to the cylinder wall.
yes, on the valve reliefs.
im in for a somewhat analysis. I'm really interested to hear what else you got to say after getting to look at or getting some info after the tear down. Its a shame that its just going to sit there and not allow anyone to take it apart.
You should contact Mahle anthony. See what they ahve to say about the boost wearing down the skirt and bearing the aluminum to the cylinder wall.
09-10-2006, 09:37 PM
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I have seen and heard to many stories on these pistons. I dont hear half as many stories about any other pistons. And if I remember correctly they have made changes to there pistons already. I will say that his hone job probably played a big also because I ran into the same issue once.
09-10-2006, 09:41 PM
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Re: (kaoss_11)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kaoss_11 »</TD></TR><TR><TD CLASS="quote">I dont hear half as many stories about any other pistons. </TD></TR></TABLE>
thats because they arent making ones compatible with FRM
thats because they arent making ones compatible with FRM
09-11-2006, 07:23 AM
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Re: (Mykizism)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mykizism »</TD></TR><TR><TD CLASS="quote">Mahle pistons suck. end of story</TD></TR></TABLE>
So Mykizism -
When did you buy them? Who installed them for you? What problems did you have with them? How long did they last? Are you sure your problems came from the pistons and not some other issue? You know what I just searched all of your topics created here on HT and you have never mentioned even owning a set. How do you know they suck? Oh, you read it somewhere that this guy who knew this guy who had them, and they were messed up and screwed up his motor. That's right!!!!!!!
Unless you have used them or have FIRST hand knowledge, please don't make statements you can't back up. That statement did no one any good. If you have some relevant info that will back up your statement lets here it.
But I have a feeling you don't or you would have contributed it before now.
So Mykizism -
When did you buy them? Who installed them for you? What problems did you have with them? How long did they last? Are you sure your problems came from the pistons and not some other issue? You know what I just searched all of your topics created here on HT and you have never mentioned even owning a set. How do you know they suck? Oh, you read it somewhere that this guy who knew this guy who had them, and they were messed up and screwed up his motor. That's right!!!!!!!
Unless you have used them or have FIRST hand knowledge, please don't make statements you can't back up. That statement did no one any good. If you have some relevant info that will back up your statement lets here it.
But I have a feeling you don't or you would have contributed it before now.
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09-11-2006, 07:55 AM
#18
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Re: (98vtec)
Well guys I don't know if this thread is really helpful in relation to Mahle's. There are just too many installation factors that are unknown which could have led to the malfunction.
I am going to lock this up until the engine is torn apart and I can inspect the piston with my naked eye. It's pretty much a pissing contest right now.
It also seems that a decent amount of people have successfully ran this piston with FI.
If you do run these pistons, make SURE you properly hone the cylinder walls and pay close attention to the ring end gap and piston skirt to wall clearance
I am going to lock this up until the engine is torn apart and I can inspect the piston with my naked eye. It's pretty much a pissing contest right now.
It also seems that a decent amount of people have successfully ran this piston with FI.
If you do run these pistons, make SURE you properly hone the cylinder walls and pay close attention to the ring end gap and piston skirt to wall clearance
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09-11-2006 07:24 AM
