My experience with the H22 Mahle "FRM Compatible" Pistons
09-10-2006, 03:58 PM
#1
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My experience with the H22 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, 04:30 PM
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that kinda sounds like the builders fault...tyler h ran those things...and beat the snot out of them. I have heard you dont need to hone...but that clearly shows they do. And how does a builder not keep records of what he gapped the rings at...i am no builder but i would never let an engine leave my shop without some sort of paperwork...
09-10-2006, 05:28 PM
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i did an h22 on boost with these pistons(.020 over) and had no problems, car was making about 450hp without any issues. Owner of the car ran it low/out of oil and spun a bearing, we tore block down and had no problems on the cylinder walls. This is def not the pistons problem. This sounds like it was a machining mistake.
09-10-2006, 06:15 PM
#7
Re: My experience with the H22 Mahle "FRM Compatible" Pistons (PrecisionH23a)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PrecisionH23a »</TD></TR><TR><TD CLASS="quote"> On the electrode you could see the color change slightly right at the middle of the bend... which insured that timing was fine.
</TD></TR></TABLE>
doesnt this tell you the heat range of the plug is correct?
http://www.dragstuff.com/techa....html
</TD></TR></TABLE>
doesnt this tell you the heat range of the plug is correct?
http://www.dragstuff.com/techa....html
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09-10-2006, 06:24 PM
#8
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Re: My experience with the H22 Mahle "FRM Compatible" Pistons (Bailhatch)
It is an ngk bkr7e plug... it's not too cold.
As I said, slightly right at the middle of the bend... meaning just after the curve as shown in this picture. I can see how you misinterpreted what I typed though.
So is anyone willing to post up some pictures of these mahle's successfully ran and dissassembled? It's funny that we've had tons of threads reguarding these pistons and nobody posts anything up. Yet when one fails everyone says they work fine, lol.
As I said, slightly right at the middle of the bend... meaning just after the curve as shown in this picture. I can see how you misinterpreted what I typed though.
So is anyone willing to post up some pictures of these mahle's successfully ran and dissassembled? It's funny that we've had tons of threads reguarding these pistons and nobody posts anything up. Yet when one fails everyone says they work fine, lol.
09-10-2006, 06:36 PM
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Re: (PrecisionH23a)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PrecisionH23a »</TD></TR><TR><TD CLASS="quote">I thought Tyler H ran a stock block until the rod snapped?</TD></TR></TABLE>
his last h22, is stock block, with mahle pistons and saenz rods, still running great, sittin in his garage, pulled because of his k motor, otherwise he would still be running it
his last h22, is stock block, with mahle pistons and saenz rods, still running great, sittin in his garage, pulled because of his k motor, otherwise he would still be running it
09-10-2006, 06:39 PM
#10
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Re: (AkumaY)
I had no clue that his current motor was running those. I'll drop him a PM...
Again like I pointed out there were some other factors that were not known with the engine. That is why I did not diliberately point blame towards the Mahle pistons.
Again like I pointed out there were some other factors that were not known with the engine. That is why I did not diliberately point blame towards the Mahle pistons.
09-10-2006, 07:23 PM
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I wish i would have taken some pics, the motor has ~15k miles on it at this point and compression is straigh across the board. I tend to stick up for the mahles, i've been using them for awhile in my Porsches without any issues.
09-10-2006, 07:35 PM
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Re: (sewell94)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sewell94 »</TD></TR><TR><TD CLASS="quote">I wish i would have taken some pics, the motor has ~15k miles on it at this point and compression is straigh across the board. I tend to stick up for the mahles, i've been using them for awhile in my Porsches without any issues. </TD></TR></TABLE>
My 1974 Bultaco Pursang 360 dirt bike came stock with Mahles.
My 1974 Bultaco Pursang 360 dirt bike came stock with Mahles.
09-10-2006, 08:04 PM
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Re: (AkumaY)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AkumaY »</TD></TR><TR><TD CLASS="quote">his last h22, is stock block, with mahle pistons and saenz rods, still running great, sittin in his garage, pulled because of his k motor, otherwise he would still be running it</TD></TR></TABLE> yup...i almost bought that before i went k...hes actually mahle gold series poster child haha...
09-10-2006, 08:52 PM
#15
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Re: My experience with the H22 Mahle "FRM Compatible" Pistons (PrecisionH23a)
I had a similar issue with one. Stock h22 with mahle pistons and aftermarket rods. On 10psi made mbt around 21* with no knock and the engine was smoking pretty bad. Checked the compression and it was actually perfect straight across which was weird 
. I'm pretty sure he damaged the motor bad though a week earlier running it on his old tune from a different turbo on a road course. I dont think he ever tore the motor apart to see what happened though.
. I'm pretty sure he damaged the motor bad though a week earlier running it on his old tune from a different turbo on a road course. I dont think he ever tore the motor apart to see what happened though.
09-10-2006, 10:55 PM
#16
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Re: My experience with the H22 Mahle "FRM Compatible" Pistons (PrecisionH23a)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PrecisionH23a »</TD></TR><TR><TD CLASS="quote">Everything was going well and the engine was making 320whp at around 15-16psi. Air/Fuel was at 11.8:1-11.9:1 and ignition timing was at 22deg at 12psi and at 17deg at 19.6psi. So as you can see, timing was very safe.</TD></TR></TABLE>
Although I do not believe it was the problem at all, i dont consider that much timing advance with that much boost conservative. goodluck figuring out the culprit and good write up
[B]
Although I do not believe it was the problem at all, i dont consider that much timing advance with that much boost conservative. goodluck figuring out the culprit and good write up
[B]
09-11-2006, 01:44 AM
#18
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Re: My experience with the H22 Mahle "FRM Compatible" Pistons (99B16Si)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 99B16Si »</TD></TR><TR><TD CLASS="quote">
Although I do not believe it was the problem at all, i dont consider that much timing advance with that much boost conservative. goodluck figuring out the culprit and good write up [B] </TD></TR></TABLE>
17 degree's is conservative/average in my opinion... especially since the maximum boost hit was 16psi and when the engine went to hell it was at 15psi. So it wasn't even in the 19psi column when failure occured.
Hopefully I will have some pictures of this. Unfortunately the guy is broke and said the car will most likely stay parked until the end of this year until he has money to purchase a new longblock.
Although I do not believe it was the problem at all, i dont consider that much timing advance with that much boost conservative. goodluck figuring out the culprit and good write up
[B] </TD></TR></TABLE>17 degree's is conservative/average in my opinion... especially since the maximum boost hit was 16psi and when the engine went to hell it was at 15psi. So it wasn't even in the 19psi column when failure occured.
Hopefully I will have some pictures of this. Unfortunately the guy is broke and said the car will most likely stay parked until the end of this year until he has money to purchase a new longblock.
09-11-2006, 06:20 AM
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Re: My experience with the H22 Mahle "FRM Compatible" Pistons (PrecisionH23a)
wow, this is scary, i have a set thats waiting to go in, i was going to put them in thi sweekend, but some stuff came up and i couldnt do it again....maybe it had something to do with the hone? does anyone know if its safe to put them in without honing, my cylinders look perfect, no scars or anything.
09-11-2006, 06:53 AM
#20
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Re: My experience with the H22 Mahle "FRM Compatible" Pistons (RudeLude)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RudeLude »</TD></TR><TR><TD CLASS="quote">does anyone know if its safe to put them in without honing, my cylinders look perfect, no scars or anything.</TD></TR></TABLE>
No, that's not safe.
No, that's not safe.
09-11-2006, 07:24 AM
#22
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Re: (B18C Turbo)
I don't fully own a dyno, so yes... the shop charged for dyno time. Pretty much any shop you go to has you sign a waiver. Reguardless if **** happens you pay.
The full street tune was 100% completed and I had probably 30min left max on the dyno. I felt bad for the guy but the malfunction was not my fault. Time is money and shops don't run theirselves for free. I did however give the guy a break.
Again this thread was created in hopes of clearing up some grey spots when it comes to the Mahle pistons. Unfortunately it looks like in this case it was engine build related. Hopefully one day I'll get the pictures of the cylinder walls as well as the sides of the pistons to further this investigation.
The full street tune was 100% completed and I had probably 30min left max on the dyno. I felt bad for the guy but the malfunction was not my fault. Time is money and shops don't run theirselves for free. I did however give the guy a break.
Again this thread was created in hopes of clearing up some grey spots when it comes to the Mahle pistons. Unfortunately it looks like in this case it was engine build related. Hopefully one day I'll get the pictures of the cylinder walls as well as the sides of the pistons to further this investigation.
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09-11-2006 07:55 AM
