Mahle Monotherms,2 years later.

John Robinson

John Robinson

New member
As many of yall know we have been running these pistons for 2 years now. There was alot of unknowns when we first put them in. The extra weight of an all steel piston spinning at 5800 rpm was a little scary at first but 2 years later i can safley say that it isnt a problem. The set i have is 380 grams heavier than a stock piston. The next generation monotherms are around 100 grams lighter. After the first season on them we tore it down & measured for rod distortion & found none!!We put it all back together rings..bearings & all & ran them all last year. We tore it down for this season & all was still good. I am changing the rings this time but everything else is going right back in there. Keep in mind that year before last we had a n2o backfire while spooling up & midway down the track the cylinder wall blew out. We re-used that piston as well. I dont care what anybody says....Nitrous is HOT!! We saw at least 2200 degrees on each & every pass & they are still flawless. This will be year 3 & I am impressed. No they are not cheap...Good stuff never is, you get what you pay for. My Mahle pistons were worth the investment in every way. They let you get by with murder as far as your tuneup goes. The next generation pistons will be a little higher compression & are aimed at the common rail market but should do just fine for the older 24 valves. They can be ran in a 12 v with some injector fiddleing but i dont know what exactley. The pistons i have are .026 below a stock deck height. The new ones will be a little higher. Here are some pics after 2 years of pure hell. There are some shiny spots between the rings on some but its cosmetic. The micrometer says no metal is missing
 

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I think that you're proving the value of these things. If they can make them lighter than stock while maintaining the strength,,, it's an exciting proposition at least.

How many sets are out there? Last I heard they weren't currently making them. If somebody called up Mahle with several thousand dollars, could they get the pistons off the shelf or be put on a short list?
 
JasonCzerak said:
Is this kind of piston ok for a daily driver?
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I havent done it but i cant see why not?

SKYNYRD said:
john what rods are those??
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Regular old brazilians.
Begle1 said:
I think that you're proving the value of these things. If they can make them lighter than stock while maintaining the strength,,, it's an exciting proposition at least.
Ive sure asked about that several times. It`s got something to do with the tooling it requires to make them. As i understand it they would have to start all over & build new moulds. The new design will be around 220 heavier but i have yet to see the weight be a problem of any kind. I will take reliability any day.
How many sets are out there? Last I heard they weren't currently making them. If somebody called up Mahle with several thousand dollars, could they get the pistons off the shelf or be put on a short list?
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The sets like i am running are all gone. I believe there were 4 or 5 sets made of the first batch. They are supposed to be making many more of the new generation pistons. They have been very pleased with what we have shown them with our set. The response has been very good for them. The new ones should be ready pretty soon. Keep in touch & i will get you some more info.
 
Couldn't agree more, love my monotherms and they are running in a CR engine. Its not my daily driver, but as far as I'm concerned I don't see why not.
I put them in my last build after quizzing John up on them.

And damn! 5800 rpm.....balls of steel I say.
 
Joesixpack said:
Couldn't agree more, love my monotherms and they are running in a CR engine. Its not my daily driver, but as far as I'm concerned I don't see why not.
I put them in my last build after quizzing John up on them.

And damn! 5800 rpm.....balls of steel I say.
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Did you actually cc them & figure out the true compression ratio?
 
John Robinson said:
Did you actually cc them & figure out the true compression ratio?
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Yeah, after decking the block .010 and using a thicker MLS with the .044 crush thickness, it worked out right around the 15.1:1. Which is were I wanted to be for that 1k+.


Balanced it to 0grams and it is amazing how smooth it runs at 4k (Damned Electronics). :bang

The extra weight has to cost some hp, did some calculations but didn't get to far.

Running a common melt down rail I'll take the HP hit for peace of mind.
 
paint94979 said:
may i ask what the ballpark price was for them?
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above 500 & below 700 each. I know thats alot but they are well worth it IMO. If it means waiting a little longer & saving up for the purchase i would still buy them. It will more than likely be the last set of pistons you buy.

Joesixpack said:
Yeah, after decking the block .010 and using a thicker MLS with the .044 crush thickness, it worked out right around the 15.1:1. Which is were I wanted to be for that 1k+.


Balanced it to 0grams and it is amazing how smooth it runs at 4k (Damned Electronics). :bang

The extra weight has to cost some hp, did some calculations but didn't get to far.

Running a common melt down rail I'll take the HP hit for peace of mind.
Click to expand...

Sounds good Joe.
 
like i said john they need a set of 6.7 pistons and i would be breaking the bank. you have made me feel better about the rods i have now.
 
John Robinson said:
above 500 & below 700 each. I know thats alot but they are well worth it IMO. If it means waiting a little longer & saving up for the purchase i would still buy them. It will more than likely be the last set of pistons you buy.



Sounds good Joe.
Click to expand...

Thank you i appreciate the honesty... that doesn't seem too bad for pistons that have lasted up to what you have put them through. Any idea how many passes you have made with them?
 
John Robinson said:
As many of yall know we have been running these pistons for 2 years now. There was alot of unknowns when we first put them in. The extra weight of an all steel piston spinning at 5800 rpm was a little scary at first but 2 years later i can safley say that it isnt a problem. The set i have is 380 grams heavier than a stock piston. The next generation monotherms are around 100 grams lighter. After the first season on them we tore it down & measured for rod distortion & found none!!We put it all back together rings..bearings & all & ran them all last year. We tore it down for this season & all was still good. I am changing the rings this time but everything else is going right back in there. Keep in mind that year before last we had a n2o backfire while spooling up & midway down the track the cylinder wall blew out. We re-used that piston as well. I dont care what anybody says....Nitrous is HOT!! We saw at least 2200 degrees on each & every pass & they are still flawless. This will be year 3 & I am impressed. No they are not cheap...Good stuff never is, you get what you pay for. My Mahle pistons were worth the investment in every way. They let you get by with murder as far as your tuneup goes. The next generation pistons will be a little higher compression & are aimed at the common rail market but should do just fine for the older 24 valves. They can be ran in a 12 v with some injector fiddleing but i dont know what exactley. The pistons i have are .026 below a stock deck height. The new ones will be a little higher. Here are some pics after 2 years of pure hell. There are some shiny spots between the rings on some but its cosmetic. The micrometer says no metal is missing
Click to expand...

Thier cool thats for sure John, glad thier working well also. Id talked to Eric ealier in the year about doing some for me in a 12v design and he said they'd just be to damn heavy to make, he seen no way at the time 'due to the offset bowl' to make them come in under 11 pounds each -wow-. The same 2200+ degrees ive ran this summer sure tore up more crap 'alum' slugs than your steel units, so ya for the 24v guys that abuse them Id say try them. .026" down... hum Im .028" out of the hole:hehe:, we'll see.?.
 
stock600 said:
Thier cool thats for sure John, glad thier working well also. Id talked to Eric ealier in the year about doing some for me in a 12v design and he said they'd just be to damn heavy to make, he seen no way at the time 'due to the offset bowl' to make them come in under 11 pounds each -wow-. The same 2200+ degrees ive ran this summer sure tore up more crap 'alum' slugs than your steel units, so ya for the 24v guys that abuse them Id say try them. .026" down... hum Im .028" out of the hole:hehe:, we'll see.?.
Click to expand...

I hear rumors of a guy named Keaton that has the ability to make these pistons work in a 12 valve.....If anybody could it would be him.
 
Micheal Keaton? As in Batman?

I was ordering a set about a year ago or more and they had one set left that someone had called dibs on, when they told the person I wanted them they bought them. So Im waiting on the lighter set now.
 
paint94979 said:
Thank you i appreciate the honesty... that doesn't seem too bad for pistons that have lasted up to what you have put them through. Any idea how many passes you have made with them?
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We did 10 events last year & 9 the year before. Add up all the test sessions & around 100 would be a safe bet.
stock600 said:
Thier cool thats for sure John, glad thier working well also. Id talked to Eric ealier in the year about doing some for me in a 12v design and he said they'd just be to damn heavy to make, he seen no way at the time 'due to the offset bowl' to make them come in under 11 pounds each -wow-. The same 2200+ degrees ive ran this summer sure tore up more crap 'alum' slugs than your steel units, so ya for the 24v guys that abuse them Id say try them. .026" down... hum Im .028" out of the hole:hehe:, we'll see.?.
Click to expand...

Correction: They are .024 down in the hole. Best i recall they have a set of 12v already?
 
truly impressive, anything else downstream take a hit from those temps ? seems the blades on the hot side would not be too happy.
 
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