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Piston failure - 2011 Apex MCX 290

lakercr

lakercr

Tech Advisor
Joined
Aug 12, 2003
Messages
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Location
Winnipeg, Manitoba
Sled has a little over 10,000 KMS on it, about 9000 of them boosted. This is a total loss engine. No sign of detonation on the plugs, but the motor went down at part throttle - cruising about 40MPH.

This is probably the 'highest miles' Apex engine that I've opened up. The remaining 3 pistons are all cracked across the saddle and were (each) an imminent failure.

Has anyone else opened up one of these higher mile boosted engines and seen similar?
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11 and up piston's are lighter and the skirts crack under higher boost levels. Machzrobie I think it was had a couple boosted 11 and newer Apex's go down from higher boost. Same thing, piston's cracking! Looks like if you're going to run 290+ hp in a newer Apex you need Pistons instead of shim!
 
I've heard that they are lighter, but when comparing side-by-side with an 06-10 piston they look identical to me. Has anyone ever put them on a scale to confirm? Either way, I'm going to weigh a few tonight.
 
Last edited:
kviper said:
11 and up piston's are lighter and the skirts crack under higher boost levels. Machzrobie I think it was had a couple boosted 11 and newer Apex's go down from higher boost. Same thing, piston's cracking! Looks like if you're going to run 290+ hp in a newer Apex you need Pistons instead of shim!
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Agreed. Mach Z Robbie & Stone 88 had piston failures & perhaps block warping as well. There is a thread or two here on it.
I think they were racing them at around 18 psi.
New Apex Engine not as tough as the 2010 & previous.
I have 7,000 km on mine, no issues but I don't run it over 15 psi & most of the time I run it @ 10 to 12 psi.
 
I don't have first hand experience, just what I read in here! I thought there was some difference in the wedding behind the skirts? Maybe Robie will catch this post other wise send him a pm. I know he has a lot of experience with this issue. This is one of the reasons I left my 12 at the 200 kit and built a different sled for 660' snow drags. My 12 at 215hp runs very strong and is as safe as any Turbo out there, I just love it!
 
I broke a skirt on a piston to and lost engine. At least put carrillo or je pistons in your new motor . My new motor has carrillo rods and pistons hopefully its safe now
 
All pistons cracked, 8000 km total. 5000 km with turbo. Engine breakdown. Apex 2011.

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A friend of mine has broken two engines in a 2011 Apex with very little km. One engine 2000 km and one engine 1000 km, but he was running higher boost, with racefuel of course and no detonation. I don't know if the pistons where cracked, because he haven't seen inside the engines.


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The first engine he run some races around 20 psi, blowed the headgasket, changed it, and then later blowed the engine.
With the second engine he runned around 20 psi, blowed the headgasket. Changed the gasket, upgraded the T19 turbo with a bigger compressor wheel/house. Porting the turbinehouse, tried running 23-24 psi and immiediately blowed the engine.

I was running around 15-17 psi.


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