S4 Rear Iron cracking question
Thread Starter
Joined: Oct 2001
Posts: 7,529
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From: Lower Burrell, PA
S4 Rear Iron cracking question
How common is it for S4s rear irons to crack under high HP loads? I know Ive heard about it happening it a few people, but is this something that is almost "guaranteed" to happen, or just a bad stroke of luck for a few engines? I have my newly rebuilt/large SP S4 T2 block sitting here ready to go in, and I really, really dont want to have it break once installed. Should I be concerned? HP output should be ~375-400 at the wheels.
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Joined: Feb 2001
Posts: 26,664
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From: n
Keep detonation in check, and you can run it up to 500hp.
I've seen them crack as low as around 240hp due to detonation.
The engine is not really power limited - it just does NOT like detonation.
-Ted
I've seen them crack as low as around 240hp due to detonation.
The engine is not really power limited - it just does NOT like detonation.
-Ted
Meesto Spakaro
Joined: May 2001
Posts: 489
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From: Redondo Beach, CA
It's mostly a tuning issue. My friend cracked his on the highway and he was having major pinging problems when under heavy boost. He was running about 1.1 bar -- his haltech wasn't fully tuned
FB+FC=F-ME
Joined: Jul 2004
Posts: 3,353
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From: Rohnert Park CA
Considering Mazda improved that area on the S5 rear housing,Id say its something not to be taken lightly.Not that every S4 iron is gonna fail,but if Mazda felt the need to spend the $$ to improve the part,it must have had an inherent design flaw/weakness.
