GN1 Plenum Hardware warning

horndog

Active Member
I replaced my stock plenum with the GN1 plenum with the 72mm throttle body. Following a few pulls of 23# the two front bolts came loose and stripped the top threads of the intake manifold. This caused a massive vacuum leak forcing the engine to idle at 5200 rpms. After being towed home, I found the issue and noticed the bolts are too short and also a weaker metal. I replaced all three of the short bolts with longer ones and also some blue loctite.

Just an FYI, not a debate.
 
how much do the bolts extend out of the intake plenum
not sticking up for them because i dont know what bolt length they supplied but its really easy to overtorge and pull out the threads on the aluminum intake and threads may have been damaged on install or previous install . they should only be torqued to 15#, overtorque and the threads will pull out
if they were too short thats something that should have been checked before install and longer bolts used.
rule of thumb is you need as much thread engagement as the bolt is wide and thats for max yield rating of the bolt , an 8MM bolt needs 8mm extended beyond the plenum and gasket , for alum i like a little more and because threads could already be damaged at the top i measure to the bottom of the hole with a caliper (thats what the thin slide thing at back is for) and get a bolt thats just a little shorter

loktite prevents backout or loosening from the bolt unspinning , for pullout it does nothing ,,if you dont have enough thread grab it wont help
 
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