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Nice to see the oil fill arm is attached securely to the valve cover. I was worried what would happen with that over time opening and closing the fill cap and all the leverage imparted on that long arm. Would sure suck to break it and have to drop the motor for that
Show me a cast manifold? The heat shield bolts line up perfectly to the tubular header. Also, the tubular headers are coated black on all the display cars.
From: Philadelphia PA (Birthplace of the USA, UNESCO World Heritage City)
Originally Posted by C8Jake
base C8 cast iron exhaust manifold heat shields
How exactly does that prove cast iron is used? There is zero cast iron visible in this picture, and the other pictures clearly show non-cast iron exhaust.
Last edited by ArmchairArchitect; Aug 8, 2019 at 04:13 PM.
A) the heat shields look to be stamped--cast iron is a poor choice for stampings
B) cast iron is a great conductor of heat--the last thing one would want in the C8 engine bay.
C) stainless steels transfer about 1/3rd the heat mild steel transfers and less than 1/5 what cast iron transfers.
D) thin stainless steel is easy to stamp, and not very expensive (303)
I am interested in what the aftermarket comes up with for the exposed engine.
A machined aluminum intake top and matching valve covers would be dead sexy.
So, since the “Z51” and the “base non-Z51 with NPP” BOTH have exactly the same HP, that means the “Z51 only” tubular exhaust manifolds add exactly ZERO hp over cast manifolds?
That’s totally awesome and happens all the time.
Or, could it be that the info regarding “Z51-only” tubular exhaust is in error, and they actually exist on ALL C8?
So, since the “Z51” and the “base non-Z51 with NPP” BOTH have exactly the same HP, that means the “Z51 only” tubular exhaust manifolds add exactly ZERO hp over cast manifolds?
That’s totally awesome and happens all the time.
Or, could it be that the info regarding “Z51-only” tubular exhaust is in error, and they actually exist on ALL C8?
NPP is what gets you the alleged 5 HP increase.
NPP Exhaust, performance, estimated 5 hp increase, aggressive exhaust sound varies with driver mode selected, with stainless-steel tips 1 - Included with (Z51) Z51 Performance Package.
That was indeed my point. It seems highly unlikely that GM would spend 100's of thousands of dollars to develop "Z51 only" tubular headers for exactly zero hp gain.
Given the stated HP numbers are the same for Z51 and non-Z51 w/NPP, I think it is far more likely that GM developed both the cast and the tubular headers, and then decided to use the tubular ones on *all* production C8 -- Z51 or not.
Less likely is the possibility that adding the NPP on the base car also adds the tubular headers. However the fact that the combo of headers and free flow exhaust still only gains 5hp -- seems weak. And since GM adopted SAE standards for HP measurement some years ago, that precludes the purposeful underrating of the HP numbers for insurance or any other reason.
