COSPEED

Anything is great to help establish a broader picture of the LT1 in general. Let me know if you need step by step instructions, there is a YouTube video showing a C7 and each step.

civicx98

So, here it is. 2014 C7 Z51 with 36,607 miles (562 of which are mine). I'm almost 100% sure that this was a lease turn in and daily driven for 30 months.

I have yet to see any evidence of any modifications to the car.

Here are all 8 cylinders.




#2




#4




#6




#8




#1




#3




#5




#7

raylo

Doesn't look too bad. I was expecting worse with that many miles.

MikeLsx

finally some good pictures of valves with decent miles.

Doesn't look to bad

civicx98

I guess its going to be crickets in here since my valve don't look any worse than the cars with 5k miles. Maybe this whole thing isn't that big a deal.

MikeLsx

Well there is valve coking in the pictures.

But from the pictures its not as bad as i thought. there is just not way that amount of coking is major power loss at this point in time. around 30-40k miles.

TennisFreak

Your pictures dont support the need to run out and buy a catch can to prevent "severe" valve coking

Yes your valves get coked; but there is a motivated interest, by certain people in here, to hype the situation into epic proportions because it creates sales for "preventative" products.

COSPEED

Excellent pictures! Very clear and show in great detail. Note the ones closest to the point of ingestion always build quicker and greater amounts so as this progresses those cylinders will be running richer, and the ones with the least (furthest from the point of ingestion) having the least will run lean as the PCM/ECU is commanding all injectors on that bank the same fuel, but the air will not enter evenly.

I expected to see worse as well, but still enough to not only disrupt the flow, but look at #3 and see how the scouring on the valve stem indicates wear to the guide from the hard abrasive deposit. We see at 20-30k miles some guides worn out of spec similar to the LS7 engines where the machining was not square and caused excessive side loading on the valves.

Even at this level compared to the 20k mile one with the before and after dyno results here:



Here is what a valve should look like as this LS engine at 142,000 miles shows. ANY deposits on the valve directly disrupt flow and velocity and will not only cause premature wear to the softer guides as it is pulled into the guide with each cycle of the valve, but power loss is unavoidable. If that amount of change in the valve shape, texture, and design was not important then the engineers would never spend the time and effort to refine valve designs as they do for optimum efficiency. Here is what a new valve looks like, and any deposit changes the dynamics of the design:


Look close at the shape, the texture, the way the stem is narrowed where the air flow would be affected, then compare to the pics. No way that has not resulted in reduced power. But, as I always stress, for those that do not care how their engine is cared for, or if it performs at peak efficiency as design, don't buy a system to prevent this. Spend your $ on wheels or neon lights or something important. But to look at those pictures and assume that is not causing reduced power and premature wear from those deposits is ignorance, but only you should make the decision on how to care for your investment. And as always, watch as time passes and this becomes more well known by the average consumer. Those pictures show a similar amount to the Aerospace Engineer that did the dynos and cleanings, and he regained over 19 RWHP. I expect a similar amount would be documented with this one as well.