Originally Posted by corvettebob1
Anything that increases the horsepower of the engine will have a direct effect on engine life!
However a S/C will have less of an effect then H/C because it only is there when you put your foot in it.
Let the mods begin
You won’t get a clear answer on this on.
H/C just swaps out existing parts of a stock motor - so it can be extremely reliable with much less to go wrong. But, to get FI levels of power from H/C you have to go with a pretty aggressive cam and bump up static compression with a smaller combustion chamber. These cams are completely different than the stock stuff and the stress on the valve train is greatly increased (even though you upgrade the springs, valves... they don't last as long as a stock configuration). This can be heard as the car idles with that sewing machine sound. This results in much more wear and tear on the top end (even in part throttle driving) and the high static compression can result in more frequent detonation (which will damage the bottom end over time). You are also going to have some reversion with an aggressive cam and this will generally make the car waste more fuel at part throttle and fail emissions. It really depends on how aggressive you go, mild H/C setups don't have these issues.
A FI setup is going to use increased dynamic compression to make power. This basically creates almost no extra stress while just cruising, but obviously puts a pretty big strain on the bottom end under boost. There are also a lot more things to go wrong with a FI setup (more parts to break or malfunction). The real beauty of FI is that you can get near stock drivability at part throttle, but have a complete monster once you get into boost.
It comes down to picking your poison. Both will reduce reliability at some level, but it depends a lot on how you are going to drive/use it.
People who beat the crap out of the car/road race... will generally get much better reliability out of a H/C setup.
Also, the things that generally go wrong with H/C packages are much easier to fix. When an FI setup goes bad you usually end up putting in a new shortblock.
Upgrading the bottom end with forged internals can eliminate a lot of the potential reliability issues with FI, but this will add about 4k to the bill.
Another important thing to consider is the tuning. NA setups are very simple to tune and it is basically difficult to screw up the WOT part of the tune. FI on the other hand, can be very tricky since the PCM was not designed to deal with boost. Low boost levels are not a big deal, but higher levels require someone who really knows what they are doing and you have to keep a close eye on it as conditions change (it won't be very adaptive unless go with some of the stuff that has just recently hit the market).
Hope that helps.