Smok3X wrote:Im sure if done properly it will be fine... Personally I feel the reliability will be compromised slightly...even if its a negligible amount. I have heard lots of storys of failed bottom ends after being rebored or rebuilt! Have you ever heard of a standard NA Motor breaking the bottom end? To each his own I guess...
Its just that from Factory a motor has so much margin of safety built into the design... Why push that down and drive a car that could be a ticking time bomb! One conrod bolt not torqued properly or something stupid like that... Bang!
I disagree with you. Building a motor that will last is not rocket science. Most factory-built engines are mass-produced with a compromise between cost, reliability, economy and performance. For example, the guys at Dynamic Balancing told me that VW manufacture / balance their rotating assemblies to within a tolerance of 7 grams.
When I built my motor they balanced the rotating assembly to within 0.1 grams. The crankshaft (OEM MK3 GTi) was 1.17 grams out, they got it down to 0.132 grams. The flywheel was 4.45 grams out, they got it down to 0.182 grams. The intermediate shaft pulley (OEM pulley) was 6.45 grams out, they got it down to 0.064 grams. The difference between the lightest and heaviest big-end on the OEM VW conrods was 4.0 grams , they made them all the same weight as the lightest one to within 0.001 grams. The difference between the lightest and heaviest small-end on the OEM VW conrods was 1.7 grams, they made them all the same weight as the lightest one to within 0.001 grams.
So while a factory-built motor may be pretty good, there is still lots of room for improvement.
PS. My motor (which was the first motor I ever built, in my back yard and I am far from an expert mechanic) was converted from 1.6 carb to 2.0 MP9 using the same short block and same conrods, and standard over-the-counter parts, has seen 7200rpm daily, many many drag races, track days and TLGPs and it hasn't missed a beat in 100k kms and it doesn't use a drop of oil between services. Chalk up one for the rebuilds.
Yes import motors are the easier drop-in option, BUT you never know how much mileage the motor has done or how it was treated by the person who had it before, unlike a rebuilt motor that has 0 kms on it and you can treat it properly from the beginning.
But like you said, each to his own.
I totally wasnt expecting that from them! So, I called up the guy who's sourcing my stuff & he's given me a quote on an import 2E, 288 cam, etc etc. Like the sound of the quote and to say I'm excited is a total understatement. 
. But if anyone knows anyone who's selling one for a decent amount - I'm IN!
K now Im worried. I have a 1.8i MP9 I have checked on my brothers 1.4i Melociti and our head codes match! Should I be worried. 
What is a 1.4i head code? The car runs very well and supa reliable. It my weekend cab so gets hammered every time I drive her. Why cant you run 13:1 compression? My MX Bike runs that on pump gas!
Also reved it to 9k for 8 laps before it blew.(stuck in 3rd gear)
I never thought of it that way 
The other thing is that... for me, playing around with the bottom end now will cost me money and the benefit from a well balanced bottom end wont be as noticeable as some head work and cams would be... So maybe not right now, but definately in the future. Thanks for that, you learn something everyday.
