Blown Engine? [Archive] - SaabCentral Forums

: Blown Engine?


spgracer
27th February 2005, 03:20 PM
i'm a newbie at 18 yrs old and i've got an 87 spg. what would be the first thing to go in the block? ring lands, bearing, piston, connecting rods? how much hp and boost could these engines withstand. i would really like to turn my car into a street/track car.

ejenner
27th February 2005, 04:52 PM
They're strong engines but you have to look after them the same as ever other engine. If your killing it the whole time then make sure you change your oil regularly. If your Mr. Average driver then just go for OEM recommended oil changes. The most regular problems are head-gasket failure, melted pistons (from det. ) and piston rings but I have not heard of much more than that. Modified 16v motors make anything from 150bhp up to 500bhp http://www.pistonheadstv.com/videos/237.avi (http://www.pistonheadstv.com/videos/237.avi)

Boost wise - the thing to watch out for is detonation or pre-ignition or knock (all those are slightly different but pretty-much the same) This basically happens when the temperature in the combustion chamber gets so great that the mixture burns because it is ignited by the temperature in the chamber and not by the spark-plug. So the burning happens at the wrong time. Also the mixture can explode in the chamber and it's not supposed to explode - just burn rapidly.

To avoid knock and run high-boost there are some thing you can do to help. Use good quality fuel, get a better charge-cooling system (like a front-mounted-intercooler or charge cooler) make sure your APC system is working properly and pulling back the boost on knock-detection, keep your spark-plugs in good order, make sure your cooling system works well, use synthetic oil(?) Make sure the amount of fuel you put in matches the extra boost your giving it - extra boost means more air which also leads to detonation through lean mixture.


So in summary:

- get air/fuel ratio correct
- make sure your cooling works properly
- service well and use performance parts (where relevant)
- make sure safety systems aren't by-passed for quick thrills