Hi all, this morning I did a compression test on my baywindow and got the below readings. What I would like to know.....is this good or bad? I have read up that as long as they are within 75% of the highest reading then all is acceptable but just looking for reassurance. Number 1 - 150 , Number 2 - 160 , Number 3 - 160 , Number 4 - 150 all readings in psi. Many thanks Sent from my iPhone using Tapatalk
I need to do an oil change so think I will use some engine flush first then put in the new oil. Then stop worrying about it. Lol Sent from my iPhone using Tapatalk
I've used engine flush in the past and it's caused a few problems mainly due to engines being old or in poor condition as it's removed crud that had nicely been sat there for years blocking leaks ect . If engines in good nik then probably fine but personally I don't use it anymore even though my engine has been rebuild and leak free now. I just tend to get the old oil nice and warm and then just drop it and replace with new Personal preference I suppose ? Sent from my SM-J500FN using Tapatalk
I'd avoid flushing. Any muck that's in your oil cooler will go straight into your main bearings. Ignorance is bliss ...
1 engine case + 2 heads + 1 carb + 4 barrel and pistons + a few other things = engine Oh yeah that's where I've gone wrong.....lol Sent from my iPhone using Tapatalk
That's an MDF workshop table top I'll have you know, and a brand new Gunsons compression tester 1st time out of the box
With the simple oil filtering on an an aircooled VW, you are throwing out oil before it gets a chance to get really cruddy. So a flush isnt worth doing. The compression test giving high values does mean that it is likely that the following is true: a) you have a high compression ratio when the engine is running a) you are getting more power from the engine b) the engine more likely to suffer preignition and damage (erosion of piston tops etc) c) the engine is producing more heat in general, so things may either crack (cylinder heads) or melt completely (exhaust valves). The engine build should at least have checked the deck height and set it in the 1-2mm region, even if the combustion chamber volume was not checked - if they are stock heads then things should not be too far wrong.. My compression ratios were very low until I pulled out some unnecessary spacers - the previous engine block had been decked when rebuilt so had 1mm spacer under the cylinders. The "new" engine block was not machined, so the deck height was about 2.5 mm with the spacers and the engine felt 'dead' . Now at 1.5mm it feels about the same as the old engine.
Not those sums . As Mike says above, if you've built up from bits and don't measure your deck height and head cc, you don't really know what compression ratio you'll end up with. A small difference can have a big effect.
Thanks for your response, everything on the engine is stock, no spacers between case and heads. Had the engine tuned a few weeks ago comment then was the tappers need looking at and adjusted. Thing is as high as the compression is I don't think it's making that much power tends to get to 55mph and sit there. Obviously I'm not pushing the engine or revving the nuts of it just slow and steady through the gears feeding throttle steady? Sent from my iPhone using Tapatalk
