[W126 Coupe] How to gain 112 bhp
Robert Karl Stonjek
rstonjek at bigpond.net.au
Mon Apr 17 19:17:42 EDT 2006
It's my understanding that one can actually test these theories with a measurement of sorts. When you screw out a plug and screw in a compression tester with, say, the coil disconnected, you get the engine compression ratio (assuming that the thread on the tester is long enough - shorter thread or even push on types leave a cavity where the plug was and this cavity lowers the compression ratio as measured).
But if you start up the engine, on 7 cylinders (hey, some cars even run on 6!!!) and burp your compression tester, you'll note a lower compression. This is because any resistance to the air being sucked in lowers the pressure of the air drawn into the cylinders and therefore the compression as measured.
So, if you now change the air induction and retest AT THE SAME REVS you can see the difference with the higher the pressure the better.
I purchased a nice little tester and did the engine-off compression to confirm that my engine was a 10:1 compression and not a 9:1. I measured 9.5:1 - slight cavity at the end of the tester's plug, the age of the engine and possibly air resistance at cranking speed conspire to lower the measured ratio from the original 10:1. But there is no way I have a 9:1 engine - after finding so many bits meant for the low power version I was starting to wonder if someone hadn't just changed the exhaust manifolds etc ...
So, has anyone actually ever tested this theory for themselves?
I have it on my 'todo' list - maybe this week.
Robert
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Saw an interesting idea on the /www.benzworld.org 126 forum. The guy had taken the air filter element out of his 500SEC intake (single snorkel) and run the MB intake tube over to the area behind the passenger side headlight. He'd then mounted a K&N air filter through the panel behind the headlight so the filter was underneath, behind the fog light, and the intake tube was connected up in the engine compartment. Cold air, low restriction intake, but don't ford any streams.
Later,
Mike R.
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