DUM DUM BULLET

So the PT4 is not a work of art!
Program is quite limited and requires being plugged into to the unit to function at all.
But the O2 sensor is still in play so it seems to be doing a great job of trimming in closed loop.
I have just populated the fuel "map" with 75% increase leaving the bottom line at 50%.
Doesent knock and pulls well, I was so happy I put it back on the bench and changed out the oem cam for the stage 2, quick job if you don't use the special tools and don't drop the cam chain or a bolt :cool:
And here's the surprise ,compression has increased bucket loads.
20250607_165434.jpg
Compared to the same build with an OEM Cam, which was 185.
So rings have bedded in?
Valves are open longer so more air gets sucked in?
I did it wrong last time?
Or the gauge is buggered?
 
Dool said:
Or the gauge is buggered?
Click to expand...
I vote for this option.
there is no logic in any change of compression due to a cam change. if "more stuff is in the chamber" where actually a valid argument then compression would change every time you change mapping.
and the rings have already been run in (if you use my set)
cheap china shit?
 
So you discount the extra lift and duration of the Cam has an effect on volumetric efficiency?
Stauff gauges would be my choice but I doubt it's the gauge.
Probably Chinese but what isn't?
 
Your are saying the rings were already bedded in but the assembly was fitted to a different engine so they would not have been so.
Since running this set I have had starting issues and low voltage mils( engine warning lights) as a result so I am not so sure.
Anyhow it will be getting topped up with 98ron tomorrow.
 
Re-assessment in the dum dum build.
I, as usual jumped steps and missed some.
The leap to the 84mm piston was a leap to far at the time.
Previously with just a 60cc increase in displacement I had been getting good results and do not think I reached the full potential before going to higher displacement.
As I have already installed the PT4 and am in no hurry to remove it! I will utilise that for moderate ignition advances and fuel increases and hopefully learn enough to determine if a bit more is worth while.

So reinstalling 411 kit, only 1 base gasket, stock head, Stage 2 cam, stock header, decat pipe and Indoori HK muffler .
 
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