Originally posted by zm830101:
you guys mention an intake obstruction, but what about exhaust? A stock y pipe would definetly limit hi rpm breathing
What is being referred to is changes that were made between the two dyno runs. The exhaust has remained unchanged between runs so, even if it were a restriction, it shouldn't reduce the readings, only reduce the gain or if it were at it's flow limit there could be no gain.
If you look at Ronan's signature you'll see that he has a high-flow exhaust already installed, MSDS headers, P&P'd heads, etc., so the exhaust shouldn't be a limiting factor.
The EGR mod doesn't "restrict" the intake, it blocks off exhaust gases being recirculated into the intake. The reason this creates a problem is that the ECU is expecting to see a certain % of exhaust gas coming into the intake stream. When the computer fails to get that reading it won't advance the timing because under normal conditions, this would lead to spark knock and drastically shorten the engines life  .
As has been stated earlier there haven't been any demonstrated benefits to doing this modification and there can be problems created by doing it, so the conventional wisdom is to avoid it.
Certainly, one can't get valid dyno numbers if this mod has been done and something else was also changed (UIM in this case). I suspect/hope that the UIM actually made some gains for Ronan and the EGR Mod wiped them out.
Regards, Alan
03 Volvo S60 2.5T AWD
98 Mystique 2.5 MTX
99 SVT - Inheriting Lil Monster's parts
98 SVT - Lil Monster (RIP) 183.7 whp
Quaife/Fidanza/UR UD Clutch
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