Wez Posted March 11, 2006 Share Posted March 11, 2006 Hey Guys, Just been reading this thread on SupraForums, very interesting post by someone called Poggie :- If CW is about would be interesting to see what he has to say about this. ================================ Use a 272 on the intake at 110 Lobe center and a 264 on the exhaust at 112.5 lobe center. You will have good torque, a wide power band with the ability to spin the motor to 9000, good fuel consumption and depending on who is going to do your tuning, great drivability. ================================ Maybe you guys should start thinking what happens inside a turbo engine. Let say you run a very efficient turbo that will give you a pressure drop ratio over the engine of 1.4 meaning that if you boost 10 PSI the pressure in the exhaust is now 14 PSI. At overlap when the exhaust cam is still open and the intake valve starts to open the minimum pressure in the combustion chamber is 14 PSI + and the intake charge is still at 10 PSI. Since the piston did not reach TDC yet and the intake charge pressure is less than the combustion chamber pressure hot combusted gases will start to move to the area with the lowest pressure which is the intake runner. Not only will this contaminate the intake charge but also heat the intake charge up. And it will keep on moving into the intake runners until the pressure in the combustion chamber is the same than the intake charge. Then only will the intake charge start to flow. This will happen when the piston is a couple of degrees past TDC. (You can not pump your tires to 30 PSI with 25 PSI pressure) Open the 272 intake cam 2 degrees later and open the exhaust cam at the same time then a 272 exhaust would have open but close it +/- 2 degrees before TDC you will: A: Be able to use peak cylinder pressures without a negative affect on engine performance. B: Prevent reversion C: Have a clean intake charge D: Spool quicker and harder E: Reduced Lag F: Wider power band with good drivability. I have used this cam setup with great success on many turbo charged engines and will not recommend something that I will not use on my own vehicle. If done correctly good gain will be achieved. Yes with stock valve springs one will most probably experience valve float but my point on the post was that the cam setup can and will allow for a very wide power band and the ability to rev the engine. ================================= EDIT: here is the thread http://supraforums.com/forum/showthread.php?t=305589 Link to comment Share on other sites More sharing options...
Chiefgroover Posted March 11, 2006 Share Posted March 11, 2006 PHR single valve springs for sale, works great with big cams, brand new in the bag, £150. :-) Link to comment Share on other sites More sharing options...
Alex Posted March 11, 2006 Share Posted March 11, 2006 Wez - I posted this months ago.... Link to comment Share on other sites More sharing options...
carl0s Posted March 11, 2006 Share Posted March 11, 2006 Wez - I posted this months ago.... Link to comment Share on other sites More sharing options...
Shovels Posted March 11, 2006 Share Posted March 11, 2006 what was the outcome??? Link to comment Share on other sites More sharing options...
JohnA Posted March 11, 2006 Share Posted March 11, 2006 Wow, that guy just discovered reversion. http://www.max-boost.co.uk/stuff/sherlock.gif Link to comment Share on other sites More sharing options...
Wez Posted March 11, 2006 Author Share Posted March 11, 2006 Wez - I posted this months ago.... Ahhh crap, what was the general concensous then, good or bad Link to comment Share on other sites More sharing options...
Wez Posted March 11, 2006 Author Share Posted March 11, 2006 Hey guys, where is the other thread, i have done a search but cannot find it Link to comment Share on other sites More sharing options...
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