miller cam set up ?

[Hemi417]

Hey was wondering if anybody had tried this ? I read about it in a book for collage I think it was called a miller cam because of the guy that enginered it could have the name mixed up but the way it works is the cam opens the intake valve and keeps it open during part of the compression stroke it only keeps it open for as long as boost can over come the compression of the clyinder the idea is during that time you can be packing more air /fuel into the clyinder I don't think it will work well on a turbo because one we have lag and it would take forever in my mind for it to finaly spool up because of that it would almost be like back firing into the intake untill we had boost .but it has already worked on supercharged cars before because you can almost build boost imediatly they still don't run very good a low rpm' but i see it being great for drag cars I don't think it will work very well on street cars at all you would also have too have a custom cam ground to do this and I don't know if the lower end of the 2.2 and 2.5 would handel it even extremly modified but food for thought ! the other thing is that you would have to probably add a lot more full but if you had a cust. cal you might
be abel to up fuel pressure and injector pulse timing and get away with it you would also have to be running probably in the are of 20+pounds of boost to make it work well and be worth your while the best of coarse would be a stand alone set up for this but anyway's there it is

[tkelly27]

What do you think goes on with your current camshaft? It actually takes it a step further, overlapping the exhaust and intake opening so that the pressurized intake can "shove" the exhaust out. This is in addition to leaving the valve open during the pistons rising phase. It works very well with turbochargers. If you want it open further during the rising phase you have a few options, grind a new cam, advance your current cam, or go DOHC and then you can tune the intake cam alone.

I dunno what book you were reading, but in the stone ages cams had to shut at BDC because the engines weren't spinning fast enough to have any kind of inertia to the air charge to help force it into the cylinder.

Maybe you were thinking of an engine that relied on the boost pressure for most of the compression, basically using the engine block as a combustion pot and something to transfer the energy into a reciprocating mass. The rest of the engine work (induction and compression basically) would be done by a huge compressor like a turbine engine kinda. That would be a fun experiment.

[amcpacer]

The miller cam design is to make an engine more fuel efficient. It is not to enhance power. The design theory is the cam holds the intake valve open during half of the compression stroke which blows some of the intake charge back out of the chamber and back into the intake manifold. Then the intake valve closes and the half filled cylinder volume compresses to TDC where the charge is ignited and the power stroke begins. The power stroke duration is nearly to bottom dead center. In this way the engine experiences less parasitic drag during the compression stroke but still has a very long power stroke to convert all of the expanding gasses to mechanical energy. This is a very efficient design and has been tested and proven. The engine in the toyota prius uses a similar engine design although without forced induction where the intake valves are held open during part of the compression stroke. This setup is optimized for relatively low rpm use less than 5000 rpm typically.

I have always wanted to have a custom cam made for a 2.5 engine with ultra long duration intake. Combine this with a custom calibration and it could be a real miles per gallon war machine.

If only I knew someone that could make me a cam...

[mopar3.0]

crolwer can make you a cam
i just had 2 v6 cams re ground for $180