OK - perhaps I was thinking of another homebrew injection system - it did squirt at the same place the CIS injectors do, right above the intake valve.
On Mon, Dec 14, 2009 at 10:12 PM, Peter Frederick <psf...@earthlink.net>wrote: > No, it won't. There is little or no benefit to pulsed injection unless > it's into the cylinder, as Bosch discovered in the 70's. Hence the CIS -- > mechanical, hence reliable, and accurate. Too accurate, in fact -- there is > no sudden throttle opening enrichment. > > Benz stopped using it mostly because the US EPA insisted that each > cylinder firing event be completely controlled, even though there is no way > to tell -- even if you had an O2 sensor at each exhaust valve, they do not > respond fast enough to tell if a cylinder has fired or not. The purpose is > to shut off fuel to a non-functioning cylinder, but no one does this. > Stupid. > > Anyway, a MegaSquirt on a Benz designed for point injection will suffer > from the same problems as a carb (since it's exactly the same thing -- spray > gasoline into the air flow remote from the cylinders): the manifolds have > both a number of turns and turbulent, not laminar, flow. The gasoline gets > thrown out of suspension as the air goes down into the bottom chamber, > swirls around, then goes up and over and down into the intake valve. Works > wonderfully for point injection, since all cylinders get the same air flow > on average, but works like crap with a carb -- almost impossible to start, > for one thing, since it takes a LONG time to suck enough fuel mist through > the manifold to get it to light. Pump the accelerator pump and you end up > with a puddle fo fuel on the bottom of the lower manifold half, nowhere near > the cylinders. Terrible mixture control, and serious drivability problems. > I've seen a conversion to a Holley 4-barrel -- worthless. Car was towed > into the shop for refit to a normal CIS. > > Peter > > > _______________________________________ > http://www.okiebenz.com > For new and used parts go to www.okiebenz.com > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > -- OK Don CONSERVATIVE, n. A statesman who is enamored of existing evils, as distinguished from the Liberal, who wishes to replace them with others. The Devil's Dictionary Ambrose Bierce _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
