Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) gdi

By vent to atmosphere do you mean something like the below?

https://www.talkmorgan.com/ubbthreads.php/topics/547178/all/Workshop_Note_-_GDI_Oil_Breath

Griffo, I can still remember when you changed your engine. At the time, I had a Mustang 2.3 4-cylinder hire car and thought about how you put a similar amount of power into the Plus 4...
Does the car still exist? Did you still like her after the conversion or was that part of the reason to sell her?

Well if we look at Lexus they know the advantages of direct injection but also the disadvantages. They are arguably the best car designers/manufacturers in the world. Direct injection would be fine if so many contaminants were not redirected through the combustion chambers to try and clean the emissions up. Port injection, ie fuel introduced prior to the combustion chamber washes the valve stems/heads as it enters the chamber whereas direct injection is introduced into the cylinder. Thus port injection cleans the valves and stops the sticky residue buildup from adhering to the valve heads and seats which causes the problems with Gasoline direct injection engines. Gdi does however give a cleaner burn as air fuel mix is better designed and this produces a more complete burn and a little more BHP? Well in theory anyway. Now back to Lexus... they use both methods to introduce fuel, in that their engines have both direct and port injection achieving the best of both worlds. Now, Morgan owners with the Gdi engines seem to fall into two camps in that some have no trouble at all with their engines gumming up and others are crippled in as little as 4000 miles, Perhaps this might be an injector issue. If the spray volume is incorrect or the spray pattern poor the engine will not breath correctly. This will produce a greater level of contaminants which are then redirected into the engine and who knows what this is doing! However I do know this, the spray pattern/fuel volume is critical in Gdi engines. Much more forgiving in port injection options as the air fuel mix relies on its turbulent journey into the combustion chamber to achieve a good mix for combustion. Interestingly I can think back to my youthful days and polishing the ports in the cylinder heads and it has subsequently been found that the rough surface left after manufacture in fact aided mixing and achieved a more complete burn! Damn! won't get those hours back!