suit in intake!?

[Scott_68B]

I didn't say the EGR itself leans the A/F ratio. Typically in a cruise situation, the computer will back off the injector pulse, creating a 15:1 to a 17:1 A/F ratio for gas mileage. Doing this only causes problems with NOx emmissions and obviously detonation issues. Like you said this is where the EGR comes in and introduces noncombustibles into the intake charge, which will allow for a proper A/F ratio, which maintains proper combustion chamber temps, preventing detonation and NOx emmissions, but using less fuel.

I think you're still wrong. EGR's have been around for years...well before FI engines were popular. I believe that the reason they were introduced was to lessen NOx emissions only with a side benefit of reducing the tendency for detonation.

Scott

[SappySE107]

The EGR on newer cars DOES allow leaner fuel mixture. Look at the fuel constant on the digital EGR cars and you will notice that the more the EGR% is, the lower the fuel constant. Older EGR setups weren't accurate enough for this type of fuel throttling so of course that wasn't its main goal. Its main purpose is of course, emissions and cooling the mixture. Not good for intake manifolds (little issue here) intake valves (major buildup on the backside = very bad for engine) and cooling the combustion process at cruise (cruise isn't where you care about power so again, no big deal).

With boost, the valve overlap wont be throwing any of the exhaust gases back into the intake, its under pressure. The only way I can see excessive soot is from intake valve float, or a bad leak on the intake valve to seat. With no compression, you are looking at no sealing on the intake side.

Im going to guess something is bent, and the exhaust valve is messed up as well which will throw all of the combustion process up the intake since it has no where else to go, even under boost.

I don't think the EGR is going to be any issue here, unless ALL of the exhaust gas is recirculating right into the closest cylinder. hmmm, very interesting concept.

[Streetrodder83]

Most facory carb cars ran a spread bore (Quadra Jet) type carb. Small primaries, and large secondaries. Under cruise conditions, the engine is drawing mainly off the primaries, which were generally tuned on the lean side. This is where the EGR would be in operation. By no means were these the most accurate way of controlling emmsions, but these carbs did make an attempt to more accurately dispense fuel, because the secondaries are an air sensing style like the Carter AFB is. Meaning that the carb can flow 650 cfm, but if the engine only required 625 cfm the secondaries would only open that far. As far as the EGR helping on cold start up, it is not open at all. If it was idle operation would be terrible. EFE (early fuel evaporation) is what helped on cold start up, and thermostatic air cleaners. To my knowledge these are only found on older carb equipped cars, because now the computer controls cold start enrichment in open loop. The EFE system had a vacuum actuated plate installed in an exhaust manifold and under vacuum would be closed and route exhaust through a passage in the intake manifold and heat up the area underneath the carb. The thermostatic air cleaner would draw in heat off of a heat riser on the exhaust manifold, to help maintain a 100 F intake temp and to prevent fuel puddling and dropout. As for the PCV valve itself its purpose is to draw in blow by by products and burn them off. You could just put a breather in. But, if you are lookig for max. performance the installation of a belt driven vacuum pump, to draw the air out of the crankcase. Because of the vacuum the pistons have little to no resistance, because of the lack of air in the crankcase.

[AaronGTR]

Yeah, I just finished reading something about how the PCV valve and crank case ventilation sytem works. It needs vacuum to pull the blow by out of the crank case because it contains substances that will turn your oil into sludge if you don't. It is also a combustable mixture, so by re-routing it into the intake and re-burning it, you are also reducing emmissions and improving fuel economy. Looks like I'll be leaving the front valve cover with the PCV valve hooked up to my intake, and I'll just put a breather on the rear valve cover to simplify the plumbing in my engine compartment a little.