Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Air Intake improvements

Thanks from me too Richard. I have been editing such links and it also works with a post revealed by a search.

Well I just completed reading this whole thread. Looks like I was a little off base with My ECU comments. But I also learned a bit and really confused. ie: The Rover Filter can has a venturi on the front end presumably to gather fresh cool air into the system. But also at the front of the filter can is a heat riser that gathers heat from the exhaust manifold and then to add a bit more heat there is a hot water heater just in front of the butterfly valve. I suspect that the ECU has parameters of just how much temperature that is optimum.

On the hand held for My MSD EFI there are two temps Engine Temp and IAT temp. I think IAT stands for "Intake Air Temp". It is hard to watch the handheld carefully and drive. Think cell phone. But it looks to Me that the IAT temp is about 10% less than the engine temp. Now My MSD system is like a Carb and just gather air from the engine compartment.

Is the end game to gather initially cool air and warm it to a temp certain that the ECU is looking for?

Button. Such are my automotive interests that I kinda switched off with the arrival of EFI, and digital controls on so very much. Thus I have little to no experience of EFI.

I am guessing that your system is a single point injection as opposed to an injector for each cylinder..? That being the case then it does indeed have similarities to a carb fed engine. As has been stated elsewhere many of us have felt improvements when operating our engines in cold air, perhaps with a degree of moisture mixed in..

I suspect it is the density of the air that has the possible effect of raising the compression ratio to provide the extra performance...? At high altitude the air being somewhat less dense seems likely to reduce the compression ratio and thus engine performance..?

As for the cold and hot air supply to the intake, I suspect the engine will run better on cold air, however if too cold, carb icing could be a problem, perhaps there is a similar effect in single point injection systems...?

On old carb engines there was a Summer and Winter setting on the air filter housing which operated a flap within. In Summer the flap could be manually set to close off the hot air intake from the exhaust system the operation of which opened the cool air intake to the carb. In Winter the flap performed the opposite operation..

Perhaps single point injection suffers from icing in some way also, thus the pre heating of the air you mention may be to resist such possibilities...?

Just passing the time thinking in type with ZERO expertise..

Button, the IAT is the incoming air temp. It effectively measures the amount of air coming in. Cold air is denser than warm air so colder IAT is like getting more air in. The map then adjusts fuelling to match this, more fuel for colder air. This creates a slightly more powerful explosion in the cylinder and small power increase.
A simplified description!
Another analogy is cold starting with a choke on carb engines. Cold air, increased fuel, engine runs. As the engine warms up remove choke (either auto as it senses a temp increase) or just push in the choke cable.
My Plus8 has Gems management and uses sensors/ evap cannister to imitate the choke method when cold by triggering fuel input from the map to suit cold air, coolant etc.. As the engine warms it moves fuel input to a different point on the map to suit conditions.

My quandary is why all the elaborate giz wizs to heat the air if the engine and EFI prefer cool air? Is it for starting and warm up? To prevent ice from forming? If so I would expect the heat supplied would be minimal. In the case of My MSD EFI (looks like a carb and frankly I would call it an electronic carb not EFI) I think I have room to access cold air from above the radiator. Now the air dam and the blocks at the back of the bonnet are making sense to Me to lower the air pressure in the engine compartment. As I do not drive in the Winter I would not worry about warm up or ice. In any event it rarely gets below freezing in the Pacific NW and I could avoid Mountain Driving.

Thanks SOSPAN. I understand GEMS (a bit) and I bought a 3.9 Hotwire (very early) that Bill Fink replaced with a Propane Carb. Because My +8 is registered as a 1973 emission laws do not apply. My MSD EFI is better than the Edelbrock Carb for emissions and self adjusts to the engine. It like GEMS also sets the timing. However unlike GEMS it is not multi point injection and achieving a steady, reliable idle has been difficult to achieve. There are now other aftermarket ECU's that could be used with the 3.9 Hotwire Unit that I think might give Me a much better EFI System than the MSD unit I am using at the moment. Sorry this is for another thread but I wanted all to understand what my interest was.

All engines prefer cool air as it's more dense and so contains more oxygen molecules for a given volume, hence bigger bang. I don't know of any injection system that has any requirement for warm air Carburettor icing is a big issue on piston engine aircraft with carbs, especially in conditions of high humidity and low throttie openings, such as on an approach. All such aircraft have a carb heat control to offset this undesirable adiabatic effect.

Then why does a Rover HotWire +8 have such elaborate stuff to heat this cool air?

I will answer My own question. It is because Rover designs engines that will be operated under all sorts of climate extremes through out the World.

But Why would I care as I am using this engine in a very special Sports Car in the Northern Middle Hemisphere in general and specifically in the Pacific NW of U.S. where the Japanese Currents keep us warm and wet.

A manufacturer tends to use a map that is a compromise for different climate regions. Hot climates and cold climates. There are variations they would put in sometimes for sufficient sales volumes or specific requests from dealers/customers. I once owned a Ford Focus that you could buy with two power output options. I researched it and concluded that it was simply different mapping. No component changes just map parameters modified. This ability to tweak mapping is the basis of the aftermarket chipping business. The true correct way is for a rewrite of the map under both static and on road driving. Small gains only in a normally aspirated engine but turbo allows more by increasing boost as well. Bigger power increases require new cams, valves, other component changes.
For the Plus8 I think the Tornado chip is a proven remap modification that can increase power and improve general running characteristics and cure some faults.

No idea, maybe you answered yourself, but found some useful stuff here. Generally fuel injected engines don't suffer from intake icing as despite having a throttle butterfly causing depression, they don't have fuel atomisation taking place in the vicinity of same (which would further lower the temperature) as fuel is injected downstream.