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

Interesting stuff Jon. Although I haven't looked at my airbox yet, it would seem that any re-routing of dirty air feed would best be performed on a virgin airbox before MMC performed their butchery.

To that end do you or indeed anyone know the source of the airbox? It appears it may be a pre 2015 Mustang version as later ones had an angle feed from box to accomodate an air manifold that feeds from the front of engine not the rear as on Roadster.

ETA: if the source of airbox can be confirmed it's likely that a K & N slab filter would be available to replace the more restrictive paper one as below.

Can confirm that the early 2011-2014 Mustang 3.7 V6 air filter is the one for similar engined Roadsters.

The equivalent oiled cotton K & N panel filter version is part number 33-2431 and available from a couple of eBay sources including one linked above. It drops straight in to air box.

This is the sales hype on back of box.



Doubt if I'll notice the improvement but there will be some based on experience selling K & N filter conversion kits for Moto Guzzi's. Here we would supply in the kit size 5 richer main jets for carbs to compensate for increased air flow. In this case the ECU will compensate.

I am not convinced that simply improving airflow in an ecu managed car would give noticeable improvement. The ecu would monitor airflow and temperature and change fuel injection to suit?
I will look up Graham Bell’s tests he has done. From memory very little, if any bhp increase. If any probably small and at higher revs...

Exactly that. To maintain correct fuel/air ratio more fuel provided so greater power. I agree the improvement will be small and only at the top end. Wouldn't be surprised if I get slight improvement in mpg for same driving style as well though.

It all depends on where the restrictions are in the intake, if any.

If the air filter is a big restriction then changing could make a significant difference.

If however it's the MAF sensor or the clean side pipework that is the major pinch point then changing the filter will make little difference. Could also be the throttle body if you make big horsepower changes.

The only way to be sure is to instrument the intake system with a series of vacuum gauges and record the losses in the system at each point.

Worth the effort when developing a race engine but probably a bit OTT on a road going engine.

Alternatively, take both filters to a dyno and see what happens in the real world.

If the new filter does allow more airflow, the MAF sensor should pick that up and compensate with the fuelling map.

Have to disagree, Cain recently fitted a K&N cone filter to my +4 I don't know if it increased the BHP but it certainly increased the low down punch.

I don't mind washable dry filters but it has been shown that oiled filters are fine when they a fresh and clean but clog up quickly with the accumulation of dust.

My daughter's Guzzi caught fire when it backfired and set alight the oiled pod filters that I had fitted. Fortunately a quick thinker on the veranda of the pub that it was parked in front of put out the fire using his shaken up beer bottle as a fire extiguisher. Following that episode I fitted a conventional air box from a sports model.

Dyno testing that was done on on motorcycles fitted with various filters and exhaust systems actually sometimes showed a loss of power over standard unless a re-map was done to tune the system to the new configuration.

I don't know about the original Morgan ECUs but my Omex ECU is set to ignore the sonda lambda sensor fuel adjustments after 4000 rpm. From that point on it simply feeds the fuel as per the map so the fuel map has to be correct and for maximum performance and is normally set a little richer than stoichiometric air–fuel ratio as achieved by the closed loop feedback using the sensor.

If the airflow is dramatically improved it may mean that the engine is running too lean at high revs and driving for extended periods in that condition could damage the engine. Fortunately few Morgan owners would be travelling at more than 4,000 rpm for an extended period on public roads so damage would be rare. Something to keep in mind if a modified, and not remapped, road car is used for a track day.

Peter,

If your OMEX is set up similarly to mine you won't have a MAF sensor and it works on a speed density principle rather than the OEM mass air flow principle.

Mine is set up such that the feed back loop maintains stoichiometric AFR up to 3500 rpm or half throttle, whichever comes in first.

Over those parameters, the ECU mapping takes over and runs richer according to a dyno developed map to get maximum performance.

The OEM ECU uses the MAF sensor to calculate the amount of air going into the engine and will therefore compensate to some degree for a less restrictive filter up to a point. The problem is that the MAF sensor itself is restrictive and will only work within certain parameters. Beyond that it can't compensate and it will run lean. (and probably throw up a warning light)

The problem with the MAF system is that you are stuck with whatever AFR the OEM chooses and that will probably be biased more towards fuel economy rather than power unless you get the OEM ECU re-flashed.

Because you have individual throttle bodies, you can't run a MAF system hence the change to the speed density type stand alone ECU's such as OMEX.

I changed to OMEX so that I could have control of the fuel and ignition map as I made modifications to the engine.

One problem of oiled filters is that they can contaminate the MAF sensor and then the ECU will get false readings. K&N dispute that by the way.

I did away with the air turbulence inducing plastic airbox,filter and plastic tube on my 2015 Roaster and replaced with aluminum tube and K&N cone filter.Sealed it off from the engine bay and created and air intake that draws cooler ambient air from outside, not preheated by the manifold.
The result is: the engine breaths freely and is really responsive. at higher revs it is very loud and pulls like buggery. At times the noise of the air being sucked into the engine is louder than the outgoing gasses from the Librands sports exhaust. Love it!

Exactly. One of the main reasons that I changed is because the standard intake system could not be adapted to the sports exhaust fitted by Aero Racing from new. At that time there were no readily available re-flashes of the OEM ECU. With the throttle bodies and Omex ECU I was able to adjust all the engine parameters to get optimum results. Some work was done on a rolling road starting with Omex's base calibration but the final tweaking I have done using recorded logs on a portable PC. A challenge and great fun.