Bolt on Filters update.

[krede]

Spend most of this afternoon in the trunk of my Murena swapping the airbox for two “Ram Flow” bolt on filters that I bought of ebay last week.
 Though the filters are only 5 cm deep It quickly became apparent that even this was too much for the left carb.. the clearance to the fuel tank is simply too small.
Thus the outer wire mesh of the filter  had to be slightly modified.... with a hammer!!! The internal plastic that keeps the foam element pressed against the mesh, still fit even though the mesh has been beaten into submission
IN spite of this random act of violence, I am still pleased with fitting the filters.
The Airbox was a home made item,  and though I am sure that a lot of time and effort went into building it, I find it hard to believe that it doesn’t pose some form of restriction to the airflow.. especially to the leftmost carb where the space to the wall in front of the inlet was a mere 2-3 cm!!
Thus no air horns were fitted, witch isn’t optimal.
I have not been able to register any in/decrease in engine performance of response since I fitted the filters.... but must say that I didn’t expect much difference anyway.
However.. the sound of the intake has definitely improved, during acceleration the engine sound is more clear and raw.
I feared that the noise would become even more tiring then before, but it seems that the “bad” sound comes from the exhaust and not the inlet.      

[Anders Dinsen]

Congrats on the filterfitting

I think the old airbox you had was also suboptimal by having many edges (at least on the outside, probably also inside?) - this is to be avoided in any air flow and in the racing industry a lot of thinking is often put into making airboxes that are extremely smooth inside. Obviously (as we've discussed before) your engine will breathe warmer air which will make a difference on the top, but I doubt if it will be noticeable and in the winter time it may actually be an advantage.

My Murena tends to have a resonanse around 3000-3500 rpm (on the meter) which I think it because the bottom on the trunk starts vibrating with the exhaust - other than that I think it's not a very noisy car inside, at least not when comparing to the outside. I always get slightly surprised sitting in the drivers' seat when the right door is opened and engine running - this somehow allows the exhaust noise to reflect into the passenger compartment, and even though it's only idling and the exhaust is pointing backwards, the noise is always surprisingly higher than I would have expected from sitting inside the car. I frequently think about what people driving behind me may think?

A virus took me by surprise (with four kids bringing all sorts of 'interesting' stuff with them home from school and day nursery) so I was not in any mood to do any work on my car yesterday. Probably not today either...

[krede]

I think the old airbox you had was also suboptimal by having many edges (at least on the outside, probably also inside?) - this is to be avoided in any air flow and in the racing industry a lot of thinking is often put into making airboxes that are extremely smooth inside

I took some pics of the old air box.. will try go get them uploaded... Im sure you will agree that is design is less then optimal.

Airbox


closer look... note how restricted the left most inlet is..


With bolt on filters

[macaroni]

Looks great. Did the electric fuel pump help matters at all?
Where have you plumbed the crankcase breather into?

[krede]

Looks great. Did the electric fuel pump help matters at all?

Not sure what you mean? I havent messed around with it... just bolted on the filters in stead of the airbox 

Where have you plumbed the crankcase breather into?

Nowhere!!!. though there are holes for connetors on the backplates of the Filters, I'll just put a small filter on the end of the hose.

[macaroni]

Sorry, I meant did the electric fuel pump help with the way the car drives over the standard mechanical pump?

Oh ok, it looks like the crankcase breather is plumbed in somewhere.

[krede]

Sorry, I meant did the electric fuel pump help with the way the car drives over the standard mechanical pump?

Hmmm I wouldnt know, as it was already installed in my murena when i bought it. But I dont think it has any effect on drivabillity compared with the mechanical unit.
HOWEVER!!
Like so many other murenas, I can see in the paperwork that came with the car, that my engine was rebuild some time back following an engine fire!! and since leaky fuelpumps have been known to cause these fires, I take it that the electric pump was installed as part af the rebuild to prevent any further accidents

[Anders Dinsen]

I took some pics of the old air box.. will try go get them uploaded... Im sure you will agree that is design is less then optimal.

Oups no that doesn't look ideal, and worse is that it's asymmetrical. Apparantly the Solex'es were designed to work even when tilted as on the original S-manifold, whereas the Dellortos should sit horisontally...

Regarding the fuel pump, it shouldn't do any change whether it's electrical or mechanical as long as it can supply enough fuel to keep the float chamber(s) full. Electrical fuel pumps may have a problem supplying too much pressure to the carb which may cause to needle valve to fail and the float chamber to overflow, this is why you can see that Krede's car is fitted with a fuel pressure regulator. Apart from that, the pressure is not critical at all. This is unlike a fuel injected system where the pressure difference between the two sides of the injectors has a certain impact on the fuel-air mixture, and for this reason FI systems are fitted with a pressure regulator controlled by the inlet manifold vacuum to keep the differential pressure from fluctuating. But this is another story...

Engine room fires are the single most common reason for people to switch the mechanical pump with an electrical (and if you look into your engine room, you will see that the mechanical pump is fitted in such a way that when it starts leaking, petrol drips down on the exhaust!)

- Anders