Air filter or no air filter?

[Dale]

I recently took off my (type unknow) pancake air filters as the foam was pretty much knackered and beyond washing and refitting. The car was running quite rich as I think the filters were restricting airflow a bit.

The engine now runs much better (and this is not the main reason for the question in the title) so as yet I haven't sorted a replacement set of filters. I also realise that with new clean filters the engine will run great too.

However, I see so many engines with carbs other than the stock Hitachis that don't have air filters on them, Webbers, Dellortos, Mikunis, that I wonder if I really need to put some on?

How much damage really is caused by the little particles in the air that get sucked in, particularly as these are mostly low mileage cars?

I think it would certainly be prudent of me to put the pancake boxes back on so that stones and small animals get stopped by the mesh and don't get sucked into the engine. Fuel being spat out and dropping onto the manifold is also a concern!

So what are everyone's thoughts? For and against?

 

[pmac]

So what are everyone's thoughts?

Im interested in your thoughts?
So here is a question for you.
What would you hope to achieve other than filling your engine with fine grit??

 

[MikeB]

And as aside, it's also an MOT fail if you turn up with no filters over the carb inlets.

But answer PMAC's question first

 

[pmac]

And as aside, it's also an MOT fail if you turn up with no filters over the carb inlets.

But answer PMAC's question first

He might not answer .... Its Dale he probably suspects a "set up"

Might be... or I might be serious???

 

[AliK]

I would personally ALWAYS have a filter, especially as last time I took the filter off my (1k miles a year) 260z I found a 50cm piece if police cordon / ribbon in the air box not to mention a tonne of fine dust, dead bugs etc.



Ali K

 

[Dale]

What would you hope to achieve other than filling your engine with fine grit??

Ok, a fair question, and I don't have a good answer for you. Which I suppose is the answer you wanted?

He might not answer .... Its Dale he probably suspects a "set up"

I certainly do! You're gonna try and flog me that air box, ain't you?!

And as aside, it's also an MOT fail if you turn up with no filters over the carb inlets

Do open trumpets count as an MOT failure too?

I would personally ALWAYS have a filter, especially as last time I took the filter off my (1k miles a year) 260z I found a 50cm piece if police cordon / ribbon in the air box not to mention a tonne of fine dust, dead bugs etc.

Thanks Ali. I see so many pictures of engines with open trumpets that it got me wondering. Some of those have a fine mesh over each trumpet but both struck me as inadequate for the very fine stuff, unless it doesn't actually cause much wear? The last thing I want is a stone or a nut or bolt being sucked in, that would be bad.

Also, in looking into this, an air box would be better for getting colder air into the engine, and also directing it into the carbs better anyway.

So another question. Standard air box vs pancakes in terms of air flow and air flow temperature?

 

[AliK]

Dale, with my Ztherapy carbs there was a very long video included on Z carburation. They commissioned an air flow study by some tech university and reckon no one has come up with a better trumpet design for the 240 z SU carbs than the stock ones; for achieving the optimal Venturi effect.

I'm certain though that trumpets and pancake filters sound better.

I have no real knowledge of the topic but it would be interesting to hear from the racers, engineers, dyno-heads and engine builders on the forum about their views and experience on this.

I particularly like what Rob G has done with the flapper carb on his blue car for getting cold air in!



Ali K

 

[MikeB]

Yes open trumpets count as a failure.

 

[jonbills]

Dale, yes, what you need is a PMAC airbox and cold air induction setup - then you have the benefits of cold air, filtered air, and dynamics of the airbox.
Only down side is that the sound is muted ;-(

On the power front, there was an article in practical performance car a few months ago where Mr Walker explained how those gauze screens over trumpets significantly reduce power.

 

[Dale]

Dale, yes, what you need is a PMAC airbox and cold air induction setup - then you have the benefits of cold air, filtered air, and dynamics of the airbox.
Only down side is that the sound is muted ;-(

On the power front, there was an article in practical performance car a few months ago where Mr Walker explained how those gauze screens over trumpets significantly reduce power.

Thanks Jon.

When you say cold air induction setup, I assume that's taking the original box and extending the front of it much further forward? Also, would air flow be better at the carbs if the filter was at the front rather than the original internal oval type. A cone filter say?

I have to say, as naughty as I'm being, it doesn't half sound good with nothing on I took it through the Tyne Tunnel the other day and it was rather nice

 

[jonbills]

Ah, yes, I didn't mean Pete's old standard airbox, I meant one of these:

As you said, it runs a hose out to the front of the rad where's there's a cone filter.

 

[Dale]

Right, gotcha. I remember seeing that a while back. Mr. Kiddell's carbon fibre box if I recall?

 

[Alphabettispaghetti]

My plan is to take an original airbox and make cut and shape to fit triples, also widen if possible.

 

[Dale]

Here's a pic of Grolls' setup.

It would mean a rethink on the petrol overflow though.

 

[jonbills]

That's it - just like mine, except Grolls' got silicone hose where I've got duct tape!
With the Dellortos, excess fuel goes in the engine via the jets - no external overflow.
Another reason for triples over SUs?


Sent from my iPhone using Tapatalk

 

[Mr.F]

what you need is a PMAC airbox

Now read MJP airbox as I have the revised moulds...