Cold air induction/airbox

ben240z

Club Member
17th place 12.79 ben stapley 240z NA close to a low 13 but the wrong side of it :) xxxxxx

not open trumpets

just saying
 

AliK

Vehicle Dating Officer
Staff member
Club Member
There's no question that Steve is right, but some of us just don't want to run with filters or airboxes...


Alan, why?

I know they sound and look better, however, the last time I took my air box off it looked like the car had tried to eat half a bird + found a 30-40cm piece of police cordon plastic strip in there (forgetting all the dust of course)!

How do you protect your engine from all that stuff?

Yesterday I was looking at sexy engine bays like this wondering how the engines survive the dust of a race track esp after they put the dusty stuff on oil spills which other cars kick up etc
6730ef204a452fde08dd4585ac8f6b85.jpg
 

Albrecht

Well-Known Forum User
Alan, why?

I wouldn't want to put UPVC windows in a Georgian townhouse either.

The cars in question (my ones, that is...) were designed and built in the late 1960s. There are hundreds if not thousands of things on the cars that the designers and engineers would do differently today if they had a free hand, but I think it's better that I don't give them that opportunity. There are hundreds of things on them that could be "improved" with modern thinking and modern technology, but where do you stop?

Of course, I have to be pragmatic. My theoretical Georgian townhouse would have electricity, and it would have hot and cold running water (and no lead pipes!), but I'd like it to retain as much as possible of the flavour of a Georgian townhouse that's lasted 200-odd years and has the patina to match. That's what a lot of this is about for me - flavour.

For what it's worth, I'm running an airbox with integral carb trumpets on one my cars. It's supposed to be ducted from in front of the radiator, but I haven't bothered. Two other engines (both S20s) run open trumpets. I don't feel overly fussed about changing that, and one of them has been that way since the mid 1970s. I'm building another L-gata with period tuning parts that will have a (primitive) airbox of the type used by Nissan's works race cars in the early Seventies (ducted to 'fresh' air, but not filtered).

I know that fully filtered, cool air and UPVC windows are "better", but I reserve the possibly slightly perverse right to reject them when it suits me.
 

STEVE BURNS

Club Member
I know that fully filtered, cool air and UPVC windows are "better", but I reserve the possibly slightly perverse right to reject them when it suits me.

Not that my knowledge on mechanical things is great in fact a nursery kid knows more than me but believe the above is 100% correct in all aspects
 

johnymd

Club Member
I'll be running trumpets just because I like them. Never liked the look of an airbox, although I wouldn't question its advantages. I will probably use the push on ramair foam filters for everyday use and take them off for show. How often do you need to make 100% use of an engines potential power on a daily basis?
 

SeanDezart

Well-Known Forum User
Sean you do a unique way of intimating that you disagree (maybe its a language thing who knows) with comments like
Quote:
I'd be very interested to hear what the engine-maker says on the subject of cold/hot air intake via airbox/under-bonnet filters.
which I take as a direct challenge then when someone supplies data to the contrary you quickly do an about face with
Quote:
I do not seek to 'debate' your findings merely add to and broaden them

A) Then do NOT take that as a challenge and simply as it was intended - merely the opinion of the engines' builder in question

B) I refuse to be held responsable for YOUR mis-interpretation of what I say wehn it's down there in black and white 'I ***** agree with you'

C) no about turn (see 'B' above)

D) I don't want to pick words with you, I want to simply discuss more broadly the whole concept of warm and cold air upon an engines performance.

I confess that I don't agree that it's ALL about an airbox and nothing else but I do NOT refute your findings - I don't know how else to say it Steve - will you stop p*ssing around sounding like a wounded victim and let's discuss more seriously.
If you start laying down discussion rules eg if I don't have 20 pages of r-road backed data I can't play, so be it - I won't.

I haven't been on here for 2 YEARS and you're acting like it was yesterday - move on mate - I have :cool:

I have considered an airbox for my L31EFi - I have one here ready but dismissed it because.......I prefer the more classic look of shiny bling K and Ns. Guess what, I don't care if I love 20bhp - I'm building a road GT and not a flyway express* so although I'm more than convinced that having an airbox is the best....I'm happy to settle for lower down the evolutionary level but that doesn't mean that we can't agree on airboxes and open the discussion.....does it ?:eek:

*that'll happen with my other shell and another L6 3.2 EFi engine with an airbox and cold-air induction but that's another story;).

Oh, and I don't like CF, either real or copied on my early '70s S30 but that's just my taste mate - love n' kisses.:thumbs:
 

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SKiddell

Well-Known Forum User
I haven't been on here for 2 YEARS and you're acting like it was yesterday - move on mate - I have

I know, I can tell by your lack of understanding of basic engineering concepts :lol:

And I had moved on .......that was until you decided to twisting my melon:p

Johhny said:
How often do you need to make 100% use of an engines potential power on a daily basis?
Its not about using 100% of your power, thats maybe where some people are getting confused, its a bit like balancing an engine, you dont have to do it, but its good practice, the engine will live longer and when you do "wring" it, it will stay together.

But each to their own ehh.
 
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SeanDezart

Well-Known Forum User
I'm not twisting your melon, never did and don't intend to - you've been twisting it all by yourself in a shadowy corner and pointing the finger at me you grubby schoolboy:D
 

jonbills

Membership Secretary
Site Administrator
Fwiw, the main value of the airbox on my car is it makes it easier to drive. Before the airbox, pulling out of junctions on a hot day was a scary thing
 

Rob Gaskin

Treasurer
Staff member
Site Administrator
I have air-boxes on both my cars - they are orange and as far as I know the cars left the factory with them ;)

One of them ('71) uses the downward facing intake as a cold air feed from in front of the rad. Best of both worlds, authentic looking and a bit more efficient perhaps.
 

SKiddell

Well-Known Forum User
Airbox examples

This is quiet a telling example of an airbox (original fitment, not a fake tudor beam or Doric column in sight) all be it on a 432 but it still demonstrates that the benefits were well understood 45 years ago.
Having the airbox on the RHS is really helped by the engine inclination, on a non crossflow L series the airbox runs very tight to the inner wing (as do open trumpets).


n2d012-orgz432_Nissan-Fairlady-Z432R-S30-640x426.jpg


We can also see an aftermarket cold air induction system on this Fairlady

n2d015_Nissan-Fairlady-Z-S30-640x426.jpg


If you look closely at an original S30 twin Hitachi air box, its design is well thought out with integral trumpets and an intake flap that can be switched.
 
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Albrecht

Well-Known Forum User
This is quiet a telling example of an airbox (original fitment, not a fake tudor beam or Doric column in sight) all be it on a 432 but it still demonstrates that the benefits were well understood 45 years ago.

n2d012-orgz432_Nissan-Fairlady-Z432R-S30-640x426.jpg

That's a 'full fat' PS30 Fairlady Z432.

Nissan's super lightweight PS30-SB Fairlady Z432-R was sold - for street use - without the airbox and air filter. Nissan's works circuit race 432-Rs were run on mechanical injection. Again, without airboxes or filters.

So, Nissan knew the benefits of cold and filtered air for sure. But - like me - they occasionally chose to ignore them:
 

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AliK

Vehicle Dating Officer
Staff member
Club Member
I wouldn't want to put UPVC windows in a Georgian townhouse either.

The cars in question (my ones, that is...) were designed and built in the late 1960s. There are hundreds if not thousands of things on the cars that the designers and engineers would do differently today if they had a free hand, but I think it's better that I don't give them that opportunity. There are hundreds of things on them that could be "improved" with modern thinking and modern technology, but where do you stop?

Of course, I have to be pragmatic. My theoretical Georgian townhouse would have electricity, and it would have hot and cold running water (and no lead pipes!), but I'd like it to retain as much as possible of the flavour of a Georgian townhouse that's lasted 200-odd years and has the patina to match. That's what a lot of this is about for me - flavour.

For what it's worth, I'm running an airbox with integral carb trumpets on one my cars. It's supposed to be ducted from in front of the radiator, but I haven't bothered. Two other engines (both S20s) run open trumpets. I don't feel overly fussed about changing that, and one of them has been that way since the mid 1970s. I'm building another L-gata with period tuning parts that will have a (primitive) airbox of the type used by Nissan's works race cars in the early Seventies (ducted to 'fresh' air, but not filtered).

I know that fully filtered, cool air and UPVC windows are "better", but I reserve the possibly slightly perverse right to reject them when it suits me.


Utterly brilliant Alan!! I laughed a lot reading this
 

johnymd

Club Member
It's nice to chew the fat and "discuss like adult" the for's and against certain things but we all have the right to our own views. I will go open trumpets because that's what I want and you won't talk me out of it. I enjoy listening to other peoples views and learning from what the clever people have to give but please don't get upset if I still chose to go my own route.

Discussion is good as we all can learn from others if we choose to listen just please don't quote every single word someone writes and look for argument as it wined's everyone up.

just me views so don't analyse and quote me on it.
 

SKiddell

Well-Known Forum User
Johnny there's two forces at work here, if you want to do something because you "want" to, then hey each to their own............live and let live.

BUT, if your doing something because of poor information/poor understanding then people will try and "steer" you in the right direction, in your case you are fully aware of the choices and you clearly dont want to run an airbox.......no one is forcing you to.

You clearly get frustrated by argument and "nit pickers", equally I get frustrated by apathy and ignorance Cest la vie
 

Rob Gaskin

Treasurer
Staff member
Site Administrator
Guys, it has been mentioned before (but not in the Thread) that there is an increase in fire risk if you run our cars on triples without an airbox.

I know of two fires occurring in this situation and so it's not to be taken lightly. Insurance consequences :confused:
 

johnymd

Club Member
Reminds me, my old Z under bonett sound insulation caught fire because of the blow back from the open trumpets.
 

andrew muir

Club Member
Agree that open carbs can cause a fire on blowback, In some countries the filters such as K&Ns are called "flame arresters".
Just a small tech point if using K& Ns etc the depth of the can (airbox) should be at least1.5 x the dia of the carb opening etc, otherwise turbulance is caused..Also good idea to run with a small ram stack inside the filter housing.

I always thought the biggest advantage of using a box of some sort was to reduce turbulance in front of the carb mouth etc. I believe the K& Ns do this but admit it that the air will be less cold etc.

My only question with regards to cold air induction is that if the intake is at the front of the car the preasure inside the box will be different at different road speeds and with carbs will this not be difficult to set up correctly?:unsure:
 

richiep

Club Member
Guys, it has been mentioned before (but not in the Thread) that there is an increase in fire risk if you run our cars on triples without an airbox.

I know of two fires occurring in this situation and so it's not to be taken lightly. Insurance consequences :confused:

I nearly posted something similar earlier in the thread. Fires have resulted from blow back from the carbs lighting up those foam socks and leading to devastated engine bays. I think the G-nosed Samuri was one victim of this issue. Something to consider...
 
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