Budget K10 4-1 Manifold

The pressure wave as such travels at the speed of sound... just to add.
 
but the speed of sound depends on the pressure of the medium it is passing through. So wouldnt you need some very complicated differential equations to correctly model what was going on?
 
richj said:
Maybe someone could start an inlet thread and explain why you need to tune the length of the inlet manifold. The exhaust makes sence to me, but the inlet I am struggeling to understand.
Click to expand...


This only works on individual runner inlet manifolds, it's also very hard to package such a manifold - look for 'long runner manifolds' on t'internet, and look at some Yank V8s.


When the inlet valve shuts, pressure backs up behind it, this sends a pressure wave back up the runner with a low pressure area behind it, when this reaches the end of the runner, a wave of higher pressure aire will travel down towards the inlet valve, if you
have the runner the correct length, then this high pressure wave will reach the inlet valve as it opens, cramming more mixture into the cylinder.

Hope this makes some sort of sense :)
 
richj said:
but the speed of sound depends on the pressure of the medium it is passing through. So wouldnt you need some very complicated differential equations to correctly model what was going on?
Click to expand...

Correct, but you can still take approximations. The thing here is it has been fully researched for many years, and is fully understood. The best thing to do is to get a decent book on it and learn the pratical aspects to it.
 
frank said:
craig

i agree you would get that effect at low revs, when the exhaust pulses were creating high/low/high/low pressure waves in the manifold, but at highish revs, it would be producing high/very high/high/very high pressure pulses,
so the adjoining pipe would have to force its way out, into that high pressure enviroment
which is why i said on the other thread, that 4 separate pipes might produce more power (the gas from 4 individual pipes only has to fight atmospheric pressure to get out)
Click to expand...

I don' t think that revs will change the mass of mixture in the cylinder, though - that is what reates the lower pressure 'wave'.

Top fuel drag cars use open headers as you describe, so maybe they are bext for maximum power, but on a road/track car the benefits of preperly tuned headers may well be a wider powerband (purre specualtion there as I've never seen a dyno grph for a drag car).
As far as I am concerned, F1 is the pinnacle of automotive engineering, they use collecter manifolds - as do the LMP and Group C prototypes.
Cr4ig
 
The pressure builds up behind the inlet valve because of the momentum of the air that has already been drawn into the inlet manifold? If so, then yes this makes sence to me Thank you! :)

Sorry Ed. Any recomendations for a good book on the subject?
 
Yes, if you imagine the air as a que of people running through a doorway, if the door is shut, then the people will crush onto the door.


Hope I haven't confused everyhting there!

cRAIG

As regards to books, can't go wrong with the Haynes 4-stroke tuning book for a good grounding in all sorts of tunings.
Either that or t'internet.
 
craig

i think inlet manifold tuning only helps the torque, making the car more "drivable"
i think for outright power and throttle response, individual throttle bodies with very short tracts are used
 
Yes, if you imagine the air as a que of people running through a doorway, if the door is shut, then the people will crush onto the door.
Click to expand...

lol yeah, thats one way of imagining it - sorry for taking this off topic.
 
frank said:
craig

i think inlet manifold tuning only helps the torque, making the car more "drivable"
i think for outright power and throttle response, individual throttle bodies with very short tracts are used
Click to expand...


I agree with your first point as torque is genereally directly proportional to air filling. What it does, though, is allow you to increase torque at a given point in the rev range.

With the second pint, you may well be correct, or also packaging concerns could come into play.


I suppose that the next step is to discuss ram airboxes a la BTCC cars :laugh:

158.jpg
 
Yes, noise considerations may well come into play, but they also seem to use 'stepped' headers which is another debateable technique to gain power...

It would be interestind to do a mega manifold rolling road compare day, but I cna't see it ever happening.
 
now thats a good mod.. take one of them in place of the jack! surely gonna save some wieght there!! lol thats awesome
 
Just an update for you guys, unfortunately something major has come up so will be unable to complete this for a couple of months if at all.
 
JStone said:
Surely that'd work better if it was more like a funnel? I.e. Large -> Small rather than Small -> Large?
Click to expand...

I would say no, otherwise they would have done it, either that or regs determined the size of the airbox entry.

Anyway, that car was on pole half the time and often fastest through the speedtraps so I don't think that it hurt it any :D
 
Craig said:
I would say no, otherwise they would have done it, either that or regs determined the size of the airbox entry.

Anyway, that car was on pole half the time and often fastest through the speedtraps so I don't think that it hurt it any :D
Click to expand...
I didn't exactly pass physics with flying colours, but I would've thought that if it started large than got smaller, the air would've been squeezed into that smaller space rather than a set amount going through a tube then being dispersed. Just my thoughts on it. :)
 

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