ch1ll1
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| posted on 27/5/06 at 06:15 PM |
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zx9r ram air
hi all
just went down to my local dyno tuners today,
spoke to them about the car.
they asked what set up it was and when i told them about the sausage filter , he said the they liked the ram (forced air ) effect on them and would be
alot better off if i could sort that out
so do i leave it as it is or should i fit a bonnet scoop ( ram air effect ) to help it
not that there's anything wrong with it as it is
cheers paul
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JoelP
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| posted on 27/5/06 at 06:20 PM |
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you can buy a thing that bolts on inplace of the sausage, which has a funnel of sorts. Its meant to be used to fit a remote air filter, but could be
adapted to be an air ram. You would have to work out the filtering still though.
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ChrisGamlin
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| posted on 27/5/06 at 06:22 PM |
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Ram air has b*gger all effect below about 120mph so absolutely worthless on a BEC.
They may be referring more to just having an airbox on there so you're sucking in cold air rather than warm engine-bay air, which is a benefit
although this is often cancelled out by the fact that the airbox is often more restrictive in standard form than a sausage filter. An airbox does have
other benefits though, as it also reduces induction noise but if its purely ram air that your tuner is talking about, tell them to get their physics
books out, do a few calculations and then come back to you 
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Hellfire
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| posted on 27/5/06 at 06:29 PM |
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As Chris says. 
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ch1ll1
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| posted on 27/5/06 at 06:49 PM |
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i thought that,
but thought i would ask
then got used to the idea of having a massive vent (blower)
stuck out in the bonnet 
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DIY Si
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| posted on 27/5/06 at 07:01 PM |
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At 150mph you would gain a boost pressure of 0.323psi. So really not worth spending more than 2 mins of your time trying to achieve this.
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mark chandler
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| posted on 27/5/06 at 07:32 PM |
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Never the less it is very worthwhile ducting cold air to the engine.
An open sausage filter behind a hot radiator is not good !
Regards Mark
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DIY Si
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| posted on 27/5/06 at 07:37 PM |
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Cold air really is worth the effort. If you can drop the intake temp by 40-45C, which is poss if you change from behind the rad to open cold air, you
can get a power increase of up to 12% due to the increased air density. This however assumes the air temp is maintained all the way to the cylinders,
so you'd probably only get a 6-9% increase, but it's some of the cheapest power you'll get.
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leto
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| posted on 27/5/06 at 08:29 PM |
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As far as I understand it the ram effect is not dependent on speed.
http://www.hotrod.com/projectbuild/113_9907_efi/index2.html
You should try to get the effect on the rev. you land on when you change to a higher gear.
“I'm gonna ride around in style
I'm gonna drive everybody wild
'Cause I'll have the only one there is a round”. (J. Cash)
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ChrisGamlin
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| posted on 27/5/06 at 08:58 PM |
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I havent fully read through that article but what I think its actually talking about is tuning the length of the inlet tract to take advantage of what
is usually known as pulse tuning. Its not actually talking about ram air (where the airbox is pressurized by the incoming airstream) which most
definitely is completely related to speed.
As I understand pulse tuning, the engine sucking air from the airbox causes pressure fluctuation inside the airbox, so one minute the pressure is
high, the next its low as its "emptied" and "refilled" (for want of better terminology). Pulse tuning is where you optimise
the inlet tract length / volume so that you achieve these high pressures just as the inlet valves of one cylinder open, so it forces a little more air
into the cylinder.
[Edited on 27/5/06 by ChrisGamlin]
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DIY Si
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| posted on 28/5/06 at 01:04 AM |
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As you said, it's about tuning inlet tract length. Which affects pulse wave tuning. As each valve shuts (I think) you get a pressure wave going
back up that inlet tract which raises the pressure in the air box. Idealy you want this to coincide with another valve opening so the pressure wave
force extar air into this second cylinder. Whilst it does aid power I don't know how affective it actually is, ie I have no figures to hand
about it as most of my knowledge of this type of thing comes from a series engines, where you can't really pulse tune anything due to siemes
ports. With the older engines it used to be a good idea to get a nice 4-6" inlet manifold, maybe a little more if poss, and don't buy
anything with a swan neck in it.
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Lippoman
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| posted on 28/5/06 at 01:54 AM |
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Ram air
The positive effect of ram air over the atmospheric pressure is negligible, but are higher than under bonnet where pressures can be lower than
atmospheric. So inlet placement may very well be something worth to consider.
"Good" areas for inlet placement on sedan type cars are above the bumper in front of radiator or at the base of the windshield.
Also the effect of "cool" air cannot be stressed enough...
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bimbleuk
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| posted on 28/5/06 at 07:27 AM |
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You may even find under bonnet pressures higher than atmo! Totally dependant on the front end design but more likely on cars fitted with an under tray
or flat panels.
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G.Man
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| posted on 28/5/06 at 10:57 AM |
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We used to run a ram air dyno at performance techniques for race bikes, the effect of ram air on a bike with a race system is worth about 5bhp on a
zx6r, 8 on a zx7r, and 10 bhp on a zx9r... but ram air is not included in bike makers stock bhp figures anyway..
engines technically do not suck air, the cyclinders are filled by the atmospheric pressure being greater than that in the cylinders, so a small
increase can make a reasonable difference, but its by no means supercharging...
It actually starts to create a difference in the torque/bhp curve at around 50 mph, depending one how free flowing your air filter si, on the race
bikes we didnt run any airfilters, so on those it makes the most difference..
If you make up a plenum to replace the sausage filter and duct it to a scoop then you can create a ram air effect, just make sure you map for it..
Opinions are like backsides..
Everyone has one, nobody wants to hear it and only other peoples stink!
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ChrisGamlin
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| posted on 28/5/06 at 11:55 AM |
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There's a good article here specifically on the Ram Air system of the ZX9, goes into
quite a lot of technical stuff and dyno testing etc.
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G.Man
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| posted on 28/5/06 at 03:47 PM |
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Looks like they were running the stock airbox/filter...
The race fairings give a better inlet tract without all the mesh and multipart pipes etc...
Dunno what fan they used, at PT we had 3, 8 feet fans to generate the wind for the dyno room...
Opinions are like backsides..
Everyone has one, nobody wants to hear it and only other peoples stink!
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wildchild
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| posted on 28/5/06 at 05:19 PM |
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quote:
Originally posted by G.Man
but ram air is not included in bike makers stock bhp figures anyway..
I bet some of them do.
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G.Man
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| posted on 28/5/06 at 09:08 PM |
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Well every kawasaki we have tested has exceeded quoted figures on the ram air dyno
Opinions are like backsides..
Everyone has one, nobody wants to hear it and only other peoples stink!
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