intake whearabouts

[powerhouse]

just thought id ask where is the best place to fit some kind of ram air scoop on a f2,ive been looking at loads of vids and pics and looked into pros and cons of location.i had one at the front nose of the outfit but by the time the air got to the box it must have been almost restricted.ive been looking into molly's periscope type intake
what are your thoughts

[Lumley32]

i wouldn't bother as the top speed of a sidecar is less than the air flow of a 600 engine at full revs if you catch my drift!

but if your still going to then for ram air you want an area of high pressure like the nose (anything that is hitting the air first really) o and the most direct route possible to the air box

the 04 onwards Kawasaki's have the air running around the headstock inside the frame!

dont forget if you put a periscope type inlet any gains you might find are cansled out by the extra drag! its best if you use something that has to be there anyway!

if you do put it in the nose then dont forget that it will fill with water stones grass depending on where you are on/off the track!

[powerhouse]

hmmm something to think about,cheers lumley.
didn't realise the airflow is greater speed of intake.

[steve-e]

Does it work along the lines of 600cc of air going into the chamber every revolution, and at 16,000 times a minutes it's taking in that much air? If it's that then it's a lot of litres of air going in every minute but then why would a road bike have pressurised airbox stuff? I know that the 125's spend a lot of time on airbox stuff, Mark at KRP is very particular about air intake and airbox stuff so it's almost definitely not that simple.

I'm an electrician and a passenger so not qualified to give any further ramblings

[Lumley32]

i think its something like that steve it depends on how good the engine is i dont think you will ever get pressure in the cylinder from the just wind speed in fact i think that at bdc there is properly still negative pressure*** in the cylinder. but i might be wrong.

to be honest i haven't done the maths, but i trust the man that did!!

but when you think about it a modern 600 solo is a hell of a lot faster in top speed than a f2 plus to get the most out of any positive pressure you need full engine management (the dreaded MoTeC) to adjust the fueling to suit

when i get round to it ill put a pressure sensor in my air box and try some stuff out!!

just fit a supercharger that will get you some ram air!

edit
*** compared to atmospheric!

[powerhouse]

ill leave it as is then cheers lads

[kwaknik]

Just read some other info on inlet ducts etc to pressurise the airbox. What seems apparent is that top end gains may not be that great but mid-range response could be the biggest benefit. However if the inlet of the snorkel is not positioned in the right place on the bodywork then it could be at a point where there is negative pressure, not what is required! Probably not worth it unless you have the means to check the increase in pressure in the airbox and that's before you start considering turbulent flow in the airbox as a result of forcing the air in which may not be consistent for each cylinder. F1 teams probably have 6 people and a supercomputer working all this out.

[powerhouse]

just a quick note.originally i had a single 65mm inlet pipe into the airbox which had so many holes in it it was stupid,so i thought i would make two 65mm inlet pipes to the airbox and seal it,making use of two naca ducts either side of the fairing courtesy of jason miller.so a big thankyou to you jason

[Lumley32]

dont forget your only alowed the same intake area as the standerd bike! no cheating now!

[tufty113]

dont forget your only alowed the same intake area as the standerd bike! no cheating now!

please be sure to read the acu hand book for the rules on f2 air intakes,as you are not allowed the same as a std bike in most cases....

[Lumley32]

havent got mine yet and tidied the old one away

Any idea what the max size is matt? i had better make sure mine is right now!

[steve-e]

18.9 AIRBOX
An airbox must be used with all four-stroke engines.
The airbox intake sizes are restricted as follows:
— If 1 intake is used a maximum of 103mm lnternal Diameter is permitted
— If 2 intakes are used a maximum of 73mm Internal Diameter per intake is permitted or equivalent
area if none circular section(s) are used measured within 50mm of the point of entry into the
airbox.
The airbox must completely close around the induction bell-mouths.
The carburettors or throttle-bodies may be entirely within the airbox.
The engine must have a closed breather system.
296 ROAD RACING
AUTO CYCLE UNION HANDBOOK 2009
The engine breather must be connected and discharge in the airbox.
The airbox must cover and collect fluids discharged from the bell-mouths.
The airbox must be constructed in such a way as to prevent any oil discharged in the airbox from
spilling on the track.
This oil containment must hold a minimum of 1000 cc of oil.
The airbox must be sealed to prevent spillage of oil or fuel.

[ianw]

A fact you should never forget. A 4 stroke engine, no matter how it's aspirated must run at a ratio of 14:1. That's 14 parts of air to 1 part of petrol. Anything above that is weak, anything below is rich. road engines have been developed with "ram air or pressurised air", racing a road engine is totally different. The only way you will keep at the optimum ratio of 14:1 is to run a non pressurised air box, so no intake that is in the air flow.

[Lumley32]

on the acu sizes with a quick bit of math's you can see that your better of running 2 73 diameter inlets by over 38sqmm thats not to be sniffed at!

dont you think that the rules should be consistent? i no its a small point but it could make all the difference

and as for 14.7 to 1 thats not that true at high revs most stuff i have seen richens off a tad and it depends on what fuel is being used air temp ect but the more air going in the more fuel you can add giving a bigger bang at least thats what i was tort!

[kwaknik]

As the ideal combustion ratio is 14.7:1 then in a normally aspirated engine the intake just needs to be able to supply enough air to allow that ratio to be achieved at peak revs. Presumably the single intake achieves that. I am sure a few minutes with a calculator would prove it. Actually getting the air into the cylinder to get good combustion through efficient inlet design to reduce turbulent flow should be a priority.