View Full Version : Effect of Ram Air Induction on Carbs?
Chris Bird
06-02-12, 01:17 PM
So for my first project at uni I will be creating a new air intake system for a Yamaha YZF R1 98-99 bike.
This is the standard box:
http://i1110.photobucket.com/albums/h450/sv650sk6chrisbird/306fa148.jpg
This is a rough CAD model of the idea in my mind:
http://i1110.photobucket.com/albums/h450/sv650sk6chrisbird/6c8fc868.jpg
Now, being as I know absolutely F*cK all this stage, I have to research every bit of info I can. It seems that anything that appears relatively simple on a motorbike, actually isn't. And every topic seems to be an all out bat **** overboard brain melting mess.
My original thought was that a new intake would be easy as pie and all I'd have to do is stick some pipes on the air box and bolt it on the bike... But no!
So now I'm concerning myself with the carburettor's.
What I think I've figured out so far is that the carbs will need re-jetting and fitting a flo-commander.
Can someone give me a heads up on anything I may have missed or got completely wrong?
N.B... I am aware that a modification of this type may only result in a power increase in the top end and possibly flat spots in the low and mid range. This is for a track bike.
Cheers.
Owenski
06-02-12, 01:42 PM
You're correct.
If you adjust the air intake, you'll need to adjust the fuel as well to maintain the fuel/air balanace.
This mixture takes place in the carb and would need to be perfected by dyno runs and jet/needle swaps - fail to get this right and the bike will run either lean or rich depending on which (air or fuel) you deprive it mostly of.
NB: IT WILL RUN< IT JUST WONT RUN WELL (as well as it otherwise could).
if you ensure the flow rate through your new airbox is the same as the standard then you wont have a problem... but that does sort of over write of the benifit of the project some what. All the best and keep us updated.
hardhat_harry
06-02-12, 01:50 PM
You will not be able to test RAMair on a dyno unless there is a posh one which can point 70mph wind into the box.
Most tuners try and compensate by running rich at the top end but only riding it will tell if its correct
andrewsmith
06-02-12, 01:55 PM
You're correct.
If you adjust the air intake, you'll need to adjust the fuel as well to maintain the fuel/air balanace.
This mixture takes place in the carb and would need to be perfected by dyno runs and jet/needle swaps - fail to get this right and the bike will run either lean or rich depending on which (air or fuel) you deprive it mostly of.
NB: IT WILL RUN< IT JUST WONT RUN WELL (as well as it otherwise could).
if you ensure the flow rate through your new airbox is the same as the standard then you wont have a problem... but that does sort of over write of the benifit of the project some what. All the best and keep us updated.
This
It maybe worth trying to get hold of a Kawasaki airbox and see how its done on a ZX10 or ZZR14. The SRAD's and TL also ran ram air systems.
Its worth bearing in mind Ram air is only effective above a certain speed (Going totally Banzai on a Airfield long enough to reach near top speed), it will be difficult to measure the BHP gain on a Dyno (unless its in a wind tunnel)
Edit: Beaten by Harry
Chris Bird
06-02-12, 01:57 PM
I'm gonna test the flow rate of the box on a flow bench... Haven't really got access to a dyno but the guy I'm making the box for might. I think the flo-commander might be the way forward though...
http://www.flo-commander.com/
hardhat_harry
06-02-12, 02:05 PM
Maybe I have seen too many smoke and mirror "improvement" mods but I'd take the flo commander claims with a pinch of salt.
One of the most successfull RAMair mods was the ZXR400 RAMair which was developed by Kawasaki for racing and copied by everyone else, you may want to look at one of those as an example of how to do RAMair on a carb bike which didnt come with RAMair out of the box
Chris Bird
06-02-12, 02:21 PM
Is that the bike that had what looked like pipes from the back of the washing machine going into the tank area?
http://i1110.photobucket.com/albums/h450/sv650sk6chrisbird/80129280.jpg
hardhat_harry
06-02-12, 02:29 PM
Thats the bike but the "pipes" are not RAMair, if you look at most ZXR400 race bikes you will see the radiator dropped down and a mouth that goes intoa RAMair box which replaces the standard airbox
http://www.bdkraceeng.co.uk/Ram-Air%20Systems.html
andrewsmith
06-02-12, 03:17 PM
Thats the bike but the "pipes" are not RAMair, if you look at most ZXR400 race bikes you will see the radiator dropped down and a mouth that goes intoa RAMair box which replaces the standard airbox
http://www.bdkraceeng.co.uk/Ram-Air%20Systems.html
Ooh Shiny carbon bits!!!!
Chris Bird
06-02-12, 04:04 PM
They stole my idea... apart from the fact they did it first of course. I was going to try and relocate the rad of the R1 and use the same principle... So what are the pipes on that 400 above for then?
hardhat_harry
06-02-12, 04:42 PM
Pipes are mostly for show
suzukigt380paul
06-02-12, 05:52 PM
You're correct.
If you adjust the air intake, you'll need to adjust the fuel as well to maintain the fuel/air balanace.
This mixture takes place in the carb and would need to be perfected by dyno runs and jet/needle swaps - fail to get this right and the bike will run either lean or rich depending on which (air or fuel) you deprive it mostly of.
NB: IT WILL RUN< IT JUST WONT RUN WELL (as well as it otherwise could).
if you ensure the flow rate through your new airbox is the same as the standard then you wont have a problem... but that does sort of over write of the benifit of the project some what. All the best and keep us updated.
i wouldnt have thought it would have much difference to the mixture on a carbed bike as the more air that is going through the carbs the more fuel it will pull through the jets,this type off mod is as old as the hills and can also be achieved by useing a fan to stop negative pressure in the air box,husqvarna have been useing a fan to up the hp on there chainsaws for years with out any carb modifications
Chris Bird
06-02-12, 07:09 PM
Any images, diagrams or sketches of this fan badger?
What course you doing at what uni Chris? Im doing Motorsport Technology BSc at Oxford Brookes. What year project is this? Looks like fun!
Chris Bird
06-02-12, 10:53 PM
I'm doing BEng Motorcycle Engineering at Swansea Met...
I'm on the foundation year at the moment as I didn't go to college so we're not really being taught anything about bike this year. Just concentrating on Maths, Physics and project work, which is what this is. So at the moment I know rod all and I'm just running at it blindfolded.
How far through your degree are you?
Scythe92
07-02-12, 08:47 AM
I'm on a BEng Mech + Auto eng course right now and from my understanding You and Owenski sum
it up pretty well. How are you finding the motorcycle eng? That was my second choice in UCAS.
Chris Bird
07-02-12, 09:09 AM
Not bad so far. Because I'm on the foundation year at them moment, I haven't touched any actual motorcycle engineering yet. I think they're just trying get us up to an A-level standard in Maths and Engineering Science. Recently started calculus, moments and stress and strain among other things. It's safe to say my brain is dribbling out my ear...
hardhat_harry
07-02-12, 09:41 AM
RAMair does make a difference to the fueling, if the jet size isn't big enough to compensate for the RAM effect it will not be able to deliver the correct amount of fuel to keep up the burn rate and the engine will lean to a point where it will start to misfiredown the straights.
The hoover pipes on a ZXR400 don't go anywhere, they're purely cosmetic and just clip on to the tank, rather than passing through to the airbox. They're only there to mimic the look of its larger brother, the ZXR750 , which did (I think) have a pressurised airbox.
If you want to get your hands on a bike that does this for real, your cheapest option is probably an old ZX7R. There's loads about and they're dirt cheap, especially if you don't mind it being a bit knackered. Most big sports bikes in the last ten years have used it to a degree though - it's rare to find one that doesn't have a duct directly from the nose to the airbox.
Scythe92
07-02-12, 04:32 PM
You'll need to consider the AF ratios, and consider the area in which the fuel curve peaks to ensure you don't run it too lean (as said above) at high rpm. In fact, focusing on the nominal ratio in peak performance at the cost of running rich outside of it.
What level are you looking at this, just theoretically? I'm on my phone sorry
hardhat_harry
07-02-12, 04:35 PM
ZXR750 ones are for looks too
sam anon
07-02-12, 04:38 PM
This may be wrong.
My ZX9R has small inlets which sit inside the main ram air vent. These pressurise the Carb Float Bowls to the same extent the airbox is pressurised to, to ensure petrol can still be drawn up through the jets into an area of equal pressure.
ZXR750 ones are for looks too
On the ZX750 H/J and K, yeah. I think the L and M (RR) had a duct more like the ZX750N (ZX7RR) and ZX750P (ZX7R), albeit only on one side, that fed a pressurised airbox.
Been a while since I had anything to do with Kwak 750s though, so I could be wrong.
Second year now. I think you dont really see the applied, interesting side of the engineering course until year 2. And thats when things really start to click if you dont come from a mechanical background. Didfor me. Of course your course might be different.
I wish i had known about a motorcycle engineering course before i applied to university but oh well i will work towards being a motorcycle engineer after i graduate from this degree.
I'm doing BEng Motorcycle Engineering at Swansea Met...
I'm on the foundation year at the moment as I didn't go to college so we're not really being taught anything about bike this year. Just concentrating on Maths, Physics and project work, which is what this is. So at the moment I know rod all and I'm just running at it blindfolded.
How far through your degree are you?
I wish i had known about a motorcycle engineering course before i applied to university but oh well i will work towards being a motorcycle engineer after i graduate from this degree.
Does Robert Fleck still do his thing at QUB? He used to run a bike racing team from the uni, which caught my interest when I was doing the UCAS thing. Didn't bother applying though, since Belfast still wasn't exactly safe at the time.
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