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| Pol Anorl |
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 Pol Anorl Banned

Joined: 13 Apr 2010 Karma :     
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 Posted: 06:24 - 16 Oct 2011 Post subject: Ram air question? |
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soo.. newb to ram air sounds cool lol.
Is it really "so much better" than a standard air intake system?
Can it be fitted to pretty much any bike?
Is it worth it to fit? ____________________ GOOD GAME BODYGUARD: https://i.imgur.com/8WePGgf.jpg
20:30:37 Pyro.: I don't sort of like men, I take every advantage to choke on dick.
Jewlio Iglesias: You live in Liverpool - Chances are, the front door has already been kicked off the hinges |
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| jjdugen |
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 jjdugen World Chat Champion

Joined: 03 Jun 2011 Karma :   
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| Teflon-Mike |
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 Teflon-Mike tl;dr

Joined: 01 Jun 2010 Karma :    
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 Posted: 08:13 - 16 Oct 2011 Post subject: |
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| jjdugen wrote: | Bit of a marketing ploy. Almost impossible to do with carburettors without a ton of plumbing and air tight tank and float chambers. A few have tried it but its far more trouble than its worth.
On F.I. equipted engines, it might add a few bar of pressure into the inlet but to get a really good charge of air would need a scoop the size of a bus at the front of the bike. You would expend as much power pushing the the air in as you would gain from the extra pressure. |
True, and falce.... ish
'Ram-Air' was used on Suzuki two strokes in the 70's, and was used to describe cylinder head finning that had wider vanes at the front to 'ram' the air through the fins to aid cooling...... in actual fact the opposite works better, having the wider end at the back to let the expanded hot air excape more easily..... as proved by Nacar ducting in the 80's.
In the late 80's Yamaha released the 'hoover-pipe' FZR EXUP with 'FAI' which ambigiuousely was reffered to as either fresh air intake or forced air induction....
System comprised a pair of forward facing air scoops in the front fairing, connected to a sealed air-box over the carburettors, with the carburettor float bowl vents plumbed into the airbox to equalise pressure to the 'ambient' in the air box, and keep carburation metering.
As said to get a true 'ram-air' supercharging effect as in a Ram-Jet engine, the intake scoop size needed to feed a 1000cc engine, would be pretty big.
To get a full cylinder fill, you need 500cc of air per revolution, at say 12,000rpm, that is 200 revs second, or 100 litres of air per second.
Lets say you are traveling at 180Kmh, (aprox 120mph) that is 3Km/min, or 50m/s.
that's 5,000cm per second.....
you need 100,000 cm3 of air per second, so if the length of the column of air you want to catch in that second is 5,000cm, you need an intake area of 20cm2
The FAI scoops on an EXUP were about 3" or 7cm in diameter, so give or take a little were possibly just big enough to get some slight super-charging effect at very high speed.
Probably not enough to get possitive pressure in the inlet manifold as a supercharger would deliver, but enough 'extra' pressure to increase cylinder fill a little.
And has been shown that on bikes like the ZZR1100 Busa & Blackbird, that in the real world, they can beat the speeds predicted in the lab, measuring brake power on a dyno and wind resistance in a wind-tunel... only explanation is the 'ram-air effect', giving the engine a little more top end power at speed, from the intage being crammed with air from the front of the moving vehicle, rather than trying to suck it from the still air around the engine in the lab.
Does it work? Yes, those tests sort of prove it.
Is it significant? Well, 2/3mph, possibly an extra 5bhp, on a 150bhp engine, when traveling at excess of 170mph....
Real world road speeds? Probably NOT very significant at all, and on a smaller engined machine, or lower powered bike?!?!
No.... not REALLY any gains to be found.
Common on modern machines, probably as much for reasons of emmissions, and as Yamaha's suggestion 'FRESH air intake', taking air from the front of the bike, rather, than as would be the case the rear of the engine, where air is likely to be that warmed from passing through the radiator and ducted by the fairing around the engine, picking up more heat, before it reaches the air intake.
Any increase in charge density, is therfore probably due as much or more to lower intake temp than it is to inertial pressure increase! ____________________ My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?' |
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| Pete. |
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 Pete. Super Spammer

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| pepperami |
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 pepperami Super Spammer

Joined: 17 Jan 2010 Karma :    
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 Posted: 10:44 - 16 Oct 2011 Post subject: |
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Hmmm? an interesting thread
What have I learnt today?
1. Forcing air into your airbox/carbs is a lot more complicated than it appears, and will require more knowledge and competence than I have
2. Well the "Ram-Air" finning/cowl on my old Suzuki GT 250 worked, as I never had it sieze or "nip up".
Maybe that was down to the fact that I always ran all of my GT`s very slightly rich?
I`d rather de-coke than do a top end rebuild, but thats just me.
3. Also if & when I finally get another project bike in the 250cc to 400cc range, putting whopping great air-scoops on the front is`nt going to help a lot  ____________________ I am the sum total of my own existence, what went before makes me who I am now! |
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| 0ddball |
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 0ddball World Chat Champion

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 G The Voice of Reason
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| temeluchus |
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 temeluchus World Chat Champion

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| Pol Anorl |
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 Pol Anorl Banned

Joined: 13 Apr 2010 Karma :     
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 Posted: 19:24 - 16 Oct 2011 Post subject: |
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| CHR15 wrote: | | Quote: | As said to get a true 'ram-air' supercharging effect as in a Ram-Jet engine, the intake scoop size needed to feed a 1000cc engine, would be pretty big.
To get a full cylinder fill, you need 500cc of air per revolution, at say 12,000rpm, that is 200 revs second, or 100 litres of air per second.
Lets say you are traveling at 180Kmh, (aprox 120mph) that is 3Km/min, or 50m/s.
that's 5,000cm per second.....
you need 100,000 cm3 of air per second, so if the length of the column of air you want to catch in that second is 5,000cm, you need an intake area of 20cm2
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teflon-mike.
knowing everything, since ever. |
I fully agree with this post. ____________________ GOOD GAME BODYGUARD: https://i.imgur.com/8WePGgf.jpg
20:30:37 Pyro.: I don't sort of like men, I take every advantage to choke on dick.
Jewlio Iglesias: You live in Liverpool - Chances are, the front door has already been kicked off the hinges |
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| Slacker24seve... |
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 Slacker24seve... World Chat Champion

Joined: 10 May 2010 Karma :   
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 Posted: 19:38 - 16 Oct 2011 Post subject: |
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I feel attempting to add ram air air to a BROS is a little optimistic
Though having said that, there were a few issues of Bike recently about extracting as much speed as possible, on a budget, from an old Divvy. Might be worth you reading [/b] ____________________ Triumph Daytona 675 track bike + girlfriend's Honda Hornet 600
Selling a hack/winter bike for less than a grand? PM me.
Banger rallies are ace |
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| jjdugen |
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 jjdugen World Chat Champion

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| Teflon-Mike |
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 Teflon-Mike tl;dr

Joined: 01 Jun 2010 Karma :    
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 Posted: 19:52 - 16 Oct 2011 Post subject: |
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| Temeluchus wrote: | | CHR15 wrote: |
teflon-mike.
knowing everything, since ever. |
Except how to keep his posts short  |
Knowledge & Application..... I KNOW how to make Nitro-Glycerin with a bar of soap and nitric acid... doesn't mean I have ever TRIED!
Did get secondary school top floor evacuated a couple of times though; most memorably dropping a sugar cube in a bottle of suphuric acid.......
Though 'master' jape at A-Level washing a nitric acid titration dropper out with distilled water, didn't have the effect intended when I squirted the colourless, oderless liquid from 'Concentrated Nitric Acid' bottle at Joanne Checkets.... who utterly FAILED to follow lab protocol for acid spill, and rip all her cloths off and dive under the shower head at the front of the lab.... she just sort of did an epileptic jiggle in the middle of the room, flapping her arms around a lot.
But then my my Lab-Tutor I think had been 'warned' about me... he didn't even blink; just stood there and watched.... I think he was he was thinking; 'Damn girl, NEVER listens to a word I say, she ought to be naked and in the shower by now!' ____________________ My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?' |
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| stevo as b4 |
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 stevo as b4 World Chat Champion
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| Teflon-Mike |
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 Teflon-Mike tl;dr

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| Pol Anorl |
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 Pol Anorl Banned

Joined: 13 Apr 2010 Karma :     
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 Posted: 02:25 - 17 Oct 2011 Post subject: |
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Does anyone else here think that might actualy be teflon mike in his avatar? ____________________ GOOD GAME BODYGUARD: https://i.imgur.com/8WePGgf.jpg
20:30:37 Pyro.: I don't sort of like men, I take every advantage to choke on dick.
Jewlio Iglesias: You live in Liverpool - Chances are, the front door has already been kicked off the hinges |
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| G |
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 G The Voice of Reason
Joined: 02 Feb 2002 Karma :     
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 Posted: 02:35 - 17 Oct 2011 Post subject: |
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I would have thought half a bar would give the possibility of pretty decent hp gains?
Google comes up with this.
So 1 psi gives 16hp boost when we're talking around 250hp.
So things being the same, .5 psi seems reasonable.
Half a bar seems rather a lot of pressure generally to me - we're then talking a factory turbo on various cars I believe? |
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| Pete. |
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 Pete. Super Spammer

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| Teflon-Mike |
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 Teflon-Mike tl;dr

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| temeluchus |
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 temeluchus World Chat Champion

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| stevo as b4 |
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 stevo as b4 World Chat Champion
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 Posted: 23:14 - 19 Oct 2011 Post subject: |
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It's a small but not insignificant amount of positive pressure that is worth having, if your going to be travelling in the 150-170mph+ region.
There are some further benefits too!
1, The small say +0.5psi of pressure can cancel out any restriction to airflow that the airbox, inlet tracts, and the filter element might have, so it's effectively like running an open carb mouth, but with a small positive pressure to feed it.
2, The other main benefit of Ram air, is that your always sucking in the coolest possible air, as the wind chill factor and the extreme distance from the exhausts, and engine heat of the intake scoops means you get the most cool dense air entering the engine, which you don't get if the airbox entry is under the set or under the fuel tank etc. |
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| Pete. |
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 Pete. Super Spammer

Joined: 22 Aug 2006 Karma :     
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 Posted: 00:19 - 20 Oct 2011 Post subject: |
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All that except for the wind chill comment. ____________________ a.k.a 'Geri'
132.9mph off and walked away. Gear is good, gear is good, gear is very very good  |
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Old Thread Alert!
The last post was made 14 years, 179 days ago. Instead of replying here, would creating a new thread be more useful? |
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