intake whearabouts

[steve-e]

It's a lot more complicated than the numbers as Keith Whiting has explained a few times at FSRA committee meetings. Same as restricting intakes etc.. it's been shown that sometimes too big makes things worse. I don't know the ins and outs of it but it's interesting at each meeting listening to someone who really knows his stuff with a lot of experience talking about intake sizes and what they do to performance. As long as you can get enough air in don't overly panic, and unless you have a lot of time with a dyno (Pete Alton will back this up) don't spend a huge amount of time on getting more in or trying to do anything clever there. It can be done but it's a black art and nowhere as simple as numbers. I know with the 125's they now use valves to alter the airbox size at different rpm.. or did about 18 months back the last time I was talking to Mark at KRP about this over some family dinner somewhere. You can imagine what family dinners are like

[powerhouse]

cheers steve my new air intakes are 2x 65mm id from two naca ducts either side of the fairing.
its got to be better than the single 60mm air intake as of last season

[teamradar]

Something else to take into account - On a hot day the air just above the track upto about 6 to 8 inches is just about as hot as the track if your intake is low down you're just scooping up hot air,not ideal.

[NickO]

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

You are right in that you have 38 sq.mm more, but that is equivalent of a 7mm diameter hole extra (not much) or in percentage terms LESS THAN half of one percent.

[sidecarf11]

like someone said large intakes are not always best if you think about it a large intake means a reduction in pressure with in the intake this also means the air is less dense which means less air into the cylinder less fuel to get the correct ratio meaning less bang Turbulent air not all bad, many years ago when i used to be involved with drag race a lot of tuners used to port out heads to a polished finish thinking along the lines of helping to get the air flowing smoothly into the cylinder this worked but what it also did was to put the fuel and air into the cylinder without actually mixing it and this lost power because it did not burn correctly lots of wasted fuel also would blow the engine so what they did was to but a honed surface finish in the port this helped to mix the fuel

[Ewan]

How you doing guys I work a lot with gas flows in my job and the way i see it is this,because of the the intakes gulping down so much air within the airbox you get a localised partial vacuum this is'nt helped by any holes in the air box which produce a venturi effect when moving forward and try to pull air out of the airbox, any forward facing ducting which forces air into airbox will go some way towards reducing the effect of the vacuum and venturi effect

Ewan

[Eurocup]

Hi
speak to Jason Miller. He changed my new fairing with the inlets. After Salzburg. With a really standart engine ( 600.- euro at ebay) i can follow the F1 uphill. Good exhaust and good airbox with inlets. Cant be andything else.
Bye Eckart
fotos of my bike. see: www.team-early-grey.de

[powerhouse]

ok so i fitted twin airducts.what a diference, the bike is so much more responsive and is more powerfull.done two 2 day meetings with derby phoenix cadwell and anglesey,found ourselves fighting for third at both circuits against injected outfits.at mallory clutch let me down on the grid.went from5th to 16th in 7 seconds then found ourselves fighting for third again!!!!! bloody clutch

[oldbelly]

By the end of practice, 1996 Moly had done 112MPH on a Thundercat, Peter Hill in the chair. I had spoken to Dave before we left for the TT. Dave said he had painted the body work and had forgoten to put any ducts in the fairing. He said he would see how it went in practice before he damaged the paintwork.

[tufty113]

in 1996 geoff...did they run air boxes???? am sure that powerhouse has just realized that what he had before was restricting his bikes air flow.....you also in 1996 had to run 32mm restrictors(eg fcr 33 carbs with 32mm restrictors)...i dont know what powerhouse is running....we all need to check our fueling on a dyno or with a fuel meter system depending on what carbs and engine etc....

[oldbelly]

We pretty much had airboxes in as much as the engine cover was a good fit to the panel under the carbs. Dave like us at the time had the front of the engine cover left open. Roy Hanks among others had the air ducted directly to the carbs from the ducts in the fairing. Im pretty sure Powerhouse is running Thundercats and Im also fairly certain that Molys Thundercat in 96 never went anywhere near a dyno .

[tufty113]

We pretty much had airboxes in as much as the engine cover was a good fit to the panel under the carbs. Dave like us at the time had the front of the engine cover left open. Roy Hanks among others had the air ducted directly to the carbs from the ducts in the fairing. Im pretty sure Powerhouse is running Thundercats and Im also fairly certain that Molys Thundercat in 96 never went anywhere near a dyno .

if the front of the cover was left open then it was a fairly large area.....yes powerhouse is on cats....i also was on cats a few years ago and we only ran one 75mm air intake...that was ample...but that was on a 32 restrictor......depends what powerhouse is on now carb size and jets...not that it will go any faster with bigger carbs....

[oldbelly]

Your right Matt, Yamahas from the longstroke 600 through to Thundercats ran at their best with a 32mm restrictor and 33mm carbs. They also ran better with an openfront rather than an airbox type set up. We tried from 33mm to 38mm carbs with and without the restrictor and there was no improvment. When the F2 club enforced the 32mm restrictor in the early 90s they did us a favour.

[bludge]

By the end of practice, 1996 Moly had done 112MPH on a Thundercat, Peter Hill in the chair. I had spoken to Dave before we left for the TT. Dave said he had painted the body work and had forgoten to put any ducts in the fairing. He said he would see how it went in practice before he damaged the paintwork.

Off topic i know but Moly did those speeds 10 yrs before most

When i did the TT in 2005, we were the 5th sidecar team to do 110mph (i think) & Simon Neary did it the same year (with little credit).

Strawbs & me were chuffed to get 110 mph.....

Moly did it 10 years earlier

[powerhouse]

yes matt im on cats,its made a difference to acceleration using the two intakes,seems more snappy.spoke to ian and we think my bike is your old one geoff, windle with the removable top tube on the right.