AMMO Posted April 18, 2004 Share Posted April 18, 2004 Haven't read all the post closely so I don't know if this has been covered. Don't forget that the engine is evacuating air from the air box. What you see in a wind tunnel has little meaning unless you have an engine on full chat on the other end of the airbox. It is of course a worthwhile excercise just as another piece of information I have done a bit of airbox testing on the flowbench for the current Suzuki GSXR BSBK of Renolds and Kagayama. Here we looked for restrictions in the airbox with the head and induction system fitted to the flowbench. The restiction was only 1 cfm. Looking at Arnies's airbox it is difficult to think that it would cause any restriction at all. The other thing to consider is that the air in the induction system with the engine on full noise is around 280 to 300 ft per second. The clever ones with a calculator can work out what this is in miles per hour. I used to know but due to my hard drive filling up and advancing age I have forgotten. Another thing that has to be considered is the proportion between the airbox capacity and the engine capacity. Bike airboxes seem to be around seven to ten times the capacity of the engine. I have one of Arnie's prototype airboxes in galssfibre that I will somehow graft onto my Duratec. Uing a tape measure I have roughly calculated the capacity at around 14 litres so on the money for a 2 litre engine. Speaking Graham Dale-Jones at IES when they were doing the Nissans he told me that they hardly saw any positive pressure in the airboxes. These were front facing and quite large. This is from the data logging whilst the cars were running on track. The benefit of an airbox is to supply cold air on demand. Cold air good. Hot air bad. Still not 100% convinced that some of the big improvement claims are credible but then I haven't done the testing to prove it one way or another. Didn't F1 cars have the backs of the airboxes opened up at one point due to a rule change. From memory this did not make much of a difference in lap times. Crescent Suzuki have rigged up a fan that will supply a 150 mph wind in their dyno cell. They still do the majority of fuelling maps at the race track using the logged lambda information. Real world requirements require real world solutions. I will give Crescent a ring on Monday to ask their data scaper guy if thery see any positive pressure and how much. I'll post the info when I have it. AMMO Link to comment Share on other sites More sharing options...
Peter Carmichael Posted April 18, 2004 Share Posted April 18, 2004 Assuming the drag coeef of the box is 1 and that its a 10cm x 10cm we get: (the units are m/s for speed and metres for area) P = 1.3 x 40 x 40 x 40 x 1 x 0.001 P = 83 W P = 0.11 bhp drag at 90mph Hoopy, Are you entirely sure you got the area right? Isn't it 0.01? Hence 830W. Hence a horsepower and a bit. Link to comment Share on other sites More sharing options...
EFA Posted April 18, 2004 Author Share Posted April 18, 2004 I would say that due to the fact that the engine is consuming air at 295cu/ft/min @8000rpm the drag coefficient would be rather less than 1.00 I guess you could work this out - anyone have the time??? Fat Arn Slay the K. Link to comment Share on other sites More sharing options...
StewartG Posted April 19, 2004 Share Posted April 19, 2004 Edited by - StewartG on 19 Apr 2004 08:54:43 Link to comment Share on other sites More sharing options...
Jason Plato Posted April 19, 2004 Share Posted April 19, 2004 Would the airflow into the box improve if the entry had a 180 radius like a traditional trumpet bellmouth ? Or is there simply sooooo much air going into this size of entry that no benifits would be seen ? Dave Lotus 7 Club Speed Champion 2003 South Wales Area Organiser C7 TOP Link to comment Share on other sites More sharing options...
StewartG Posted April 19, 2004 Share Posted April 19, 2004 I'm not sure of the maths or my ability to explain them (perhaps someone more technical can help) but here goes. The engine consumes 295cu ft /min at 8000rpm Thats 509760cu inches/min The airbox entry is approx 16sq inches In one minute the column of air flowing into the airbox with cross section area 16 sq inches would be 31860 inches long In one hour it would be 1911600 inches long that's 30.17 miles It would appear that at speeds above 30mph more air is going into the airbox than the engine is consuming. Link to comment Share on other sites More sharing options...
AMMO Posted April 19, 2004 Share Posted April 19, 2004 More info. I spoke to Crescent Suzuki this morning. The airbox pressure does go slightly positive on fast straights. Pulling out of slow corners the pressure will go negative. Their data scraper will email me more detailed information after the race at Snetterton this weekend. They monitor both airbox pressure and manifold pressure. I also spoke to Graham Dale-Jones who said that the maximum positive pressure he has ever seen is in the region of 30 millibar. It would be interesting to fit a compound manometer to one of Arnie's airboxes to see what is actually happening. AMMO Link to comment Share on other sites More sharing options...
Nemesis Posted April 19, 2004 Share Posted April 19, 2004 I thought I would post this as this thread is getting old and no one will look The reborn K2 RUM is the fastest car I have seen/experienced Fcuk Me the Blat on SUnday was amazing I don't want a car that performs like it but you have to admire it WOW!! Now don't tell anyone! Nemesis The number 1 Curmudgeon Click here to see Fat Arnie as you never have before!!! Edited by - Nemesis on 21 Apr 2004 08:26:30 Link to comment Share on other sites More sharing options...
I reply to every thread Posted April 20, 2004 Share Posted April 20, 2004 Anyone fancy a pint........................? Link to comment Share on other sites More sharing options...
AMMO Posted April 20, 2004 Share Posted April 20, 2004 Aves Now you are talking! I have one of the top ten Adnams pubs in Suffolk only two minutes walk away from my house. You have inspired me. It would be rude not to go for a pre-dinner pint. 😬 AMMO Link to comment Share on other sites More sharing options...
Paulo Posted April 20, 2004 Share Posted April 20, 2004 Ammo, Would you mind drinking one for me. Thanks, Paul Link to comment Share on other sites More sharing options...
Morls Posted April 20, 2004 Share Posted April 20, 2004 Karen took me out for one tonight, with Fish 'n Chips in the Duke of York, overlooking a sunny Whitby Harbour... Wonderful Mark Look it's Mavis here and Jubilee 7 here Link to comment Share on other sites More sharing options...
Tight fart Posted April 20, 2004 Share Posted April 20, 2004 Stuck with only bottled Broadside here Ammo, ☹️ T.F@O.F. A7 RDP Pics here Link to comment Share on other sites More sharing options...
Tight fart Posted April 20, 2004 Share Posted April 20, 2004 Mind you on Sundays, a few pints of the good stuff and a few roasty's I can have a few air box problems myself. 😬 T.F@O.F. A7 RDP Pics here Link to comment Share on other sites More sharing options...
EFA Posted April 20, 2004 Author Share Posted April 20, 2004 Are we not deviating from the scientific cross examination here.... I spoke with the wind tunnel guys today and the bar figures I quoted in the first post on this thread are in fact not bar but just a numeric representation of pressure. Apparently they do it this way in order to scale the relationships of models to real size. Fat Arn Slay the K. Link to comment Share on other sites More sharing options...
Anthony Posted April 20, 2004 Share Posted April 20, 2004 Thanks for the update Arnie How does this change please the discussions above Regards Link to comment Share on other sites More sharing options...
AMMO Posted April 21, 2004 Share Posted April 21, 2004 Richard We have Broadside and Regatta on tap at my local with occasional appearances of Oyster stout and Tally Ho (dangerous stuff). You should come around and try some. They do a good Sunday roast. The landlord is very fussy about keeping his beer just right. Best Adnams in Woodbridge without a doubt. Thirteen pubs in Woodbridge and as a bit of market research I've been in all of them at some point. My local is the closest and the best. Broadside in a bottle is OK but not like the real thing. Paulo I had a pint of bitter on your behalf. It was very nice 😬 AMMO Link to comment Share on other sites More sharing options...
I.Mupferit Posted April 21, 2004 Share Posted April 21, 2004 Coincidentally i was reading the Dave Walker book on engine management last night and he states that airboxes produce little beneficial ram effect below about 160 mph. If that is so does it not negate any benefit on a road car other than perhaps ducting cooler charge air into the engine if required? PM Money can't buy friends but it gets you a better class of enemy. Link to comment Share on other sites More sharing options...
Sheds Moderator Posted April 21, 2004 Share Posted April 21, 2004 Oh for a pint of bitter. I'm with Paulo on this one. Here at Leeds South I'm missing the taste of Tetley's. Saumur Brut just isn't the same. Apart from anything else I'm no good for anything after 2 pints of the stuff. ☹️ Link to comment Share on other sites More sharing options...
caterhamnut Posted April 21, 2004 Share Posted April 21, 2004 ..apart from a bike ride home eh Battered 😬 Don't knock it - I would move there in a flash! 'My First Race - SPA' pictures here 60,000miles in 3years Link to comment Share on other sites More sharing options...
Morls Posted April 21, 2004 Share Posted April 21, 2004 Think of it this way, Saumur Brut is probably cheaper per pint down there, than Bitter is in the SE of England, and you can enjoy it outside the bar, while we're still huddled round the coal fires And IIRC the road out of town along the river is lovely Mark Look it's Mavis here and Jubilee 7 here Link to comment Share on other sites More sharing options...
Bananaman Posted April 21, 2004 Share Posted April 21, 2004 Where can i seee pic'e of this ????????????? Link to comment Share on other sites More sharing options...
MikeE Posted April 21, 2004 Share Posted April 21, 2004 I think you'll find some images of it here somewhere here (along with a load of other modified cars that value form over function everytime 😬) Link to comment Share on other sites More sharing options...
Sheds Moderator Posted April 21, 2004 Share Posted April 21, 2004 Yes, 'tis true the road along the river near Saumur is very nice indeed, as is the little lane out the back of my place. No complaints and the SE of England still holds no charms for me at any price. With Saumur Brut at 3 quid a bottle it's not too surprising. Angus, 😬. Yes, still cycling back and forth and have so far managed to avoid any obstacles after a wee drinkie or three at 2 am. 😳 You'll be pleased to hear my back has now recovered completely. The only thing that worries me is that I'm often the most sober at hometime as I cycle home and everyone else gets in their cars . This country still has a bit of progress to make on road safety and attitude change. Link to comment Share on other sites More sharing options...
Paulo Posted April 23, 2004 Share Posted April 23, 2004 Ammo, Thanks for that. I feel much better now. Paul Link to comment Share on other sites More sharing options...
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