chrischild Posted September 30, 2009 Posted September 30, 2009 Running elite 5 speed 1:1 final drive, any ideas on diff ratio, looking for top speed of around 140-145mph. Currently running 7.2/20/13 on 8" front A91 compound and 9.2/20/13 on 10" rear A15, what would you circuit racers suggest, size and compound, races about 20 mins long. Rear wings anybody got one , use one, do they work? Feedback please. Front aero any suggestions especially if you have rear aero. Any advice welcome. Chris Quote
John Loudon - Sponsorship Liaison Posted September 30, 2009 Posted September 30, 2009 Need your engine revs to work it out Quote
chrischild Posted September 30, 2009 Author Posted September 30, 2009 Hi John, 8000rpm although we might push up to 8250 but base it around 8000 to be safe. Spoke to Nick Algar earlier and he thought there would be a wealth of knowledge on here. Cheers Chris Quote
John Loudon - Sponsorship Liaison Posted September 30, 2009 Posted September 30, 2009 Are you sure about the rear tyre size? Avon rcaings website doesnt list 9.2/20/13 Avon Racing Website Quote
John Loudon - Sponsorship Liaison Posted September 30, 2009 Posted September 30, 2009 OK - a 3.54 diff (tallest in the English range) will just about give you 140 @ 8250 Really you need 21 inch rear tyres Quote
chrischild Posted September 30, 2009 Author Posted September 30, 2009 John, I will be replacing tyres so I can easily go to 21 or 22, is there any benefit or disadvantage to having bigger walls? Is the 3.54 the RS2000 diff? Chris Quote
John Loudon - Sponsorship Liaison Posted September 30, 2009 Posted September 30, 2009 OK - if getting new tyres, go with 22 inch ones and stick with a 3.89 diff (assuming that what you have now). This gives 140mph @8000rpm Yes - 3.54 is an RS2000 one Taller side walls usually give a bit more compliance but the tyres weigh more and usually cost more Quote
chrischild Posted September 30, 2009 Author Posted September 30, 2009 Cheers John Any ideas on compound or will BMTR be best for that? Best and/or easiest to fit digi dash and data logger? Chris Quote
John Loudon - Sponsorship Liaison Posted September 30, 2009 Posted September 30, 2009 Compounds- speak to BMTR Data logger? not my thing Quote
conibear Posted September 30, 2009 Posted September 30, 2009 No argument, your best choice is A11 or A53. A15 and A91 are too soft for 20mins, they will be shot very quick as those are wet race spec or hillclimb dry 10" rear wheel takes a 9.2" x 22 X 13" beautifully in A53 compound. 8" front wheel will take a 8.2" X 20 X 13" beautifully also in A53. Can't really accomodate those wheels with A11 compond as they only do them in 7 & 8.2" Forget BMTR, ring Steve Smith at Avon and confirm that your racing with 750MC as no doubt you are, your then save about 30% I have the Elite box as well, but with final 0.87, but thats not important as long as you can achieve your speed. Aero? are you referring to rear difusser Where you racing? Quote
Annie Posted September 30, 2009 Posted September 30, 2009 Front aero any suggestions especially if you have rear aero. Any advice welcome. Chris My Seight was built by Westfield with the 'Flymo' nose and also has their standard rear diffuser plus a floor that is as flat as possible (including below the rear suspension). Although I don't have any hard evidence, the package does seem to be fairly stable at speed given the size of the engine and the restrictions of Speed Series Class B (mainly the List 1A tyres). The nose looks fairly sexy but I suspect that any real work is being done by what amounts to an 18" splitter/flat sheet below it. The nose makes it important to be aware of speed humps (the car is driven to all events and quite a few humps are apparently above the 100mm legal maximum) and we have modified the diffuser strakes to be adjustable in height for the same reason. We are planning a Class F car for 2011 and will probably follow the same aero route (unless the rules become more liberal in the meantime). If you pm me I can send you some piccies. Annie. Quote
chrischild Posted October 1, 2009 Author Posted October 1, 2009 Thanks. The car is currently hillclimb spec and thus the tyres. I am thinking of the Castle Coombe GT championship. Would the current compound cut A15 / A91 for wets or still be too soft? I currently run with a rear diffuser and flat floor but am considering rear wing, front splitter and front spoiler. Any comments? Chris Quote
Darren B Posted October 1, 2009 Posted October 1, 2009 Hi Chris, I have been racing my Westfield for a couple of years now and in your position I would do the following: If your avatar is accurate then get a full cage to start with. Sort out your basic package before going all aero (including getting some race school tuition) Work on minimising drag rather than trying to increase down force None of the front running Cateringvans run wings and unless you have a wind tunnel to hand then I suspect you'll do more harm than good. Running a flat floor and CSR style cycling wings with a rear diffuser seems to be a good starting place A rear wing on a '7' seems pointless given the open cockpit clutter. I ran a nose width splitter and airdam for a race or 2 and apart from grounding it on the track under heavy braking, I took it off and went 0.1 second faster a lap. Get onto the track, have a few races and then decide where you want the car to go Mine handles very well without any big wings and a recent package of minor engine upgrades gained me nearly 4 seconds a lap at Cadwell, without any chassi mods or aero Quote
chrischild Posted October 1, 2009 Author Posted October 1, 2009 Cheers Darren, Old avatar, now have full Caged cage. I have on order with Nick Algar new front CSR type wings and front splitter. What tyres are you running and diff ratio? Chris Quote
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