MIRA Sprint 8th August

[David]

Good to meet Graham Forsdyke (Striker-4A-GE), Peter Rosenthal (Fury-Zetec SE) and Nigel Cresswell (Fury-'Busa) for the first time at the NSCC sprint at MIRA yesterday. There were more JP designed cars present than Westies! Really pleasant group of people (including the Westies) -- and some good times put in. Look forward to seeing you again at future events, gentlemen -- and hope the engine issues are minor, Nigel.

[Strikerxe]

David

How did you and the others get on ? Be nice it there was a results page somewhere on the site to see how members are doing in competion .

John

[David]

Hi John

Price for showing interest is to get the full works........

Hope this functions. Results at http://cid-19142f8dc0e7886c.skydrive.live.com/self.aspx/.Public/MIRA%20Results,%208th%20August%202009.pdf
Double-clicking the "empty icon" should work! Note to self: master the damned technology.

Very few competitors -- but that allowed us two practice and five timed runs

Explanations:
Classes 2A/B required full windscreens, but allowed 1B tyres. Peter was using 1Bs all day (888 I think, or possibly AO48), Graham switched from his 888s to 1As before his first practice run because the 1Bs were fouling his arches, but switched again to a set of CR28s for the final three runs (see his 64ft times).
Class 3D did not need to be road-going. Both my Striker and (I think) Nigel's Fury are road-going but do not have screens. Nigel put on his slicks; I don't have any, so was on ACB10s. Unfortunately, Nigel suffered engine problems on his second timed run which ended his day -- otherwise I'm sure I'd have been toast.
Martin was double driving with me because he had lunched the engine in his Westy at Hethel the previous weekend. He had literally never sat in my car until the convoy lap.

David

[David]

Oh, and I agree with the results page suggestion

[Strikerxe]

David

Works a treat Many thanks for that .

Looks like another good result , well done

Oh, and I agree with the results page suggestion

Mods, Can we have a competion results section as well please ?

John

[David]

Looks like another good result , well done

Thanks John -- but Nigel (at least with a functioning engine) is pretty formidable

[Strikerxe]

David

Showing my complete ignorance of tyres How much difference ( time wise ) do you think slicks would make ?

Also if you don't mind me asking how 'loud' is you car ? It looks like you're running the same induction system as me ( Jenvey tapered throttle bodies ) and my car has a lot of induction noise at WOT I haven't managed to get it on track yet but I'm a bit worried about a drive by noise test . Fairly sure the exhaust should be ok for most tracks as it passed the SVA no problems .

John

[David]

Hi John

Tyres -- difficult question to answer objectively, particularly for slicks. This is because most competitors who change from road legal tyres to slicks also take the opportunity to dump the weight associated with road legal status (much of the loom, lights, etc.) at the same time.
Obviously, the chief advantages derive from increased grip, allowing later braking, faster cornering and enhanced entry speed to straights. The advantages seem to vary in their influence of time from circuit to circuit. At Llandow, for instance, where the entry to the two long straights is via fast, unfolding bends, the advantage seems less than on a circuit like Curborough, where there are frequent changes of direction.
Some anecdotal evidence is available. Andy Rushworth (very capable Westie driver, and owner of CAT Motorsport) moved from ACB10s (Avon cross-ply 1Bs) to Avon slicks in the middle of last season. He lost some weight on the way but the engine (I know) and gearing (I think) were unchanged. His Curborough times (double lapper) improved from the high 59s to 57s. I had a similar experience moving from 1As to 1Bs -- with the car otherwise identical, my personal target time at Barkston Heath moved immediately from 53s to 49s.
Grip evidence is available also from the 64 ft times in the results posted above. For a front engined kit-car on 1As (Graham's early runs, for instance), 2.60-2.80s is a normal performance, on 1Bs (Graham's last three runs, me) 2.40s is easily achievable, Nigel (on slicks) managed to go under 2.20s. Clearly, these numbers will be affected by driver ability, and the number of drivers represented is nowhere near statistically relevant -- but anecdotally again you get the picture. I'd advise you to look at an improvement, on an average circuit, of at least 5% for the transition from 1As to 1Bs and another 3-5% from 1Bs to slicks -- but please remember that slicks and the better 1Bs are available in several compounds, and sprinters almost always use the very softest..

Noise -- yes, it's noisy. Marmelade (the family name for the car) is especially noisy as it is required to run a cat under MSA rules, and, if I'm to maintain the (rather long) SBD spec for the 4-2-1 exhaust manifold, the only place for it is in the can (meaning less silencing). With only minor disingenuity with regard to the maximum revs, we normally test (static) at 98-102 Decibels, which is OK for most MSA events. We don't however do public track days (9 litre fuel tank and tyres which begin to melt after two laps), or compete at Goodwood (where pass-by sound checks are made).

HTH

David

[Strikerxe]

David

Many thanks for the info with the tyres . A mate bought an ex sprint Striker just before Christmas with the idea of having a go at sprinting this year but he's since lost his job We'll have to try and get along to a sprint or to this year to see what the score is and he'll perhaps have a go next year when he's sorted some employment out .

Re noise . I had to cut some out of my secondaries to get a decent length of silencer on my car .I'm now running SBD length pimaries with 6 inch shorter than recommended secondaries . Unfortunately I don't know what difference this has made to the power as I've only had it on the rollers in its shortened state . It still made good ( to me anyway ) power though . We've got a noise meter at work so I'll have to try a drive by noise test sometime to see how bad mine is , I know some of the Westy boys have gone for big inlet scoops on their throttle bodies but imo they look really ugly but I suppose needs must

John

[David]

John

I have a second exhaust manifold with "shorter than SBD spec" secondaries (but only 100mm shorter) -- on the rollers it made 4bhp and a couple of lb.ft difference, and the power band was a little shorter. Nothing really to worry about though -- that sort of difference is completely eclipsed by driver talent.

HTH

David