NS Dev
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| posted on 27/7/05 at 09:41 AM |
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As you've probably guessed, I race a class 9 (it's the one in my "avatar" with a Vauxhall XE in it. Pretty std class 9 fare
but I did the chassis from scratch with a few unique features which have subsequently provided "interest" for a mr Chris Allanson!
I won my class at club level last year (which was my first full year racing) but this year I'm struggling trying to get some gear ratios that
work at other tracks and being let down by a certain gear cutting company.
For next year (as long as the 7 is finished!) I'm looking to build a class 7 on a bit of a budget and was looking at Saab turbo power but the
Audi V8 looks like a tempting alternative at that sort of money!
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Volvorsport
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| posted on 27/7/05 at 10:17 AM |
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hmm class 7 - just sold me 242 , so thats not a possibility - id get shot for doing that anyway . What cars are normally used anyway ?
Sorry for the off topic marc !
oh , theres a chap selling a DTA pro for £600 , if youre interested . Comes with all the bits , never used
www.dbsmotorsport.co.uk
getting dirty under a bus
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NS Dev
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| posted on 27/7/05 at 10:50 AM |
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Really is off topic, very sorry for the total Hijack Marc!
"Normal" ( ) cars used in class 7 are pretty much anything small and light, currently popular are metros/rover 100, mini (old type!),
fiat seicento/cinquicento, fiat punto, vw polo. All those sorts of things.
The rules for this year have been slightly changed so that with a slightly "imaginative" interpretation (that is entirely
scrutineer-proof) you can now fully spaceframe the 'shell, which was "technically" illegal last year. (you previously had to
"step" the tubes where the main cage passed through the front bulkhead to mount the double wishbone setup at the front. The two were
supposed to be seperate, linked only by the body shell, but that rule was just daft so they have changed it now, which is why I'm now
interested!)
Going well at the recent big meetings that I have been to were - a variety of twin hayabusa powered seicentos and metros, (the twin bike cars tend to
be doing a lot of th winning) and then stuff like a transverse rear engined supercharged rover v8 pug 106, and a couple of transverse rear engined
millington 2.5 powered metros. one of the quickest cars I have seen in recent times is a metro with an Impreza turbo engine in the back, but with a
vortech supercharger in place of the turbo. Also a twin turbo mazda rotary powered metro has been setting the pace well too.
I think that Audi v8, on throttle bodies and mappable ECU could give em a run though!
What comes with the DTA ECU for £600?
[Edited on 27/7/05 by NS Dev]
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Volvorsport
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| posted on 27/7/05 at 10:57 AM |
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it comes with the laptop link , and software (i think) - it was bought to run ona V8 but can only run high impedance injectors .
The reason why the guy was selling it because his 1400 hp drag car wont idle because the cheap option is low Z injectors and resistors - but at such
a big flow rate the injector is so slow , you cant tune the thing .
youd be ok on low z injectors to about 700 hp - they just get too big after that - another reason why im using megasquirt that allows dual table ie
small and big !!
ill give you his phone number if youre interested . ITs a Pro version
[Edited on 27/7/05 by Volvorsport]
www.dbsmotorsport.co.uk
getting dirty under a bus
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NS Dev
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| posted on 27/7/05 at 11:03 AM |
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moved to U2u
[Edited on 27/7/05 by NS Dev]
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Volvorsport
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| posted on 27/7/05 at 11:13 AM |
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Moved to u2u
www.dbsmotorsport.co.uk
getting dirty under a bus
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MikeR
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| posted on 27/7/05 at 11:13 AM |
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ahem Nat, V8  1300 quid, does the misses know what she's going to be competiting with?
now ........ how about slapping a super charger or two on that engine .......... come on, you know you want too...........
Marc, back onto topic - i'm curious why people are using so much bent tube in chassis these days?
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NS Dev
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| posted on 27/7/05 at 11:36 AM |
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Can I throw my answer in and see how it compares to Marc's!
Less time consuming welding. Less stress raisers produced by welding. Lighter construction. New tube bending technology allows very accurate fits to
be achieved.
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marc n
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| posted on 27/7/05 at 01:05 PM |
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quote:
Less time consuming welding. Less stress raisers produced by welding. Lighter construction. New tube bending technology allows very accurate fits to
be achieved.
hit the nail squarely on the head with all of the above,
the acuracy is incredible,
the less stress of a bent tube over a series of cuts and joins or intersecting tubes is limited to round tube only as from our tests although
primative show that rectangular section bent does not elongate properly
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marc n
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| posted on 27/7/05 at 01:07 PM |
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and of course less fishmouths to notch in the tube, we can get such accuracy that most tubes can be bent so they meet at 90 degrees which is much
easier to notch than larger angles
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MikeR
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| posted on 27/7/05 at 01:14 PM |
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interesting, i didn't want to mention the old Chapman comment about a bent tube is pre-failed. But if what you say is correct, this suddenly
makes complete sense (and a rather tastey chassis).
I guess this also adds to faster (and therefore cheeper) construction for you.
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NS Dev
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| posted on 27/7/05 at 02:11 PM |
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Is that chapman comment taken out of context perhaps? I'm sure he didn't mean it in this type of application.
A tube is manufactured by "bending" effectively.
I seem to remember some talk on here a while back about bent tube wishbones being weaker, which in that context at the time was true, as the wishbone
layout put the tubing away from the load path and set up bending stress in it under load, rather than nice straightforward tensile and compressive
load, but that isn't the case here.
Though the tube is bent, the load paths are in straight lines.
Where the technology gets really nice (but also really expensive and really out of reach of small companies!!!!) is when you can combine a cnc tube
cutting laser with a cnc bender on one line.
A friend of mine works for a stainless and alloy fabrication company in Shropshire and they now have such a setup (as do Safety Devices and Caged I
believe, to name two more)
The beauty of this is that the laser cnc profiles the fishmouths onto the ends of the tubes, then puts the calculated bends on, thus putting all the
fishmouths in exactly the right orientations, and meaning no hand fettling when it comes to welding together.
My mates recent projects have included the design of some stainless modular buildings (for ticket offices and toilets on stations apparently) and the
laser cutting is so accurate that they can make the buildings "slot-together" by having slots on the stainless tubular posts and
connecting pieces that just slot in. They even laser etch the assembly instructions onto each tube on the cnc tube cutter!!!
Ain't technology brilliant!!
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MikeR
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| posted on 27/7/05 at 02:17 PM |
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yep, most probably out of context - just remembered the comment.
At least i now understand the concerns over the bent wishbones. Makes sense when put like that.
Oh, technology is only brillient when i get to play with it
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Jon Bradbury
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| posted on 27/7/05 at 03:24 PM |
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All those bent tubes remind me of the Robin Hood chassis. Are you saying it's structurally unsound because of the bends? Surely not!
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MikeR
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| posted on 27/7/05 at 04:02 PM |
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I was concerned due to the out of context comment i'd heard about bent tubes from a certain Mr Chapman.
NS DEV has explained the comment and basically bent tubes are unsound in certain situations. In this chassis design they should work out at least as
strong as square tube and most probably stronger (plus looking sexier)
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NS Dev
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| posted on 27/7/05 at 05:44 PM |
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ahhh, now I wasn't comparing Marc's chassis to the Robin Should one!!!
If you look at that one, there are untriangulated bends in it and a general lack of triangulation..............a very different animal!
Funny that should be mentioned as I was just flicking through PPC mag and saw their advert and was just contemplating the chassis!
Bends are not a problem at all, just as welds are not either, but they have to be in the right place. Just as you would prefer not to put a butt weld
in the middle of a stressed straight tube, neither would you put a bend in the middle of one without otherwise supporting it.
Re. the Robin Should chassis, areas of concern for me are the diagonal from the front that comes up towards the steering wheel, this has a double bend
in it with no additional support. The vertical tube that this connects to is triangulated neither top nor bottom, and nor is it's partner on the
other side of the tyransmission "gap" in the middle of the chassis! The tubes that kick up at the rear to mount the rear coilovers and the
roll hoop base also look rather flexible!!!
Further to this contrast the design of marcs chassis with the number of "open" tube ends on the Robin Should design, where a number of
tubes are welded to the edges of each other, that is really poor design with round tube, there is no excuse for not fitting the tubes properly, nearly
all the strength of the joint is lost doing it this way!!
anyway, need dinner so I'm off to the pub with Elaine
see you all later!
Nat
[Edited on 27/7/05 by NS Dev]
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Winston Todge
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| posted on 27/7/05 at 09:20 PM |
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This is one very interesting thread!
Very informative...
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marc n
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| posted on 28/7/05 at 07:01 AM |
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of course the other benifit is related to the fewer weld s the less likely the chassis is to pull when welded,
re robin hood we have had one in recently to do a large mount of work on, the main issues with the chassis are as ns dev has pointed out particularly
the welding of tubes side to side rather than butt welded, and the fact that there are so many open ended tubes and virtually no triangulation, and a
very weak pedal box area, but as stated on there website somewhere it takes them 20 mins to bend the tube and 1 hour to weld together, in contrast a 7
car takes us three days to manufacture before powdercoating, and the wishbones a day for a set !!!
at the end of the day you get what you pay for robin hood make no claims at being the best car out there but simply the cheapest form of 7 type car in
kit form,
although the last couple we have had in have had owners with no skill at welding / fabricating so have had to employ a third party to make
modifications and alterations and have thus stood ther owners at 8 k + and in one case it still isnt on the road or svad !!!!,
that aside i have also seen some of the owners cars at shows who have with the same collection of parts have done wonders and produced a very tidy car
( although not without a lot of time in some cases four years and deication )
i think the main point is that the robin hood is for the enthusiat / model engineer who can weld and fabricate which will mean you will very rarely
see two the same which some will say is the appeal of them.
i think it is a very bold project to start if you have limited experiance and equipment and are looking for an easy build
all this my own personal view
and i stand corrected if i am wrong
best regards
marc
[Edited on 28/7/05 by marc n]
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marc n
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| posted on 28/7/05 at 07:15 AM |
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hi nat
havent weighed it yet the laser cut brackets didnt arrive yesterday so the engine is still proped in position but hope to do today for you, would be
interested in getting involved in your build we are actually going to make a new class 8 chassis for a mate of mine this winter, and probably a class
7 too for one of the lads who works for me
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NS Dev
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| posted on 28/7/05 at 07:49 AM |
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Hi,
Cheers Marc, I'm certainly very interested in knowing the weight of that engine and gearbox!
It'll be a few months before I can get started on the grasser project, as I need the "locost" 7 out of the way first, and I need to
keep an eye on finances! (not too bad but I have to remember things like the £500 I'll be paying shortly for the new gearbox for my class 9,
apparently all the bits are ready now, just needs putting together!)
I'll certainly keep you informed of any developments,
I'll be needing some dimensional info on the Audi engine when I come to considering bodyshells too. I was determined to use a mini shell, but I
think it just isn't going to fit and still leave me anywhere to sit!!! The main consideration for the shell is the easy and cheap accessibility
of outer body panels!
Interesting that you are building some grasser chassis'. The existing manufacturers vary in the quality of job that they do, but none are cheap
now by any stretch of the imagination! (i.e. I would think there is a modest profit to be made, whereas 5 years ago I don't think there really
was)
Cheers
Nat
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MikeR
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| posted on 28/7/05 at 11:34 AM |
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Nat the engine will fit - just put it in at an angle and call it counter balance, if its still a problem, mini pickup!
come on .... lets get creative (or get on a diet). Most small cars are similar sizes so it won't fit any car. Now i've got an escort shell
you can have if you're interested
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NS Dev
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| posted on 28/7/05 at 11:47 AM |
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You like the angled engine idea don't you Mike!!! I think with the v8, especially with nice tubular manifolds on it, it might be a bit wide for
that idea.
Pickup is an interesting plan, I certainly know of two chevy v8 powered mini pickups (one supercharged) in the st Neots club, and I'm sure
there's a supercharged rover v8 mini pickup in the Evesham/Radford club?
Certainly worth considering, as the front end panels are the same anyway I suppose!
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MikeR
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| posted on 28/7/05 at 04:45 PM |
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you've noticed I just think for weight balance on a car that spends half its time going round a right hand bend its worth investigating.
headers, smeders......... you've got a fireproof suit on ....... just get some tin foil or something
Marc - should we go back to discussing your car now?
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G.Man
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| posted on 24/9/05 at 09:24 AM |
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May be a bit heavy for bike engine power, but what about twin bike engines?
Opinions are like backsides..
Everyone has one, nobody wants to hear it and only other peoples stink!
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