I'll start t his by saying that I'm totally not interested in competition, especially the winch dominated garbage we have to put up with, but any way, In any rule book you have to look at all the things that aren't mentioned instead of all the things that are.
I've had a quick look though the regs. you will note though that wheelbase must remain standard....
In relation to this and your G13BB swap, bear in mind you will be heavily chellenged if you were to do well. Mostly because you don't drvie a GQ.
There are a couple of areas of contention in the rules that I can see. The rules state that all glass must be retained, however, sierras are legally able to be used on the road with doors and windscreen removed.
There is no mention of interior except to say it must be a safe environment.
I can't see any minimum weight. (like in buggies where 1000kg is mandated)
Here goes:
Find 1.0/drover 1/2 doors. These are super light. gut the trim. You'll loose at least 25kg this way.
Ditch the windscreen. you'll be wearing helmets anyway and I strongly strongly suggest a 6 point cage. that means you can ditch the washer bottle too.
Ditch the heater.
Gut the dash, vents, etc.
Find the lightest seats you can afford and use aluminium side plate mounts. fix the seats. (ditch the rails-they're heavy.)
Bolt the passengers seat straight to the floor as an example. (The lower the co driver, the lower the COG - have a look at WRC)
Ditch the B pillar bar. Mount the belts to the cage. (This will require engineering but is not impossible.
pull all the sound deadening, including all the underbody stuff.
loose the pinchweld strips
stereo, speakers,
coilers have an aluminium radiator
find the lightest alloy wheels you can. Look at redrilling the pattern on old centrelines or convo pros. This will save masses of weight. I think you can groove tyres too. Bingo. Loose weight and improve bite.
No skid plates
No driving lights
the smallest lightest spare you can run- i suggest a 16X4.5 LJ rim and 6.00X16 bartread, best heavily worn (lighter)
Speedhole every piece of non structural metal you can find. Remember inner guards etc are not structural on a Sierra and can legally be modified.
Run extractors, much lighter than a cast manifold. Keep the exhaust light by running minimum bends and mufflers, but also choose pipe size carefully - 2" pipe is much lighter than 2.25 as the 2" is also lighter wall.
Guard cutting is permitted... get carried away - you'll be able to loose a lot of weight this way.
Don't run any aftermarket gauges.
LED lights are lighter than stock lights.
Ditch the rear bumper.
run a disc transfer handbrake, a rear disc conversion, heavily drill the brake rotors and run willwood superlights as rear calipers.
Sierras have lots of redundant wiring in their loom. When you're going G13BB, strip the stock loom. You'll loose a lot of wiring. Copper is heavy.
The winch needs to be mounted directly to the chassis - easy in a sierra with a 2" BL, but I'm trying to think of ways to move the battery up closer to the winch so it's lower - maybe on the passenger side chassis rail opposive the steering box - It will have very short cable runs from the alternator to the battery and from the battery to the winch. Cables are HEAVY.
If you MUST run dual batteries, run a tiny oddessy (I think they're 30AH is the smallest) as the starting battery. These have a steel cover that can be removed dropping another few grams (about 100, apparently).
Take some scales with you and weigh things as you are shopping for them - you will find that lots of similar parts have very different weights, especially mufflers.
Let's say your car now weighs 1150kg and has 67HP. It has 17kg/HP.
If you get weight to 900kg (I say this is possible to do in a legal car, and with a decent exhaust etc you have 85 HP = 10.8 kg/HP.
That's like your car now with 106HP, more power than a G16B puts out.
900KG is possible - it's only 30KG lighter than a stock soft top sierra. Maybe even 800KG is possible with very light rims and stuff - that's equivalent to your car now with 122hp.
PS if you REALLY wanted to run light - go K6A. 130HP with a "ECU change" and a free exhaust (legal under your rules) and a much lighter engine and gearbox. (1.0litre size) If a G13BB is legal in production class, then a K6A shoudl be no less legal... but woudl REALLY pi$$ people off. That would get you down to 6.5 Kg/hp... legally for your class, equivalent to a big patrol with 370Hp.
The real challenge is meeting the CCDA rules with a K6A
and having a legal car. The best way to achieve this might be with a "commercial" (van) 1.0 hard top. I believe a K6A can be legal in one of these. 1.0's have lighter chassis, unboosted brakes (lighter) and a lighter dash too.
Just something to mull over.....
Steve.
[quote="greg"] some say he is a man without happy dreams, or that he sees silver linings on clouds and wonders why they are not platinum... all we know, is he's called the stevie.[/quote]
Then just wear a wetsuit lol
