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Ok, well I've read that with weight reduction, removing 50 lbs is about equal to adding 1 horsepower. I'm assuming that this is dealing with sprung weight, like removing the rear seat or something. My question is, how much of a difference will removing unsprung weight make? Specifically, about 35 lbs, by going to some lightweight wheels instead of heavy stock steelies.

 
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Reducing unsprung weight by using forged wheels will allow the car to reduce weight and also lighten the load on the engine by decreasing rotational mass. This would allow less drag on components and allow the engine to essentially rev faster (same idea as a lightened flywheel). I'd like to see some calculations on how much an effect that would have on a bhp scale.

 
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I would like to know that too because my DX doesn't have that 200 pound AC like the rest of you guys.

 
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This has been covered before

What we can say here is that weight removed from the wheels as at least a 70% more positive effect on performance than weight removed from the sprung part of the vehicle.
I.E. every LB taken off the wheels is equal to 7 LBS off the chassis. also that test was done with a Higher hp/torque car then ours. so It could be said that with a lower powered car the effects would be More noticable.

 
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remember not to go too big on the wheels like 18's. You willa ctually be slower becuase of added weight.
I myself went to allow tenzo rs5 17inch with yokohama avids. They are a dry weather , high grip tire. I basically got more grip than I need right now rofl.
the backseat doesnt way that much, and replacing the front seats with racing rally tenzo, will save you a wopping 6 pounds each.
Also carbon fiber hood will save between 2 to 3 pounds. We got good hoods as is.
someone currect me if Im wrong about the hood

 
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The simple way of doing this calculation is for every 100lb of sprung weight removed takes ½ sec of your ¼ mile time. For every 100lb of unstrung weight removed it takes of 1 sec of your ¼ mile time. To take off 100lb of sprung weight you will have to remove the back seat, spare tire, spare tire cover, spare tire jack and tools and spoiler. You can also get a full carbon fiber hood and trunk and racing seats. It is beater to take off unstrung weight like lighter wheels and full racing coilovers. Having racing coilovers you can remove lower torsion bar. I don’t know if they make light lower control arm but that will remove unstrung weight.

 
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You guys need to specify between wheels and suspension components. Alot of suspension components are unsprung weight and have the same "speed-related" effect as removing chassis weight, but reducing suspension mass drastically increases the effectiveness of your suspension.

 
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^^ yup, and also if you change wheel sizes (larger) even if the larger wheel weigs less then the smaller wheel it will have a larter Moment of Inertia = Its harder for the engine to get that wheel to spin = Slower acceleration. So if you are in to performance, nothing larger then a 15 will do.

 
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Unsprung weight: All parts of car not suported by suspension system: wheels, wheel bearings, tires, spindles, brake parts and rack and pinion gearbox and related ccomponents.

 
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Yes, but rotational weight is slightly different. Un sprung wieight is precicly what you described, however that deals mostly with improving handling rather then acceleration/braking.

Rotational weight is any thing that spins (wheels, tires, driveshafts, gears, clutch, Fly wheel ect.... this weight affects acceleration, and the Gears/driveshafts/wheels/tires affect braking.

So, if all you are concerned is 1/4 mile times then taking weight off your control arms isnt really going to help you much, but if you lower the amound of rotational mass then you will.

 
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thanks for the great info everybody, and especially for that link zzyzx. specifically, i was looking at the OZ Superleggera 16" (im not hardcore enough to go with the 10 pound 15s, but i do want a light wheel). it looks like running these wheels should give me some noticable improvements, plus traction would be much improved getting rid of the firestones. my only concern is the fragility of getting a lightweight wheel, anybody have experiences of these wheels bending/cracking?

 
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Boilermaker1 ran a set of 17" Superlaggera for autocross last season, so I dont think you'll have any strength issues.

 
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Unstrung weight is heavier than sprung weight (any thing above the suspension system). What is the biggest robber of HP friction and load? Ok this is how it works sprung weight floating weight and unstrung weight puts a lot of load on the car. Acceleration has two enemies’ weight and traction. If you lighten unstrung weight you put less of a load on the engine and it improves how your suspension system works. A good suspension system will give better traction on acceleration or braking. Braking is stoping the momentum of a car. The brake system stops rotational weight of the wheels and tires. Most people will say go for a light 15in wheel that will improve your acceleration. But that is not exactly true. It is the combination of wheel and tire height and weight. This is the reason, the smaller tire and wheel combination the easier for it to spin. To much spin you lose traction and your car stars to hoop on acceleration. But if you have the right combination of tire and wheel you will improve traction and acceleration. Front wheel drive dragsters biggest problem is traction.