It's the Kind of thing I think about at 2am. I've always owned lightweight cars and had to do the most labor intensive things to make them faster. We all know adding power is expensive.
For any future purpose I'm starting to lean toward a car that already has ample power, but weighs more and I can just lighten it some. Is it more expensive to reduce weight in the long run? As a benchmark, let's aim for 10:1 power to weight.
Things such as gt mustangs, 350z, BMW all come to mind.
Depending on how nice you want the car to be. Cutting things out can be free. If you have to start replacing metal with other materials it's probably a wash cost wise on cars like you've described.
Depends on what you're doing with it. If it's a DD, most of the best ways to lighten it would be getting rid of stuff you'd want in a DD (air conditioning, nice seats, insulation, glass vs. lexan, etc). With a car that is already lightweight in stock form, adding power won't make it a crappy DD because you'll still have all that stuff.
From the outside looking in, it seems like adding power is the more economical way to do things. I'd imagine a lot of that would vary on the platform you're starting with, especially if it's one you know the ins and outs of.
And like irish said, it depends on your intended purpose. You can make some huge sacrifices for weight reduction (MightyCarMods had a good video on this a while ago where they completely cut up a car and made it faster) but sometimes those sacrifices are not livable depending on the purpose of the car.
10:1 power to weight in what units? Lbs:hp? Just making sure.
Probably easier/cheaper to get a fox body mustang to 300 hp than down to 2250 lbs.
Easier to get a Miata to 200 hp than down to 1140 lbs.
Maybe easier to get a 1998 xjr down to 3700 lbs than to get it up to 400 hp?
I'm having trouble thinking of cars that are easier to reduce significant weight than to make a few extra hp. Most cars probably have about 100 lbs of easy weight to remove, but past that it gets expensive or uncomfortable fast. And most cars probably have an easy 10 hp to gain as well.
a BMW E36 M3 can be lightened considerably without ruining it's daily use. Speakers, amplifier, sunroof motor, Carbonfibre hood and trunk, airbags, and if you do not mind the heat, the aircon system and take a few hundred pounds out of. Add in light weight wheels and you should be under 3000 pounds.
There are lots of little mods you could do too, removing the mirror power mechanisms, lightweight seats (stock seats are HEAVY) and so on can get you pretty close to 10:1
I am sure you could do the aforementioned with an E46 M3 and really get a good ratio, They already had around 330hp and 3400 pounds, so you would be there with just a seat swap
I've always had the mindset that more power is the solution to everything. I don't like gutting cars and removing nice things like AC (which you really need in Phoenix) so I'd rather just add more power. Sure, it'll cost more, but you won't be left with an unpleasant shell of a car— unless you're aiming for a track-only car.
MR-2 Spyder? Light, and easy to obtain more power (2ZZ swap)
Guess I should specify that it wouldn't be a daily, rather, a autocross or hoonigan drift mobile. I've always had two cars. One, a fine daily, and the other one on the ragged edge of sanity.
Why not both? Getting a Fox mustang down to 2800lb, AND 280hp should be easy in both directions, with plenty of room for more, either way.
Lighter weight is going to give better handling and better braking.
Power is easy, chassis tuning and weight loss is tough. Swap time.
if the goal is to be the lightest possible car with the 10:1 ratio then i would start light and build power. Like wvumtnbkr said light weight will have better handling and braking. Personally i would shoot for a chassis that is/can easily get under 3k lbs and figure out how to get the power up.
For example my Z31 has the all HVAC, power steering, emissions, bumper supports, etc. removed and i haven't weighted it yet but id guess at most weights 2800 lbs. With the bigger turbo it's making 285 hp to the wheels. Only took a little bit of weight reduction and a little bit of engine work to hit 10:1, nothing drastic in either direction to get their.
Somewhat related, my brother was just telling me of a Car and Driver (I think) article where they took a dead stock Corvette on-track, established a baseline time, then started removing weight. The point of the experiment was to see how weight affected lap times. As expected, as the weight went down so too did lap times - to a point - after which further weight reductions caused the times to start inching up.
I thought it was an interesting thought experiment to explain the time increase. My reasons included tire pressure, tire compound, and spring and shock rates. (I'm ignoring tire wear, weather, track conditions, and driver fatigue.)
I'll see if I can get a link to the video.
In reply to kb58:
Aerodynamic issues. At some point removing the windshield, hood, and front bumper makes you lighter, but definitely not faster.
Certianly alignment could become a problem too as ride height increases.
In reply to Robbie:
The increased ride height would also lead to worse aerodynamics and possibly some suspension geometry issues. Those are both fixable if you adjust the suspension back down to the original height to compensate for the removed weight though.
In general, the advantage to starting heavy and gong lighter is the chassis is already engineered to handle the power.
A heavy powerful car will also tend to ride better in the real world and be worse on track than it's lighter ratio counterpart.
I have a big car that is something like 8.8/1. It's fast and wonderful, but a stock NB on decent shocks is faster and more fun at autocross.
Robbie wrote: In reply to kb58: Aerodynamic issues. At some point removing the windshield, hood, and front bumper makes you lighter, but definitely not faster. Certianly alignment could become a problem too as ride height increases.
I'd imagine at some point too, depending how extreme they went, the chassis might lose some rigidity. Removing things like shock tower braces, underbody bracing, and things like that might make the car faster in a straight line but lose some handling capabilities.
When MCM did their experiment, they did it on some economy car and I believe they used a reciprocating saw to help. Not practical for real-world weight reduction, but you can get the idea of removing "too much."
As someone else opined, light weight is better but you do reach point of diminishing returns. Increased ride height may be part of the problem but you must also consider balance.
We ran into this phenomena with our full body but gutted C4 challenge car. We got it down to 2700 lbs (down fromm 3350 stock) but we were light in rear causing massive oversteer. We ended up with 65% front weight bias...as opposed to 55/45 stock. This year we've removed an additional 300+ lbs while maintaining a semblance of a full body...but 200+ lbs is off front so we will be getting a little better balance.
GENERALLY SPEAKING it is easier to remove weight on the end opposite the engine. True of corvette and my Porsche 911. Something you need to consider.
Warning Will Robinson: If you like light, you may never be able to cop down to heavy, no matter the PTWR. It just feels different. And having owned a pretty well-sorted stockish Foxbody a couple years back, there are some chassis I can't cop down to, period.
There have been some interesting posts on Bimmerforums lately from guys who run their classed (E36) track cars with and without ballast, in the 200# delta range, and report very little change in lap time. Which surprises me, given they have what, 160 RWHP?
Generally, I'm with Colin Chapman on this subject, but that's just how my taste in whips works. My '79 3 series is 2,400# and 140 RWHP dyno. It's Miata-fast and tons of fun. My E92 M3 is what, 3,500# and 365 RWHP? Way more than Miata-fast, and tons of fun, but not as fun as the '79. And OMG, the tire prices . . . .
captdownshift wrote: Power is easy, chassis tuning and weight loss is tough. Swap time
This times 1000!!!
If this is something you want to autocross than find something that already handles great and figure out how to add power.
I have very limited fab skills, and even I could get a 240 hp ej20 shoved in the back of a fiat 850 up and running (kind of). stupid fun, about 1400 lbs, so well ahead of your target weight.
I gave up on it when I realized I would never be able to fix the handling, I simply don't have the ability or know how to redo the tragic suspension.
One other thing to consider, do you want to be competitive in a class? or just go out and have fun? either lightening or powering (is that the right word) can bump you up into stupid classes with the SCCA.
Like everyone is pointing at here it's a matter of striking a balance.
I suggest finding the lightest 4 cylinder car that will take a n/a 250-300 hp v6 motor swap or something like that. Then strip what weight you can. (This goes for front or rwd cars. Much beyond those power limits go with rwd/awd cars)
Once you get near 3000lbs weight limit tires and wear items start increasing the pay to play margins. This is if you find common available cars, with fair aftermarket ie older mustang, Camaro, Civic, cobalt, sentra, as a starting point.
My brother responded. https://www.youtube.com/watch?v=UfpQTAFoTU4
Best to do both.
Lighter is better for a few reasons. Miata is the answer for autocross but not for drift mobile. Look at the size/power of most all drift mobiles they are closer to 240sx, Mustangs. Seeing Time Attack cars recently I wonder if the short wheelbase of the Miata can be a detriment on larger tracks.
I had a KITT car and it definitely felt stable/more at home at higher speeds on more open roads, not so much tossable. You can add speed holes, even better pressed with a die to make them stronger, or start to make a light tube chassis for part of the car but be aware of your crumple zones and roll cage situation if you go that far.
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