designed24

Scion xA (manual) = 2340 lbs
Scion xB (manual) = 2395 lbs

Horsepower: 103

Scion xA ratio: 22.7 lbs per horsepower.
Scion xB ratio: 23.25 lbs per horsepower.

The general agreement among SL members is that Cold air intake + Headers + Axle back roughly developes 7-10 hp in our cars.

xB and xA with CAI/header/exhaust horsepower: 111

Scion xA ratio: 21.1 lbs per horsepower.
Scion xB ratio: 21.6 lbs per horsepower.

This is approximately a 7.5% increase in horsepower.

Besides adding a pulley, there is not many more worthwhile performance options while staying non turbo, non superchargered (n/a).

The only way to get some improvements is the shed the weight. I think 150-200 lbs is a good goal.

Scion xA (manual) = 2340 lbs - 200lbs = 2140
Scion xB (manual) = 2395 lbs - 200lbs = 2195

Scion xA ratio: 19.3 lbs per horsepower.
Scion xB ratio: 19.7 lbs per horsepower.

200 lbs makes 10hp. Simply proved by if 2340 (stock weight) divided by 113 (stock hp + 10 horsepower) equals 20.7 hp per lb. 2140 divided by 103 equals 20.7 lbs per hp. Its that same thing.

This is a 9.3% increase in horsepower and a 17.6% increase in horsepower over stock!

Cool, but how the hell are we gonna get 200 lbs off our egg or box?

Please note that weight reduction can go as far as you want to take it at the expense of comfort, convenience, and $.
It is important for YOU the driver to figure out how far you want to take it.
Just because it is listed above does not mean I recomend it.

Red top battery <--- i gotta check but I think you can lose 20-30 lbs on this one.
leight weight wheels <-- i have 15" falken hanabis with 195/50 falken ziex total weight 27 lbs each. about 7 lbs lighter than stock. 7x4 = 28lbs. 28 x 3 (rotational mass 1lb equals 3lbs of dead weight) = 84lbs !
remove back seat + spare tire <--- back seat is heavy!! I think it is around 60lbs and spare is approxe 20lb. total weigth reduced 80lbs.
random junk you have in your car <-- i bet you get find a misc 10lb laying around
get your lazy ___ on a diet <--- 10lbs.
*ADDED*
Carbon Fiber Hood + Hatch <---- waiting for numbers.
Drive on half a tank or less 6 gallons x 4.5 = 27lbs reduced.
Drain window washer fluid <--- 2-3 lbs.

Total weight reduced : approximately 250 lbs! BEYOND our goal!



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Just to give you an idea of other cars horsepower per lb ratio:

Scion tC (auto) = 18.45
Mazda 3 i = 18
07 Mitsubitshi Eclipse = 20.2
Ford F150 V8 king ranch = 23.5
Camry 2.4liter = 21
VW Rabbit (4dr) = 19.4
base Nissan Sentra = 20.8
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Also, Perrin claims that their 1.2lb pulley is equal to a weight reduction of 100lbs. I have not installed this mods so I can not comment on this. Althought I have heard it does free up some power as claimed.

Scion xA with CAI/header/exhaust = 111hp. Goal wieght of 2140lbs + Perrin pulley = 2040
Giving a new ratio of 18.3lbs per horsepower... which is better than that of the tC (as shown above)

Easyoboe2

You are getting drastic with the rear seat and spare tire. If you want to really get drastic, you have the carpets, the underlayment and the sound insulation under the hood, under the two rear compartments, etc. strip it out baby.

THE_DON

Carbon fiber hood / hatch?

-THE DON

evosky

i don't carry around my spare tire at all. no need to in my mind. i think the most realistic weight reductions are:
- spare tire
- yourself dieting
- light wheels
- replacement

Boxer_Rebellion

I like where you're going, but I think a better solution for many would be lightweight seats (carbon, etc.) for the rear AND front, which would save even more weight than just removing the stock rear seat and give way more practicality for those of us w/families (or friends )

Also, I think the spare tire and all the stuff associated with it weighs closer to 40 lbs, just a guess.

Besides that, I agree with THE_DON that hood and hatch replaced w/carbon should make a big difference.

designed24

I forget where I read it but the CF hood for the xA only reduces weight by 4 lbs. For the money is not worth it.

I understand where your coming from with keeping the back seat. Maybe the 75ish lbs isnt worth it, but understand that many of us are dropped so much that no1 here is volunteering to take 4-5 people around town.
I usually ask if we could take someone elses car when more than 2 people are with me for that reason.

THE_DON

I removed the two large tow hooks that are bolted to the frame in the rear. They felt like about 5lbs each.

These cars are pretty light as it is. There's not much you can do without gutting the interior and loosing functionality. The biggest problem is ADDED weight. I felt a huge improvement after tossing my 18" chromes for lighter rims, replacing my big 12" sub box with a Bazooka, ect.

I refuse to take out my leather seats though

-THE DON

THE_DON

Oh, and I also shaved the rear wiper and removed the motor. It was only about 4 or 5 pounds worth of parts though.

-THE DON

pandaslayer

carbon fiber hatch, hood, fenders, lightweight 15" wheels and tires, no A/C, no PS, No radio, no speakers, take out all that wiring, replace glass with lexan, remove spare, remove sound deadening, take off side panels, remove rear seat and carpet. need I say more?

Boxer_Rebellion

We can take off the doors, Mini Moke style! they do it in the Bahamas...

JDMbB21

I removed my backseats and all it contents, plus i've added CF hood, fenders, and hatch. To say the truth it felt lighter.

jct

take out the front passenger seat, replace the drivers seat with a lightened racing seat

JDMbB21

That's what i'm talking about, but you need a passenger for the girls. Atleast two CF front seats. That should help.

Gsnorgathon

Take out the airbags, take out the motors for the windows, take out the actuators and other hardware for the keyless entry...

Reactor

Headliner. No idea how much it weights, but removing any kind of weight from the top will improve handling, especially on the tall xB.
Also moving my battery to the rear made difference in how the car handles (but thats weight distribution).

Lizard1

In racing, we used 7lbs = 1hp. So, loose 70 lbs, get 10 hp. Not sure about your equation...

Nonetheless, one thing to consider before you rip out seats and all the weight you're talking, consider balance. If you pull off 7- lbs. in the back and only 20 up front, you're not balanced. Equal weight distribution is more key than just getting hog wild on pulling parts.

These cars are 100 hp if lucky - and not to the ground. A current crop 600 cc sportbike STOCK is more hp with less cc's. Outside of strapping the thing to a fighter jet, your cost per hp is going to be pretty damn high. Even then you're lucky to get close to 200 hp.

A stock GTi is more than that.

Power to weight is one thing, but outside changing motors, it's kinda a lost cause...

Graeme

Interesting thread. We have to constantly balance weight and utility. Yeah, we can strip out everything, but will we want to drive them.

Big "power" increase in small diameter, lightweight wheels. Wheel weight is rotational mass that has to be accelerated. I've read that one pound cut from wheel/tire weight is equal to two or three pounds of dead weight.

Although it's not weight saving, running high quality synthetic oil and gear lubes like Red Line have shown significant increases in WHP through reduced friction. Dyno test on 5.0 Mustang showed over 5hp at wheels.

Lizard1

Very good points, Rotational mass is a BIG killer of HP. Wanna see proof? Dyno your car and check the hp. Most say they are around the 85 hp range. That's over a 15% loss from motor to the ground. So, reducing that loss can be done with a light rim/tire combo.

The thing about oils and such is simple. The lighter the oil's weight, the less hp it takes to turn a motor. In race machines, 0w oil is used. NOT recommended for street use.

Here's the bottom line. If you can get a 180 hp XB, you have spent an insane amount of money that if an owner of (Let's use the previous poster's car example) a 5.0l Mustang spent the same amount on his machine, they'd be over 350hp easily.

Point is, and I absolutely love my car, it is kinda like polishing a turd. $5k in getting to 160-180 hp is lame. Know how many stock machines roll off the assembly line that has at least that much power and much, much more in under that price range?

The issue isn't "well, take $5k and add it to the $15k price and it becomes a better value". Add hp like that to an XB and you're buying suspension, wheels, etc. I'd wager that if done right, minimally, you'd be into an XB for almost $30k. There's a laundry list of cars under that with more power and better handling.

Not being a downer, but just be mindful of what these are...

Now, if you can find a Celica with a good motor that is totalled, that I'd like to see. Something along those lines. Bigger motor, better power delivery, more dependable and a true sleeper. Modding a 1.5l and using a charger or turbo just isn't as impactful...

jones75254

Replace the steering wheel with lightweight wheel, remove the AC all together, rear hatch replacement with CF hatch as well as putting in plexiglass instead of the big heavy glass in the hatch window, no need for the CF hood, no big diff there. replace the front seats with lightweight racing seats. You have done everything else, cant think of much more than that, other than maybe replacing all the windows with plexi, but thats extreme.

jones75254

Oh and Lizard, you make good points, but there is a reason we have THESE cars. We know there are many other cars out there we could purchase with more HP but its not about that. Its about getting the most out of THIS car, becuase we like the style and it is a fun hobby to get the most out of it. If we wanted a 13-14 second production vehicle we would just go out and buy a cheap 02-04 mustang GT, or 03-04 Evo or WRX. The amount of $ spent to get our cars faster would prob equal the amount of $ to purchase one of those cars, but thats not what its about. Anyone can go out and buy one of these cars, not do a thing to it, and have a fast car. Thats not really much fun though, making something out of nothing is the fun part IMO.