WRX lightening

The modifications to my WRX (the wagon project car) have dropped it in Street Modified class in the SCCA autocross world. A turbocharged two-liter with AWD and tires narrower than 275mm means my minimum weight is 2620 lbs. With wider tires, it's 2820 lbs.

With a half-tank of gas and the driver in it, the WRX weighed in at 3378. That's a big gap.

This is merely a thought exercise because the WRX is my daily driver and will soon also be a baby hauler. But here goes.

Is there any way to bridge the gap to 2820 lbs. in this car (I don't know if super-wide tires will fit, but let's assume so) while still staying within SM rules?

Alan, someone made a comment on the latest project update about a lighter subframe and bumper.

Yes, I saw. I'm pretty sure those aren't legal in SM.

The subframe wouldn't be legal, but the bumper might...

My 02 sedan with cage and a full tank is 2980. Cage is chromoly. I think you can get there, but the extra parts in a wagon will add to the challenge.

I have all stock glass. Interior and sound deadening removed. Roof liner retained. Front door cards retained, but carved for cage. No a/c parts. No passenger seat. Sparco seat. All stock dash, but air bag parts removed. Sparco steering wheel. Front subframe brace removed. Front radiator support removed, and replaced. Front bumper beam replaced with DOM. No fog lights. Front bumper cover minimalized. No radio. No speakers. No spare/ tools. No plastic under tray. Wheel liners, semi worn away. Stock wheels/16 inch toyo ra1 tires. Stock brake calipers and rotors.

Glass removal is next on my list. Also I use a stock battery which is heavy.

What do the seats weigh? You could put lighter driver and passenger seats in, and SM allows you to pull the rear seat completely for events. And did you weigh it with spare and jack and so forth?

PRE-EDIT CAVEAT: I changed a couple of things as I tried to reduce the pulling-numbers-out-of-bad-places, but may have made quick addition/subtraction errors which I will dutifully feel embarrassed about but am not going to triple check right now...

3378 minus a conservative 150 for driver is 3228
minus 27 for the back seat is 3201
minus 35 for lighter buckets is 3166
minus 35 for spare and miscellany is 3131

You started out 408 overweight (SCCA weight is sans driver, right?)
We got to 311 over with no real sacrifices to usability at all. If it is legal, the bumper could ditch another 22, and right off the nose, too...

sachilles wrote: Also I use a stock battery which is heavy.

Ah, that's another good one! And again, right off the nose...

In reply to nosleeves: My corner weights would have liked it if I moved it to the passenger side rear at stock weight. Balance is very important with them. Weight off the front is important.

275's will fit a wagon, but you'll need the right wheels and roll the fenders. It's a lot of weight to run something that big, wheel choice is important.

I should also mention that if you leave the shell in the northeast, some of the weight rusts away as well. Strategic placement of grm stickers makes it less obvious though.

Oh, and congrats on it it being a baby hauler!

Alan Cesar wrote: Is there any way to bridge the gap to 2820 lbs. in this car (I don't know if super-wide tires will fit, but let's assume so) while still staying within SM rules?

I just dropped 400+ lbs from my SC300 build (3400 -> 2960 lbs) by tossing the interior, OEM seats, sound deadening, A/C, power steering, and sunroof and there's still a ton of weight to take out of that car.

I'd have to read through the SM rules to see what's legal, but I think if you can spend some cash on lexan, an uber light battery, racing seats, super light wheels/brakes, AND you're ok making the car a miserable daily driver then it's almost certainly possible.

What type of times did this car put down on the challenge autocross course?

Lithium battery will drop a few pounds. You could save a few more pounds with a tubular header. Some other that havent been mentioned might be plastic manifold and plastic TGVs and pick up some power at the same time. If you still have a diff guard you could remove that and the rear wiper as well.

With the "merely a thought exercise" in mind, here's what you could do within the rules and limits of feasibility:

• Remove spare tire, jack, etc
• Lightest wheels you can buy
• Really dial in the handling bias with spring rates and toss your sway bars
• Custom super-light exhaust
• Lightest racing seats you can get
• Remove rub strips, mud flaps, fog lights, bumper lips, rear spoiler
• Ultra-lightweight battery
• Aluminum oil pan
• Thin-wall tubular steel headers
• Aluminum accessory pulleys
• Toss the A/C system
• Toss the interior mirror and sun visors
• All-aluminum calipers, smaller cross-drilled rotors
• Aluminum radiator
• Lightweight cooling fan
• Aluminum flywheel, lightweight clutch/pressure plate
• Toss entire window washer system
• Lightweight, bare-bones steering wheel
• Toss remaining airbags, wiring, controller modules
• Toss the fuel tank, install 5 gal. fuel cell
• Replace all steel suspension arms with aluminum units
• Toss power steering, install lightweight, manual rack
• Carbonfiber hood, fenders
• Toss the rear seats, belts, hardware
• Toss the stereo, speakers, associated wiring
• Replace side mirrors with sportbike mirrors
• Sunroof delete

Additional things that I don't know how to interpret:

"front & rear facias, and side skirts may be modified or replaced, and may be attached with removable fasteners. Associated hardware including latches, hinges, window washer system, and hood liners may be modified, removed, or replaced."

I think this sums up most of the significant weight reduction modifications possible. I was wrong about being able to remove most of the interior panels and replace glass.

It looks like it should be possible to hit your target weight if this were to be prepared to the limit of the rules. For reference I get about 500 lbs worth of stuff to toss when I add this up using what I think are pretty conservative estimates and not including any bumper modifications.

Aside from generic info like RPF1s or some kind of forged wheels and whats said above on a WRX you have bumper bars remove or JDM bumper bars which are significantly lighter and a "stealth" mod i guess, titanium exhaust is made cheap if you have a 08-present Wagon WRX on NASIOC a company sells it for $800 and it SIGNIFICANTLY lighter than stock i believe the previous car they made titanium exhaust for as well.

http://forums.nasioc.com/forums/showthread.php?t=2131391 - this is a group buy on there for titnium exhaust for 08+ i'm sure you can find the site that sells them from that. I think a JDM company called JIC makes titanium exhausts for previous model years.

apparently after some searching litespec makes 02-07 WRX/STI titanium exhaust as well. Here is the thread for that. http://forums.nasioc.com/forums/showthread.php?t=2202702

Thanks for all the input!

SCCA weights are with driver, I'm pretty sure. It's 3200 without driver (I'm 178 lbs, but I appreciate the generous guess of 150).

I just gained about 2 lbs. on each front corner by upgrading to Brembos, but the calipers themselves are several pounds lighter. If I go to some aftermarket rotors with aluminum hats, that would shave that down some.

I wasn't sure it was even close to possible, but the weight target does now look within the realm of reason. I'd love to make that happen, but it's completely impractical. I got a wagon because it's useful! A full SM build would absolutely not be.

Oh, as for what times I got on the Challenge autocross: My memory says I got a 46.6, but it might've been a 48.6. Either way, if the time was impressive, it's because I was in an AWD car on all-season tires on a very, very wet track when the rest of the fastest cars were on Hoosier slicks. I definitely didn't have a problem with traction.

It is worth noting in terms of practicality, light wheels/tires are very worth it. The 02's gearing, combined with the less than ideal torque down low, keeping un-sprung weight off the car will be beneficial. You really have to keep your course choices in mind, as some of the bigger tires really are not worth the weight penalty. Actually downsizing the brakes and going with a smaller diameter tire can really combat some of the gear challenge that comes with the bugeye wrx. In terms of shedding weight, it's pretty easy to remove the rear seats if a weekend autocross is on the schedule.

Alan Cesar wrote: Thanks for all the input!

There is a thread on NASIOC that outlines what everything on a WRX or STi weighs btw.

This is the 04/05 project car? STX builds still come in around 3000lbs or even slightly under with driver for the wagons. The sedans can get under 2900.

What is on this one making it so heavy?

Why not just do an STX build? They are silly fun STX cars.

nosleeves wrote: The subframe wouldn't be legal, but the bumper might...

The subframe would be legal if it facilitates an engine swap.

I'm hearing "Rotrex'd H6 boxer," right?

Alan Cesar wrote: Thanks for all the input! SCCA weights are with driver, I'm pretty sure. It's 3200 without driver (I'm 178 lbs, but I appreciate the generous guess of 150). I just gained about 2 lbs. on each front corner by upgrading to Brembos, but the calipers themselves are several pounds lighter. If I go to some aftermarket rotors with aluminum hats, that would shave that down some. I wasn't sure it was even close to possible, but the weight target does now look within the realm of reason. I'd love to make that happen, but it's completely impractical. I got a wagon because it's useful! A full SM build would absolutely not be. Oh, as for what times I got on the Challenge autocross: My memory says I got a 46.6, but it might've been a 48.6. Either way, if the time was impressive, it's because I was in an AWD car on all-season tires on a very, very wet track when the rest of the fastest cars were on Hoosier slicks. I definitely didn't have a problem with traction.

SCCA weights are WITHOUT driver when concerning Solo competition.

Which makes the Escort that i may or may not ever get back to fixing really interesting, since i CAN hit minimum weight, and in "fighting trim," i can weigh as little as 135-140lbs myself.

Under 2200lbs with driver? Sure!

What does this mean? Not a whole lot, really, just that you can make up some of the minimum weight deficit if you're tiny and your competitors aren't.

It's not that I want an SM build, but the light flywheel that I got the car with already put it in ESP. Then I put light rods and pistons in there after the engine asplode, which bumped it into SM.

Swank, you've got an Escort SM build possibility? Do tell.

Alan Cesar wrote: It's not that I want an SM build, but the light flywheel that I got the car with already put it in ESP. Then I put light rods and pistons in there after the engine asplode, which bumped it into SM.

This sounds like the modification path followed by 99% of people on Nasioc who mod a car and later decide they want to autocross.