Shedding Pounds

91Firecrow305TBI  Mar 31 2006 - 5:10pm   

This article has been written to help shed unwanted pounds off of your Camaro/Firebird to lower your ET, help your gas mileage, reduce drivetrain strain, and help even your car's weight transfer ratio. There are two different types of weight we will be dealing with; rotational weight and general weight. Rotational weight is more important than general weight, because this weight will have more effect on how fast your engine speed will climb under wide open throttle. General weight has an effect on this as well, but not as profound. By lowering your car's weight, the engine will use less gas to produce the same amount of accelleration, thereby increasing your fuel economy. It is generally understood that every 100 lbs saved is worth about 0.1 seconds, and a 1 or 2 mph in the 1/4m. An engine pulling 4000 pounds at a given speed mathematically works 33% harder than the same engine pulling 3000 pounds, therefore lowering your car's weight will increase your drivetrain's life, and help keep more money in your pocket. Most F-body owners love to carve corners on the street or at the track. A balanced weight transfer (50/50) lends to much better handling and stability under hard cornering. The stock third gen f-body weight transfer ratio is around 57 front and 43 rear.

Now that you know of the benefits of a weight loss program, lets get into the nitty gritty, and see what can be done to shed some pounds. We will begin with reducing rotational weight because it is the most important, but not necessarily the easiest.

  • We will begin with the flywheel or flexplate (manual or automatic). A light weight, yet durable flywheel/flexplate will allow the engine to spin up more quickly, and send some more hp to the wheels from reduced drag.
  • Moving on to the driveshaft, most stock thirdgenner's recieved a heavy balanced steel driveshaft that weighs approximately 20 lbs. RPO code JG1 indicates an aluminum driveshaft, which weighs in at about 11lbs, almost half of what the steel driveshaft does, sending more power to the wheels. For even less weight, and no noise from the driveshaft, several companies like Inland Empire Driveline (http://www.iedls.com/) sell carbon fiber/composite driveshafts that weigh 3 or 4 pounds! These driveshafts are quiet, and do not vibrate at higher speeds like the steel & aluminum driveshafts.
  • The stock wheel castings are very heavy compared to the newer wheels out there. Weight savings here can be 15-20 lbs quite easily @ 5 lbs a wheel savings.
  • Lifting the valve covers, replace the stock stamped steel rockers with lightweight aluminum roller rockers. This will provide less friction, and free up some valvetrain weight.

We have shaved off a lot of rotational weight here (45 - 60 lbs), created more horsepower, and freed up a decent amount of power to the wheels.

Now that we have the engine spinning up faster, it is time to remove a lot of fat from the car. We will start up front where the weight loss benefits our weight transfer and move our way back.

  • Radiator; The stock radiator is pretty heavy when put next to a lightweight aluminum radiator such as that from Be Cool. You will also get a more efficient radiator as an added bonus. Approximately 10 lbs
  • Moving on to the engine block, your heavy cast iron water pump can be replaced with a much more efficient aluminum water pump such as Edelbrock, or Weiand, that will save you around 15lbs in weight, and also free up some horsepower off of the crank, as they are move efficient.
  • Removing the smog pump from your belt assembly, along with all of the AIR tubes will free up atleast 20 lbs in weight, if you are keeping your manifolds, 1/4" tapered pipe thread plugs will seal the holes. There is a technical article on how to remove this.
  • If you are like me, and your A/C does not work, and you run with your t-tops off all summer, remove everything underneath the hood including the A/C radiator. If you have a serpentine belt assembly, you cannot remove the pulley because of the location of the tensioner. Don't fret, it does not drain any horsepower to leave it there. If you want to keep your A/C, you should convert to the newer style, because R12 is becoming very expensive.
  • Removing the heavy cast iron manifolds, in favor of a set of Jet-Hot or Cerama-coated headers will create horsepower, and free up about 10 lbs. They will last just as long with these coatings, and let the engine breathe much better.
  • If your car came with a 305 V8, you have a set of heavy cast iron heads on your engine. Replacing them with aluminum heads such as L98's, GM Vortec Fast Burn, or another aftermarket head will free up 50lbs of weight from the front of your car, and the Vortec fast burn & other aftermarket heads will be an improvement in terms of horsepower, as the stock head design is usually a huge restriction. While swapping heads, make sure you get the heads milled so that the combustion chambers are 58cc to keep stock compression ratio. Also purchase an aluminum intake manifold that matches the heads, and camshaft that will as well. The intake manifold will free up 15 lbs of weight, but having a balanced engine combination is more important.
  • If you never use it, remove the washer fluid and fluid reservoir from the engine bay. This will only free up 2 - 10 lbs, but will help open your engine bay up.
  • Relocate your car's battery to the trunk. Taking weight off of the front and putting it in the rear will add rear traction, and help your weight transfer ratio 2 fold of the battery's weight.
  • For the TPI car's there is a technical article on porting/siamesing the TPI runners, manifold, & plenum. This will reduce a little bit of weight due to less material, but the most significant change will be much more upper rpm air flow. 10 ounces?
  • Remove your stock steel hood in favor of a fiberglass hood. This will drop 50 lbs off of the front, and you can retain your oem latches, and struts. This is also a good oppurtunity to get fresh air in from a ram-air style hood, or through cowl induction, creating more power.
  • Replace your front bumper with a fiberglass bumper cover. This will save you about 15 lbs on the very front of your car.
  • If your car came equipped with glass T-tops, replace them with plastic T-tops. They are much lighter. Not sure of the weight difference
  • Remove your rear seats if you do not use them. It also gives you more cargo room. 30 lbs
  • Remove your floormats. 4 lbs
  • Remove the hatch curtain if you do not use it. 10 lbs

We have saved atleast 225 lbs here not counting the rotational weight. All told, this is worth atleast 275 lbs of saved weight on your car, plus a large increase of power over a stock vehicle.

 
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