Tech; Weight Reduction

  Weight reduction can & does help, if done correctly.  Taking 200lbs off the backend only will really reduce traction and handling because of the front rear weight balance. Since the front is heavier it would be best to pull the most of the weight off there but that isn't always possible. Depending on how & where you use your truck can limit some of your choices. Be practical. If its your daily driver the wife n kids need a seat! In the country, you want that spare.

Where do I start?

Driveline Weight Loss

The largest increase in performance is gained from weight removed from the driveline. Driveline includes anything that physically spins or reciprocates from fan, alt, rockers, pistons, tranny, dshaft, axles to the lug nuts holding the wheels on.  The less weight the motor has to spin the more power that gets to the pavement.  245hp at the crank comes out to approx. 185hp rear wheel. That is a loss of 60hp or 25% (5.9 4spd auto). Racers quote for every 25lbs = .1 sec of et reduction when its rotating/reciprocating wt removed but that is on a 3000lb car, not a truck with 50% more wt and 50% higher drag coeff.  That said, expect on a Ram truck the ratio is around 50-60lbs = .1 seconds off ets. Power to wt ratio is much lower on a truck.

Examples of modifications for reduced driveline loss

  • synthetic oils in motor, tranny and differential (for so many reasons start here)

  • light weight billet dist.

  •                     crank

  •                     rods

  •                     pistons

  •                     pins

  • alum roller rockers

  • lightweight springs, retainers and locks

  • blueprint/balancing

  • windage tray (less oil hitting crank reduces its weight)

  • alum under-drive pulleys

  • electric fans/viscous fan removal   

  • electric pwr steering 

  • bypassing a/c & pwr steering (with your fanless belt )

  • lightweight rims/tires/lug nuts

  • rear disc conversion

  • alum/carbon fibre driveshafts

Static Weight Loss

 Static (doesn't move vehicle) weight removal most racers quote the ratio of loss vs gain is roughly 100lbs=.1 in  et reduction.  Again based on a 3000lb car, sure, but not on Ram p/u. I've found that # to be high, I figure about 100lbs=.05-.07 reduction in ets. So much wt to remove the ratio improves as the truck gets lighter.  Weight location plays a role in how much reduction in ets there actually is. 65lbs off the rear by removing bumper & swapping to a roll pan would reduce weight but will also reduce traction. Ideally all static weight would come off the front of the truck reducing the front rear weight difference giving better traction off the line plus better handling n cornering (unless traction issues are addressed)
By lowering the weight of your truck in other areas (non driveline) your increasing the power to weight ratio. This is a free increase in performance in some cases (part removal). As well, any power adding mods added after will give more gain than on a stock weight truck.

Examples of modifications/removal of static weight

  • Lightweight bumper or drilled

  • lower driving lights remove

  • block heater remove

  • shorter bolts or ground ends off fasteners

  • fan shroud remove

  • pcm cover remove

  • wiper washer reservoir/pump/lines remove

  • wiper motor, linkage & wiper blades remove (lower drag co-eff. w/out blades)

  • convert to rack n pinion steering 

  • a/c remove

  • alum heads 

  • weather strip on top of cowl remove

  • headers

  • upper and lower control arms for lowering (not sure on spindles)

  • side exit in front of rear tire with the single exhaust

  • antenna remove (lower drag coeff.)

  • all pwr options remove

  • ss mirrors

  • lightweight seating

  • airbag remove

  • stereo and speakers remove

  • undercarpet insulation

  • center seat remove

  • jack, & tool remove

  • empty the glovebox

  • behind seat storage remove

  • tailgate remove

  • spare tire, crank and assembly

Relocation of Weight

  • battery relocated to the bed (behind axle/right side)

  • fuel cell located behind the axle

  • any electrical added mounted as close to firewall or in-cab

  • move rad closer to engine, wt neutral, front rear balance improvement

If you can't remove weight look to see if there is anything you can move back. Under the hood, instead of mounting something at the front by the grill try to mount it as close to the fire wall or in cab if possible.  I mounted a MSD Digital 6 ignition underneath the passenger side bucket. My battery is relocated to a small toolbox in the bed. I hoped to have it below the bed behind the axle but its currently ahead of the axle.
Tire & rims equal approx 136lbs of weight reduction (66lbs off rear wheels) and reduce driveline loss. They give  my 392 rear a 4.18 final. Got rims n rubber front n rear plus lowered the truck 2x4 back in 98. Race rubber it sits 3x5.5" lower. Weight reduction, traction increased , rwhp better, weight transfer improved (lower rear) & lower drag coeff. were the benefits.

What I've done

My Indy started at a weight of 4455lbs approx @ 1/4 tank of gas 96 with maybe 185rwhp 16.3 et, July 96 195rwhp 15.89.  By October 01, the race weight is down to 3860lbs with stock 5.9 na  best @255rwhp= 13.99@95.86.
7/04/04 hit 3800lbs estimated.  October 05, S/C, many gauges and more electronics and the wt probably hit 3900-3925lbs.  Best et was severely limited by a stock computer and the fact I had an extra 200-250lbs in/on the truck still ran 12.91/102mph (approx 390rwhp). 06 with the new 408 going in the wt should be back in the 3860lb range(alum heads) Expecting to see hi 11s with 7psi & approx 500rwhp.

List of parts I removed, relocated or replaced with lighter parts

all tools, jack and stuff
empty glove box
Pulled my cass./head, 12pck cd, amp & Kicker spkrs. (everything but Kickers back in/05)
                                                                                                                                                                      center seat removed (35lbs)                                                                                                                                            
switched to lightweight race buckets with modified pedestals (lighter)
tailgate (65lbs)
spare tire, carrier n crank ass.
pan instead of bumper (factory for weight reasons)
wiper blades (lower drag-coeff)
wiper reservoir, pump,  wiper motor n linkage                                                                                                             
removed viscous fan (Flexalite210B)
fan shroud

light weight battery relocated to bed (Red Top Optima)
lower driving lights in the bumper
underhood insulation
cover for pcm
block heater
foam seal on top of cowl to hood (flows more under hood air + slight weight)
Headers instead of stock ex manifold
exhaust side exit in front of rear tire
drive shaft shortened (slightly, due to launches & lowering)
Weld Draglite rims front n rear (don't run center caps)
lightweight lug nuts
M/T Sportsman tire front with Ets out back (stock rims/rubber vs race rims/rubber-136lbs total)

MSD box under passenger seat

Edelbrock 2.02 alum heads (46lb lighter)                                                                                                                                                                            
Above list is fairly complete but I always forget something. I figured when I got the Indy I could get its race weight to under 3800. Hoped for 3750 but wasn't sure if I could make it.  Reached 3800 even estimated in 04. 05 will probably have a low race weight of close to 3900lbs as many new parts added. 06 hope to get back to 3800 if possible.

Return to Tech;

Return to Tech;

Copyright 1999-2009  RM Indy's RAMPAGE