AutoX E36 Weight & Power Vs Cost

[megatron]

I'm twiddling my thumbs here waiting for some parts to come in and I was listing where I could lose more weight on my car. Well being a nerd, 15 minutes later I had a spreadsheet with weight vs. cost and power vs. cost. It was a little surprising to see which weight mods were most/least economical and which power mods as well. Some of my figures may be a little off, but they are in the ballpark:

Hopefully this will be a good reference to someone getting into BSP, STU or Street Modified to use as a step-by-step as to what to target first for weight/power. I'll add the TS and other stuff into here once they are on the car.


________________________weight__power___cost_____$/lb
Rear Seat Delete________50______0_______0________0.0
A/C Delete______________38______0_______0________0.0
Rear Speakers Delete____10______0_______0________0.0
CD Changer Delete_______5_______0_______0________0.0
Amplifier Delete________5_______0_______0________0.0
Front Undertray Delete__5_______0_______0________0.0
Front Speakers Delete___3_______0_______0________0.0
Stereo Delete___________3_______0_______0________0.0
Front Valence Delete____2_______0_______0________0.0
Front Porkchop Delete___2_______0_______0________0.0
Fender Liner Delete_____1_______0_______0________0.0
Foglight Delete_________10______0_______12_______1.2
ASC Delete______________5_______2_______12_______2.4
Lightweight Battery_____40______0_______100______2.5
Fan Delete______________10______5_______100______10.0
Sparco Pro 2000 (2)_____90______0_______1000_____11.1
Carbon SR/ SR Delete____30______0_______500______16.7
Aluminum Engine Block___50______-15_____1000_____20.0
Carbon Hood_____________25______0_______500______20.0
Air Injection Simulator_5_______0_______100______20.0
AA Test Pipe____________20______10______450______22.5
Steering Wheel Swap_____10______0_______250______25.0
Lightweight Flywheel____20______5_______500______25.0
Kosei Wheels____________28______0_______800______28.6
Aluminum Doors__________55______0_______1600_____29.1
Carbon/Ti Exhaust_______25______5_______800______32.0
Forgeline Wheels________28______0_______1600_____57.1
Underdrive Pullies______3_______5_______175______58.3
Dinan CAI_______________10______5_______600______60.0
SS Headers______________5_______5_______850______170. 0

________________________weight__power___cost_____$/hp
ASC Delete______________5_______2_______15_______7.5
Fan Delete______________10______5_______100______20
M50 Manifold (w/ SW)____0_______15______500______33.3
Underdrive Pullies______3_______5_______175______35
AA Test Pipe____________20______10______450______45
3.5" HFM________________0_______5_______400______80
Lightweight Flywheel____20______5_______500______100
Dinan CAI_______________10______5_______600______120
Carbon/Ti Exhaust_______25______5_______800______160
SS Headers______________5_______5_______850______170
Bored TB________________0_______1_______250______250
Aluminum Engine Block___50______-15_____1000_____-66.6

[CodeMonkey]

2lbs for the pork-chops? 10lbs for the foglights? sounds a little optimistic there.

[John V]

2lbs for the pork-chops? 10lbs for the foglights? sounds a little optimistic there.

If you remove both foglights and their brackets, 10lbs sounds about right.

Pork chops are probably closer to 1lb for both of them, maybe 1.5lb. They're pretty heavy for a couple pieces of plastic.

[///Mracer]

I think I will finally remove my A/C since it has not worked in over a year. Anyone got a DIY or list of items to remove?

[///Mracer]

is stereo and speaker removal allowed in BSP? The LTW came with no stereo correct?

[megatron]

If you remove both foglights and their brackets, 10lbs sounds about right.

Pork chops are probably closer to 1lb for both of them, maybe 1.5lb. They're pretty heavy for a couple pieces of plastic.

yah there is a bunch of glass in the foglights and the brackets have a few long metal adjustment screws in them.

[megatron]

I think I will finally remove my A/C since it has not worked in over a year. Anyone got a DIY or list of items to remove?

hey matt, i wrote one up a while back:
http://forums.bimmerforums.com/forum...t=a%2Fc+delete

[///Mracer]

hey matt, i wrote one up a while back:
http://forums.bimmerforums.com/forum...t=a%2Fc+delete

great thanks

[jmott]

now if we can create a simulator to complete "tenths of a second saved" for given HP and weight increase

we can build a spreadsheet of "$ per tenth of a second"

heh

[megatron]

now if we can create a simulator to complete "tenths of a second saved" for given HP and weight increase

we can build a spreadsheet of "$ per tenth of a second"

heh

in fsae days, we did a model of the competition parameters against each part to see what the gain in time was, loss due to extra cost was, design points, etc. and ultimately if an engineering decision would be expected to gain or lose points. this took into account the types of courses (speed creep was starting to happen then), where design judges' preferences were moving, etc. it's amazing how such a model can really help justify or debunk rationale of an parts choice. of course that model has been heavily evolved since my days and is also pretty guarded.

[trackpipe]

Can you delete the sunroof assembly, carpet, and sound deadening in Street Modified? Or would that put you in BP?

[magnetic1]

great thanks

Matt, a lift would help GREATLY in this endeavor

[megatron]

Can you delete the sunroof assembly, carpet, and sound deadening in Street Modified? Or would that put you in BP?

sunroof assembly - yes
carpet - no, but you can backdate to an ltw carpet
sound deadening - only to the extent the ltw had it deleted. better have official documentation as well that whatever was removed was in fact NOT in an ltw.

[ComBIRDable]

The $/hp part of the chart is interesting. Basically, there is no cheap mod for hp with the M3. It pretty much does all it can from the factory, and to get any more power takes

The only place I expect to spend money on is suspension, at least in the near term.

Scott

[MdMcoupe]

now if we can create a simulator to complete "tenths of a second saved" for given HP and weight increase

we can build a spreadsheet of "$ per tenth of a second"

heh

[megatron]

The $/hp part of the chart is interesting. Basically, there is no cheap mod for hp with the M3. It pretty much does all it can from the factory, and to get any more power takes

The only place I expect to spend money on is suspension, at least in the near term.

Scott

actually the twinscrew will probably work out to 75$/hp, which is not too shabby.

[warriors]

Why would an ally block lose power?

[megatron]

not inherently due to the block, but it's a 2.8 block and going from 3.2 -> 2.8 will drop some power. also the largest you can realistically go on a 2.8 is about 3.0 so it would still be a drop in power from a 3.2.

for a 328, it's gravy....

[SlammedE30]

Why would an ally block lose power?

It's a 2.8, not a 3.2.
-Ted

[warriors]

Euro 3.2s are cast iron?

[megatron]

yep.

[warriors]

Bugger!
So how do I get 3.0 from the ally?

[megatron]

US 3.2 crank (89.6mm stroke) will get 89.6mm stroke x 84mm bore

(84/2*10)^2 * 89.6 * 6 = 2979cc.

you can do this on all stock bmw parts, but your compression ends up being around 11:1. this is commonly referred to as the "2.9L stroker"

do a 20 thou = 0.020" = 0.508 mm overbore and you get

(84.508/2*10)^2 * 89.6 * 6 = 3015cc

you can do this with custom pistons and if you want, custom rods.

a 20 thou overbore is probably as far as you can really go on the aluminum block, given the sleeves are pretty thin as it is.

edit:
for street mod and the 3.0L forced induction cap, ideal would be a 10 thou overbore = 0.010" = 0.254mm

(84.254/2*10)^2 * 89.6 * 6 = 2997.3 cc

[warriors]

But I cant bore an ally block tho can I?(nikasil)

[megatron]

But I cant bore an ally block tho can I?(nikasil)

6 cylinder alloy block has steel sleeves. i'll take pics when i'm assembling it. it's really a gorgeous peice with oil squiters aimed at the bottom of the pistons, main cap braces, all sorts of good stuff not on the us e36 m3 motor...