im tellin ya id do anything to make my lude as quick and nimble as my friends old 94 GS-R...except deface my interior/seats. Also want to keep AC and PS. lets do a little math here...

4th gen weighs in at about 2930 lbs, i took out my spare which probably gave me 15 pounds. so i guess im at ~2915 lbs.

only 2 things i can think of to help
CF hood -~30 lbs maybe?
lightweight battery moved to trunk -~50 lbs

well that puts me at 2835 lbs... about 200 lbs off where i wanna be.
wtf makes the Lude so much heavier? only other things i can think of are lighter upgrades like exhaust/header. btw i searched.

 

****, seems to me ur lude should be more quick than a gsr anyday, mind that he isnt Forced Induct.

 

My 92 Si with H22 tipped the scales at 2850 with no weight reduction except no spare, jack, or tools.

 

of course its quicker as far as speed goes but i want it to feel lighter. im REALLY considering getting some light weight wheels. like 11 lbs. thats 5 lbs off each wheel (i think the stock 96 wheels are like 16 lbs?) for a total of 20 lbs which is (multiplyed by 8) 160 lbs of chassis weight

 

for the guys with light weight 16's , do you really feel a difference? does the car just feel lighter in general?

 

hey satan is goin to have cf sunroof ready by next year. i bet that ill take a load off.

 

96 wheels are more in the 22 lbs. region, but go with some rota's or volks

 

yea light wheels are going to help you alot yea they make it feel lighter hehehe

 

The 94-96 Si and VTEC sawblade style are right at 17lbs.

 

ok then i plan on getting 11 lb wheels which is 6 lbs off each for a total of 24 x 8 = 192 lbs chassis weight. w00t

 

Everybody loves comparing a GS-R to a Prelude and complains the Prelude is too heavy but they dont' do the math.

The Prelude has a better Power to weight ratio.. do the math and remember it has 20 more hp not to mention the extra torque.

It is heavier, mainly because of the engine, and with the extra torque, the tranny and driveline has to be beefed up making it more heavy. With the extra weight, the suspension and brakes have to be upgraded also making it heavier... you see the viscous cycle???

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by KB96VTEC &raquo;</TD></TR><TR><TD CLASS="quote">ok then i plan on getting 11 lb wheels which is 6 lbs off each for a total of 24 x 8 = 192 lbs chassis weight. w00t</TD></TR></TABLE>

how are you getting 192 lbs? what is the 8 you are multiplying for?

 

Seriously, I see SO many myths running around because of wheel weights, we need to multiply by 4 or now 8... I think we should really tackle the question of how much wheel weight REALLY weighs on our cars...So I guess Ill try to start this off:

I've given this much thought, and here's what I think. Essentially our car's acceleration is our WHEELS acceleration, we can look at the wheel's as a system with torques etc.
The acceleration of a rotating object is given by T=I*a, where variables I is moment of inertia (different for each rotating object), a= angular acceleration, where also, a = R*A, where R= radius of the tire, and A= translational acceleration.
Now, moment of inertia for a solid cylinder is 1/2*M*R^2 (which is essentially a wheel simplified)
Let's take the angular acceleration equation again:
T=I*a=1/2*M*R^2*a;
Now, given a constant torque from the crank/tranny
Clearly, as Mass increases linearly, so does angular acceleration decrease linearly,
And as the "radius" wheel increases linearly, angular acceleration decreases quadratically.
Now given there is no slipping between the wheel and ground, angular acceleration=R*translational acceleration
let's substitute back into the original equation:
T=1/2M*R^2*R*translational acceleration=1/2*M*R^3*translational acceleration.
Given a constant torque, we can clearly see that as:
M of the wheel increases linearly (if R stays constant), translational acceleration DECREASES linearly.
Similarly, if M stays constant, and R increases linearly, translational acceleration decreases to cubicaly.
So from this:
The WEIGHT of the wheel matters as much as the chassis weight no goddamn 8X trash im so sick of hearing.
The RADIUS of the wheel matters to the acceleration cubicaly, where essentially R= distance from center of wheel to center of mass of a "infinitely small piece" of the "rim and tire" combo.
Conclusion: no 8X or 4X ****, but we should all take care in reducing R, whether by reducing the size of the rim, other ways.
PLEASE if anyone thinks I missed something, SPEAK, I want to know where my mistake is, if there is a mistake.

 

what you're neglecting to take into consideration (which is where the 8x or 4x or 6x comes into play) is sprung vs. unsprung weight. all of the rotational mass stuff is on the right track in thinking that you want to reduce the OD of a wheel to improve acceleration, but weight reduction not only improves straight line performance, but also CORNERING, which is of great interest to the non-drag racers out there.

how the calculation for 8x or 4x came to be i'm not sure. but being that the wheels are unspring, or are not being supported by the suspension, it makes a much greater difference being that the suspension cannot redistribute their weight across the chassis.

also to the original poster, relocating your battery to the trunk may give you better balance but it's not gonna make the battery disappear unless you've got a bag of holding in the trunk...relocate the battery and get yourself a SLA lightweight battery which will save you approximately 26 lbs.

so redoing your math you'd be 25 lbs heavier.

at this point, the options you have left are: lexan side windows and rear (60 lbs), lightweight bucket seats (30 lbs), satan srv's CF sunroof insert (30-50 lbs, not exactly sure cuz it doesn't exist yet) or raceplates' CF sunroof replacement which they say is a 50 lb savings.

also keep in mind that tires do weight alot. 20 lbs/tire, and there are definitely lighter tires out there. generally speaking the HIGHER the aspect ratio, the lighter the tire, given the tires are the same width.

hmmm. aside from gutting the interior that's all the stuff that i can think of, unless you've got some spare titanium alloy or steel tube laying around and want to replace stuff like crossmembers and sidebeams...

 

Thanks for the suspension insight bad-monkey:
The 4X,6X,and 8X come from the idea of quadratically decreasing acceleration etc, with linearly increasing mass. For example for quadratically decreasing acc. with linearly increasing mass. For example, if we double'd the radius then moment of inertia becomes 1/2 M*(2R)^2 which also equals, 1/2 M* 4 *R^2...So that is what I believe these numbers are coming from , but im not sure either, id love to figure out if this is fact or fiction. Im leaning hard toward fiction

 

hmm interesting. i think it would be fruitful to get on the chalkboard and draw up a BIIIIIG free body diagram(s) of the car and assume some weights, spring rates, damper rates, speeds, and calculate some of the forces at play while under cornering stress.

but being that there's no way i remember that much physics, *I* myself would not be able to accomplish that. i would like to watch as someone did, though.

in the meantime i will take my liberal arts education and research skills and see if someone has written something sufficiently clear on the subject.

 

Hahaha, I'm capable of doing that big free body diagram ur talking about, in fact, i started to draw one...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by homesauce &raquo;</TD></TR><TR><TD CLASS="quote">Hahaha, I'm capable of doing that big free body diagram ur talking about, in fact, i started to draw one...</TD></TR></TABLE>

haha nice.

tell me how it goes...

some insight from our very own H-T boys with regards to the nature of an double wishbone suspension (read Kb58's post) https://honda-tech.com/zerothread?id=275134

as far as the numerical standard that "they" (the unknowable they) have come up with, the 8x, 4x, 2x seems to be indeed fictional, or at least that's my initial prognosis...

 

dont' forget the front and rear re-enforcement. The front one is heavy as well, I assume it weights at least 50 lbs, the rear one weight maybe 20-30 lbs. that's 70-80 lbs weight reduction,,,, if you are deperate enough not to worry about safety issues. Rota slip streams weight around 12 lbs I think, that's 10.5 lbs each less than 92-93 stock rims. You can also try to remove the tar on the floor, someone reported it weights 65 lbs altogether, but don't count on my word on this.

 

carbon fiber trunk lid

 

where did i get the 1 lb (unsprung) to 8 lbs (sprung)? click this link and scroll down to where bad-monkey replyed. https://honda-tech.com/zerothread?id=689268 see, i DO search!

 

Man oh man I hate dynamics...and come to think of it, I hated physics I too...

 

yes i've said it before, but i've been parroting guys who seem to know better than i do.

upon researching further i'm not sure WHERE that number came from but hey, it makes sense to me, that unsprung weight would make a much bigger difference to handling than sprung weight. i guess i have to do some math

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by KB96VTEC &raquo;</TD></TR><TR><TD CLASS="quote">where did i get the 1 lb (unsprung) to 8 lbs (sprung)? click this link and scroll down to where bad-monkey replyed. https://honda-tech.com/zerothread?id=689268 see, i DO search!</TD></TR></TABLE>

 

A couple years back, Dave Coleman investigated the wheel weight inertia thing pretty thoroughly in his "Technobabble" editorial (Sport Compact Car). If I remember correctly, for acceleration purposes the affect of rotational inertia at the wheels was significant, but less than indicated by many. Also, I believe gearing was a factor - the affect was a lot more significant in the lower gears than in the higher.

It's been too long for me to remember any details, though - I'll see if I can dig up some back issues.

 

Not only does light weight help you go faster in a strait line but it really helps you at cornering and stopping. I'm allways trying to find a legal way to make the car less fat.