In the recent suspension thread, it was stated that "1 lb on the wheel is worth about 10 on the car due to the wheels rotational inertia." And that Spoon and Mugen wheels weight 11 pounds less than stock.

This equals out to the equilevant to 110 pounds of unsprung weight, which is equal to ruffly 7.7 WHP. If all of this is true, it beats out just about every bolt-on mod you can make.

Anyone know if this is true? Anyone have 1/4 mile times of a ITR with spoon wheels?




[Modified by jond, 11:43 PM 12/12/2001]

 

Actually ITR oem wheels weigh 15.6 lbs. I believe. Someone correct me if I'm wrong. And Mugen/Spoon wheels are a tadf under 10 lbs.

But they are the best bolt on in the sense that with a good wheel, I've seen people drop a couple of tenths in the quarter, and result in quicker lap times on a road course.

Plus no warranty discrepencies

 

well i dont have any figures for you, just some thoughts. reducing rotating weight not only helps acceloration, but handling and braking. so its like 3 in 1 benefits. but then again that is much more expensive. my ideal solution would be bolt ons and light weight wheels

 

There are some mods that can't help but improve your car's performance: Lighter weight (anywhere) is at the top of this list, wheels offer the added bonus of being unsprung weight. Things like shorter gearing are also pretty incapable of not improving your car's accelration. Your standard I/H/E boltons can actually loose you power, i've seen it a number of times (no matter how expensive they are). Most I/H/E will loose some weight...but if you loose power at the same time, you're just spending your money. Lightweight wheels rock.

 

sorry about taht i lost control. im going crazy right now.

 

I took off my 16" spoons for the winter and put the stock GSRs back on. I can feel a difference in takeoff. I know the wheels weight less than 12 and the oem one almost 16 lbs, but with tires on the OEM w/ Toyos feel heavier than the Falkens on the Spoons. I'm sure the aluminum lugnunts probably took off a few ounces too.

I'd imagine lighter wheels would work nicely with a lightened flywheel.

 

What?! I beg to differ.....

 

SCC did a two part column about this in their June '99 and August '99 issues, which I don't have. But, they revisited it in their September '01 issue and here's how it breaks down:

Saving 1 pound per wheel is equivelent to removing 1.5 pounds from the car itself. So, if a set of Spoon wheels are 11 pounds lighter than stock, your total perceived weight savings would be more like 16.5 lbs. Tires, who's weight is distributed to the outside of the wheel is more like 2 lbs on the floor of the car for every 1 lb of tread.

They also gave a formula for calculating the effective weight savings of a lightweight flywheel.

where:

We=effective weight savings
Wf=weight of flywheel
Rf=radius of flywheel
G=gear ratio
F=final drive ratio
Rt=tire radius

We=.5Wf[(RfxGxF)/Rt]^2

In their example, their flywheel was 12.5 lbs lighter than stock, which equated to a perceived weight savings of about 250 lbs in 1st gear! Now that might have to be the most cost effective performance mod...

Does anyone have some numbers to plug in for a lightweight flywheel for an R?

-Floyd

 

good point about the braking... this is something that is often overlooked by people as most focus on the better acceleration. IMO, it is improved braking that is the most noticeable effect and most important reason for having lightweight wheels. on a circuit course, ur car is at speed already, so there is less of an acceleration issue, ie. inertia... rotational mass... etc. but with all the braking on a circuit course, light wheels make an important difference... faster brake response, less stress on the brake system, etc.

there was an article in Sport Compact Car dealing with one of their project cars, i think it was a nissan sentra, where they dynoed the car with 17" wheels and 15" TE37 and found that with TE37, there was a 3hp difference... can't remember the details... but worth looking into

 

i know i was going to say something cause if i remember right mike k ran his car with the ats fd and his 60ft was worse due to traction but 1/8 or 1/4 mile time was better.

Black R - have you timed your car in the 1/4 ?

 

yeah mike k was quicker in the 1/8th...he didnt know his quarter time but it would have been lower too...

 

I felt difference when I changed from my 17"´s to the stock Enkei 15"´s. If I could I would sell the ATR rims but due to lack of Honda´s with 5lug here in Iceland it´s impossible 6 ITR´s, 1 S2000,1 ATR and 1 Accord V6 coupe

 

quote:
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Things like shorter gearing are also pretty incapable of not improving your car's accelration.
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What?! I beg to differ

So do I!

Whats up with that statement?

A.

 

if you read the sentence, it does make sense, but it's not proper English...he used a double negative, which makes the statement really mean

Things like shorter gearing are also pretty [in] capable of [not] improving your car's acceleration

 

i think this is a double negative guys..read it better.

if i'm translating this correctly.... it means that shorter gearing is incapable of hurting a cars acceleration.

if not then forget what i just said.

 

I put some 11 pound wheels on my ITR with NSX front tires all the way around (215 x 16 series) and I can really feel the difference. Definitely worth it. Now for the 2.0 liter engine!

 

Hehe, i wrote "things like shorter gearing are pretty INCAPABLE of NOT improving your car's acceleration". I use double negatives when i'm being obvious, to mix it up sorry for the confuzzlment...and i know some drag racers go for longer gearing when they get insane power, but for your average ITR, shorter gearing is the bee's knees....i drove D's, now i want my clutch to die so i can do flywheel and gears

 

can anyone back this statement?

 

that is not true. You do not need low profile tires for good handling. The side wall just need to be very stiff. Look at F1 cars, their sidewalls are rather tall

 

My car had 17 in. kosei racing senekas when I bought it, and (thank god) the stock rims in back. With the 17's I was unimpressed with my teg, it felt rather ordinary, but It looked mad cool and I didn't know enough to blame my 25 lb rims for my average driving teg. I sold to senekas to a guy with an rx7 and ordered a set of slipstreams. (I wanted te-37s, but I'm not flossin' like that) This is getting really long. sorry.The stock rims made my car noticable quicker and the slipstreams, imo, made it feel like a totally different car. I have no idea why people (including me not too long ago) get the impression that low profile tires handle better. I though my car felt nervious. I'm a newbie though, so you'll probibly be better off ignoring me.

 

Damn! Everyone that I've heard about, that gets a lightweight flywheel can't believe how much of a difference it is.
The stock ITR flywheel is 15lbs.
Comptech 7lbs.
1st Gear Ratio 3.23:1
Final Drive Ratio 4.400:1
Anyone up for the math?




[Modified by jond, 9:47 PM 1/6/2002]

 

I need to know the radius of the stock flywheel and the radius of the Comptech flywheel in oder to solve it. Anyone?

 

Doesn't that kind of depend on where (radius wise) on the wheel, all the weight is located? Just pointing out that you cannot have a uniform formula.

 

bingo! light flywheel makes the best bolt on performance part.

i spoke to one of the techs from ACT at great lenght once and he told me that in 1st gear its about the equavilant to 200 lbs of unsprung weight. in 2-5 he said its roughly the same as 80 lbs of unsprung weight.

anyone who has a light flywheel knows of the big cool-aid smile you got the 1st time you took it out

 

BTW. In F1 they are not allowed to use rims larger than 13". It's in the regulations. For safety reasons or something......