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Old 08-11-2005, 06:53 PM   #11
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.................interesting.
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Old 08-11-2005, 08:22 PM   #12
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Quote:
Originally posted by havoc7476
what about rotational mass like wheels and brake rotors. how would you figure that out, cause its rotating and changes with the speed of your car.
Well, it depends on how Carrera is figuring these ratios. Carrera, in the rotational weights, are you including the subtraction of the raw weight itself?

Quote:
Originally posted by Carrera26
And don't forget the ratio of weight loss.

Sprung weight = 1:1 ratio
Unsprung Rotational weight = 1:3 ratio
Driveline Rotational = 1:15 ratio
Example:

The 1:3 Ratio of Unsprung Rotational Weight may just be referring to the rotational properties, and ignoring the fact that scale measureable weight is also being removed.

To answer your question though, assume that you just use the ratio flat out without any conversions, and you'll be close. Want an example? Great! Here's one.

2600 lb Car
30 lb Flywheel stock (I have no idea what the actual weights of Flywheels are, I'm just guessing here.)
20 lb Flywheel upgrade

Since we're losing weight on the flywheel, that's considered Driveline Rotational Weight, which is a 1:15 ratio. This means, take the weight, multiply it by 15, and that's how much "normal weight" you're removing.

30 lb stock
20 lb upgrade
-----------------
10 lb loss in DRIVELINE ROTATIONAL WEIGHT

10 lbs x 15 = 150 lbs Sprung Weight Equivalent.
This applies to accel/quarter mile based equations only, not handling/slalom!

When you're thinking about handling, consider it to be 10 lbs Sprung Weight.

Thank you Carrera for those Ratios! I will add this to the first page.

havoc, I hope I answered your question.
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Old 08-12-2005, 03:50 AM   #13
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Hot Rod Magazine did an article in 1987 about this very thing. The title was "Caddy Hack". They took an old caddy and began removing weight eventually down to the frame. The conclusion was 1000 lbs.= 100 hp. as far as acceleration was concerned. This would mean that 100 lbs. =10 hp.


http://www.corral.net/tech/horsepower.html
Cut and paste this hp calculator. Or google for your own.
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Old 08-12-2005, 08:32 AM   #14
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"Every time you remove weight, you have to redo the equation and it gives you a new lb/hp ratio."

It's called Calculus. Issac Newton figured it out a few years back.
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Old 08-12-2005, 09:08 AM   #15
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Quote:
Originally posted by penguin
"Every time you remove weight, you have to redo the equation and it gives you a new lb/hp ratio."

It's called Calculus. Issac Newton figured it out a few years back.
Exactly. I'm just trying to keep explinations as simple as possible.

The whole equation works on a curve, and the best way I can think of to explain it (and make it more accurate) is to tell people to rework the equation for every integer tick on the curve.
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Old 08-12-2005, 09:51 AM   #16
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Quote:
It's called Calculus. Issac Newton figured it out a few years back.
This turned into a math lesson real quick, glad to see there are still some smart people in the US!!!
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Old 08-12-2005, 09:59 AM   #17
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The ratios I got were from a driveline engineering book. They got it from repeated testing, and then extrapolated the data. Same car, same day, tire temp, IAT, elevation, etc. They dropped each type of weight in degrees and recorded the results. When they were done, they came up with those ratios.

Of course, it's still different for each kind of car, but that's going to be the best "from the hip" estimate.

Consider this. Going from the stock SVT wheels to SSR Comp H's with titanium lug nuts drops 41 upsrpung rotational mass. That's going to be the same accelerative gain as dropping A/C, back seat, and an appreciable amount of sound deadening. Not no mention the huge handling gains....
Going to a Fidanza lightweight flywheel drops something like 20 (maybe more) pounds, even keeping the stock clutch. Imagine what you would have to do to take 300 pounds off of your car, and what it would be like to drive afterward...

The funny thing about these mods is it doesn't feel like you added a bunch of power. You aren't actually changing the shape of the power curve, but simply pulling it up a bit. It feels more responsive, but not like adding 20-30 BHP. However, the improvement is quite definite and telling.

Anybody know the calculus for the weight, BTW? That would be good to know.

One last thing, there are a couple very easy weight drops. Going to a very lightweight battery (Oddesy, etc) can drop 25lbs in the best place. Out in front of and above the front suspension. Especially if you relocate that, it's a cheap and easy fix. And you CAN tell when you take 40lbs out of the nose of a car. The other one is of course, the cat and resonator. There's about 60lbs right there. It's not going to make as much of a handling difference due to placement, but it's good to remember just how friggin heavy those things are.
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Old 08-12-2005, 10:07 AM   #18
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You speak truth. I'm also interested in the book you're referring to!

It's funny, when it comes to weight removal you have to ask what kind of gains you are looking for, accel/quarter mile or handling. Removing 100 lbs sprung weight will give you better handling gains than removing 10 lbs driveline weight. However, the 10 lbs driveline weight will help free up your engine for acceleration! It's one big see-saw.
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Old 08-12-2005, 10:24 AM   #19
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did i do something wrong?


The Corral - Horsepower Estimator

Your trapspeed was 90 miles per hour
and your vehicle weight was 2798 pounds.

You are making 223203 hp.
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Old 08-12-2005, 11:01 AM   #20
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I've heard that you can make 223203 BHP with this chip you can get off of Ebay...
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