Less weight = more power; Have you lightened your Z? - MY350Z.COM Forums



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Old 03-26-2004, 03:06 AM   #1
jng1226
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Default Less weight = more power; Have you lightened your Z?

This came up in another thread and I wanted to start a new topic on it.

Usually when people talk about aftermarket exhausts, one selling point they mention is how much lighter it is than stock. Ok, so Borla is somthing around 11-pounds less than stock, which is a saving a of (wait for it) 0.3%! (11 lbs / 3250 lbs curb weight).

Some people say that every bit helps, and specifically that 100lbs equals about .1 a second in the 1/4 mile. So where else have you taken weight out of your street-driven Z? Most people I see are adding way more in stereo equipment, aftermarket bodywork and larger wheels.

I understand reciprocating mass such as crank pulleys and flywheels, and [B]unsprung rotating weight[B] of lighter wheels is going to make significant differences in performance, but do you really think 11 lbs (again 0.3%) is going to make a difference?

Just my ****-retentive rant because so many people are hung up on weight here and there. Our car is no S2000...

Last edited by nis350ztt; 02-14-2005 at 07:51 PM.
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Old 03-26-2004, 04:24 AM   #2
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I'm actually probably a few pounds over stock with solid sway bars and a roll bar. Take out the spare with tools, and that's about 40lbs. I saved about 20lbs with test pipes, and I'll be doing a lightweight battery soon and scraping away some of the sound deadening material in the back.
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Old 03-26-2004, 04:30 AM   #3
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Default Re: Less weight = more power; Have you lightened your Z?

oops - mistake post.

Thanks for replies guys, so far this confirms what I was thinking. That's a great point about the Grand Am race 350Z, I also read about that it had a target weight of 2800 pounds but actually came in at around 2900 pounds after suspension upgrades, roll cage, etc.

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Old 03-26-2004, 04:35 AM   #4
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Dry Carbon Fiber hood, Remove Spare, run on 1/4 tank gas, titanium coilovers, carbon fiber hatch, carbon fiber doors.. with all that, over 10,000, you'd save around 125-150lbs - my guess..

Not really worth it IMO.
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Old 03-26-2004, 04:57 AM   #5
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The maths;

StockZ weight @ 3250lb (for example)
StockZ power @ 287hp (again for the example)
Pop power increase @ 5hp
Spare Wheel/jack @ 40lb


Stock Z power/weight = 0.088 hp/lb
Z with Pop = 0.089 hp/lb
Stock Z without spare/jack = 0.089 hp/lb


Conclusion? If you can feel the difference by fitting a popcharger, you should be able to feel the difference by junking the spare and jack.
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Old 03-26-2004, 05:54 AM   #6
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There have been some other threads on this topic with some interesting numbers. Getting 200-300 lbs wouldn't be all that difficult or expensive: Some approximate #

- spare wheel - 60#
- "true" CF hood - 20#
- wheels - 50# - (most folks "upgrade" to larger diameter, but smaller wheels is where the weight savings are at)
- full Ti exhaust - 35#
- remove front Al bumper - some intercooler folks are already doing this - 20#, of course, this is risky.
- ......

200# from 3250 = 6.2% higher acceleration. For 0-60 thats close to .3 sec improvement assuming a great launch and flawless 1st shift. For the 1/4 it wouldn't translate directly to 6.2% because of aero drag but you'd probably see over .5 sec improvement.

have fun
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Old 03-26-2004, 07:04 AM   #7
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Quote:
Originally posted by John
I'm actually probably a few pounds over stock with solid sway bars and a roll bar. Take out the spare with tools, and that's about 40lbs. I saved about 20lbs with test pipes, and I'll be doing a lightweight battery soon and scraping away some of the sound deadening material in the back.

Wow...I've been thinking of adding some, my Z rattles like a 89' camaro sometimes.

--wes
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Old 03-26-2004, 07:12 AM   #8
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Quote:
Originally posted by boyze
There have been some other threads on this topic with some interesting numbers. Getting 200-300 lbs wouldn't be all that difficult or expensive: Some approximate #

- spare wheel - 60#
- "true" CF hood - 20#
- wheels - 50# - (most folks "upgrade" to larger diameter, but smaller wheels is where the weight savings are at)
- full Ti exhaust - 35#
- remove front Al bumper - some intercooler folks are already doing this - 20#, of course, this is risky.
- ......

200# from 3250 = 6.2% higher acceleration. For 0-60 thats close to .3 sec improvement assuming a great launch and flawless 1st shift. For the 1/4 it wouldn't translate directly to 6.2% because of aero drag but you'd probably see over .5 sec improvement.

have fun
Have you actually weighed any of this stuff?

My spare wheel was closer to 40#

aftermarket wheels, while smaller should = lighter, that's not always the case. It depends on if it's forged, 1-2-3 piece, materials etc. I know of quite a few 18" wheels that are lighter that the stock 17's

Bet you that you don't find 20# of weight savings with any hood without stripping metal off of it. The stock hood is pretty light.

Stock exhaust is 70#, to put on a Ti exhaust (which I sincerely doubt will save you half of the weight) would force you to go with the same design as stock (ie. no dual) and would most likely make you lose HP.....in other words, a lot of wasted money for no gains at all, but hey, you lost 20#

Is the front bumper really 20# ? Seems a bit heavy to me, especially if it really is Al.

--wes
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Old 03-26-2004, 09:18 AM   #9
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Quote:
Originally posted by was wesman
Have you actually weighed any of this stuff?

My spare wheel was closer to 40#

60 sounds optomistic to me too. but that depends what model you have I guess. the Z has full sized spare, and in the case of the touring, that is 52lbs of tire and rim(weighed it myself).

pull the jack and all that too, 60 is possible.

aftermarket wheels, while smaller should = lighter, that's not always the case. It depends on if it's forged, 1-2-3 piece, materials etc. I know of quite a few 18" wheels that are lighter that the stock 17's

my rims weigh 19lbs(or so Im told) stock weigh 26lbs, so thats 7x4=28lbs. not bad for rotational weight. could have gone lighter with gram lights too. of course we are talking about those that go forged, again, not everyone looks at it this way.

Bet you that you don't find 20# of weight savings with any hood without stripping metal off of it. The stock hood is pretty light.

hood weighs 22lbs or something, so... yeah 20lbs is possible, cause dry CF would weigh like 20ounces. problem is thatd be 3-4grand. as things go, thats the least worthy thing to replace with CF considering cost.

Stock exhaust is 70#, to put on a Ti exhaust (which I sincerely doubt will save you half of the weight) would force you to go with the same design as stock (ie. no dual) and would most likely make you lose HP.....in other words, a lot of wasted money for no gains at all, but hey, you lost 20#

its not a joke, actually an understatement, stock EXHAUST is 70lbs, and titanium have come in with low 30's, yeah it is single, ussually totally single, meaing 1 tip. the Z has no NEED for dual exhaust, just as easy to run 1 3" pipe. tack on another 20lbs to the weight lost if you replace the cats too. probably another 5 or so for headers. so your up to 60lbs lost total there.

Is the front bumper really 20# ? Seems a bit heavy to me, especially if it really is Al.

Im skeptical on this as well. I would have guessed closer to 10. theres one in the rear too though if your feeling daring.
--wes
also there is the battery, you can save like 20lbs with a light weight battery(bonus points if you relocate it to the rear to help with weight distrobution)

beyond that, you could drop 100lbs easy if you strip the interior, take out all the plastic, mats, hell if your going to the track screw the passenger seat. even more if you take out the power windows(bonus points if you take out the windows too and replace it with mesh.

obviously Im heading straight into race car not street car territory and then may as well tear out the AC, air bags, and whatever else you can find.

I dont see why you couldnt lose plenty of weight, just depends how far your willing to go.
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Old 03-26-2004, 09:38 AM   #10
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Quote:
Originally posted by ares
also there is the battery, you can save like 20lbs with a light weight battery(bonus points if you relocate it to the rear to help with weight distrobution)

beyond that, you could drop 100lbs easy if you strip the interior, take out all the plastic, mats, hell if your going to the track screw the passenger seat. even more if you take out the power windows(bonus points if you take out the windows too and replace it with mesh.

obviously Im heading straight into race car not street car territory and then may as well tear out the AC, air bags, and whatever else you can find.

I dont see why you couldnt lose plenty of weight, just depends how far your willing to go.
Very confusing reply...

On the hood.....ain't no damn way in hell you're going to get a hood anywhere even in the ballpark of 20 ounces....you do realize that is less than 2 lbs right ? The shear size of the hood makes it impossible to get it near that light. The stock hood is Alum, it's possible to get it lighter, but not much.

I guess I got ripped, I don't have a full size spare, don't see why a different model would have one ??? Mine's a 16 I do believe.

I know there are plenty of rims out there that are lighter, especially the forged.

On the exhaust, pretty much every exhaust that has come out for the Z that wasn't a dual has lost HP. Sure you cna save weight, but what good does it do if it doesn't perform as well as the stock one ?

There are tons and tons of things you can take off, but like you said, why buy the Z in the first place if you're taking everythign out of it ? May as well buy a miata.

--wes
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Old 03-26-2004, 10:36 AM   #11
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Quote:
Originally posted by boyze
...200# from 3250 = 6.2% higher acceleration. For 0-60 thats close to .3 sec improvement assuming a great launch and flawless 1st shift. For the 1/4 it wouldn't translate directly to 6.2% because of aero drag but you'd probably see over .5 sec improvement.
If you want to see the advantage of removing weight from your car, just check out how the G35 compares to a Z. The weight difference is about 250lbs. It seems like the G's are running about 3/10ths slower than a Z in stock form.

BTW, the standard formula for calculating 1/4mile times has the following format. (keep in mind that there are way more variables than this formula has, so it's just an estimate).

1/4mi E.T. = C*(weight/hp)^(1/3)

where the constant C is usually in the low 6's somewhere (6.1-6.2).

If you expect a stock Z (3250lbs, 287hp) to run a 13.9, then the value for C is 6.19.

So, with a Z that you'd removed 200lbs of fixed mass, you'd have...

E.T. = 6.19*(3050/287)^(1/3) = 13.61

I would like to iterate again that this is all speculation and is just a general guideline to go by.

One more, less accurate formula deals with trap speeds. If your level of traction remains constant, the product of your ET and trap speed will also remain (relatively) constant.

If you assume that a 350Z, while running a 13.9 in stock form, will trap at 101mph, then...

ET x Trap = 13.9 x 101 = 1404

If you reduce the weight by 200lbs and run the 13.61 calculated above, your trap would be around...

Trap = 1404/13.61 = 103.2mph

Many people may find fault with this last formula, because more often than not, the reason our 1/4mile times are changing is because our 60' times (ie launches) are changing. To see why traction affects this last formula, you can compare two runs (one with good traction, the other with sorry traction). We've all seen something like this before:

Run #1 - good launch:
60ft = 2.050
ET = 13.61
MPH = 103.2

Run #2 - crappy launch:
60ft = 2.200 (spun tires for instance)
ET = 13.86 (much slower)
MPH = 103.2 (about the same)

In this case, the product of the ET and trap does not remain constant. This is why I stated before that this last formula assumes that the level of traction has not changed. Another example showing how traction affects this product is cars running slicks. I've seen cars running low 13's and not even trapping 100mph. That product is in the low 1300's, not 1400's like our stock (street tire) Z's.

Anyhow, this was WAAAAAAAY longer than I expected it to be. Feel free to play around with the formulas to get some rough guidelines, but ultimately, you'll have to confirm them at the track!
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Old 03-26-2004, 10:47 AM   #12
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not all single outlet pipes lost hp. dynos are horribly inaccurate when measuring things that are within 5hp of one another. people doing 3 runs on the same setup get variations of 8 or more hp. not to say some single pipe setups dont lose. but I beleive the titanium models are atleast breaking even.

Im sorry, I thought we did have a full size spare, I had a brain fart, its that we can FIT the full size flat tire. 40 might be a bit more accurate then.

regaurdless, randomly adding choosing a modification that can gain 10lbs or lose 10lbs is a 20lb variation, and while alone it might not be drastic, but it is there, and shouldnt be ignored.
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Old 03-26-2004, 11:00 AM   #13
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Quote:
Originally posted by ares
regaurdless, randomly adding choosing a modification that can gain 10lbs or lose 10lbs is a 20lb variation, and while alone it might not be drastic, but it is there, and shouldnt be ignored.
This is a very good statement. If you consider that we're in the 10lb/hp range, a 20lb weight difference is equivalent to about 2hp.

I don't have the exact numbers here but in Sport Z's shootout, the Stillen made more HP than the Borla, but it also weighed more. Once you factor in the weight difference, they may be more even.

This is also the main benefit with Titanium exhausts, especially since exhausts on our Z's & G's aren't making a lot of power. You could get a mediocre performing Ti exhaust making 4hp and be equivalent to a Stillen exhaust, weighing more than stock, that makes 8-9hp.
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Old 03-26-2004, 11:42 AM   #14
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for ppl who is keeping their car N/A(like me), weight saving is a really big issue.
i'll have to use every thing that is lightest on the market(flywheel, pully, battery, Ti exhaust+Ti y-pipe+ test pipe, and CFRP made racing seat, lightweight 18" rims, racing sterring wheel , and take off those spare stuff in ur car ),this should get off a good 100 kg! and still keep the car streetable!
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Old 03-26-2004, 12:38 PM   #15
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Didn't someone swapped a SR20DET in their Z, and it weighs only 2700lbs? If you're serious about weight reduction, that may be a good choice.

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Old 03-26-2004, 06:52 PM   #16
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I think some practical stuff like:
Lighter rims
Flywheel, exhaust.
Seats could also be a biggy. Leather is pretty heavy. Some nice looking sparco or brides could save about 20 pounds each. That electric seat mechanism is pretty heavy. So you're going to lose about 60 with the seats and it still looks good and functions just as well. As for the battery... I would get a re locator kit and put it in the rear. Less weight up front and more in the back means better weight transfer. It isn't all about weight reduction, but weight transfer as well.
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Old 03-26-2004, 06:58 PM   #17
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i dont know if its just me, but i'd do almost anything for an edge over someone else in a race.

smaller and lighter 16x8 drag rims
test pipes instead of cats. the cats are very heavy.
no after market stereo equipment
take out spare tire.
empty out the wiper fluid tank. sad, but i do it.
1/4 tank of gas or less.
sometimes, i makes sure i havent had too much food (if any) before going to the track. oh and be sure to drop the kids off at the pool before leaving for the track. (you know what im talking about)

hopefully a true CF hood in the near future will help out some more. oh and a lighter battery.

thats probably as for as ill go. i couldnt handle taking the seat off everytime i go to the track, let alone stripping the interior.
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Old 03-26-2004, 09:50 PM   #18
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Quote:
Originally posted by was wesman


On the exhaust, pretty much every exhaust that has come out for the Z that wasn't a dual has lost HP. Sure you cna save weight, but what good does it do if it doesn't perform as well as the stock one ?

--wes
Whare you talking about? This is the first I have heard that every exhaust, with respect to true dual, has caused a loss in horsepower. As far as I know, that's totally untrue.
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Old 03-30-2004, 12:25 AM   #19
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Quote:
Originally posted by MySunset350Z

hopefully a true CF hood in the near future will help out some more. oh and a lighter battery.
Stock hood weighs about 24 pounds. Lightest CF I've ever seen is 15. You could lose half of that again by cutting out supports and braces, but then your hood would flap in the wind.

Gas weighs 6.5 lb/gal, so we can carry 130 lbs of fuel on a full tank. That's something else to consider.
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Old 03-30-2004, 01:15 AM   #20
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[QUOTE]Originally posted by UsafaRice
Stock hood weighs about 24 pounds. Lightest CF I've ever seen is 15. You could lose half of that again by cutting out supports and braces, but then your hood would flap in the wind.

Gas weighs 6.5 lb/gal, so we can carry 130 lbs of fuel on a full tank. That's something else to consider.
[/QUOT

Hell yeah a full tank of gas makes a hugh difference in my car. I never fill my gas tank more than half way and even a half tank makes a diffferent. As for me, i'm a 236 pound male who just put about 60 lbs of sounds into my car so if i can lose about 41 lbs , i'll be able to off set most of the additional weight that i put into the car. Oh yah, minus the spare and the jacks and i will be able to off set the full 60 lbs and then some...lol! Every little bit counts right?
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