Can anybody explained the benefits of weight loss versus BHP increases or vice versa?

 

The context being, that I want to make my slicktop faster and more powerful but definitely without sacrificing the creature comforts. In fact I plan to add some weight with the ICE system and soundproofing that I am lining up.

 

Is there a rough guide of say - 50kg (for all of you still on the old imperial system :tongue: ) of weight loss would be equal to an approximate x amount of BHP increase. I do realise an equation like that wouldn't be that simple as there would be other factors etc.. but just as a guide.

 

Cheers

Obviously saving weight doesnt increase bhp (bar things like lightened flywheels,pulleys and propshafts, its more like the release power due to less unsprung mass).

 

Extra straight line speed is only one of the benefits of wieght reduction, and its probably one of the biggest increases.

 

I would say the biggest benefit is handling. Trying not to state the obvious, but if you have less mass, then for instance quick left right lefts, the car will be more agile (be able to make changes of direction quicker) and more stable due to the fact that less load will be placed on the tyres and suspension. Hence why cars like lotus elises' will run rings round cars like ours on the twisty b roads.

 

Braking is also going to be improved, but probably at the same sort of proportion as speed increase.

Is there a rough guide of say - 50kg (for all of you still on the old imperial system :tongue: ) of weight loss would be equal to an approximate x amount of BHP increase.

 

Obviously saving weight doesnt increase bhp (bar things like lightened flywheels,pulleys and propshafts, its more like the release power due to less unsprung mass).

 

Thanks Nick. I didn't explain what was going on in my head enough. From a speed perspective, I was hoping for guidance with figuring out if I increased my BHP through engine upgrades, would this have the same effect as reducing the overall weight by xx kgs? This equation probably doesn't even exist.

 

The handling issue is something that I hadn't even thought about and what you say makes absolute sense. When I get the respray and have the engine out, I'll remove some of the unnecessary items to try to compensate for the increased soundproofing.

 

Thanks,

Colm

No worries mate,

 

Take a look at this to see what options are available to you http://www.300zx.co.uk/forums/showthread.php?t=120393

 

HTH

 

Nick

A BHP increase only helps accelleration performance and top speed.

 

Reducing weight helps accelleration, braking and cornering!

 

As a certain Colin Chapman once said "For speed, add lightness......" he was a gifted genius in his day. Maybe the best ever F1 designer ever. :bow:

!

 

As a certain Colin Chapman once said "For speed, add lightness......" he was a gifted genius in his day. Maybe the best ever F1 designer ever. :bow:

 

Tis indeed true that one. :cool:

 

Doesn't always work lol ;) The makers of the Trabant built their car out of paper and, it was one of the world's slowest cars! LOL ;)

 

Tis indeed true that one. :cool:

 

Doesn't always work lol ;) The makers of the Trabant built their car out of paper and, it was one of the world's slowest cars! LOL ;)

 

and very noisy 2!:D

BHP per Tonne is the figure to look at.

Increasing power makes you quicker in a straight line, but losing weight makes you quicker EVERYWHERE

 

..as mentioned weight loss really comes into play with Handling and braking which Power does not.

 

You can work on BHP per Tonne, but even in terms of just straight line performance you can't really calculate weight loss vs Power increase because as you increase speed then weight becomes less significant and power becomes more.. They have different affects. At low to mid-range acceleration then weight plays an important part, whereas at high speed and top speed, power is more important.

 

Be careful with weight loss though, you need to take into account weight distribution.

Edited December 28, 200816 yr by Yowser

Thanks to all for the replies so far.

 

From a weight perspective I suppose I'm lucky in that mine being a SWB slicktop with no cruise control etc, it weights about 100kgs lighter than most LWB Zed's. Jimmys post linked by Nick, gives me a good guide as to what I can remove or would like to remove.

 

Regarding the weight distribution, if anything with the additional soundproofing, amp, carpc and sub, the weight in the rear will increase slightly versus the front. Is this a good thing?

 

Can I ask also the following - what are the benefits to retaining the AIV, EGR etc?

 

On the Hicas front, I refreshed mine with new parts and I'm more than happy with retaining it.

Thanks to all for the replies so far.

 

From a weight perspective I suppose I'm lucky in that mine being a SWB slicktop with no cruise control etc, it weights about 100kgs lighter than most LWB Zed's. Jimmys post linked by Nick, gives me a good guide as to what I can remove or would like to remove.

 

Regarding the weight distribution, if anything with the additional soundproofing, amp, carpc and sub, the weight in the rear will increase slightly versus the front. Is this a good thing?

 

Can I ask also the following - what are the benefits to retaining the AIV, EGR etc?

 

On the Hicas front, I refreshed mine with new parts and I'm more than happy with retaining it.

That guide is ok as a general guide, but bear in mind a lot of it is innaccurate and/or guesswork. Its about 5 years old and was originally posted on tt.net.

 

If your going to load it up with ICE and you dont want to lose aircon or hicas or replace the seats, then at best you can hope for is to try and compensate for the some of the extra ICE weight rather than reduce weight for increasing performance.

 

AIV and EGR are both to do with emissions, but are not needed to meet emission regulations.

A few things i noted on my NA through the drag racing challenge this year:

 

- Changed wheels from 275/40/R18s to the stock 225/50/R16s and knocked .5 of a second off my quarter mile

 

- Removed the two seats and rear bench and replaced with a single carbon kevlar bucket seat when racing and knocked another 0.5 seconds off the quarter mile

 

Admittedly the car's running about the 230-240bhp mark rather than the full TT 280bhp mark but still it's bloody impressive what you can achieve. It sharpened up the handling and the acceleration blew me away with how responsive it is.

 

Mine is missing the fuel return system, the carbon filter, the aircon, the cruise control etc and it's pulling close to 14.5 second quarter miles which isn't bad for a none turbo 2+2

 

Try it out by just removing the seats, the spare etc and see what happens :)

 

- Changed wheels from 275/40/R18s to the stock 225/50/R16s and knocked .5 of a second off my quarter mile

 

 

Wow - it's amazing that the wheel choice made such a difference. I presume its down more to the tyre width than wheel diameter?

Nope, it's just simple mechanics.

 

It's all about leverage, if you think when you can't turn a nut by hand you use a lever.

 

If a wheel's bigger it take more force to move it but it covers a longer distance, the smaller the wheel the better the acceleration but lower the top speed, the larger the wheel the higher the top speed but lower the acceleration.

 

So by moving a to a smaller diameter wheel i reduced the turning force needed to accelerate thereby improving my acceleration but reducing the speed range i could cover in the gears if you get what i mean?

 

Also the weight of the actual wheel makes a big difference too

Nope, it's just simple mechanics.

 

It's all about leverage, if you think when you can't turn a nut by hand you use a lever.

 

If a wheel's bigger it take more force to move it but it covers a longer distance, the smaller the wheel the better the acceleration but lower the top speed, the larger the wheel the higher the top speed but lower the acceleration.

 

So by moving a to a smaller diameter wheel i reduced the turning force needed to accelerate thereby improving my acceleration but reducing the speed range i could cover in the gears if you get what i mean?

 

Also the weight of the actual wheel makes a big difference too

 

I misread the wheel size of the 18's. Because mine are 30/18's I had assumed yours were too when in fact they were 40/18's. The 30/18's would have kept the "complete" wheel size the same. Amazing how the eyes read what the mind perceives.

631mm diameter (16") versus 677mm diameter (18")

 

Doesn't sound much but that's a 7% decrease in size and drag

 

Tyre and wheel sizes confuse me immensely lol

 

Bear in mind this pic was taken with stock suspension height, they only just fit in the arches...

 

Edited December 29, 200816 yr by bantambunny

wrong profile tyre = decreased gearing and slower acceleration

heavy cast alloys = slower performance all round (stock alloys are quite light - approx 17lbs)

That's the badger :D