The most basic way to lose 150-250 lbs would be to

-replace rear decklid with a non-hydrolic spoiler (gt2 wing and decklid, cf if wanted))-15 or so lbs
-change the seats over to comp seats(putting in Recaro SPGs or Sparco Pro2000 or similar seat should save nearly 60-80 lbs
-take out rear seat-shelf-35-50 lbs(forget what it is exactly and not going to search)
-lighter wheels, race wheels like fikses, bbs motorsport etc can save you up to 8 lbs per wheel...and thats unsprung and which on a car dynamics base is a 4-1 vs taking a lb out of the interior...so you in essence lose 32 lbs per WHEEL when you change out to lghtweight wheels
-carpets and spare out-50 lbs or so...
-headers back system for up to 40 lbs off...




that shoud get you a pretty light TT...but as someone in a movie said...thats kinda like being the smartest kid with downsyndrome(excuse my lack of PC/sensitivity)

 

I have met Silver Shark and Tom and both were just being funny I think,
No harm meant. It is like Oak and I, love us or hate us for our Sarcasm...


MK

 

Thanks Marty, There was nothing disrepectful towards Tom.
My children call me the grump often and we still like each other.

 

Ok peace. Sorry...I probably took it the wrong way...my bad...now back to the thread (that could have been searched in the first place )

 

sechsgang

I am not sure I follow, to the original poster's question on how to reduce weight, mass in itself does not change regardless where you remove it from, so 8lbs per wheel savings is not like 32lbs per wheel savings simply because it is unsprung weight.

If one is guaging (sp) the impact of unsprung weight on the track lap times, then there might be something to it, but how much, is highly debatable IMO. In straight line acceleration I believe the impact is minimal (sprung vs. unsprung weight)

Out of curiosity only do you have any formula to arrive to the 4:1 equivalent stated above?
Thanks

 

the gt3 cup doors? Whats the sacrifice with these?

 

You sacrifice body stiffness and safety and therefore have to get a full roll cage which weighs a lot. They are light, but cant take impact like factory doors.

 

There is a formula, I dont know where it is but unsprung weight has a much bigger impact on acceleration than sprung weight.

 

Thanks

Christian

 

GT3 Cup doors are CF and not to be used for a street car. They do not bolt onto the frame with hinges and were designed that way so that they detach in case of an accident. Also, they do not have side impact bars, and the glass is a type of plastic that is glued to the window frame, it can be either fully closed or removed. Some aftermarket suppliers provide LW doors for a street usage with side impact bars, heavier, but I would only get those.
HeavyCheavy

We are in agreement as far as LW wheels having an impact on acceleration, however it is quite limited, and certainly not 1:4. The impact is more important going around corners I believe.

Removing one pound of wheel mass has same effect on kinetic energy as removing from 1, and up to 2 pounds of nonrotating mass maximum.

If you remove the mass from wheel center, the effect is near 1:1 (almost no effect). If you remove all the wheel mass only at the outside surface (which is unlikely), the effect is at a maximum 1lbs = 2lbs.

This is why tire weight has much more impact on acceleration than wheel weight (which is spread all the way from the hub to the border of the rim.)

Add to this, that this only affects acceleration, not velocity, meaning a perceptible impact would only be applicable to 1st gear and then some.

A LW flywheel rotating at 7K RPMs has more impact than a wheel weight impact, and this has been calculated, for a 12lbs saving in a Sachs flywheel weight, to be about 0.1 seconds faster from 0-45mph in first gear (Thanks Todd K.). In second gear, acceleration gains are almost imperceptible, third less, etc, since it related to thrust, and thrust gets reduced dramatically with higher gears.

Basically I would never buy lighter wheels just to improve acceleration times because of it being rotational mass, but rather because they simply save a lot of weight.

Sorry for the mumbojumbo, I hope it clarifies a little the rotational mass myth. Of course, I don't do this for a living so I might be wrong

 

Actually I dont think the difference has as much to do with kinetic forces as it does Drivetrain loss. Kind of like how vipers have bigger drivetrain loss because it's bulletproof and MUCH heavier, it's almost close to AWD loss numbers. If you add this weight to the rotating mass not only are you increase kintetic resistance but you are also increasing drivetrain loss because it sapps more power in turning the wheels. I have to agree 4-1 is a big number but I have heard that before, however I'd think maye 2-1. Cornering is also affect by this as well. But I think it can only be a big number like 4-1 if you are decreasing mass and size of the mass because then many more factors come in to play.

 

Sounds like cup doors are not for me, but the light weight doors you mention could be! Could you aim me at such a vendor?

I would like light weight doors (a cf skin would be awesome). Light weight CF hood, and if I can front fenders.

Thanks,
Seth

 

Seth, I agree with you, on a street driven car it is not the best idea.

I know that Techart, FVD and Cargraphic all sell them, I am not sure about the guys at Getty and Mashaw or some other board sponsor, but don't think so. They will not be as light, but definitely an improvement, and a safe one.

 

first off, i love that you always give an educated response that appears to be from real experience and not just dyno/internet raceing...

with that being said, where can i get the light weight doors with impact bars??? do you know how much weight you can save?

 

I wasn't really talking about faster 0-60 or speedwise, just faster to react to driver inputs and overall faster around a roadcorse...

As for the 4:1 claim...its just the generally accepted (meaning there is proof somewhere but noone really cares to find it) that this adage is mostly true and a decent ballpark figure for the felt effects of unsprung weight.



As for the cup car doors...I would say unless your car is going into some serious racing...then hell no...as you should be in a legit cup car at that point anyway.