Responsiveness.........

[R1CSO]

My zs 180 feels more responsive when i put my foot down with a pretty full tank of fuel than it does when its very low. Is there a reason for this or am i just imagining things? :wacko:

[andys1981]

if its very low then the fuel might not be going thru your fuel pump,and you will be dragging all the gunk thru your fuel filter aswell mate

[caled]

have to say, Ive noticed this. Feels more planted, too, but thats probably got something to do with the extra 50L of fuel sat in the rear.
I reckoned it was probably due to an increased fuel pressure or something?

[stamford]

All in the mind.....................as you have alot of fuel you tend to drive a little bit harder and quicker, whereas a low tank means your driving style changes to make the most of what is left in the tank.

[Phate]

I disagree Mick.

Full tank will make it heavier causing more enertia so it'll carry more speed into the corners etc?

[Ritchy]

i dont think that jake, but know what you mean

im sure ive noticed this on my zs too(said to kev and gary and they looked at me like i was stupid like of course it goes better if it has fuel in it lol), never sure if its just me or it actually is, i know the old 600 or 800 had a problem where it had a plastic fuel tank, and if there wasnt enough fuel in it then the tank would lift in the centre partially blocking the inlet to the fuel pump, fix was to cut a 45 degree cut in it and it was fine
zs has a metal tank though so it shouldnt deform and cause that,
possible whst caled said but id think the actual weight of the fuel wouldnt be that great over the 20-30 cm considering its getting pumped at pressure anyway the only other thing that i could think it could be is the weight transfer towards the back, only way to test this theory is to get someone about 8 stone to sit in the back seat and see if it makes it feel more responsive on a fll tank

[Phate]

Well I remember watching a video that was an interview of the guy who designed and built the Nissan GTR.

The GTR weighs in at 1700kgs, yet its so rapidly quick and corners better than a Lotus.

His theory was that it weighs alot so it can enter and exit corners at the same speed, IE, you don't lose speed in the corners when you aren't on the gas as the enertia was carrying it through the corner and when you hit the pedal it would slingshot it into uber fast acceleration :)

So weights gotta have something to do with it imo.

[Ritchy]

yeah because its got a greater momentum (P=MV(Momentum=mass x velocity)) but Ricso says it feels more responsive when he accelerates, whicnh in theory extra weight is going to hinder.

[R1CSO]

yeah ritchy, thats what i cant understand. It feels more responsive under acceleration with a full tank than with an almost empty tank?! I'd have thought (logically) it shpuld be the other way around. I think andys1981 has a point which may explain what i'm experiencing

[talkingcars]

I find that I tend to drive harder when the tank is fuller, was thinking about it this morning I came to the conclusion it was all in the mind.

If some one wants to test the theory suggested above try a couple of 25kg bags of sand in the boot when the tank is nearly empty, that would be close to the extra weight of a full tank.

Personally I don't agree with the extra weight theory as one would find the car was quicker after a supermarket trip, mine tends to accelerate and brake more cautiously!

[Jay-ZS+]

I disagree Mick.

Full tank will make it heavier causing more enertia so it'll carry more speed into the corners etc?

Whats enertia? Heard of Inertia ;)

The weight is only of any use if the suspension can deal with the shift in center of gravity. If it was down to the weight race cars would be lined with lead, instead of an carbonfibre and aluminium honeycomb.

Personally think you will find its all in the head, only possible solution is that the fuel pump is more efficient when you have a full tank but cant imagine its noticeable tbh.

[caled]

Looks like we're not the only people who have found this...

Example 1 - BMW e30 forums (http://e30tech.com/forum/showthread.php?t=8746)

Example 2 - Acura forums (http://tl.acurazine.com/forums/showthread.php?t=768530)

General consensus (from scanning the above topics) seems to be that its in your head, pretty much.

Perhaps it's simply to do with the change in weight distribution? As you would be going from one extreme to another. Not saying its faster, but just feels different.

[coreygraham180]

Looks like we're not the only people who have found this...

Example 1 - BMW e30 forums (http://e30tech.com/forum/showthread.php?t=8746)

Example 2 - Acura forums (http://tl.acurazine.com/forums/showthread.php?t=768530)

General consensus (from scanning the above topics) seems to be that its in your head, pretty much.

Perhaps it's simply to do with the change in weight distribution? As you would be going from one extreme to another. Not saying its faster, but just feels different.

Personally what I think it might be is that when u floor it more weight is going back and feeling more of a jerk and maby the combination of more weight on the wheel it might feel more grippy too

[haGGard]

I can't say i've noticed this. If anything, the car definatly feels more sluggish after i've filled the tank from running on empty.

[stamford]

I stand by what I said ;)

If a full tank was the way to go then why do we run swirl pots and as least fuel as possible on track? How can adding 38kg of fuel make the car quicker?

A full tank will make the car unstable in high speed corners with the weight shifting going on, getting worse as it slowly empties to a point where a non-swirl pot set-up will get airlocks leading to a missing engine.

[p_b82]

It's in your head....Zombie (sorry can't help but add that after that dammed cranberry's song :laugh:

If your fuel tank was higher than your fuel pump then you 'might' get an increase in pressure.. but it would be negligable....

and the comment about momenetum is just rubbish, as under the accerlation it takes more effort to get the higher mass moving (and change direction) etc.....

and the GTR is is qiucker than an elise cos it has got a lot more power (and torque more importantly), and better mechanical grip, thus enabling it to go round corners faster - nothing to do with the weight itself....