Fuel volume affecting time

[mku01]

This has been a topic that I'm sure some people would bring up after drags, does weight really play into the role of affecting lap times or 1/4 times?

As in comparing a car with full tank and close to empty. Let's say a dc2r with full and close to empty tank, the difference is roughly around 25kg when compared from full tank(45l) to 10 litre

What does everyone think? does this weight can really affect the performance of the car, or just an excuse for someone to use when they've lost to a race? also doesn't fuller tank have a higher fuel pressure?

[krogoth]

imo, its mostly an excuse

and i wouldnt want to run my car through a race unless i had a FULL tank

not good for many reasons

ur pump over heats because it may not be covered entirely in fuel....

also because the tank isnt fuel, and ur probably mostly on full load all the time, so that means the pump is trying to suck in the maximum amount of fuel since thats wat the engine needs

and if u havent got enough fuel in there, the pump mite not be drawing enough fuel sometime, which means the injectors wont get enough to put into the cylinders

so, a lower fuel pressure, and this means the combustion will run lean...or leaner than it should be esp at constant high rpm, the cylinder and piston wil be very hot, increasing the possibility of spontaneos combustion

ther is more to it, but yeh, som1 else can explain better

point is, advantage or not(i think there is no advantage), always run with a full fuel tank

[grumpy rooster]

It does make a difference with the lighter your car to start with, the more difference it makes.

Plug a cars weight into an ET calculator, with and without a full tank and look at the results.

[dasicvtec]

My mates give me shit about this but (Ive taken my interior out for a short time just to test it out) ive got all of my rear interior - from the two front seats back- stripped. I saved roughly 40kg by taking it all out. I did make the car a bit more 'zippier' and lighter handling and slightly better braking and more fuel economy.

So for example. Original Car weighs 1000kg with full interior, full fluids and full tank fuel (45L tank so roughly weighs 35-40kg). It does 15 flat down the 1/4mile.

Take out 40kg for interior and also have 1/4 tank in car and that would then make your car weigh approx 70kg less. So in the end the car weighs 930kg. The general understanding is for every 100pounds (45kg) taken out u get around 01.-0.2 down the 1/4 mile off. So one would expect with this (if every conditions same) for you to then do 14.7 down the 1/4. This is just a general example.

The easiest way to put this is when you have an extra passenger in your car, you can tell that the car is heavier and has a different characteristic to it. You notice this more with a lower power car. That's been my observation.

[barefootbonzai]

Since we drive honda's, and have little power. Yes weight makes all the difference in the world. Just put 1, 2 or 3 passengers in your car and race daniel. You'll see how much a difference it makes. Even the 25ish kg's you save from the fuel, it all makes a difference.

[DLO01]

Of course it make a difference. Your changing your power to weight ratio. Either increase power or decrease weight.

If you say you lost a race cause your heavy. In turn you might as well say you lost cause you did not put your pod filter on.

[krogoth]

ok, then my post is inaccurate

how much time difference are we talking about?

and when going through a track, it means ur pedal is on the floor most of the time, meaning the pump is working to its max capacity

so if u have 1/4 of a tank flying around, the pump might not get enough fuel to send to the engine right?

and esp with track conditions the cylinder needs to be filled with the right amount of fuel or running slightly rich to protect from knock?

correct me if im rong

[krogoth]

wat ur saying is the pump is always drawing in much more fuel than is ever needed, and the regulator then takes wat is needed and sends it to the injector

so ther is little chance that the pump will draw a less than required amount of fuel, ok makes sense

and there is no worry for the pump overheating if it isnt always covered in fuel because its designed to cope

also that swinging intake arm sounds really interesting

and remember we are talking about circuit racing not drag racing, u dont need to explain that any weight removed is a good thing, thats a given

yes of course it will give u a difference in time, wat i would like to see is 2(of course more would be better) lap times with the same driver and car, one with a full tank one with a 1/4 tank, preferably honda

it may make 0.5sec dif? 1 sec? more?

[DLO01]

Not sure with other cars, but with the DC2R fuel tank, the in tank fuel pump is incased in a surrounding baffle.

[Zilli]

Not sure with other cars, but with the DC2R fuel tank, the in tank fuel pump is incased in a surrounding baffle.

thats an answer to a question i was wondering about a while back!

thanks Dean