GR Yaris How much power is needed

[peeler]

Can anyone give me a rough idea of how much extra power would be need to have the same 0-60 times , laps times etc as a 100kg lighter car

So example is I have 300bhp 1500kg but want my car to be as quick as it would be with 1400kg ( hope that makes sense ) so how much bhp would be needed ? I’m sure there’s loads of variables so just after a rough figure

Thanks

 

[Onehp]

= 300 * (1500/1400)
= 321bhp
Mind, the whole power curve and thus torque should take a similar jump. This is only straight ahead of course, less weight matters in all directions, if you want that too, too many variables

 

[corgi]

http://www.torquestats.com/modified/index.php?pid=calculator will help...

Shows, assuming 4WD,

300 bhp and 1500kg: 0-60 5.2 sec, 0-100 13.3 sec
300bhp and 1400kg: 0-60 4.9 sec, 0-100 12.8 sec

so to achieve those times with a 1500kg car

330bhp and 1500kg: 0-60 4.9 sec, 0-100 12.5...

Close enough?

 

[Onehp]

Good link corgi, the diff with the simple power to weight equation is that cars usually aren't just lighter but tend to be smaller also if using a database, and that more power isn't necessarily available everywhere.
As said, this all merely reflects 0-60.

If talking lap times, it might very well be 350bhp...

 

[Steve]

That site is great, used to be called letstorquebhp and is a stato’s dream.

It also gives pretty accurate estimates when compared with real world performance tests. For instance it shows that even with 257 bhp (that we all know is lower than the GR’s actual power), a kerb weight of 1,280 kg gives a better 0-60 time than 5.5 s:

4WD - 257bhp & 1280kg

Power to Weight:​ 204 bhp/ton 0-60:​ 5.1 0-100:​ 13.2 60-100:​ 8.1 1/4 Mile ET:​ 13.63 1/4 Mile Terminal:​ 101 Dragstrip 1/4 Mile ET:​ 13.28 Dragstrip 1/4 Mile Terminal:​ 104

If you put in 270 bhp and 1,280 kg you get much closer to the actual recorded figures for our cars:

4WD - 270bhp & 1280kg

Power to Weight:​ 214 bhp/ton 0-60:​ 4.9 0-100:​ 12.9 60-100:​ 8.0 1/4 Mile ET:​ 13.41 1/4 Mile Terminal:​ 103 Dragstrip 1/4 Mile ET:​ 13.06 Dragstrip 1/4 Mile Terminal:​ 106

So 270 bhp, which is what many dynos have recorded for standard cars, tallies with the estimates above, and real world times.

 

[peeler]

Thanks

Great link too I’ll have a play

 

[peeler]

http://www.torquestats.com/modified/index.php?pid=calculator will help...

Shows, assuming 4WD,

300 bhp and 1500kg: 0-60 5.2 sec, 0-100 13.3 sec
300bhp and 1400kg: 0-60 4.9 sec, 0-100 12.8 sec

so to achieve those times with a 1500kg car

330bhp and 1500kg: 0-60 4.9 sec, 0-100 12.5...

Close enough?

That’s actually really impressive, 100kg 0.5 sec 0-100 some I’m guessing that would be a couple of seconds per lap,

 

[GRWTF]

That’s actually really impressive, 100kg 0.5 sec 0-100 some I’m guessing that would be a couple of seconds per lap,

Who would have thought Chapman and Lotus had the secret sauce all along. "Simplify, then add lightness"

 

[Steve]

Ditching 100 kg from the GR Yaris would be quite tricky though. The rear seats only weigh 20 kg. It starts getting expensive after the limited sound deadening has been binned.

Probably why many are choosing the extra 30 bhp+ from a tuning box for the same straight line returns!

 

[GRWTF]

Ditching 100 kg from the GR Yaris would be quite tricky though. The rear seats only weigh 20 kg. It starts getting expensive after the limited sound deadening has been binned.

Probably why many are choosing the extra 30 bhp+ from a tuning box for the same straight line returns!

1200 is actually quite hard if you are doing it properly with a cage. @Phil1291 has real data on what he has lost and gained from removing and adding parts.

 

[Onehp]

Some perspective, we're so spoiled with performance...

Yaris vs Group B homologation specials performance data:

https://zeperfs.com/en/match524-1023-1709-3764-5011-8589.htm

 

[AlphaDelta]

Who would have thought Chapman and Lotus had the secret sauce all along. "Simplify, then add lightness"

Lightness is something that's going to be in short suppy as we move to BEVs Absolutely agree though, the lighter the better. I'll cling on to small lightweight cars for as long as I can.

I'd guess stripping 100kg from a car that is already very light for what it is would be expensive. I seem to remember Harry Metcalf's review pointing out it's lighter than a Delta Integrale, even with all the modern safety kit & technology! My guess would be close to £10k to drop 100kg out. For that kind of money you could get many hours of 1on1 driving tuition and shave seconds off your lap times.

 

[Michael Knight]

That site is great, used to be called letstorquebhp and is a stato’s dream.

It also gives pretty accurate estimates when compared with real world performance tests. For instance it shows that even with 257 bhp (that we all know is lower than the GR’s actual power), a kerb weight of 1,280 kg gives a better 0-60 time than 5.5 s:

4WD - 257bhp & 1280kg

​ Power to Weight:​ 204 bhp/ton 0-60:​ 5.1 0-100:​ 13.2 60-100:​ 8.1 1/4 Mile ET:​ 13.63 1/4 Mile Terminal:​ 101 Dragstrip 1/4 Mile ET:​ 13.28 Dragstrip 1/4 Mile Terminal:​ 104

If you put in 270 bhp and 1,280 kg you get much closer to the actual recorded figures for our cars:

4WD - 270bhp & 1280kg

​ Power to Weight:​ 214 bhp/ton 0-60:​ 4.9 0-100:​ 12.9 60-100:​ 8.0 1/4 Mile ET:​ 13.41 1/4 Mile Terminal:​ 103 Dragstrip 1/4 Mile ET:​ 13.06 Dragstrip 1/4 Mile Terminal:​ 106

So 270 bhp, which is what many dynos have recorded for standard cars, tallies with the estimates above, and real world times.

Add the weight of the driver too, assuming you're not driving the car with a remote control?

 

[Onehp]

Add the weight of the driver too, assuming you're not driving the car with a remote control?

Actually depends if database is built with kerb weights (edit: discription says kerb weight = car weight with all fluids incl fuel) and actual performance data (that automatically add 'a driver')...

 

[Michael Knight]

Actually depends if database is built with kerb weights (edit: discription says kerb weight = car weight with all fluids incl fuel) and actual performance data (that automatically add 'a driver')...

don't know. weight is a weight.

 

[Ralf]

Can anyone give me a rough idea of how much extra power would be need to have the same 0-60 times , laps times etc as a 100kg lighter car

So example is I have 300bhp 1500kg but want my car to be as quick as it would be with 1400kg ( hope that makes sense ) so how much bhp would be needed ? I’m sure there’s loads of variables so just after a rough figure

Thanks

Sorry for the off toic, is this the same Peeler as on the MLR? If so welcome!

 

[peeler]

Sorry for the off toic, is this the same Peeler as on the MLR? If so welcome!

Thanks Yes mate, reliving my youth in a GRY !!

Fantastic little cars they take me back to the good old Evo days with the tuning scene , big community etc

 

[GRgrampa]

Thanks Yes mate, reliving my youth in a GRY !!

Fantastic little cars they take me back to the good old Evo days with the tuning scene , big community etc

I remember you from the MLR as well. I was Trev-the-Rev on there.

 

[peeler]

I remember you from the MLR as well. I was Trev-the-Rev on there.

Hi mate Seems there’s a few of us , I’ve had a Evo or 2 in the garage constantly for the last 20 odd years, obviously love punishment

 

[GRgrampa]

Hi mate Seems there’s a few of us , I’ve had a Evo or 2 in the garage constantly for the last 20 odd years, obviously love punishment

Haha, yeah know what you mean.
I had my last one for over 12 years but decided to sell it at the end of last year as it was getting just too valuable to continue throwing it around race tracks.