57 replies to this topic

[mini93]

nooope iv worked out my aparent power to weight of an engine im gona build (in years) and its power to weaight is loads better than a starndard top spec evo 8 everything depends on gear train loss, gearing, wheel radius, wind resistance, frictional resistance on the road and hella lot more

so even tho the power to weight might be awesome unless u radicly alter the gearing its unlikyl to kill down an evo (still give a nice fight tho)

[mini93]

yes also true about the torque the engine is running torque = turning force is the engine doesnt have the turning force to accelerate it at that speed it obviously cant do so

[Jimi30]

don't forget that your quoting bhp figures at the flywheel, in a mini you going to have ghuge transmission losses so power at the wheels is significantly less where as a subaru has 4wd and a far more advanced system all round so will keep more of its horses. You've also got to take into account gear ratios and final drives, a subaru will be set up for a compromise between top speed, acceleration and reliability, you may be able to setup a well tuned mini to keep up with a subaru up to 60 but it aint gonna stay with one up to 150mph or so. But yer if you want something to brag about in the pub if you have an 85 bhp mini you can quote it as 130ish bhp per tonne:

Power per unit mass= power/mass
= 85/0.66 taking minis mass to be 660kg or 0.66 tonnes
= 128.8bhp per tonne

Compared to a bmw 2.0 Z4

Power per unit mass= power/mass
= 150/1.295 power and weight taken from bmws website
= 115.8bhp per tonne

In theory

Edited by Jimi30, 07 June 2007 - 07:44 PM.

[silverdalian]

Crikey, this conversation is going more and more in depth!!! your loosing me a bit here!!!

Jp

[Pandora]

The thing is Torque counts. It doesn't matter how much bhp you have. Yeh its nice, but in my opinion, where are you going to get top end speed anywhere in the uk, apart from a strip or track. Its got to be off the line that counts. People will be more impressed, if you can nail it off the line, and wipe that smerk of the guys face in the bigger car!

[Jimi30]

Personally find it more impressive to see a clearly very quick car being driven sensibly...at the other end of the spectrum whats ultimatly unimpressive is a slow car being driven like their in a caterham on a track...

[johnnysti]

Very true.

The car is set up really for bottom end and know i wont be able to keep up with the big boys. As it is at the mo i out acelerated a WRX and my friends 3.0 V6 laguna upto about 100MPH before it started to catch up. All on a private road aswell
So bottom-mid range is what im after.

Johnny

[Mini-Dave]

do your wheels just not spin at every given chance tho :S

must be fun tho lol

[whiskymac]

Torque is what counts, but remember you cant have torque without power.

Torque is directly related to RPM and BHP.

[johnnysti]

do your wheels just not spin at every given chance tho :S

must be fun tho lol

Before when i had falkens, they spun all the time. Since ive got the Yoko 48's its been brilliant. I realy didnt think that tyres really mattered all that much. So wrong!!!!!

*makes mental note* Might be a good idea to uprate the brakes!!!!!!!!


Johnny

[Tomf]

Yes i agree that torque is very important however in a mini if you have loads or torque the the wheels will just spin and you will go no where lol, so i think that there needs to be a ballance between BHP and torque.

[Bri_46ss]

on a diffrent note-

my RC car has 508.03 BHP per ton

Bri

[paulrockliffe]

So the power per tonne is doubled as the car weight half a ton.

.....then again I could be talking complete and utter rot. If so I'll blame the voices and carry on smiling.

Just thought I should point out that a tonne and a ton are two different things; a tonne is 1000kg, a ton is 2240lbs, or 1,016.0469088 kg

[mini-majic]

BHP is pretty much purely a pub figure. you can sit next to someone who will laugh at you all day because you have less bhp than them but when you get out on the track and wreck them because you have a better set-up and possibly more torque, who's laughing?? a good set-up is far far more important than just squeezing every bhp or torque out of your car.

[The Matt]

How have you got your mini down to 550kg???

Even if it was 550kg:

= 327.27/ton

Say your car is 600kg:

Power/weight= 300bhp/ton

But that's probably flywheel BHP, say you had 10% transmission losses:

Power/weight = 270bhp/ton.

Either way, expect some fun! How's yer gearbox? Set up well enough to cope with that sorta BHP? With a blower you're gonna have some serious torque too. How's yer driveshafts?