Anonymous

Flywheel to the wheels ?

Kel said somert bout 15%

Is this about right...

My car made 320 at ava so this points to about 370 @ the flywheel

big_wig_074

jb fletchs made 373bhp at wheels which was calculated at 425 at flywheel

Mike Rainbird

iTrader: (3)

As a guestimate, add 15% to the first 100bhp at wheels, then 17% to the next 100bhp, then 19% to the next and so on...

This makes it approx 375bhp at flywheel...

Matt

rainbums was 395 wheels at ava werent it and 515 on dyno

@ 373 wheels on a t34 car, take it to ava

Matt

speak of the devil

Mike Rainbird

iTrader: (3)

Matt,
That's 515bhp SAE rated (as explained previously on numerous posts) .

Anonymous

There isnt a hard and fast figure, its not an amount of a perentage, its an extremely complicated equation containing oil viscocity and temperature among other things.

15-20% is a good "rule of thumb" though.

big_wig_074

i would,but apart from me having blown the engine up about 18 months ago!!!!! AVA is miles away,and why are they the be all and end all? just cos they read lower than every other fucker dont mean they are right! and it made 418 on harveys engine dyno so i was happy anyway.and im pretty sure that a t34 at 45 psi would have made that power !

Mike Rainbird

iTrader: (3)

LOL at 45psi . Just out of curiousity, what gauge was that measured on ?

SPADGE

Mike do you remember when i accidentaly ran approx 45 psi through my T34 at Brunters Lasted half a straight on boost

glenis

if its 15-20% on a RWD car...

then what is it on FWD car ? more loss or less loss

big_wig_074

mike,i dont know,i only ran 34 psi on my graham goode gauge,he apparently ran 45 odd peak!!! i didnt ask what gauges he used when i bought the engine!

Mike Rainbird

iTrader: (3)

Spadge,
I do indeed, and like you, it wasn't pretty .

SPADGE

Pretty is for girls you tart

Anonymous

My turbo don't run 45psi ever LOL.....

38 peak...

Dyno is ok for a bench mark in performance but very far from actual power in car IMHO...

Mine made 405 on dyno and made more at the wheels at AVA than any T34 car (think this still stands) Be good to see what its like now

Christian and Beccy

iTrader: (14)

But whats the relevance. Apparently Rolling Road figures aren't worth shit.

Anonymous

LOL I am not arsed about the actual figures just a rough power loss...

I mean karls made 540 @ wheels +20% = 648 on low boost

Anonymous

FWD is normally less losses than RWD

Billabong

Ring any bell's?

Christian and Beccy

iTrader: (14)

RST's normally lose between 25-35bhp through the transmission, depending on Tyre's, Gearbox Oil/Temperature etc.

Anonymous

dependant a lot on power too, a 130 ish bhp standard one will lose far less through any given box than a 250bhp monster will.

Matt

pretty sure why?

big_wig_074

because i am. dont have to be right to be sure.end of.

FletchCossie

iTrader: (4)

Jb Fletch Postin...

The T35 on me old engine used to love boost in a big way (ask anyone who went in it), went off the scale of my 2.5 bar gauge and when I was down Powers one day with a friend they let me stick their gauage on mine to run it up the road. Bang on 3 bar which is about 43.5 psi. It had been on the dyno & 2 or 3 rollin roads producing in excess of 420 hp on each. I was happy

AVA might be the daddies on the Rollin Road but fook drivin all that way bruv !

Jb

Anh

Biggest loss of power is via the tires, around 5-6% of total power loss. The transmission accounts for around 2%, the differential another 3% and then there is the prop shaft and joints and oils take the rest away.

I found this formula to be the most reliable.

Crank HP - 12% (if RWD, 10% if FWD)
- 10 hp
= horsepower at the wheels

Matt

with such a reasoned reply and definition of "sure" im now also sure that your sure

rapidcossie

add about 30 bhp to change the ATW to ATF figs if using AVA RR.

rapidcossie

how can you add 20% of a given figure?

surely the loss stays the same no matter the power.

why would a car with 600 bhp lose more thru the transmission than a car 400bhp?

my car makes 290 on AVA RR but will make a GOOD deal more in the next couple of months.
i wont be adding more to the figure tho will always just add 30bhp.
.

Matt

because more power = more heat = more losses

rapidcossie

dont think it makes that much difference.
ok say a car that makes 1000bhp loses 20% thru the transmission..thats 200 bhp.
that amount of heat would melt the box!

Matt

i suggest you speak to alan next time your at ava

GARETH T

rapidcossie,

helical gears which try to push thenself appart,, give them more power,, and they try even harder to do so, increasing thrust loading,

thats just one example

Anh

There are fixed losses that mean you will lose x HP no matter how power you make, and there are proportional losses. Around 4-5% through the entire drive train of a RWD car. Remember, most of the losses are through the tires, I don't think anyone noticed that from my previous post.

Christian and Beccy

iTrader: (14)

To be honest, it doesnt make that much difference.

e.g. A FWD car with 130bhp, but very cold, thick Gearbox oil will have higher losses than a 300bhp FWD car with a nice warm Gearbox.

At the end of the day, although more power will equal slightly higher losses, that car is still essentially running that same tyres, the same gearbox, the same driveshafts etc. So the losses shouldn't really be that much different.

Anonymous

Surely it has to be a percentage loss and not a given figure

Standard Rs2000 don't loose 30bhp Btw

Dave^

it depends on a shit load of variables.....

condition etc of gearbox, diff....

weight of the driveshafts/wheels....

pretty much the weight and mechanical condition of every moving componant between the flywheel and the tarmac........

so there's no percentage or given figure, that's bullshit....i know of a freelander [yeah shit i know, but keep reading.......] that made 44bhp at the wheels due to shagged transmission, the engine was absolutly fine.......

big_wig_074

you sure?