Lets discuss

recently i saw i think it was FF(maybe an old one..?), but i dont remember it may have been on a site but an escos made like 330bhp at the fly but only 230bhp ATW, Is this correct? can they lose as much as this???

seems pretty bad i think

think a 2wd saff only lost something like 30bhp

so surely a 300bhp saff which only lose 30 thru the trans so therefore

270BHP ATW

would be quicker than

a for instance 330bhp ESCOS which now has only 230bhp ATW???

is there anyway in reducing this loses?? newer transmision parts a better diff etc?


thanks

carlos

 

I lost 98bhp on the rollers where i went

 

2wd losses about 40 and 4x4 about 60...

if you lost 100 bhp thru the transmission your gearbox would look like your turbo after a ful boost run

 

397bhp @ flywheel and 332bhp @ wheels on Dyno Dynamics rollers

 

Oh no another thread about losses...

 

sorry ollie aint seen one



anyhow... rapidcossie didnt mention that the box was nackerd just it lost that much..? when you say 40 then 60 do you mean %???

 

mean BHP

 

well surely on a 1000bhp car it would lose more than just 60 bhp thru the transmission

surely its all relative

you have 100bhp cant lose 60 can ya

 

why would it lose more?

what changes in the transmission?

 

no answer to that mate, but then again ive had a beer, ill come back with one tomo

 

How can this be?

If B9 kos lost 65bhp on rwd? i take it it is 2wd? so what your saying is

the rollers are wrong?

Forgive me if its not rwd

 

not saying rollers are wrong...

 

no listen it is relative. if you stuck a standard 1600cvh carb in a 4x4 saff cossie your saying it would lose 60bhp and become 30bhp i dotn think...

 

forget what i said....

i only talk about wheel figs....

this is one of the reasons why...

it all becomes too confusing...


food for thought tho..

i was once at a MLR RR day at AVA and a bog stadard evo 6 (276bhp) made 237 ATW..

 

Changing to a lightweight carbon prop is said to reduce transmited losses.

Less weight, less rotational mass.

 

yeah so back to the orginal question

would it be quicker

 

Its 4x4 mate

Edited to add: So lost 65 bhp which agrees with what Euan said

 

Damm

Your car was flyin at donnington buddy well impressed

 

im spot on then

well almost

 

Cheers mate

Would of gone quicker if i didn't have comedy Yoko Paradas fitted

Mind you sideways out of Coppice with Nash in hot pursuit in his 2wd was a right laugh

 

as in chris nash?

 

If he owns a white 2wd Saff with Comp MOs that likes grass tracking then yes

 

Thats what i got paradas

a case of mistaken identity buddy was only spectating that day wish i had of been out there with you guys

 

Where did you get them from? Jefferies in Bromsgrove ?

Mistaken identity with my comedy spoiler, surely not

 

No i know where u mean thou

The bro in law works at HI Q and got them for Ł59 each inc vat & fitting

think jefferies sell them for Ł69 fitted which is a good price

take it thats where you got urs from?

 

Yeah, known Simon for years. Had too many sets of wheels off him to remember

Thats a good price you got them for

 

Yeah i sort of know simon he is a sound bloke, nobody else round here

can touch him on price

 

The more power you have the higher the trans loss,

This is due to all the trans getting hotter and more force on them thus adding more friction.

a 200 bhp car will lose less than a 500 bhp car and as there is more gears and shit in a 4x4 therewill be more lost.

but there is a small gain on a 4x4 car the front wheels do not need to be pushed so that unsprung weight and rotional mas is compensated for in the trans.

 

I see what Carl is saying, surely like he says it must be relative to an extent.

So with the example of a 1600 in a 4x4 cos thats 90bhp @ Flywheel you are saying it will loose 60 Bhp? Therefore producing 30bhp @ Wheels which can't be right, surely?(i assume thats Carls point.)

 

Losses are calculated by heat and so Euan is correct in a sence, however losses can come from many areas not just transmission. The greater the heat, the greater the loss.

 

But as Johnny says, the more power/force is put through the box the hotter it gets. So obviously the more tranmission loss there is.

But if thats the case as to how it's worked out then it's not as straight forward as Euan put it. As it is relative to the heat, therefore there is no correct figure for the loss of either setup?

 

That's why I said in a sence, it's a debate that will go on forever. Power loss is heat, the more heat the greater the loss, so higher output will mean greater loss through a less efficient drivetrain. What Euan has said is correct, if the loss was solely through the gearbox it would melt, however a 4x4 has 4 wheels, 2 diffs, etc, to lose heat.

 

It is neither an equation of the type
X = Y * Z
nor an
X = Y + Z

(x= bhp @ wheels, y=bhp @ fly, z = the "answer" people are looking for)

its far more complex than that, including adders, multipliers and powers, some relating to the box itself and others to the power of the engine, not to mention the rpm of the engine too, and specifically the gear you are in as well.


If you want a total ballpark for a 4wd cossie, try something along the lines of 20bhp + 15%, its likely to be closer than anything quoted in this thread, but still falls under the "complete and utter over simplified bollocks" category at the end of the day.

 

Stop wasting your time with flywheel guesstimations, as every set of rollers will guess them in different ways.

Wheel figures should be more consistent, and are whats being measured anyway. Why try and manipulate these figures just to achieve higher unreal numbers ??

All BS pub talk at the end of the day......the road/strip/track will tell the true story.

 

177 @ the fly = 93 @ the wheels
2.9 sierra 4x4

170 @ the fly = 92 @ the wheels
2.9 sierra 4x4

different day, different readings

 

my 89 Xr3i got 91bhp @ wheels which i worked out equated to 117bhp @ fly. I agree, the only figure to use is the Wheel figure.

 

Guys even the ATW figure can not be taken as gospel (far from it in many cases). If you look at how a RR works and the physical constraints and forces involved you will realise no RR can be correct. RR's are very good for diagnostics, mapping and comparisons.

People also used to swear by Engine Dyno's, which have the same issues with Real Life comparisons as RR do (if for different reasons), but again without doubt have their uses.

As already stated...... to find out how powerful your car is, get some timings down the strip or track..... thats the reality!

As regards to Cossie transmission loss..... it has always been quite high. Have you seen the size of the diff's on Cossies compared to other cars for starters!

 

hi shaun


the cossie 4wd tranny loss can be improved by having all the vc's reset

most of all the cossie vc's are fooked and i bet none of the owners ever had them reset lets be honest here how many cossy people have there diffs service i bet you would just about count them on one hand

all the vc's had 50Nm of torque when they left the factory most of them have got about 20Nm or even less ( lost viscoity)


marco

 

This topic will always have disagreements.



-As a RR measures power @ the rollers,
-hub dyno's measure power at the hubs, which is different to power @ the wheels.
-Engine dyno us the only accurate way of doing power at fly.
and all need to done correctly on the right dyno mode/settings.



i believe power losses is not a set bhp, due to it being a resistance. so more power at the fly, the more lose.
But i also agree that Most RR's quote incorrect power losses from fly to wheels.



NISSAN MOTOR COMPANY, quote the power loss on their Pulser GTIr to be 77bhp from fly (227bhp) to wheels (150bhp), which is 34% losses.


Also the gearbox isn't the only thing that causes losses, Props, driveshafts, cv and uj joints, wheel bearings, tyres, and all the rotateing wieght of the whole lot.

 

Absolutely mate!!