Power/Torque loss & gain

Hello i am new to these forums, now i work for the largest fuel/turbo shop in Perth and we dyno 4wd's daily with mods,gas,exhaust,chips and a figure of 1/3 or 30 % CANNOT be attributed as a general rule.

Now this is due to the fact that people use differentoils, tyres, pressures, etc,etc.

Normally power loss ona typical GU/GQ nissan is around 20 Kw with STD A/T tyres.

Hi Mattche

Might be worth re-checking that figure. 20kw out of the GU 114kw is simply not a realistic figure , it equals a 17.5% drivetrain loss which is a figure that few 2 wheel drives can even deliver.

The 30% is a very typical Patrol figure. Its used as a general rule of thumb and is supported by back calculating from the standing quarter times of the cars.

Robin Miller

Nah dont have to, ive seen it time and time again at around 20Kw, yes some are higher but the majority are AROUND not exactly the 20Kw figure with STD tyres.

I assume we are talking ZD30 here not TD42.

Sure some will be higher.

Ok Mattche

Makes no difference - as all have same drivetrain - if you applied the 20kw to some of last centurys engine which only had 85 or so kw they would sound better.

I know some porsche engineers over here who would love to know how to get drivetrain loss of 17.5%

Robin Miller

Robin

This is an age old argument and it comes down to what you feel is correct.

Are you telling me just because these engines make more power they will have greater power loss????

Hope not,for every Kw you add to the engine through different mods etc it reaches the wheels which is why i DONT believe in percentages they just dont fit.Otherwise you would be losing a percentage of your upgrade !!!TRUE>

Ive got a 68 model toyota mate that loses 10Kw and the engine makes 155Kw thats justa tad less than 17.5% true.Nah thats not fair different kettle of fish.

Anyhow we are getting very good results from our upgrades and for every Kw over STD all of it gets to the wheels.

Its a touchy subject isnt it.

Matt

Hi there Matt

Was wondering what your name actually was.

The engine is largely irrelevant in these things - the type of gears used simply have a certain fundamental percentage loss and thats all their is to it.

You can work out approximate loss for most cars by following thru each meshing drivetrain gear.
I.E. gearbox, diff etc this usually is 20% , unless grossly wrong oils etc are used then on top of this comes tyres and a bunch of very small things.

Yours mates 155kw with 10kw loss is not "a tad less than 17.5%" its actually 6.45% and this is theoretically impossible

So I think there might be a mix up in terms here or perhaps some wrong info on a car horsepower reference sheet or something similar.

But next time I'm in perth I'm gunna bring my 4800 patrol with me and if it comes out with only 20kw down on its 185kw at back wheels then get ready cause I'll be showering everybody with gifts.

Robin Miller

P.S heres a link to the only patrol chart I could find in a hurry

Site Link

It shows the TB45 145kw engine delivering 91 kw for a loss of about 35% power

Robin MIller

Yeah no worries come on around and we will run it up for you, the total power loss at max power level will be around 38Kw , but on average over the whole power run will be around 20Kw.

What have you done to it to make 185Kw at the wheels mate,. thats very impressive indeed. Aren't they only rated 180 odd Kw at the engine.

Good luck with it.

Had a look at the dyno run, but couldnt actually find how much power loss it had.

Pity i cant show you mine of my nissan patrol.

Give me your email and ill send it to you,shows power at engine then wheels and also power loss and torque.

Hi Matt

That was meant to read 185kw at engine - mine only has a uni-chip and a few little extra's and only has bit over 200kw at engine and 130 kw at rear wheels unfortunately.

Its 10pm (in Vic) so I'm off for now , see ya

Think you said you haven't been on here for long - my email etc can be seen by clicking on the underlined members Rig & profile link that is next to little picture of my car that comes up with this post.

Robin Miller

Yeah no worries thanks for the chat,email sent.

Ill graba copy of some GU TD 42 ones on monday for you so you know where im coming from .

Trevor,

Thanks, I realise that there would be variances based on drive train setup, tyre size, etc. Thanks for the reply.

That figure seems very low at the wheels,is it ZD30.

What tyres are you running.

Hi Matt,

I am presuming you are talking to me.

The 66kw at the wheels was prior to modification of my 4.2 Turbo GU (Non-intercooled). Now it is running 126kw at the wheels and I am more than impressed considering it has done 315K. It has had the turbine housing modded with bigger turbines, intercooler added, dump pipe, 3" maundrel bent exhaust, boost and fuel increased and I could go on and on. All figures are on the dyno sheet in my rig pics. I have seen one done with the result of a little less HP but heaps more bottom end torque which I also liked but with my crawler gears the bottom end was not so much of an issue for me in offroad situations. Horses for courses.

Hope this answered you question.
Regards, Trevor.

Sorry Matt, Tyres are 265.75 16's

Trevor

Sounds like you done a good job on it mate to get 126Kw's, that should haul it along nicely.

Yeah the crawler gears certainly add to the low down torque capabilities for driving the tyres hard.

based on those percentages my 2.8 Patrol would be giving me a negative result at the wheels! ;) seems like I am going backwards most of the time NOW its proven

Cheers Stefan

Argh nothing wrong with the ol RD28 stefan ,they just need a few RPM to keep them going.

Yeah mate i dont believe in percentages, anyway have you had yours dynoed as they DO respond to a LITTLE more boost.

Matt

Stefan,

Motson's do a chip for the 2.8 and it adds plenty to the driveability of the rig. Member Pezza has one and I reckon his goes great. But his s/charged shorty goes better LOL!!!

Cheers, Trevor.