Bogus Torque Figures?

[xsv_32]

Hi all, was recently reading through the post about the 1002hp GTT recently tuned and found out that there seem to be two different ways of measuring torque but yet both read in Nm?!?

I was browsing trademe and found this auction where a guy here in CHCH New Zealand builds RB30s and sells the motors online. Now, the auction states he can build anything from mild set-ups with factory pistons etc or something more aggressive like his s15 running mid 700hp. BUT the tourque for such motors outs over 2000Nm! Previous auctions of his show dyno sheets of these figures but after reading the above mentioned thread, im curious as to how these readings differ to those of the monster 1000hp GTT?

Anyone info would be great - just want to expand my brain a little more lol.

Here is the link if you want to check it out for yourselves.

http://www.trademe.co.nz/Trade-Me-Motors/C...n-183775348.htm

[grem]

torque, in my opinion should always be measured at the flywheel.

gears and differentials will amplify torque. most people use 4th gear on a dyno because it is the closest to a 1:1 ratio supposedly, and will give a more accurate torque figure, using first gear would give a torque figure maybe 5 times higher because of the lower ratio.

ive heard a few people say they have 2000nm of torque and they laugh at ford f6's which make 550nm. in truth the ford would probably chop them. its all about where you take your reading with torque.

hope that answers your question.

[R31Nismoid]

Its tractive effort - not torque.

[FineLine]

Its tractive effort - not torque.

What he said. divide your tractive effort figure by your diff ratio and you will get near enough to your torque figure.

[grem]

im no engineer but would tractive effort just be a fancy word for torque measured at the wheels?

[Bumblebee]

no it has a different meaning altogether

tractive efforts can go fairly high, with most gen 3's n 4's sittin the 6000n+

where most sr20s will sit @ around half that...

[Beer Baron]

usually dyno dynamics dynos measure 'torque' in N. netwons. not Nm, newton metres which is what car manufacteres give. it's a differet measure and there is no 100% accurate simple conversion. the number only means something when compared to other cars measured in the same way. people often mistakenly think they can compare the dyno reading with other qutotes torue figures. sadly that's not the case...

[Guilt-Toy]

MPH at the track. Thats the only way to compare.

[Adriano]

Dyno dynamics measure(or display) either "TORQUE" in Nm, or tractive effort in N. I can see where they get tractive effort from, as thats the force loaded against the roller, but the torque figure would require you to know the rolling diameter of the drive wheels, and all the transmission gear ratio's for the given test gear. Basically the tractive effort should be able to tell you how fast a car will accelerate at a given gear/speed if you know the weight, and take drag into account.

[Kranker]

yeh if your tractive effort is greater than tractive resistance at a given road speed, then you have acceleration

comparing dyno results has always been a bit of a pissing contest. its a brilliant tuning tool, but you just keep hearing about fudged results. if someone dynos their car in 3rd and every1 else is doing it in 4th, then the first dude's tractive effort will be greater. doesnt necessarily mean hes making more torque at the engine. but this often isnt explained by the dyno operator

guilt-toy has is right, if you want to compare the power of two cars power (actually power/weight), trap speed is the way to go. if its good enought for the worlds fastest drag cars, then its good enough for u and me.

[STATUS]

the only dyno to give accurate torque readings is a dynapack or an engine dyno. the readings from a roller dyno are good enough to compare between each other but have no real world comparisons. whereas we can come quite close the 383 chev we had in yesterday was within 3% of the engine dyno.

[Guilt-Toy]

so your saying your dyno reads engine horse power then ?

the only dyno to give accurate torque readings is a dynapack or an engine dyno. the readings from a roller dyno are good enough to compare between each other but have no real world comparisons. whereas we can come quite close the 383 chev we had in yesterday was within 3% of the engine dyno.

[Swiper the Fox]

so your saying your dyno reads engine horse power then ?

from another thread...

i am mearly saying if anything my dyno reads conservative compared to older versions and nearly bang on to late model DD's.

Everyone was comparing this result against regular dyno results obtained from a Mainline unit and/or a DD unit in shootout mode. Ive spent time with Andre Simon at his Wellington business (he tunes the Heat Treatments GTR) and he assures me they read more like engine horsepower not wheel horsepower.

so what is it...almost the same as a DD or is it an engine dyno...you cannot have a foot in each camp...you seem to have proved the statement i made above correct

Edited October 29, 2008 by DiRTgarage

[dano4127]

here we go again...

[STATUS]

so your saying your dyno reads engine horse power then ?

sorry i should have expanded more, based on his previous engine results on the engine dyno then on the dynapack we worked out the driveline loss (auto), with the new engine the "calculated" difference between the dynapack and the engine dyno was 3%.

ps DIRTGARAGE you need to pipe down considering your latest engine life spans.... news travels fast...

Edited November 2, 2008 by URAS

[Guilt-Toy]

so your dyno reads within 3% of a engine dyno?

[blitzxtr]

ps DIRTGARAGE you need to pipe down considering your latest engine life spans.... news travels fast...

What engine life spans & who's?

[Swiper the Fox]

What engine life spans & who's?

ol' Trent is getting a little shirty cause he's been caught out yet again...hehe

this must be what you are on about as ive only lost one engine...as you can see it was purely a mistake by Dave...he got all excited but forgot to follow clear instructions that were given to him. Its old news Trent...sorry to disappoint you.

When the engine was gettng transported we needed to close the engine up so no foreign objects got in. Which meant all the covers,harmonic balancer,timing belt ect ect were getting put on.

Paul did say that the timing belt was only put on for transporting the engine and would have to be redone when we had the engine in the car.

So in all the excitment we forgot. And after the final tune we went for a drive to see its potential.

With a tight timing belt each time i got on and off the gas the shaft holding one of the pulleys would flex back and forth, so after about 6 hrs the shaft failed due to metal fatigue, the timing belt let go,and as a result the engine went out of timing.

The pistons smashed the valve train causing bent and snapped valves,also punched a nice hole in the face of the head.

Now before everyone jumps to conclusions Paul is not responsible for this engine failure as he did tell me that i would need to re-tension the timing belt.

When i called Paul after this had happend he was very sympethetic and agreed to help me out as much as i needed to get this thing back to the way it was.

I have since bought new bearings,new valves, new valve guides,new valve seats and will be ordering new pistons as soon as i get my rego and insurance sorted.

So hopefully next month ill be driving back up to see Paul with my engine to get the ball roling again.

Yes as you could imagine i was quite guttered after this had happend, but after about a day or two i was fine.

"Shit Happens" as they say and its nothing that cant be fixed. But rest assured she will be back with a vengence very soon!

Thanks to all of you for the kind words(sound like a death in the family) lol

But especially to Paul for agreeing to go further than needed to, to help a guy out.

Edited November 3, 2008 by DiRTgarage

[STATUS]

so your dyno reads within 3% of a engine dyno?

(bear with the V8 comparisons as these guys tend to spend more money and get their built engines engine dynoed, jetted then chassis dynoed, i have yet to have a customer with a RB, JZ or SR engine dyno thier setup)

yes we had a 3% differrence (over) our local superflow, i will see how reliable our conversion is once we get a 393 cleveland i just built back from them and fitted in a car hopefully the big stall (5900) does not make this too difficult, the chev only had a baby 3500 rpm stall (this car had a 112hp loss through the T400 and 10bolt) i expect the clevo to have a little more (9") but the boxes sap about the same, the trimatic is a bit better (but generally weaker) The last 351 clevo manual toploader lost 78hp from engine dyno to the dynapack.

on some crazy high stalls there is a big differrence between engine dyno and chassis dyno due to converter slippage... the dyno can read 150-odd horses down on your average 500hp v8.

ps nice cover up dirtgarage.

Edited November 3, 2008 by URAS