NZ 300ZX Owners Club Forum

[ZILVER]

Usually the variable of the transmission gear ratio gets omitted from dyno runs (likely unknown) but it should be a factor of the final calculation.
However 2079x.7(5th gear approximation) =1455Nm hmmm its still nuclear.
(750~1000HP ?)

[NozMonkeys]

I just bolt stuff on to make mine go faster

[TT_ZX]

From what I have seen, a dyno run is done in 4th, ie 1:1. Therefore the torque at the wheels would equal to flywheel torque multiplied by the diff ratio minus friction loss. I cant see much point in comparing torque readings at the wheels. You could do a dyno run in 1st gear and get a really high number to brag to ya Honda driving mates .
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When in doubt................C4!

[Zeeman]

Yeah thats right, 4th gear pulls so its 1:1.

Most of the time you will see dyno guys then factor in the diff ratio or something crazy stuff like that which is completely retarded. Wheel hp is whatever is getting put down on the rollers, why some people then add correction factors is beyond me.

2079 / 3.69 = 563.

For some reason the ratio in the dyno sheet says 3.75, 2079/3.75 = 554

300kw, 563 (or 554) nm torque. Does that sound more realistic? I certainly think so.

While I am not saying that this is exactly what has happened here, if the dyno is done properly I bet you its going to be something around that mark judging from past experience.
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it is surprising how well things bounce at 50kph

[ZILVER]

Ive never dabbeled with a dyno run myself - was just theorising earlier, that some variable unique to the model of car can radically sque results.

[Zeeman]

lets just say i have seen 1 or 2 pulls around the 300kw+ mark and they don't have 2k nm
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it is surprising how well things bounce at 50kph

[Mungyz]

OK here are a couple of points being overlooked here:

Rolling road dynos NEVER show true torque @ the wheels or at the engine, they can't plain & simple there are too many variables for any man, machine or calculation to state the actual figure.

Torque is an equation of force times distance, if the distance (IE diameter of the tyre) is changing constantly you can not do the maths plain & simple. Ever watched the tyres while a high HP car was on a rolling road? ever watched them squirm around & deform = bye bye any chance of a decent reading.

All rolling road dynos are built with a large amount of guess factor in the calculations, most guess wrong & then adjust the final reading to something that makes more sense = useless, only good for comparing changes to the same car on that same dyno.

Hub dynos are obviously bolted to the hubs & therefore can show the torque being delivered to the hubs, drive train losses are still an unknown but can be estimated more accurately with decent hub dynos.

Correction factor is used to eliminate the variables of air temp, humidity, atmospheric pressure etc. all these things affect performance so there are calculations made to obtain a reading as if these variables were at a known constant (sea level @ standard atmospheric pressure & standard humidity)
The same correction calculations should be used no mater what dyno you use.

Take a look at my hub dyno print out (in the garage) : 337Kw & 2597Nm

The bulk of modified turbo engines make more HP by increasing boost & therefore torque, it is not all that common for them to produce more revs to make the extra power. (Maybe 10% go to the trouble of increasing RPM)

Back on topic:
I have no idea why you would spend so much on a car then sell it

Current market value for that car is ~ $12000 if you are lucky rebuilt engines are worth nothing when the car is up for sale unless you have hard evidence it has been done right & will last with no issues - that seems to be lacking a little here but maybe it's the way it comes across via the advert.
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Always blow on the pie
Safer communities together.

[Zeeman]

[Mungyz]

No toes were harmed in the above posts
I agree with what you have said re easy to spot bung readings, it's well known how to check them & (not having a go at you zeeman) on a lot of overseas forums it is thrown around waaaay to much in efforts to disprove power figures.

This is where the rolling road thing comes in to a shady area, a lot of the print outs will show torque at the rollers but NOT the torque figure used to make the power calculation (because they know the torque at the rollers is wrong for the actual calculation).

When's our next dyno day?
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Always blow on the pie
Safer communities together.

[Zeeman]

After my car gets fixed would be good!
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it is surprising how well things bounce at 50kph

[NozMonkeys]

Was I right about your car Zeeman? Or did I mislead you.