Does Lower Final Drive Change Dyno Numbers?

[barefootbonzai]

So yeah, my question is does lower final drive affect power read outs on the dyno. From my understanding FD is kind of a torque multiplier, so does this affect the power reading or not?

For Example.

Same CAR

Run on Dyno with EK4 box - 4.4 FD
vs
Run on Dyno with EK4 box - 4.9 FD

Would the power figures change?

[DynoDave]

So yeah, my question is does lower final drive affect power read outs on the dyno. From my understanding FD is kind of a torque multiplier, so does this affect the power reading or not?

For Example.

Same CAR

Run on Dyno with EK4 box - 4.4 FD
vs
Run on Dyno with EK4 box - 4.9 FD

Would the power figures change?
Torque makes HP so you answered your own question,so it will change the dyno figures by a small margin.
Regards Dyno Dave

[aaronng]

Is it true that certain dyno software require you to enter your FD ratio, otherwise the dyno is plotted as power vs road speed?

[barefootbonzai]

bugger, it's because i got more power than my mates car with similar setup. Must be because of the final drive, *shattered* my engine probably doesn't make as much power as i thought after all.

[STOCK]

how much more did your mate car make compared to yours?

[barefootbonzai]

I made 10kw's more. But it's kinda hard to compare now that i think about it, our setup's ain't really similar at all. Just both running B18CR's, mine AUDM and his J-SPEC but different combination of bolt ones.

[string]

The car with the shorter final drive will most likely give a smaller read-out.

Inertial loads will require more power to accelerate as you shorten the run time. By increasing relative wheel torque (to your friend for example) you will shorten the run time, thus increasing angular acceleration on all rotating parts in the engine, incuring a greater (engine) torque loss.

Conclusion: Dyno figures are a very general measure of power output. Don't take them to heart, since in this case, the car with the lowest 'read-out' will be quicker in most likely, every situation (all else equal).

[barefootbonzai]

The car with the shorter final drive will most likely give a smaller read-out.

Inertial loads will require more power to accelerate as you shorten the run time. By increasing relative wheel torque (to your friend for example) you will shorten the run time, thus increasing angular acceleration on all rotating parts in the engine, incuring a greater (engine) torque loss.

Conclusion: Dyno figures are a very general measure of power output. Don't take them to heart, since in this case, the car with the lowest 'read-out' will be quicker in most likely, every situation (all else equal).

lol, i think you're totally off the mark mate.

[kayot1k]

lol, say no to drugs

[string]

Well you're welcome to prove me wrong, just saying "you're wrong" doesn't really do much for your case however...

And, giving examples of dyno figures is not proof; we all know exactally how static they are.

[barefootbonzai]

If you didn't notice, dyno dave gave me the answer i was looking for. And just so you understand.

My car made MORE Power with the 4.9 Final Drive then my friends car. Our Dyno numbers where run 5 mins after each other on the same dyno. So there's nothing to proof, i just wanted to know if my FD helped me in pulling a bigger figure than he did - and it did. Not sure what you're on about.

[string]

DynoDave's answer in no way helps anyone who has any genuine intrest in knowing exactally how a final drive will relate to outputted power figures.

Were both motors identical in every way? Were both run conditions identical in every way? Were both cars identical in every way? (wheels, drive-train i'd especially like to know). Did you dyno test both cars with the same final drive, and find them producing the exact same power? Until you can answer yes to all of these questions, your point is moot.

There are so many variables in this type of real world dyno testing that you can never rarely compare two outputs, unless you are simply comparing, 'figures'.

Realistically, a final drive will increase wheel torque, i.e. available power, at every car speed. If you measure power output on a non-intertial dyno, it will not change (disregarding inconsistencies), and as a bonus, you'll get higher figures to gawk at!

[WhiteAP1]

A different ratio will increase the amount of times ure drive shaft turns per revolution of the wheels.(obviously)I wouldnt put ure 10 extra kw down to FD. It MAY do something for ure torque figures, but ive never heard of any dyno gains showing due to FD. Perhaps if u put ure car on the dyno before and after the different FD, u would see what Dyno Dave means by a "small margin", practically nothing. Many S2000 owners have changed their FD and apart from a shit load more response and shorter gears, there are no reports of increased dyno figure, then again they're different cars with a different layout. Any advantage ure FD has over ure mates car wouldnt really be evident on the dyno. Thats my 2c in my experience.

[barefootbonzai]

it's no biggy, was just asking if it affected it or not, and if it did it would increase the number not decrease. But string was saying the opposite...

[barefootbonzai]

first post

incuring a greater (engine) torque loss.

2nd post

a final drive will increase wheel torque

WTF is that shit!

[WhiteAP1]

Ure new ratio has shortened every gear. Hence shorter run time, and due to that, a smaller read out/plot.

[string]

A torque on an object causes angular acceleration. The ammount of energy needed to accelerate an object to a given rate of rotation is a constant, regardless of the time taken to get it there. Power is defined as energy over time.

Wheel torque, is defined as the ammount of torque acting at the wheels, i.e. engine torque * gearing ratios. As you increase the final drive multiplier, you increase wheel torque, which is what accelerates the car.

Doing a 1000->8000rpm run for example; two otherwise identical engines, one with a shorter final drive, i.e. higher wheel torque, will run through the RPM range FASTER. In this shorter ammount of time, the same drive-line components must be accelerated at a greater rate. Greater rates of angular acceleration = greater torque required to do so = less engine torque available to spin the rollers of the dyno = less 'read-out'.

Now chances are, that this incured loss may be so small (due to any number of factors specific to the setup) that individual result variations may be greater, so testing for this in the real world is difficult.

Realistically the best test of real, usable power is the drag strip. Dyno numbers are a wank.

[barefootbonzai]

my bad. you're way too technical for this brother. but yeah i think i know what you're saying.

[string]

It's hard to believe theory, when real world results sometimes say the opposite. The problem is there is so many variables in the real world, that it's so difficult to attribute a single cause to a single effect.

The problem I have with dyno figures is that they are similar to, for example, the BMI way of measuring obesity. The general public require a non-technical way to measure a car's performance, and "at the wheels" figures are the common place measure. I think they are a great measure (inertial dyno's anyway) of performance, and you can get pretty close estimates of quater mile times, just from simple rules of thumb. The problem occurs when people start to take the numbers seriously, and compare them as if dyno figures are the word of god.

[fatboyz39]

barefoot, FD does effect dyno number. Don't think there will be a BIG difference, but numbers will change.

[Encor3]

read what string wrote and +1 rep point for you because i learnt alot from it good on ya ;)

[barefootbonzai]

I'll tell you what, String was getting wat too technical to really benifit me. Fatboyz and Dyno Dave have pretty much answered what i wanted to know. Theory doesn't mean much to me, i'm more of a do it sort of guy.

[string]

Well I can't say I havn't tried... I think I need to find a more appreciative audience :P

So i've got these magic beans right...

[barefootbonzai]

lol, Encor3 is your man.

[SPEEDCORE]

So i've got these magic beans right...
LMAO!

[JasonGilholme]

Drag strip is the best way to find out???? But theres even more variables!?!?!?! :O

[Cold Fusion]

+rep to string, good info, helped me :) and even though he had people saying he was wrong he still tried helping them to figure it out eventually.

[barefootbonzai]

lol, dam missed out on what the forum security deleted. I think if string just said that he had the magic beans from the start, it would have made things a lot easier.

[string]

Drag strip is the best way to find out???? But theres even more variables!?!?!?! :O
Doesn't stop teams/individuals from running relatively consistent runs.

[Limbo]

depnds on what your measuring. String your looking at how fast the car is.
Over a drag strip your still going to have more variables than in the workshop on a dyno. That's why people still have different times on a dragstrip. Also comes down to drivers reaction also.

They way Barefoot & his mate compared theirs was if their cars actually made more power. Since they were on the same dyno at the same time that would be the most consistent way of finding it out. They weren't looking to see who was the faster car + faster driver.

btw look at it this way. A dyno run in 3rd will result in a bigger output. 4th will result in a lower output. This has been done and proven alot of times. Now will a shorter final drive give a bigger number? I think you the answer.

[string]

btw look at it this way. A dyno run in 3rd will result in a bigger output. 4th will result in a lower output. This has been done and proven alot of times. Now will a shorter final drive give a bigger number? I think you the answer.
Please give me "alot" of links to these proofs.

Sorry but same dyno same time doesn't mean accurate results. There's plenty of variables on the dyno aswell; especially when the entire car is being changed, not just a different run on the same car.

[fatboyz39]

btw look at it this way. A dyno run in 3rd will result in a bigger output. 4th will result in a lower output. This has been done and proven alot of times. Now will a shorter final drive give a bigger number? I think you the answer.

:thumbsup::thumbsup::thumbsup:

[EK4R]

anyways what was your power figure and your friends barefoot??

[barefootbonzai]

Please give me "alot" of links to these proofs.

Sorry but same dyno same time doesn't mean accurate results. There's plenty of variables on the dyno aswell; especially when the entire car is being changed, not just a different run on the same car.

You seriesly got issues. How the f u c k realistically can you get a better indication of who's making more power than running one after another on the same dyno?

And yes it's more accurate with it's on the same dyno. F U C K E N H E L L.

[barefootbonzai]

anyways what was your power figure and your friends barefoot??

mine - 118kw
mate - 108kw

both untuned
we are getting tunned this week hopefully, i'll post up some results if a certain someone ever gets around to tunning our cars.

[aaronng]

Please give me "alot" of links to these proofs.

Sorry but same dyno same time doesn't mean accurate results. There's plenty of variables on the dyno aswell; especially when the entire car is being changed, not just a different run on the same car.
At least there are less variables on the same dyno when compared to being on the drag strip. Human influence is the largest variable and that is what a dyno tries to minimise.

[string]

I think you all need to brush up on your basic comprehension skills if you think I said that track times are a good comparasin between two cars power outputs. I simply said that the quater mile was the best place to test out a cars usable power (isn't going fast the reason you modify in the first place? A dyno sure isn't that exciting in my opinion).

Barefootbonzai, is there a reason you are getting so hostile? Apart from not being able to understand my simple remarks, you are not adding anything by trying to insult me. Because you are so aggressive, I assume I must be in the wrong here, which means that of course when you took your car off and put his on, you took your front wheels off and he used them right? You also had a wheel alignment on both before, giving you the same alignment settings? You monitored both coolant temps and made sure that before each run they were exactally the same? There are an infinite number of variables I can come up with as to why you could get different results 5 minutes apart on two different cars. It's a completely dumb comparasin unless they are deadset identical.

Finally the truth comes out that both motors are untuned.

Does Lower Final Drive Change Dyno Numbers? - Nowhere near as much as not tuning your car properly.

First I give you an answer which apparently is "totally off the mark", basing part of this on results which are 100% invalid in the first place.

You're turning into the boy who cried wolf, but instead, your the "boy who claims wrong"; you are simply becomming anoying to reply to, as you are more interested in hearing what you want to hear, rather than facts.

This entire thread is completely useless until you get both cars tuned. Then come back with the results and we might be able to have a reasonable discussion on why each car produced what.

fatboyz39: Do you have links to these claims from Limbo, or are you just agreeing with him for fun?

[barefootbonzai]

i swear you got some super issues. what has tunning the car have to do with anything? who the f uck in there right mind would do any of the things that you are suggesting? The numbers i'm producing tuned or un-tuned has nothing to do with my orginal question. man you're a ****en ediot.

[string]

Are you kidding?...



My car made MORE Power with the 4.9 Final Drive then my friends car. Our Dyno numbers where run 5 mins after each other on the same dyno. So there's nothing to proof, i just wanted to know if my FD helped me in pulling a bigger figure than he did - and it did. Not sure what you're on about.

Now, you being un-tuned is incredibly relevent, since your dyno figures were the basis for your claims that I was wrong, which, by being untuned, are absolutely useless.

Who would do the things I said? NOBODY WOULD. Which is EXACTALLY why you cannot compare two cars, no matter how close they follow each other, unless they are deadset identical. Alignment settings, coolant temperatures, and the big one, drive-train inertial moments are all contributing factors to dyno "read out" (and in the case of coolant temperature, actual output, though, this is largely irrelevent).

Please stop with the insults already, you're not hurting my feelings, and you certainly aren't aiding your case. As a general recommendation please go back to school and learn how to understand, and construct an intelligent argument. You'll learn that I don't say things for the hell of it, and you might even realise that things I say are relevent somehow!

If you think every post in this thread pertains to your original question to the dot, then it is you sir, who has issues.

[barefootbonzai]

yeah mate, i'm just a doubt ass mechanic. You're too fuc ken intelligent to explain things to the likes of me. You're right about me not understand what the hell you're on about.

PS. I asked a question on this thread, and everyone has tried to help answer it apart from you. At least they understood the question to begin with.

[aaronng]

Nice quote string. It's much clearer now. And I agree with you that the dyno runs of 2 cars on the same dyno tells NOTHING of whether it was the FD or a better conditioned engine that contributed to that power difference.

But I disagree with all the arguments. Barefootbanzai... Stop the swearing and the insults. Any more arguing and the thread will be locked to cool down.

[barefootbonzai]

yeah that's kool man. but the question was, did the FD contibute to the power difference or not, not who's making more power.

[Professional]

Increasing torque is increasing power at the same time. If i am wrong, pls correct me.

[fatboyz39]

fatboyz39: Do you have links to these claims from Limbo, or are you just agreeing with him for fun?

Yes but i CBF posting it up mate.

[string]

yeah mate, i'm just a doubt ass mechanic. You're too fuc ken intelligent to explain things to the likes of me. You're right about me not understand what the hell you're on about.

PS. I asked a question on this thread, and everyone has tried to help answer it apart from you. At least they understood the question to begin with.
Again with the making a fool out of yourself.

If you care to open you eyes, you'll find my answer to your question on the first page. Infact, out of everyone in this thread, i've probably tried to answer it the most.

How a vauge response (such as the one you dismissed mine in favour of) answers your question entirely is perfectly clear now. You are actually mentally handicapped. My condolences.


Increasing torque is increasing power at the same time. If i am wrong, pls correct me.
Correct, however remember power is a factor of torque and rpm. Gearing and final drive does not simply boost torque. You trade off rotation rate (wheel rpm) for an increase in torque. With a shorter final drive you might increase wheel torque by 10%, but relative to standard, you are spinning at a 10% slower rate, so over-all you have a net power gain of zero.

[aaronng]

yeah that's kool man. but the question was, did the FD contibute to the power difference or not, not who's making more power.
You can't tell from running both cars on the same dyno. The only way is to run your car on the dyno with the stock FD and then again after installing the shorter FD.

[barefootbonzai]

You can't tell from running both cars on the same dyno. The only way is to run your car on the dyno with the stock FD and then again after installing the shorter FD.

and that would be not practical. if i could do that then i wouldn't ask the question now would i.

-edited swearing- you've got PM. - aaronng

[Limbo]

String just a question, how many cars have your modded?

how many cars have you run on a dyno or taken to the track?

[riceball]

String - Seriously, the man got his answer and just wanted to stick to that simple conclusion. FD increases power but only by a small margin ( as stated by Dyno Dave ). If he wanted to know how power and gears worked he would of asked. IMO, you are the one that has caused all this mayhem in here... some people have shorter temperaments then others, so why push it even further. Now everyone is angry. Respect that and move on is what i believe.

Btw - FD ftw

[aaronng]

A dyno measures your power not only by measuring torque and engine RPM. It also uses the speed of the dyno rollers in order to get a power reading. Otherwise, a change in FD from 3.0 to 5.0 would give you a huge jump in power readings.

[froggy]

STRING i never thought i'd say this but you are 1 weird F....I love everyone in this world and I never say any1 is a weird F but mate you are a true F,, SERIOUSLY WHAT IS WRONG WITH YOU????? CAN I BORROW SOME OF YOUR WHAACKY TABACKY??? its doing wonders for you!!!!! man but seriously i love you but just F LIFE AND F EVERYHTING AND F KEEP UR F COMMENTS F TO YOURSELF... my civic has a dyno reading of 90HP thats lower then everyones elses does that mean i'm gonna go faster.. CUS F i HOPE SO. you would be my HERO!!!!!!!

ANYWAYS lets all touch each other in the sweet spots we can have a big ol or-gy yummy yummy.. touch me now string touch me.. ooo yeh baby touch me

PEACE OUT BROTHERS AND SISTERS

[aaronng]

froggy... :thumbdwn:
Because of you, this thread has to be closed.