Lies, Damm Lies, and Flywheel Dyno numbers

[GMan]

Hey all,

I have been a member of this great forum for a little over a year now, and while this forum is filled with Massively good information and helpful members, I am amazed that some of the myths/"old wives tales" about cars are still prevalent, I'd like to address some of them here.

 

A little background on myself, I earned my degree in Automotive Engineering at Three rivers College in New London Connecticut in the US. I then decided to do something completely different and join the US Army for 10 years.

I have now come full circle and am back into cars with a passion I lacked as a teenager.

 

Ok enough about me.

 

The First thing I'd like to address is Flywheel horsepower, which is basically a marketing ploy used by the auto industry to present a larger number to the public, what you make at the wheels is the only thing that matters but since we usually only have the MFR claimed power to go off of we use correction factors to try to match it up,

Fair enough

The ONLY way to truly measure parasitic loss would be to mount an engine to an engine dyno with the FULL exhaust system mounted to it, then mount that very same engine and accessories in a chassis and dyno that. Then you would have the parasitic loss for that engine with that transmission with those wheels on that Dyno. This can give you the basis for an educated guess on similar setups. And that is what everything else is, An Educated guess, an uneducated guess, or an outright lie. A dyno drag/coast down test is the second best option but is only as accurate to about 5% of the dyno's accuracy.

 

I can and will get into specifics of why the percentage system is inherently flawed but time has proven that it is the least flawed system available without actually dynoing every engine and every car separately (Discussion Later)

 

Ok what started this Rant/post was when someone suggested after my dyno run that a RWD automatic transmission was only losing 20% to the wheels. This wasn't done maliciously, just out the misinformation found on the web, That's why I didn't take issue with the poster and hit my books for some proofs.

 

Attached are the baseline Dyno sheets for several manual transmission cars New and Old from Import Tuner. I like them because they don't screw around with Engine power and go Straight to the wheels.

 

2005 Nissan 350z 6sp Manual

300 fwhp - 232.7 rwhp = a 22.4% Loss

2008 Infinity G37 6sp Manual

330 fwhp - 273.0 rwhp = a 17.2% Loss Damm Good

2010 Hyundai Genisis 2.0T 6sp Manual

210 fwhp - 161.5 rwhp = a 23.1% Loss

2003 Honda S2000 6sp Manual

240 fwhp - 198.0 rwhp = 17.5% Loss

2005 Acura RSX type S 6sp Manual

210 fwhp - 167.1 rwhp = 20.4% Loss

1991 SR20det swaped 240sx with intake, 5sp manual

205 fwhp - 152.6 rwhp= 25.6% Loss

So at this point at 20% loss Toyota has produced the most efficient 16yr old torque converter automatic transmission in history, far more efficient than most 6speed manuals!

 

In reality at school we found most conventional automatic transmissions lose between 27% and 34% to the wheels.

So I stand by my 30% so my 181 rwhp converts to 258.5 fwhp or a 38.5 hp gain at less than 1000 US dollars.The GE does respond well to basic bolt ons, so just wait and see when my new detcans and digital timing gun (and some hot weather) get here.

 

 

Any other Myths you guys want me to dispel, just ask.(my dyno sheet does the whole "n/a's need back pressure myth") the reason they lose power with big exhausts is because of exhaust gas velocity and scavenging.

 

Let the discussions begin:Popcorn:

Edited March 22, 2010 by GMan (see edit history)

[Dave17]

 

Myth Busted!

[scotty71]

And your point is??

 

You have just spoiled the fun for everyone:(

 

Next you will be telling me that WWE is fixed:eyebrows:

 

scotty

[garethr]

2005 Nissan 350z 6sp Manual

300 fwhp - 232.7 rwhp = 22.4% Loss

 

2008 Infinity G37 6sp Manual

330 fwhp - 273.0 rwhp = 17.2% Loss

 

Are the flywheel figures from an engine dyno or the manufacturer's claimed figures?

 

Seems odd that two similar cars from the same manufacturer would have such different losses.

[Paul]

Would one of these help ?

 

http://cgi.ebay.co.uk/TURBO-EXHAUST-SOUND-WHISTLER-MG-MGTF-TF-MGF-ZR-ZS-ZTT-T_W0QQitemZ350127680427QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item51853c6bab

[Wez]

Hang on a minute, so you went through all that to try and convince us and possibly yourself that a few bolt on mods to your NA have given you a nice increase in HP

[GMan]

Hang on a minute, so you went through all that to try and convince us and possibly yourself that a few bolt on mods to your NA have given you a nice increase in HP

 

yes and no

 

I really get annoyed at the General scorn N/A supras get on this and other forums and when people use bad information to justify their comments.

 

and I love a good argument and underdogs.

 

and

 

Can't tell you how great a feeling it is to go to a meet here get harassed by some fanboi's in a golf with a big wing and stupid size tires for not having a "Real Car" only an N/A manual, then soundly whopping that ass on the next stretch of unlimited autobahn.

 

and last but not least

being able to drink a cup of coffee whist driving my daily driver to work in stop and go traffic. (was a bit of a chore in my skyline I assure you) and pay 2/3rds the insurance rate as a TT

[GMan]

Would one of these help ?

 

http://cgi.ebay.co.uk/TURBO-EXHAUST-SOUND-WHISTLER-MG-MGTF-TF-MGF-ZR-ZS-ZTT-T_W0QQitemZ350127680427QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item51853c6bab

 

exactly the kind of person this thread is aimed at proves my point: there is always some snob wanting to feel better about himself

[Scott]

You are dreaming bud.

 

J-Spec TT has 280hp at the fly as standard. I guarantee you if you ran a stock J-Spec it would have not much less than that at the wheels due to the Japanese lying about the figures to begin with.

 

You have just stated for accuracy the figures need to be taken from a chassis dyno and in the same breath you have said you can use the manufacturers claimed HP figures... which is it?

 

If you want to prove everyone wrong, get your car on a chassis dyno, I'm 99% sure it would be you with the egg on your face bud. In fact, even better. Take all the mods off your car, dyno it completely stock, see what you get at the wheels and then compare with what you got with the mods. My guess is 10rwhp tops.

[GMan]

You are dreaming bud.

 

J-Spec TT has 280hp at the fly as standard. I guarantee you if you ran a stock J-Spec it would have not much less than that at the wheels due to the Japanese lying about the figures to begin with.

 

You have just stated for accuracy the figures need to be taken from a chassis dyno and in the same breath you have said you can use the manufacturers claimed HP figures... which is it?

 

If you want to prove everyone wrong, get your car on a chassis dyno, I'm 99% sure it would be you with the egg on your face bud. In fact, even better. Take all the mods off your car, dyno it completely stock, see what you get at the wheels and then compare with what you got with the mods. My guess is 10rwhp tops.

 

I'm fairly sure the 181wheel hp was on a chassis dyno, or what do you call that thing i strapped the whole car to with some rollers under the rear wheels?(SEE DYNO SHEET!)

 

I also thought I spent the most of the first post explaining why I am converting the wheel hp to a figure more closely approximating the engine output,

 

So in short I found the most conservative dyno I could, and put down 181 whp with 0% correction for air temp/humidity/elevation on a car that by all of the work I just did above to prove mfr claims are bs (like you just pointed out) should be putting out 145 rwhp using the same formula

So which part am I dreaming?

 

Did Toyota seriously understate the power of the N/A?

is the N/A auto box the most efficient automatic ever made?

(by your calculation it is 22% or so, better than most of the manual cars up there)

 

or fill in your answer

 

Looking for a frying pan for the egg

Edited March 22, 2010 by GMan (see edit history)

[Scott]

Hub dyno or a wheel dyno.

 

Regardless, they will all throw out different figures. The only thing you can do is compare. That is the reason the guys on here us SRR as a base. A lot of people have had their cars dyno'd there and it is taken as the base measure. The guys could then take their cars to thor and get higher readings (as tends to be the case).

 

Basically my point is that you are shouting about the inaccuracies and the lies spouted throughout the web/forums etc yet you choose to pick and choose figures that suit yourself.

 

FWIW I'm sure I saw someone with a stock N/A getting around the 180rwhp mark. You are dreaming if you think a filter and an exhaust will get you 40hp.

[Paul]

'Snob' !?

[Scott]

'Snob' !?

 

Typo?

 

 

 

 

 

 

I'm only joking Gman (sincerely), I just couldn't resist

[Paul]

Typo?

 

LOL, b*stard

[Wez]

J-Spec TT has 280hp at the fly as standard. I guarantee you if you ran a stock J-Spec it would have not much less than that at the wheels due to the Japanese lying about the figures to begin with.

 

Interesting Scott, very interesting indeed

 

Can you show some evidence to back this up

[Scott]

Interesting Scott, very interesting indeed

 

Can you show some evidence to back this up

 

Proof of the Japanese being liars or that J-Spec TT's have approx 320hp?

 

No

 

However, if the Jspec only has 280hp then it is a million miles ahead of the UK spec given that it can produce 53% more power by upping the boost to 1.2bar. UK spec can only manage a 31% increase at similar boost levels (1.3bar iirc).

[GMan]

Hub dyno or a wheel dyno.

 

Regardless, they will all throw out different figures. The only thing you can do is compare. That is the reason the guys on here us SRR as a base. A lot of people have had their cars dyno'd there and it is taken as the base measure. The guys could then take their cars to thor and get higher readings (as tends to be the case).

 

Basically my point is that you are shouting about the inaccuracies and the lies spouted throughout the web/forums etc yet you choose to pick and choose figures that suit yourself.

 

FWIW I'm sure I saw someone with a stock N/A getting around the 180rwhp mark. You are dreaming if you think a filter and an exhaust will get you 40hp.

 

Like I said I found the lowest reading dyno I know of, Wheel dyno not hub so even lower, I will eventualy visit one of the much higher reading dyno dynamics hub dynos, in shootout mode, that people use to make themselves feel better for a laugh.

Only an Intake & Exhaust?

How about equal length manifold?

Every ignition component replaced

Lowest impedance & grounded.(checked with multimeter) sparkplug wires i could find (nology hot wires) double decat

I made 10 more rwkw in the mid range just by pulling out the apexi Active tail silencer. which opens up at wot anyways.

 

So now again to the manufacturer figures, I said they were bs in the first place but we are comparing apples to apples now.

 

You didn't Answer my question, there are only a few choices here. Ok so a bone stock NA makes 1 less RWHP than me,

Was it an AUTO or manual? Dyno sheet? Corections?

 

So Toyota claimed the NA put out 220 bhp stock , you say they all make make 180 to the wheels

so your options are

 

1)They lied to make the turbo look better it really makes between 240 and 260 stock? They did lie about the power of the j spec turbo to stay under the 280hp limit,

 

2)I proved above that Every car tested(manuals no less) read 17 to 26% less at the wheels than their claimed figures. that only gets worse with age. so if 180whhp =220 fwhp toyota built the most efficient automatic transmission ever known to man even 16years later at 20%

 

I would bet that a TT loses more than 20% with a Getrag,

 

3)every dyno in the world overeads N/A supras by 40hp or so?

 

so which one is it?

Edited March 22, 2010 by GMan (see edit history)

[GMan]

Proof of the Japanese being liars or that J-Spec TT's have approx 320hp?

 

No

 

However, if the Jspec only has 280hp then it is a million miles ahead of the UK spec given that it can produce 53% more power by upping the boost to 1.2bar. UK spec can only manage a 31% increase at similar boost levels (1.3bar iirc).

 

I'm loving the discussion by the way. good man

[Scott]

Not sure bud but lets say it was a 5spd manual.

 

20% losses would probably be about right. Now, lets say that all the mods you have done give you 20hp (I'm pretty sure someone proved that the manifold gave 15hp but the peak torque dropped). That would mean your transmission losses were approx 25% which I would say was about right.

 

What I don't agree with is you pulling 35% figures out to give yourself 260fwhp.

 

 

As a comparison I had my AWD Evo RR'd at 300fwhp (I can't remember the exact figure as I don't pay much attention to fly, thats pub talk) and 218rwhp. The accepted loss on an AWD system was approx 30% which is just about bang on give or take a couple of %. Now, I know Auto's aren't great but there is no way I would accept that they create higher losses than an AWD system.

Edited March 22, 2010 by Scott (see edit history)

[GMan]

Not sure bud but lets say it was a 5spd manual.

 

20% losses would probably be about right. Now, lets say that all the mods you have done give you 20hp (I'm pretty sure someone proved that the manifold gave 15hp but the peak torque dropped). That would mean your transmission losses were approx 25% which I would say was about right.

 

What I don't agree with is you pulling 35% figures out to give yourself 260fwhp.

 

 

As a comparison I had my AWD Evo RR'd at 300fwhp (I can't remember the exact figure as I don't pay much attention to fly, thats pub talk) and 218rwhp. The accepted loss on an AWD system was approx 30% which is just about bang on give or take a couple of %. Now, I know Auto's aren't great but there is no way I would accept that they create higher losses than an AWD system.

 

I'm using 30% not 35%

In school 1995 we tested an auto 1994 Mustang drive line, we hooked an electric generator to the input shaft of the transmission (engine was out) the car was strapped to something similar to a dyno but the roller is powered electrically (it is a very precise measurement device used to test drivelines, loss was 27% on a car 1 year old

[Scott]

I think there would be a massive difference between what the Japanese produced drive train wise in 1994 and what America produced.

 

Just look at the axle in a GT500

[GMan]

As a comparison I had my AWD Evo RR'd at 300fwhp (I can't remember the exact figure as I don't pay much attention to fly, thats pub talk) and 218rwhp. The accepted loss on an AWD system was approx 30% which is just about bang on give or take a couple of %. Now, I know Auto's aren't great but there is no way I would accept that they create higher losses than an AWD system.

 

They can and do

look at mpg figures for Subaru fwd auto vs awd manuals, with the same engine

the manuals still win, when you use a fluid as a power transportation medium you create lots of waste heat.

Ever wonder why automatics need so many coolers to be reliable as the fluid heats it becomes less dense and will create even more heat when you try to compress it again. it is a vicious cycle which is why automatics are so sensitive to heat. 25% would be good for a cold automatic.

[GMan]

I think there would be a massive difference between what the Japanese produced drive train wise in 1994 and what America produced.

 

Just look at the axle in a GT500

 

good point:p

 

But Most US built automatics will handle much more than a tt automatic ever can.

We American Love Automatics!

Drag Supras often switch to TH400's who's design is 30 years old

Edited March 22, 2010 by GMan (see edit history)

[GMan]

so you Believe the the ge is underrated by the same percentage as a tt gte

[Scott]

You need to take into account a lot more than the transmission losses for a fuel economy comparison.

 

Ok, lets brainstorm for a second here.

 

I have proven figures based on 30% for my Evo. I dare say a lot of people have similar figures for Imprezas etc.

 

What you are telling me is that they all lie, every dyno in the world lies and that AWD cars actually have more RWHP than any dyno in the UK will show? I can guarantee you that the transmission losses for an AWD car are calculated as higher than RWD Auto's.

 

If what you say is true then everyone in the UK who has had their AWD car dyno'd actually has more RWHP than they have been told.

 

I'm sorry mate, you are obviously very clued up in what we are talking about here but I just can't justify your reasoning in order to backup your claim of having 260hp.

 

How about this.... if your theory is true, why do stock Auto's and stock Manuals have similar FWHP on the dynos? Surely if the auto calculation was so far out, they wouldn't even be close? Guys do well to pull 210 off these old cars, which I think is a fantastic achievement.

 

You have to understand where I am coming from. Your train of thought has 1 goal, to back up your claim of 260hp. Me following your train of thought only finds holes given the comparisons over the years of being on here.