AirBusPilot

They count for alot, but only in relation to showing changes on your car and setup. Other than that, they don't mean much and that isn't a slam against you. This subject has been beaten to death since dyno's and the internet met.

ChopShop1

You are deff right, no offense taken. I jsut find it funny how quickly people jumped on me to post the details and the sheet cause it wasn't possible but once I posted, not one of the posters who doubted the numbers has responded. Thanks to all who have wished well,

No offence taken, I love my car, and it is a deiiferent animal now, so much fun to drive.

PowerLabs

From one enthusiast to another: Nonsense,
This is a Mustang Dyno:



There are heavy steel rollers, supported by bearings. Those rollers attach to an eddy current absorber unit which consists of a large metal disk spinning past a row of electromagnets; the electromagnets induce a current on the metal disk, which opposes the magnetic field, creating electromagnetic drag.
Your car's weight, drag and frontal area are inputted into the dyno and a ramp rate (how many MPH it picks up every second) is set; the absorber unit then applies a varying load to the wheels. By looking at how quickly your back wheels accelerated the rollers, and how much load was absorbed, the dyno estimates how much power your car made. It then runs a correction factor based on the temperature and humidity recorded at the shop to estimate how much power it would have made under SAE-Standartised conditions.

Now, here we go...

Your tires deflect as they roll over the dyno; as they deflect, they absorb power. That depends on tire size, width, rubber hardness, temperature, how much pressure they are inflated to, and how hard the car is strapped down to the dyno.

The bearings on the dyno rollers absorb some power too. That depends on their age, condition, and how well oiled they are.

The power absorption at any given current input level for the eddy current absorber depends LARGELY on its temperature, and its temperature changes as the run progresses because the absorber is converting absorbed power into heat.

The temperature and humidity recorded by the correction box may not be the temperature and humidity of the air your engine is taking in

The mass and other specs inputted into the program will change the appearent power measured

The ramp rate inputted will change how much power is measured; the faster you perform the test, the less power the car appears to have.
So, how do you know that the correction factors apply to the exact same resistance your tires, that absorption unit, and that particular set of rollers ACTUALLY have?

I'll bet you the cost of a dyno run that I can take your car, pump the tires up to 50PSI, strap it down lightly and put some bogus numbers on the dyno computer and lay you down a 480WHP run EASY.

I also bet if you bring it to another Mustang Dyno of the same brand it will not read the same.

I'll make a 3rd bet that if you dyno it tomorrow it won't read the same, and that's even if all the inputs remain the same.
And, again, realize that if you read + - 15WHP (which is what everyone here is disputing), you are talking about a 3% error in a machine that has no aspirations of being lab grade equipment...

So, no, it is not "as accurate as one can get", and even if it was, that doesn't really mean much.

For more information, I encourage anyone excited about dyno racing to pick up a copy of:



16 dollars very well spent... You'll even learn HOW you can play with your car and the dyno to get even more "record breaking" numbers

ChopShop1

Wow powerlabs...you are a real know it all wise a$$. I have followed many of your posts and there are usually very intelligent and informative, but you seem to feel the need to always show how you know more than the next guy. Whatever, quite frankly, I love the forum in general and most of the members are cool, but comments and attitudes like this are stupid. Thanks for showing everyone how intelligent you are because you are an enginere and know more than me. My numbers are what they are and the car feels fast now. Have a great day

PowerLabs

I am sorry if you feel like me not agreeing with you is insulting, but unless you have some better information than what I posted, I'll stick with what my education, and that of the people who wrote that book, says... You have a nice day too.

turboffr

I can't say that I've lost power because I have no comparison. I do agree though that the tune was not optimized. Once I go back I will report the new numbers. The Predator is not the best tuning device, but if you know how to use it does the job just fine for bolt ons. Once I get a cam I'll ditch the Predator. The main reason I got it was to familiarize myself with the car and shut off the o2 codes for the LT headers.

Most people just install the performance tune and drive the car expecting great results. This doesn't work., you still need to tweak the tune. My fuel trims were way off and PE fuel also needed some work as well to lean it out.

ChopShop1

I understand the point about the equip. but it was the sarcastic tone of the post with the laughing faces that pissed me off. Anyway, people were not disputing that the machine was not spot on, they were saying that my car with my mods could not have posted those numbers, corrected, and not smoothed way out. It did, I rest my case.

No offense man, Thats jsut how I feel, and I don't take kindly to being talked to like a child

k0bun

LSCHLEM

JAKE, Thanks for posting your numbers. 409 RWHP is yours to keep as
a matter of record for a LS2 with the full compliment of BOLTONS. There
have been many CF members in years past who said I got 400 RWHP with
only LT's & a tune. When asked, when scrutinized, when the NA sayers said nobody has produced those kind of numbers with those mods only
the OP just faded away and never returned. You produced a sheet of documentary evidence that your car has in fact produced the 409 RWHP
on that day with a specific DYNO
It doesnt matter what dyno you used and we all had our fill of dyno arguments and somehow concluded that the dynojet is the presumptive standard on this forum. OH I spoke too soon CARTEK now has a dyno
that factors in what DIFF RATIO you have and simply factors it in with
other parameters. We add 10 RWHP on our dynojets and others as it is
determined that the 4.10 gears skews the dyno reading by 10 RWHP.
Some believed that and some dont.
I would like to see you put a PORTED FAST on your car and return to the same mustang dyno and blow some minds. The NA sayers would never take the bet that those numbers then would be lower on a dynojet or other.
Enjoy your new animal because soon you will want a little more and
contact the MOD BUG and here we go again. Leon

Boomer111

Dyno's are nothing more than a tuners aid, period. Comparing is useless. Also useless is not knowing the base numbers. If you want big numbers just think flywheel horsepower.

ChopShop1

Thanks Leon, I appreciate it!! I will most likely get a "spin fast" and a very mild cam in the next month or so. I am trying to decide whether I want the new wheels and widebody first or the blower. I am thinking of waiting for the blower, as we all know, no matter how fast you make it, after some time it will just seem normal. The longer I wait ( within reason of course) the longer I will stay happy with the car

Seriously though, thank you for your support on this, I appreciate that you responded after I posted the sheet. I don't get why those people that even bother, at some point someone will find out that they are full of it, and telling people that their cars made more power than it did wont make it feel faster. Take care

Jake

PowerLabs

Actually I can think of at least 2 other people who have claimed well over 400WHP from a bolt-ons LS2 on this forum within the last 2 years.

And any load bearing dyno will show no difference in readings due to different final drive ratios. Cartek has always had a Dynojet, which is non load bearing, unless that changed since 2 weeks ago.

LSCHLEM

Yes it was in the past 2 weeks or so that CARTEK got a new DYNO. I did not know that and added 10 RWHP/TQ to my recent numbers W CAM only on dynojet. I know its different getting a reading with it factored in as opposed to saying I GOT 443 but its really 453 because of the DYNOJET skewing the numbers by 10. SPIN has a thread out there about this subject and he always emphasizes the calibration loss when we are talking about DYNO numbers thru 4.10 Gears.
I know you have a nasty machine there and I probably would be afraid to drive it.
As far as the Op is concerned I give him the benefit of the doubt as he learns there will be many questions especially from others who did not achieve those power levels he did with the same or more boltons than he did.

ChopShop1

Once again, thank you Leon, I appreciate your post. I still have much to learn about the new corvettes and fule injection. I am used to building old carb muscle cars with my dad, when you could stand IN the engine bay to work on the motor. This forum has been a great tool and I really enjoy most of the coversations.

Last night I took the car out again, the temp was about 60 and crisp. The car seemed to run noticably stronger.(it seems to love that slightly cool weather.) I look forward to the cam and fast and posting those numbers real soon.

Wass

ECS uses a Dynapack chassis dynamometer that bolts directly to the wheel hubs. It costs something like $75,000. ECS will factor in differential gear ratios.

FloydSummerOf68

I'll say again...get the car to a track one night and see what kind of mph you can pull in the 1/4 to get a TRUE testiment of your power.

ChopShop1

I look forward to it. I did a "test run" last night, on a closed road of course, and the car boogies. Can't wait to get it out there, gotta get the wide body and get rid of the runflats though.

LSCHLEM

OH I may have been wrong about CARTEK having a new DYNO. It may indeed have been ECS that got the new DYNO. We were talking about
the ability to program or input the DIFF ratio used and not have to add it on as a calibration error.

Wass

Yes, it came up in a thread I posted last week where Doug (ECS) chimed in and mentioned that he factors in gear ratios.

glass slipper

PowerLabs wasn't trying to be a know it all although he can be a wise azz at times like the rest of us. However, what he said is correct and he was just trying to show you how the Mustang dyno isn't the most accurate as you had claimed. It's a common misconception about the Mustang dyno because the operator inputs the weight and aero characteristics of the car and it's claimed to make it more accurate. However, they are just fudge factors that soon become tools for manipulating numbers...think about it, the car is sitting stationary on the dyno rollers, what does the weight and aero of the car have to do with the engine producing HP? Absolutely nothing! And that was the point PowerLabs was trying to make. Without a baseline run before your mods, these numbers are really useless as far as most members here are concerned. A chassis dyno is a tool to tune an engine and track HP improvements from mods and nothing else. Don't forget that HP is one of the least understood entities in the universe...just ask AirBusPilot.

It's hard for "tone of voice" to carry over the internet but you really shouldn't get all worked up about this discussion as it's just a number that really doesn't mean anything. I've noticed many posts where you've enthusiastically claimed how happy you are with your mods and for me, that's the only thing that matters. The fact that you've made a lot of good "friends" on the forum is just icing on the cake. Enjoy your new found HP!