dunkd

Modified by dunkd at 11:51 PM 5/19/2005

wantboost

iTrader: (2)

mustang dynos are **** IMO. we put a stock dx on one for a few runs to see how well they read.... 1 pull was 50hp and 190ft lbs of torque... the next was 130hp and like 60ft lbs of torque

dunkd

i would say mustangs are that bad... I think it has a lot to do with if they are calibrated correctly. This dyno was giving consistent numbers.

B18CXr

looks to me that the "end speed" was not met at the end of the run

wantboost

iTrader: (2)

how many runs produced this result? just one or all of them/

dunkd

total of about 15 runs, this was the last one after all the tuning was done

blundar

I had to recalibrate the dyno speed several times when tuning Jeff's turbo GSR. It took 3 tries before the dyno and car were hitting the revlimiter at the same RPM.

DO NOT TRUST YOUR DASH TACH!!! DATALOG RPMs!!! Use the datalogged figure for speed calibration of the muffstnag - works 100% better.

beepy

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dunkd &raquo;</TD></TR><TR><TD CLASS="quote">Actually reving out to 9000 RPM not 7300 like the dyno graph says... I dont think the dyno graph stopped at 7300, maybe it was just calibrated wrong on the rpm axis?

By doing the "Horsepower = (Torque * RPM)/5252 RPM" formula at 9000 rpm and about 250 torque the graph should be around 425whp.
</TD></TR></TABLE>

If the RPM numbers are off then the horsepower will also be off. A dynomometer doesn't measure horsepower, it measures torque and calculates horsepower.

Based on your injectors, you should be making about 400 hp with a BSFC of 0.6. Of course if your AFRs are dropping into the 11's your BSFC could climb rapidly, making the shown hp beleiveable.

I am most interested in the diparity in RPM. The one good thing a dyno does all the time is measure RPM. Even if the torque was completely miscalibrated, the RPM should be set in stone. I would trust it before the tach in the car. It seems to me that 9000 RPM is pushing the envelope on even a fully built Honda engine.

Then again, your clutch could have been slipping.

blundar

The local Muffstang dyno has two calibration methods. Most of the time, they use the first one (which is inherently exceedingly poor accuracy):
1. Hold car at a fixed RPM (usually 4000) and measure speed on the rollers. While dynoing car, use measured speed on rollers and the calibrated RPM/speed to figure out RPM.
2. Pickup on plug wire

#2 is inherently accurate. #1 is inherently inaccurate.

legendboy

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by wantboost &raquo;</TD></TR><TR><TD CLASS="quote">mustang dynos are **** IMO</TD></TR></TABLE>

lol

dunkd

the car that was done after mine was a b20vtec 12.5:1, built for all motor but running ~6psi and the mustang dyno said it was only making 208whp... when two months ago it said the same car made 200whp all motor.

both of these cars were tuned by JDogg so the tuning is good...

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by beepy &raquo;</TD></TR><TR><TD CLASS="quote">It seems to me that 9000 RPM is pushing the envelope on even a fully built Honda engine.</TD></TR></TABLE>

it seems to me you dont know of many built honda engines.


Modified by dunkd at 6:16 PM 5/17/2005

BodyKits NW

Jdogg

Glad you got that all tuned up.

B18CXr

If the RPM numbers are off then the horsepower will also be off. A dynomometer doesn't measure horsepower, it measures torque and calculates horsepower


Incorrect.

On a Mustang Dyno there is a Load Cell attached to the PAU that measures the force applied to the rollers NOT the rate at which they are accelerated like on an inertia dyno.

Arturbo

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18CXr &raquo;</TD></TR><TR><TD CLASS="quote">If the RPM numbers are off then the horsepower will also be off. A dynomometer doesn't measure horsepower, it measures torque and calculates horsepower


Incorrect.

On a Mustang Dyno there is a Load Cell attached to the PAU that measures the force applied to the rollers NOT the rate at which they are accelerated like on an inertia dyno.</TD></TR></TABLE>
This is 100% correct. For the most part Mustang dynos are good tools. There are very few people who know how to set them up correctly. Unfortunate I found this out the hard way on a H22..hehe. another thing to check out is horsepower at 50mph..another opps. LOL

art

legendboy

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Arturbo &raquo;</TD></TR><TR><TD CLASS="quote">
For the most part Mustang dynos are good tools. There are very few people who know how to set them up correctly.</TD></TR></TABLE>

Bingo

9341civic

lets meet up and run our cars on a dyno jet just to see the difference?

Arturbo

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 9341civic &raquo;</TD></TR><TR><TD CLASS="quote">lets meet up and run our cars on a dyno jet just to see the difference? </TD></TR></TABLE>
but it doesnt work like that. Mustang dynos will vary ONLY because the calibrations are set up differently from shop to shop. The only reason a dyno jet is "accurate", if you want to call it that, is because it has a given mass which are the rollers. So the rollers all way the same from shop to shop. So take F=ma where the masss (m) is a given and then you can accelerate that mass to get the force, then does some funky math to figure out what your HP is.

Anyways, dont be so hung up on dyno #'s they are stupid.

Arturbo

Oh one more thing, the start speed doesnt start at Zero so it must be fake. Sorry, inside joke I had to let out...

dunkd

the shop said that they use 11.0 as the HP @ 50 for all cars.

B18CXr

the shop said that they use 11.0 as the HP @ 50 for all cars

That really scares me...

PeakBoost

remember it takes a different amount of hp to keep different vehicles @ 50.
there is a good download available on http://www.mustangdyne.com that basically lists every automobile/motorcycles "rated" hp @ 50.
also, most people "guesstimate" the weight of the vehicle when running a power curve test. a weigh station is your best friend, if youre looking for a more accurate number.

i totally agree with art, people have a distorted view of the purpose of a dyno.
you dont use a torque wrench to brag about how many ft. lbs your headstuds are torqued....

also, there are many different ways that ANY dyno #'s can be skewed, its all in the software calibrations.

mustang dynos are great, but it seems that some people give them a bad rap based upon disappointment of hp bragging rights.

peak

edit: by the looks of your dyno sheet and the explanation of the run, i would have to say that the calibrations in the dyno parameters menu are off..
have them shoot me an email, i have a number for a guy that worked at Mustang for over 10years, and now freelances calibrating the Mustang dynos.

david@didrace.com

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18CXr &raquo;</TD></TR><TR><TD CLASS="quote">the shop said that they use 11.0 as the HP @ 50 for all cars

That really scares me...</TD></TR></TABLE>

Agreed. The whole point of Mustang dynamometers is that they take into account weight and wind resistance to calculate a realistic horsepower measurement. With ours we have an Adobe PDF file that has all of the HP @ 50's and weights from like 1960 to the present. The inductive pickup is the best way to calculate rpm's, the speed-based rpm input should be used as a last resort. The shop that did the dyno runs should read their manuals.

trickeng

where you using there inductive rpm pick-up or were they ratioing because the mustang inductive sucks.

if you were not using there inductive, then what you are probably seeing tire slipage. specially if you were on a md250.

smart ratio is a last resort which mustang needs to use as a standard.

ok, here are a couple things i see in this post which i would like to clear up.

1) the weight of the vehicle does not increase or decrease hp. the amount of traction you have which is a direct relationship of the force in which your tires contact the rolls does give you the ability to put more power to the rolls. after strapping the car down, the weight of the vehicle is not much of a factor with traction.

2) on a dynamometer with a load cell and load absorption the HP will always be correct(if the system is calibrated correctly), but it will be reported at the wrong rpm if slipage and/or tire growth occur.
a mustang will report the correct hp which is being transmitted to the rolls.

and if you want to get real HP #'s don't even think of getting them from a dynojet. depending on mph we testing vehicles to we get from 8-17% exagerated numbers from dynojet's.

they are the crayons of the graphic design world.

its pretty sad when you can take an engine off the dyno put tranny, axles, wheels, tires ect.. and get the same numbers from a dynojet.

we just purchased a DYNOmite Dynamometer. they are a fast growing bad *** dynamometer company which offers real engineering grade chassis dynamometers. ????? call them and see if you can find one in your area.

beepy

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Incorrect.

On a Mustang Dyno there is a Load Cell attached to the PAU that measures the force applied to the rollers NOT the rate at which they are accelerated like on an inertia dyno.

</TD></TR></TABLE>

Well, thanks for verifying what I wrote. Dynos measure force, not power. Power must be calculated, and if the RPM is off then the power calculation will be off.

Rtype16

I bet you can take your car to two different dyno jets here. Take your car to R&D dyno in Gardena and than take it to XS Engineering in Huntington Beach and I guarantee you they will be off by about 10 horsepower.

Our Mustang dyno in fact gives the same power numbers as R&D dyno within 1-2 horsepower of each others. R&D being a dynojet and ours being a Mustang. Why you may ask is because ours was specifically calibrated that way because we use both dynos and want our numbers to be consistant with each other within a realm of course. We also do not use the horsepower at 50 function. What I have also found out is if you do the hold the car at 4000 RPM in the gear it is pretty accurate within 100RPM or so compared to the other pickup. As long as you are getting a good RPM number and not just looking at your tach.

The next thing would be in your graphs I can guarantee you were going to 9000 RPM in your car. A couple of things your pickup is loosing signal or you didnt calculate roll speed correctly. The other thing is for the graph you are using there is a setup where you have to input the roll speeds and RPM data you want to graph. If you look at your test in the other graph it should go all the way out to 9000.