[walto]

I am in a weired situation never understand...

Here is the story.

last summer, I have my car get dyno'd, with these mods:

:::

integra GSR 94, 150xxxKms
Topfuel SRI/Invidia Catback/
Iridium plugs/Redline motor oil with 100km milege on it
Redline MTL/ and Husky 94 Octane(Bowtrail)

the result was,, avg 148.2 whp 113.1 wtq on a MD250 machine.

after that,,

I made some more mods on my car:
and put my car on a same dyno today.

:::

DCsports 4-2-1 2pc SS header
(used one but condition was good, and installed it properly)
/Mugen Coilover
/Energy Suspension Motor mount inserts
/Gold coated negative Ground wire kit
/Exhaust Ground wire kit(widens actual inner diameter)
/Valve Clearance Adjustment at Acura dealer
/Mobil1 5w30 about 5000kms old
/94 Octane Husky, same gas station as last time

thats it..

but the result was,,, avg 136whp, 103wtq
:thumbsdow

and here is the comparison sheets:



->A/F ratio. it came thinner than before. isn't it means more power?
and still I can't understand what mods made this change.
I didnt do anything about A/F mapping since last time.




->this sheet is 1:1 comparison of the power/torque.
black and white curves are the last summer's.
I lost 10-ish power among entire band ! :dunno:


right after my run, my friend let his Tibby GT w/CAI do the same thing.

He put 145 whp 155 wtq. :nut:

the most confusing part is,,,
He knows and I knows,, that my car is a lot faster on the road.
even today,, it was true.
(We didn't do race. but we have been sharing our ride so often,
and He agrees my car is even more faster(G-force) then last year)

What can be wrong then????

where my 12 horses gone??

welcome any possibilities, any opinion!

help!

ps. someone said maybe the header was too big,
but my header has just 2" collector which is same as stock one.
(I have 2"(header) - 2.25"(cat)-2.36"(catback) exhaust.)

 

[Vi3tB0i7o7]

wat kinda dyno was this run on?

 

[walto]

it was mustang dynamometer MD250.
stock GSR puts around 128 whp on that shop(machine)

 

[rocka589]

Do a compression check on your cylinders, something may have happened in that extra 50k km added?

 

[StatGSR]

temperature and humidity?

 

[walto]

I just ran about 8000kms more since last summer;;hmm
and i was just doing base line runs - about 3 times

and temp/humidity/pressure was checked and given, too.
I saw what he is doing on his computer...

 

[Dominick331]

Run a compression test, or even better leakdown.

 

[walto]

ummm what is the "leakdown" means?
sorry I am not good at English..

 

[gsrious]

dyno calibrations could have been off???

 

[HJLau75]

dyno calibrations could have been off???

yea, if you look at the charts, the graphs look almost identical except for the fact that they are around 12 hp lower like you said.

Could have just been a miscalibration.

 

[Weston]

Are the numbers SAE corrected? If not, we'll need to know the temperature and barometer numbers.

Also, are you sure that your A/C was off? How long have was the car parked before it got on the dyno (ie was it heatsoaked from driving)?

 

[shore96teg]

looks like your torque curce is better now. That header shifted some of the power around so now instead of a bigger peak number you are getting a flatter curve which in turn makes you faster. Atleast thats what I think the right answer is. There are also other variable that you cant control like others have mentioned: atmospheric conditions and calibration. Also....u cant compare your car to ur buddies. Thats comparing apples to oranges. 2 differnet cars have different engines and power to weight ratos. Its probably simply because your car is lighter

I would sweat over it much though. Try doing a tune up and see what happens then.

 

[TheGSRGuy]

Cramming all that exhaust through the stock cat won't help.

 

[walto]

Are the numbers SAE corrected? If not, we'll need to know the temperature and barometer numbers.

Also, are you sure that your A/C was off? How long have was the car parked before it got on the dyno (ie was it heatsoaked from driving)?



Oh,, I didn't think about SAE correction.
but,, still my buddy's Tibby made a lot higher numbers
with almost stock setting.

and I removed A/C last year, and,,
I tested my car right after arrived to the shop.
thx man.

Quote: shore96teg on Feb/06/06 looks like your torque curce is better now. That header shifted some of the power around so now instead of a bigger peak number you are getting a flatter curve which in turn makes you faster. Atleast thats what I think the right answer is. There are also other variable that you cant control like others have mentioned: atmospheric conditions and calibration. Also....u cant compare your car to ur buddies. Thats comparing apples to oranges. 2 differnet cars have different engines and power to weight ratos. Its probably simply because your car is lighter

I would sweat over it much though. Try doing a tune up and see what happens then.

thx! good info...
but I think normally, a "traditonal" 4-2-1 header
can make better low-rpm torque numbers than stock,, isn't it?
but the graph is saying I have lower torque from the start (2000~3000rpm range)

I remember I felt good low-torque right after header work is done..

 

[walto]

I had couple of runs with that Tibby.

Video

I think.. there was something wrong with calibration..
regarding the tibby and GSR runs very close when they are stock (same horse power rating - 170hp)

if the Tibby is making 10 more horse power and 50lbs more torque than my gsr, (like at the dyno numbers)
he should kill me on the rolling test. isn't it?

 

[gsrevo]

Didn't you just say you didn't street race. What did you looks very wreckless. As for the lost of power, go do a compression test and leakdown test like everyone suggested.

 

[ACK94]

dyno numbers dont tell everything. There is weight, gear ratios, tire ratios, rev limits. just cause it made more on the dyno doesnt mean its faster.

 

[TheGSRGuy]

Right. Transient response defines how fast a car is. We actually have a great article on this................

 

[MichaelDelaney]

dynos should mostly be used as measuring devices to determine the amount of change after adding on a new part and tuning the engine to harmonize the package to the new part.

there's a lot of reasons why peak numbers don't jive with the acceleration numbers at the track.

I usually validate the performance gain by looking at the et. barring any tranny mismatch or traction problem issues, presuming that the driver knows how to launch/drive/shift properly.


the dyno is just a tuning measuring tool and nothing more.

the truth is at the track.

you'll know right away at the track whether your car actually makes 200 whp NA regardless of how the dyno operator set the calibration and correction factors.

 

[MichaelDelaney]

right after my run, my friend let his Tibby GT w/CAI do the same thing.

He put 145 whp 155 wtq. :nut:

if Tibby made 155 wtq, he wouldn't be at 145 whp.

you made a mistake there.

either way, a calibration can be off by as much as 8 whp from dyno shop to dyno shop on the same car without any changes to the motor or tuning or wheel/tire overall diameter/tire pressure or gearing.

look, let's put some perspetive on this: it's not like you're going to be breaking into the 13's any time soon.