Welcome to the North American Subaru Impreza Owners Club Sunday April 20, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Normally Aspirated Powertrain

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 12-08-2008, 09:39 PM   #1
watchunglava
Scooby Specialist
 
Member#: 168862
Join Date: Jan 2008
Chapter/Region: NESIC
Location: Portland Maine
Vehicle:
2007 ej253n/a 5speed
Red Sox Nation Lifer

Default calculating horsepower

173 hp is what my motor put at the crank stock .when I look at my stock map the highest g/rev value is like 1.3 I think. Can I equate those?

Like can I say now I'm putting out x g/rev figure out what percent that is higher than the stock max value and then add that percentage to the stock. Hp number

If that makes sence?
* Registered users of the site do not see these ads.
watchunglava is offline   Reply With Quote
Old 12-08-2008, 10:03 PM   #2
Back Road Runner
Scooby Guru
 
Member#: 60082
Join Date: Apr 2004
Chapter/Region: MWSOC
Location: Minnesota
Vehicle:
2004 Forester STI
Silver

Default

You could worth back through the math. Mainly what you need is the correlation between force and time. Any method will need additional information like car weight, gearing, etc. In the end, you have to work your way back down to the physical torque that the tire applies to the road and at what rpm.

One of the easier routes, kinda, is to simply do a series of pulls in the car and record sensor information. RomRaider is a good tool for reading and storing this info. All you really need is rpm. Time comes along with it, and the change in time and change in rpm will give you all that you need. There's another program called Data Log Lab (not free but a trial version that you can play with). You simply open the rpm recorded log file from RomRaider in it, and input the specs for your car (mass, gearing, aerodynamics), and it will generate your torque and horse power numbers with the press of a button. Well there's a couple more setup steps like grabbing the romraider definitions from romraider's sight for DLL. There's also pre made up car data available for a number of Impreza models too.
Back Road Runner is online now   Reply With Quote
Old 12-08-2008, 10:07 PM   #3
watchunglava
Scooby Specialist
 
Member#: 168862
Join Date: Jan 2008
Chapter/Region: NESIC
Location: Portland Maine
Vehicle:
2007 ej253n/a 5speed
Red Sox Nation Lifer

Default

nice i just downloaded the trial version yesterday i havent had the time to check it out sick to hear its got sweet tools on it though.

ill definatly check the hp on their, but if your right and i can equate the g/ rev like i said in the o.p. then im at 198 hp at the crank right now . before ecu tuning
watchunglava is offline   Reply With Quote
Old 12-09-2008, 01:02 PM   #4
yarrgh
Scooby Specialist
 
Member#: 80465
Join Date: Jan 2005
Chapter/Region: RMIC
Location: Aurora, CO
Vehicle:
2001 2.5RS
Black Diamond Pearl

Default

g/rev is more for torque than HP.
yarrgh is offline   Reply With Quote
Old 12-09-2008, 01:05 PM   #5
watchunglava
Scooby Specialist
 
Member#: 168862
Join Date: Jan 2008
Chapter/Region: NESIC
Location: Portland Maine
Vehicle:
2007 ej253n/a 5speed
Red Sox Nation Lifer

Default

right on, well what it came down to was like 18% more g/ rev so whatever that equates to. im souped about 18% just from bolt ons .
watchunglava is offline   Reply With Quote
Old 12-09-2008, 06:48 PM   #6
Counterfit
Scooby Guru
 
Member#: 124254
Join Date: Aug 2006
Chapter/Region: NESIC
Location: Rhode Island
Vehicle:
2006 06 SGM Slowbaru
"The Scoobinator"

Default

Quote:
Originally Posted by yarrgh View Post
g/rev is more for torque than HP.
HP = (torque x RPM)/5252
Torque is in ft-lbs.
Counterfit is online now   Reply With Quote
Old 12-09-2008, 08:20 PM   #7
ProDarwin
Scooby Specialist
 
Member#: 134943
Join Date: Dec 2006
Chapter/Region: MAIC
Location: Oakton
Vehicle:
94 SW2, 95 SW2
9(?) Lemons Car

Default

accel = (overall eff*engine power - road load power)/(effective mass * velocity)

Ignore torque. It has nothing to do with acceleration. If so desired, you can calculate it from rpm.
ProDarwin is offline   Reply With Quote
Old 12-10-2008, 12:17 AM   #8
williaty
Scooby Guru
 
Member#: 71092
Join Date: Sep 2004
Chapter/Region: MWSOC
Location: Delaware County, Ohio
Vehicle:
2005 2.5RS Wagon
Regal Blue Pearl

Default

You're only up 18% if your MAF scaling was perfect before and after the changes. Trust me, I've been down this path before. Hell, the stock tune, stock engine claims to hit a 1.29g/rev peak load. Scale the MAF properly and that drops to 1.13-1.14g/rev for a real number. I know you haven't scaled your MAF in the upper ranges yet because you don't have a wideband. So your engine load numbers are meaningless, sadly.
williaty is offline   Reply With Quote
Old 12-10-2008, 12:20 AM   #9
watchunglava
Scooby Specialist
 
Member#: 168862
Join Date: Jan 2008
Chapter/Region: NESIC
Location: Portland Maine
Vehicle:
2007 ej253n/a 5speed
Red Sox Nation Lifer

Default

true that i was like damn 168 !!!
watchunglava is offline   Reply With Quote
Old 12-10-2008, 12:21 AM   #10
watchunglava
Scooby Specialist
 
Member#: 168862
Join Date: Jan 2008
Chapter/Region: NESIC
Location: Portland Maine
Vehicle:
2007 ej253n/a 5speed
Red Sox Nation Lifer

Default

wide band is coming as soon as i can get the exhaust squared away .
watchunglava is offline   Reply With Quote
Old 12-10-2008, 12:23 AM   #11
williaty
Scooby Guru
 
Member#: 71092
Join Date: Sep 2004
Chapter/Region: MWSOC
Location: Delaware County, Ohio
Vehicle:
2005 2.5RS Wagon
Regal Blue Pearl

Default

Dude, you have got to start learning to put more than one sentence in a post. This whole string-of-1-line-posts-every-minute is going to end up with a mod penalizing you for being a post whore
williaty is offline   Reply With Quote
Old 12-10-2008, 12:28 AM   #12
watchunglava
Scooby Specialist
 
Member#: 168862
Join Date: Jan 2008
Chapter/Region: NESIC
Location: Portland Maine
Vehicle:
2007 ej253n/a 5speed
Red Sox Nation Lifer

Default

wow really? how fascist . and incorect, it should be post slut, im not recieving any money out of the deal.
watchunglava is offline   Reply With Quote
Old 12-10-2008, 11:29 AM   #13
zavier
Scooby Specialist
 
Member#: 141189
Join Date: Feb 2007
Chapter/Region: Tri-State
Location: Philadelphia
Vehicle:
2007 2.5i (NBP)
2014 BRZ (DGM)

Default

Quote:
Originally Posted by watchunglava View Post
wow really? how fascist . and incorect, it should be post slut, im not recieving any money out of the deal.
no but you def went from a newb to a specialist super fast because of the 1 sentence per post
zavier is offline   Reply With Quote
Old 12-10-2008, 12:27 PM   #14
watchunglava
Scooby Specialist
 
Member#: 168862
Join Date: Jan 2008
Chapter/Region: NESIC
Location: Portland Maine
Vehicle:
2007 ej253n/a 5speed
Red Sox Nation Lifer

Default

i dont see what the difference is 1 sentence or 1 paragraph as long as it has substance ,i dont even know how rankings are set up like newbie specialist or whatever . i thought i got promoted becuase i was the man . or because im sleeping with the boss. or because im about to be an ase certified tech ? or because my wang is as big as a babies arm. whatever the case is im definatly no newbie .

not my fault its allmost 2009 and i ussually post on my blackberry, instantly ,. ill just have to post longer post? i dont know whatever dont hate !

this is so off topic anyway. but i guess the op was answered so im going to unsubscribe anway . good discussion everyone.
watchunglava is offline   Reply With Quote
Old 12-10-2008, 01:22 PM   #15
sniper1rfa
Scooby Specialist
 
Member#: 141040
Join Date: Feb 2007
Chapter/Region: NESIC
Location: Designing things
Vehicle:
07 2.5i wagon
UGM

Default

What is g/rev?


from some searching, it appears to be air mass ingested per revolution?
sniper1rfa is offline   Reply With Quote
Old 12-10-2008, 01:26 PM   #16
watchunglava
Scooby Specialist
 
Member#: 168862
Join Date: Jan 2008
Chapter/Region: NESIC
Location: Portland Maine
Vehicle:
2007 ej253n/a 5speed
Red Sox Nation Lifer

Default

the axis value “Load” for ign and fueling tables, given in unit of g/rev, can be obtained from a MAF reading in g/s and the RPM of the engine. example: My engine logged 202 g/s at 5666rpms. so, in order to convert 202 g/s to g/rev, we do this: divide rpms by 60 to turn it into rev (which is actually revolution per second, not revolution per minute, which is pretty much uniformly referred to in the ECU as RPM. I denote this because in conversation “revs” usually refers to RPMs. NOT FOR ECUS IT DOESN’T!) so, 5666/60=94.434 then, we divide g/s by rev so, 202/94.434=2.139 g/rev, which is what the axis is in.
watchunglava is offline   Reply With Quote
Old 12-10-2008, 02:03 PM   #17
sniper1rfa
Scooby Specialist
 
Member#: 141040
Join Date: Feb 2007
Chapter/Region: NESIC
Location: Designing things
Vehicle:
07 2.5i wagon
UGM

Default

Still haven't told me what g/rev is.

I know what it's *for*, i just don't know what the unit means. g could be a unit of acceleration, for example, or perhaps a unit of mass (grams), or if your forget the caps key it could be the gravitation constant or the shear modulus of a material.

Last edited by sniper1rfa; 12-10-2008 at 02:10 PM.
sniper1rfa is offline   Reply With Quote
Old 12-10-2008, 02:09 PM   #18
watchunglava
Scooby Specialist
 
Member#: 168862
Join Date: Jan 2008
Chapter/Region: NESIC
Location: Portland Maine
Vehicle:
2007 ej253n/a 5speed
Red Sox Nation Lifer

Default

it says it right there , its gallons per rev. take rmos divide by 60, youll get rps ( revs per second.) thats your revs. then take your gallons per second and divide by the rev # .

youll get gallons per rev. its measuring how many gallons of air your sucking in per revolution.
watchunglava is offline   Reply With Quote
Old 12-10-2008, 02:12 PM   #19
sniper1rfa
Scooby Specialist
 
Member#: 141040
Join Date: Feb 2007
Chapter/Region: NESIC
Location: Designing things
Vehicle:
07 2.5i wagon
UGM

Default

gallons?

Weird.
sniper1rfa is offline   Reply With Quote
Old 12-10-2008, 02:14 PM   #20
watchunglava
Scooby Specialist
 
Member#: 168862
Join Date: Jan 2008
Chapter/Region: NESIC
Location: Portland Maine
Vehicle:
2007 ej253n/a 5speed
Red Sox Nation Lifer

Default

im pretty sure its gallons. why would it be wierd?
watchunglava is offline   Reply With Quote
Old 12-10-2008, 02:16 PM   #21
sniper1rfa
Scooby Specialist
 
Member#: 141040
Join Date: Feb 2007
Chapter/Region: NESIC
Location: Designing things
Vehicle:
07 2.5i wagon
UGM

Default

because gallons of a gas is dependent on pressure.

I was thinking grams, but that's a pretty small number. Although at atmospheric, maybe it's not.

EDIT: no, that makes sense. One liter at STP is about 1.3 grams

Also, gallons isn't metric.
sniper1rfa is offline   Reply With Quote
Old 12-10-2008, 02:16 PM   #22
watchunglava
Scooby Specialist
 
Member#: 168862
Join Date: Jan 2008
Chapter/Region: NESIC
Location: Portland Maine
Vehicle:
2007 ej253n/a 5speed
Red Sox Nation Lifer

Default

accually it might be grams! my bad lol . im not ase certified yet!!!! lol
watchunglava is offline   Reply With Quote
Old 12-10-2008, 02:18 PM   #23
watchunglava
Scooby Specialist
 
Member#: 168862
Join Date: Jan 2008
Chapter/Region: NESIC
Location: Portland Maine
Vehicle:
2007 ej253n/a 5speed
Red Sox Nation Lifer

Default

in fact its definatly grams im so sorry i have no idea why my brain made me write gallons but whatever im here correcting myself sorry
watchunglava is offline   Reply With Quote
Old 12-10-2008, 02:47 PM   #24
Un0RiGiNaL
Scooby Specialist
 
Member#: 189748
Join Date: Sep 2008
Chapter/Region: MAIC
Default

this is too confusing just take your car to the damn dyno

Last edited by Un0RiGiNaL; 12-10-2008 at 02:59 PM.
Un0RiGiNaL is offline   Reply With Quote
Old 12-10-2008, 06:09 PM   #25
RaceFaceXC
NASIOC Supporter
 
Member#: 165749
Join Date: Dec 2007
Chapter/Region: South East
Location: stupid Florida
Vehicle:
2007 No YELLING
on the bus!

Default

its grams. gallons is a unit of volume not mass. Its also an imperial measurement, so it has more than one correct value (U.S. Gallon is not = to Imperial gallon).
RaceFaceXC is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
APv2 Horsepower Performance Calculator Stames_wiltz Proven Power Bragging 2 10-11-2008 05:26 PM
Accessport Horsepower calculations Shakes AccessPort 0 02-18-2008 09:04 AM
Fun with drives ... Power and Horsepower calculations Brady Off-Topic 6 11-30-2005 03:05 PM
calculated horsepower??? geronimo66 Proven Power Bragging 11 10-01-2003 08:37 PM
Formula for calculating horsepower needed for AutoLogger LiquidForce Engine Management & Tuning 6 06-10-2003 06:58 PM


All times are GMT -4. The time now is 04:09 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.