Welcome to the North American Subaru Impreza Owners Club Friday May 27, 2016
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Archives > NASIOC Archives > Technical Forum Archive

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. 
 
 
Thread Tools Display Modes
Old 09-15-2000, 10:00 AM   #1
RidinLow
Scooby Guru
 
Member#: 329
Join Date: Sep 1999
Chapter/Region: Tri-State
Location: NJ
Vehicle:
1995 325i
Arctic Gray

Question power gain from cams

Hi,

It's not my intention to knock Trey or anybody at Cobb Tuning or anything, but I'm just wondering how realistic the measured dyno gains are in real world situations.

The reason why I'm asking is because in the Honda world, DC Sports headers are "dyno-proven" to make 14 hp (people that get them say more like 3-4), AEM Cold-Air Intake is "dyno-proven" to make 12 hp (more like 5), etc...

Where's this discrepancy coming from? I really want the Cobb Cams because of the $399 deal, but not if they'll only give me 5 hp. I'd rather put the $ into my turbo fund.

Thanks,
~G
* Registered users of the site do not see these ads.
RidinLow is offline  
Sponsored Links
* Registered users of the site do not see these ads.
Old 09-15-2000, 10:07 AM   #2
Matt Monson
Scooby Guru
 
Member#: 832
Join Date: Jan 2000
Chapter/Region: RMIC
Location: Teh Ghetto Garage, CO
Vehicle:
99 2.5RS, '85 911
'73 914 and 2012 BRZ

Post

It is hard to compare dyno numbers for intake and exhaust parts versus engine internals. In general, intake and exhaust parts historically show inflated dyno performance because the hood if open with a fan blowing. In the real world, the temps tend to be much hotter with less airflow, so street numbers drop.
Cams are not subjected to as large a variance in temps because they are inside the engine already. The numbers may still be a little inflated because the air temps in the test are still cooler than real world, but probably does not have as large an impact on the engines internal temps.
Matt Monson is offline  
Old 09-15-2000, 10:10 AM   #3
8Complex

Moderator
 
Member#: 922
Join Date: Feb 2000
Chapter/Region: MWSOC
Location: Schaumburg, IL
Vehicle:
16 WRX (white)
04 FXT (red)

Post

I think that the real difference is that butt-dynos aren't very accurate and that sound really screws with it's perception. Maybe G-Tech'ing it would be able to tell for sure, but I don't trust G-Tech too much. *shrug*
8Complex is offline  
Old 09-15-2000, 10:13 AM   #4
RidinLow
Scooby Guru
 
Member#: 329
Join Date: Sep 1999
Chapter/Region: Tri-State
Location: NJ
Vehicle:
1995 325i
Arctic Gray

Post

But usually, the butt-dyno is more prone to perceive a larger gain than there actually is, not the other way around... it's really bad if you perceive no change in power!
RidinLow is offline  
Old 09-15-2000, 11:01 AM   #5
Willis
Scooby Newbie
 
Member#: 424
Join Date: Oct 1999
Location: Lowell, MA
Vehicle:
2005 WRX STI
Blue

Post

Hey Ridinlow,

When those magazine ads claim 14hp, they're not telling the whole story. Just claiming an increase in 14hp tells you absolutely nothing. For an extreme example, their before and after max hp #'s could be 500hp and 514hp, respectively, and its not false advertising. But that increase is only 2.8%.

In Trey's case, you are given a before and after max hp of 128.3 and 142.2, respectively. That's an increase of 10.8%. There is no deception there - just straight, col' smack ya in the face hp.
Willis is offline  
Old 09-15-2000, 04:55 PM   #6
nizz
Scooby Specialist
 
Member#: 188
Join Date: Aug 1999
Location: New York
Vehicle:
2004 Forester XT
24k gold on white

Post

Also, you have to note that "dyno proven" results usually do not state clearly how the car was setup on the first run compared to the second run. They also do not state whether the gain is at the peak of the curve. What good is another 14hp at idle when the car loses 8hp at peak? Cobb Tuning has provided us with detailed specs of the conditions of the runs unlike some Honda tuners.

nizz
nizz is offline  
Old 09-15-2000, 04:58 PM   #7
nizz
Scooby Specialist
 
Member#: 188
Join Date: Aug 1999
Location: New York
Vehicle:
2004 Forester XT
24k gold on white

Post

Also, you have to note that "dyno proven" results usually do not state clearly how the car was setup on the first run compared to the second run. They also do not state whether the gain is at the peak of the curve. What good is another 14hp at idle when the car loses 8hp at peak? Cobb Tuning has provided us with detailed specs of the conditions of the runs unlike some Honda tuners.

nizz
nizz is offline  
Old 09-15-2000, 08:13 PM   #8
Wreckleford
Scooby Newbie
 
Member#: 887
Join Date: Feb 2000
Post

Another thing to think about is that you only read about the "Dyno proven 14Hp" in the manufacturers ads. When the magazines and independent people do dyno test the parts, they only find the 3-4 hp you were talking about. It is not as if all dyno testing shows 14hp but when you test for power in another way (using an accelerometer for example) you only get 3- 4 hp.

What you need to really do is get your gulible buddy to buy the cams and make him do a before and after test, wether it be on the Dyno, using a Vericom or at the drag strip.

[This message has been edited by Wreckleford (edited September 15, 2000).]
Wreckleford is offline  
Old 09-15-2000, 09:00 PM   #9
SCRAPPYDO
Scooby Guru
 
Member#: 873
Join Date: Feb 2000
Chapter/Region: TXIC
Location: Just outside of Houston TX
Vehicle:
2014 GLK/allroad
Datsun 71 240Z & 68 2000

Post




well here are the dyno charts of the COBB cams. there is not peak spike anywhere. Its a smoother gradual gain that leads to more area under the torque curve. This should pull harder right from idle.

Cams are for real people. They are not like an intake that has 20 differernt variables that can make a difference. Cams change the behavior or attitude of the engine. It in effect makes it practically a whole new engine with respect for performance. I belive these cams are for real, and you are looking at the first Mr. Gullible right here.

SCRAPPYDO
SCRAPPYDO is offline  
Old 09-15-2000, 09:35 PM   #10
ColinL
Scooby Guru
 
Member#: 114
Join Date: Jul 1999
Chapter/Region: MWSOC
Location: Wichita, KS and Whoring, OT
Vehicle:
'03 Evo, Rice White
'01 Erion CBR 929

Post

Get in line buddy.

Got the Haynes Legacy manual tonight and checked out the service procedures for the 2.2L SOHC, since no similarly cheap resource covers the 2.5L SOHC (yet?).

It doesn't look bad at all.
ColinL is offline  
Old 09-16-2000, 08:02 PM   #11
SpeedKills
Scooby Newbie
 
Member#: 2341
Join Date: Sep 2000
Location: Winter Park, FL
Post

Where can I get cams for $399?!?!
SpeedKills is offline  
Old 09-17-2000, 09:05 AM   #12
ColinL
Scooby Guru
 
Member#: 114
Join Date: Jul 1999
Chapter/Region: MWSOC
Location: Wichita, KS and Whoring, OT
Vehicle:
'03 Evo, Rice White
'01 Erion CBR 929

Post

ColinL is offline  
 

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
Anybody have any power gains from an Invidia G200? Moshpit552 Factory 2.5L Turbo Powertrain (EJ Series Factory 2.5L Turbo) 3 12-14-2005 02:23 AM
Expected power gain from Protuning with my setup? txl146 Engine Management & Tuning 2 08-17-2005 06:11 PM
Power gained from a FMIC faiwu Factory 2.5L Turbo Powertrain (EJ Series Factory 2.5L Turbo) 2 02-27-2005 08:35 AM
How much power gain from head P&P work? Davenow Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo) 6 05-19-2004 12:43 PM
Power gains from a stock car w/ECU reflash? Mauricio Normally Aspirated Powertrain 22 10-27-2003 01:44 PM

All times are GMT -4. The time now is 09:51 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2016, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2016 Axivo Inc.
Copyright ©1999 - 2016, North American Subaru Impreza Owners Club, Inc.