PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

Untapped horsepower?

Thread Tools
 
Search this Thread
 
Old Jun 7, 2015 | 03:06 AM
  #1  
RikkiTorment's Avatar
Thread Starter
TECH Enthusiast
 
Joined: Mar 2009
Posts: 522
Likes: 0
From: West Chester, PA
Default Untapped horsepower?

Hey guys, I had a question... If you are running 4.10's in your car, but the ECU is still set to recognize 3.42's, is there any untapped potential horsepower due to the difference in revs or is it going to be a minimal difference?

Also, can anyone calculate the difference in power digit-wise?

P.S- Also burned out my wiring harness to my knock sensors, which was not throwing a code at the time of tune.

Last edited by RikkiTorment; Jul 10, 2015 at 01:27 PM.
Reply
Old Jun 7, 2015 | 04:22 PM
  #2  
RikkiTorment's Avatar
Thread Starter
TECH Enthusiast
 
Joined: Mar 2009
Posts: 522
Likes: 0
From: West Chester, PA
Default

lol nobody?
Reply
Old Jun 7, 2015 | 04:28 PM
  #3  
JakeFusion's Avatar
Super Hulk Smash
20 Year Member
Liked
Loved
Community Favorite
iTrader: (7)
 
Joined: Aug 2004
Posts: 11,258
Likes: 146
From: Pace, FL
Default

Your speedo is going to be off. The gear swap is probably eating 10-15rwhp.

Is that enough to throw off your tune? Not really.
Reply
Old Jun 7, 2015 | 04:57 PM
  #4  
RikkiTorment's Avatar
Thread Starter
TECH Enthusiast
 
Joined: Mar 2009
Posts: 522
Likes: 0
From: West Chester, PA
Default

Originally Posted by JakeFusion
Your speedo is going to be off. The gear swap is probably eating 10-15rwhp.

Is that enough to throw off your tune? Not really.
So with the 4.10's in the car and the ECU being tuned for 3.42's, 410/405 is more closely to about 425/410.

As for the knock sensor harness being burned out while the car was tuned (not throwing a code at the time), is it possible that my timing is going to be advanced now that it was replaced?
Reply
Old Jun 7, 2015 | 11:47 PM
  #5  
Blown06's Avatar
8 Second Truck Club
iTrader: (32)
 
Joined: Apr 2006
Posts: 5,181
Likes: 8
Default

Why would a gear change change the output of the motor?
Reply
Old Jun 8, 2015 | 12:08 AM
  #6  
RikkiTorment's Avatar
Thread Starter
TECH Enthusiast
 
Joined: Mar 2009
Posts: 522
Likes: 0
From: West Chester, PA
Default

Originally Posted by Blown06
Why would a gear change change the output of the motor?
Not necessarily the output of it, but rather the accuracy of the dyno results.
Reply
Old Jun 8, 2015 | 07:45 AM
  #7  
redtan's Avatar
TECH Junkie
iTrader: (5)
 
Joined: May 2008
Posts: 3,764
Likes: 17
From: Belmont, MA
Default

So with the 4.10's in the car and the ECU being tuned for 3.42's, 410/405 is more closely to about 425/410.
I wouldn't really think of it that way. With that mindset you can say the car with 2.73 gears you car would put down 500rwhp...

Gearing has nothing to do with the tune or any of its parameters, so the only thing that is problematic with you not updating the tune is going to be the speedometer being off.
Reply
Old Jun 8, 2015 | 09:10 AM
  #8  
JakeFusion's Avatar
Super Hulk Smash
20 Year Member
Liked
Loved
Community Favorite
iTrader: (7)
 
Joined: Aug 2004
Posts: 11,258
Likes: 146
From: Pace, FL
Default

Originally Posted by Blown06
Why would a gear change change the output of the motor?
Lower gears have more parasitic loss. It doesn't change the output of the motor - but shows up on the dyno. However, it doesn't show up at the track as a lower gear will help move the car with more mechanical advantage.
Reply
LS1 Tech Stories

The Best V8 Stories One Small Block at Time

story-0

Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

 Verdad Gallardo
story-1

6 Common C5 Corvette Failures and What's Involved In Repairing Them

 Pouria Savadkouei
story-2

Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

 Verdad Gallardo
story-3

Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

 Pouria Savadkouei
story-4

Top 10 Most Powerful Chevy Trucks Ever Made!

 
story-5

Hennessey's New Supercharged Silverado ZR2 Has 700 HP

 Verdad Gallardo
story-6

Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

 Verdad Gallardo
story-7

Awesome K5 Blazer Restomod Comes With C7 Corvette Power

 Verdad Gallardo
story-8

10 Camaros You Should Never Buy

 
story-9

10 LS Engine Myths That Refuse to Die

 Verdad Gallardo
Old Jun 8, 2015 | 10:29 AM
  #9  
2xLS1's Avatar
TECH Senior Member
20 Year Member
Photogenic
Photoriffic
Shutterbug
iTrader: (25)
 
Joined: Nov 2001
Posts: 5,649
Likes: 9
From: Warr Acres, OK
Default

I think what the OP is asking is if you do a pull with the tune unchanged for the new gears then do a pull with the tune changed for the new gears will it show up in different dyno numbers for the 2 pulls. And for that the answer is no.
Reply
Old Jun 8, 2015 | 05:16 PM
  #10  
RikkiTorment's Avatar
Thread Starter
TECH Enthusiast
 
Joined: Mar 2009
Posts: 522
Likes: 0
From: West Chester, PA
Default

Originally Posted by 2xLS1
I think what the OP is asking is if you do a pull with the tune unchanged for the new gears then do a pull with the tune changed for the new gears will it show up in different dyno numbers for the 2 pulls. And for that the answer is no.
A dyno algorithm determines horsepower based on speed and acceleration rate, if my speedo is off due to a difference in gear ratio versus what my ECU is programmed, how are my numbers going to be accurate?
Reply
Old Jun 8, 2015 | 09:18 PM
  #11  
2xLS1's Avatar
TECH Senior Member
20 Year Member
Photogenic
Photoriffic
Shutterbug
iTrader: (25)
 
Joined: Nov 2001
Posts: 5,649
Likes: 9
From: Warr Acres, OK
Default

The dyno doesn't care what your speedometer is showing. It has it's own speedometer on the rollers. And if it is a dynojet it is far from accurate anyways. Real dynos measure actual torque and calculate HP based on the math formula tq x rpm/5252 = hp. Dynojets measure rate of acceleration of 2 fixed weight rollers, and backwards calculate HP and tq with a fudge factor.
Reply
Old Jun 9, 2015 | 09:03 PM
  #12  
murphinator's Avatar
12 Second Club
iTrader: (2)
 
Joined: Sep 2009
Posts: 1,650
Likes: 1
From: southern Maine
Default

a gear change without a tune will have more issues than just the speedo off , all your mph thresholds for up and downshifts will be off - its worth getting it tuned.
Reply
Old Jun 9, 2015 | 10:16 PM
  #13  
2xLS1's Avatar
TECH Senior Member
20 Year Member
Photogenic
Photoriffic
Shutterbug
iTrader: (25)
 
Joined: Nov 2001
Posts: 5,649
Likes: 9
From: Warr Acres, OK
Default

Look at his sig. It is a Manual trans.
Reply
Old Jun 10, 2015 | 07:50 AM
  #14  
murphinator's Avatar
12 Second Club
iTrader: (2)
 
Joined: Sep 2009
Posts: 1,650
Likes: 1
From: southern Maine
Default

Originally Posted by 2xLS1
Look at his sig. It is a Manual trans.
guess I missed that lol
Reply




All times are GMT -5. The time now is 04:54 PM.

story-0
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-1
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-2
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-3
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-4
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-5
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-6
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE
story-7
Awesome K5 Blazer Restomod Comes With C7 Corvette Power

Slideshow: A heavily reworked 1972 K5 Blazer swaps its off-road roots for a low-slung street-focused build with modern V8 power.

By Verdad Gallardo | 2026-03-09 18:08:45


VIEW MORE
story-8
10 Camaros You Should Never Buy

Slideshow: There are thousands of used Camaros on the market but we think you should avoid these 10

By | 2026-02-17 17:09:30


VIEW MORE
story-9
10 LS Engine Myths That Refuse to Die

Slideshows: Which one of these myths do you believe?

By Verdad Gallardo | 2026-01-28 18:10:11


VIEW MORE