Dyno loss with 4.10's?
Thread Starter
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Dyno loss with 4.10's?
Did anyone do a before and after dyno to see what the driveline loss is when you add 4.10's?
I hear varying amounts and was wondering if there was a person in the know.
From this thread on LS1tech.com:
http://www.ls1tech.com/forums/showthread.php?t=4552
He listed this as his differences at each rpm. There could be other varyance accounting for some of the change but I wanted to know what other people experienced.
These are the values measured (and I said values "measured" so please spare me the "it isnt actually lost power from the motor"......I know, Capt. Obvious...the engine is still producing the same HP) that he saw lower at each rpm:
rpm HP
2500 2.9
2600 2.5
2700 3.1
2800 2.1
2900 2.8
3000 1.1
3100 3.0
3200 3.0
3300 3.8
3400 2.6
3500 2.0
3600 2.1
3700 4.9
3800 2.9
3900 2.2
4000 1.5
4100 2.3
4200 2.4
4300 4.1
4400 2.5
4500 3.4
4600 5.3
4700 6.3
4800 6.4
4900 6.5
5000 6.7
5100 7.8
5200 8.9
5300 9.1
5400 11.3
5500 12.6
5600 12.8
5700 11.9
5800 12.1
5900 13.5
6000 16.0
6100 16.3
6200 17.7
And please dont post about how dyno's read the power and inertia loss, yada yada. I am asking for people's observed lower readings not a lesson on how dyno's work. Please excuse the abruptness, I dont want this thread deteriorating into a 'how a dyno works' thread. Just looking for some comparative data.
I hear varying amounts and was wondering if there was a person in the know.
From this thread on LS1tech.com:
http://www.ls1tech.com/forums/showthread.php?t=4552
He listed this as his differences at each rpm. There could be other varyance accounting for some of the change but I wanted to know what other people experienced.
These are the values measured (and I said values "measured" so please spare me the "it isnt actually lost power from the motor"......I know, Capt. Obvious...the engine is still producing the same HP) that he saw lower at each rpm:
rpm HP
2500 2.9
2600 2.5
2700 3.1
2800 2.1
2900 2.8
3000 1.1
3100 3.0
3200 3.0
3300 3.8
3400 2.6
3500 2.0
3600 2.1
3700 4.9
3800 2.9
3900 2.2
4000 1.5
4100 2.3
4200 2.4
4300 4.1
4400 2.5
4500 3.4
4600 5.3
4700 6.3
4800 6.4
4900 6.5
5000 6.7
5100 7.8
5200 8.9
5300 9.1
5400 11.3
5500 12.6
5600 12.8
5700 11.9
5800 12.1
5900 13.5
6000 16.0
6100 16.3
6200 17.7
And please dont post about how dyno's read the power and inertia loss, yada yada. I am asking for people's observed lower readings not a lesson on how dyno's work. Please excuse the abruptness, I dont want this thread deteriorating into a 'how a dyno works' thread. Just looking for some comparative data.
Last edited by SpinMonster; Nov 19, 2007 at 08:16 PM.
Drifting
Joined: Jul 2003
Posts: 1,796
Likes: 1
From: Annandale VA
Spin, in the past I have seen other tables posted on LS1TECH.COM showing the measured drivetain losses for several different gears (3.73, 3.90, 4.10), using the 3.42 gear as a baseline. I don't remember the actual percentages, just that it was a fairly linear progression.
Collections Hold
Joined: Aug 2002
Posts: 2,899
Likes: 6
From: Fort Wayne Indiana
Did anyone do a before and after dyno to see what the driveline loss is when you add 4.10's?
I hear varying amounts and was wondering if there was a person in the know.
From this thread on LS1tech.com:
http://www.ls1tech.com/forums/showthread.php?t=4552
He listed this as his differences at each rpm. There could be other varyance accounting for some of the change but I wanted to know what other people experienced.
These are the values measured (and I said values "measured" so please spare me the "it isnt actually lost power from the motor"......I know, Capt. Obvious...the engine is still producing the same HP) that he saw lower at each rpm:
rpm HP
2500 2.9
2600 2.5
2700 3.1
2800 2.1
2900 2.8
3000 1.1
3100 3.0
3200 3.0
3300 3.8
3400 2.6
3500 2.0
3600 2.1
3700 4.9
3800 2.9
3900 2.2
4000 1.5
4100 2.3
4200 2.4
4300 4.1
4400 2.5
4500 3.4
4600 5.3
4700 6.3
4800 6.4
4900 6.5
5000 6.7
5100 7.8
5200 8.9
5300 9.1
5400 11.3
5500 12.6
5600 12.8
5700 11.9
5800 12.1
5900 13.5
6000 16.0
6100 16.3
6200 17.7
And please dont post about how dyno's read the power and inertia loss, yada yada. I am asking for people's observed lower readings not a lesson on how dyno's work.
I hear varying amounts and was wondering if there was a person in the know.
From this thread on LS1tech.com:
http://www.ls1tech.com/forums/showthread.php?t=4552
He listed this as his differences at each rpm. There could be other varyance accounting for some of the change but I wanted to know what other people experienced.
These are the values measured (and I said values "measured" so please spare me the "it isnt actually lost power from the motor"......I know, Capt. Obvious...the engine is still producing the same HP) that he saw lower at each rpm:
rpm HP
2500 2.9
2600 2.5
2700 3.1
2800 2.1
2900 2.8
3000 1.1
3100 3.0
3200 3.0
3300 3.8
3400 2.6
3500 2.0
3600 2.1
3700 4.9
3800 2.9
3900 2.2
4000 1.5
4100 2.3
4200 2.4
4300 4.1
4400 2.5
4500 3.4
4600 5.3
4700 6.3
4800 6.4
4900 6.5
5000 6.7
5100 7.8
5200 8.9
5300 9.1
5400 11.3
5500 12.6
5600 12.8
5700 11.9
5800 12.1
5900 13.5
6000 16.0
6100 16.3
6200 17.7
And please dont post about how dyno's read the power and inertia loss, yada yada. I am asking for people's observed lower readings not a lesson on how dyno's work.
The one thing we do twice a year that most shops probably don't, is that we go down into the dyno pit and thoroughly clean the accumulation of dirt, dust, grease, grime and rubber that add weight to the roller drums.
We inject synthetic grease into all 4 saddle bearings twice a year also, just to keep the stacked-parasitic drag from accruing over time. Any additional weight or parasitic drag that accumulates over time that would otherwise not have been there as delivered new from Dynojet, would skew any power readings as the machine aged, because the system software has the original weight/drag tagged specifically to each drum roller set sold.
Keeping clean maintainance of this machine by keeping those original weight/drag co-efficients as close to as-delivered-when-new specs is paramount to keeping data results accurate over time.
Hope that helps.
Phil
Race Director
Joined: Jan 2000
Posts: 12,375
Likes: 406
From: Florida
I asked OCC to do a before / after with the gear install. The result was a 19 HP loss at the 400RWHP level. I don't have the dyno sheet but I remember this well, because I was intially shocked it was this much.
However, this was on freshly installed gears that were not even broken in, so true losses are probably closer to 10-12 or so, but that is just a guess. This was a real before/after however.
However, this was on freshly installed gears that were not even broken in, so true losses are probably closer to 10-12 or so, but that is just a guess. This was a real before/after however.
Le Mans Master
Joined: Aug 2001
Posts: 8,145
Likes: 1
From: Bradenton FLORIDA
I asked OCC to do a before / after with the gear install. The result was a 19 HP loss at the 400RWHP level. I don't have the dyno sheet but I remember this well, because I was intially shocked it was this much.
However, this was on freshly installed gears that were not even broken in, so true losses are probably closer to 10-12 or so, but that is just a guess. This was a real before/after however.
However, this was on freshly installed gears that were not even broken in, so true losses are probably closer to 10-12 or so, but that is just a guess. This was a real before/after however.
Thread Starter
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
That's a little higher than what we've observed, but for all practicle purposes, that's fairly comparitive to what we've documented here with our Dynoject 248c in-ground chassis dyno here +/- 1-2.
The one thing we do twice a year that most shops probably don't, is that we go down into the dyno pit and thoroughly clean the accumulation of dirt, dust, grease, grime and rubber that add weight to the roller drums.
We inject synthetic grease into all 4 saddle bearings twice a year also, just to keep the stacked-parasitic drag from accruing over time. Any additional weight or parasitic drag that accumulates over time that would otherwise not have been there as delivered new from Dynojet, would skew any power readings as the machine aged, because the system software has the original weight/drag tagged specifically to each drum roller set sold.
Keeping clean maintainance of this machine by keeping those original weight/drag co-efficients as close to as-delivered-when-new specs is paramount to keeping data results accurate over time.
Hope that helps.
Phil
The one thing we do twice a year that most shops probably don't, is that we go down into the dyno pit and thoroughly clean the accumulation of dirt, dust, grease, grime and rubber that add weight to the roller drums.
We inject synthetic grease into all 4 saddle bearings twice a year also, just to keep the stacked-parasitic drag from accruing over time. Any additional weight or parasitic drag that accumulates over time that would otherwise not have been there as delivered new from Dynojet, would skew any power readings as the machine aged, because the system software has the original weight/drag tagged specifically to each drum roller set sold.
Keeping clean maintainance of this machine by keeping those original weight/drag co-efficients as close to as-delivered-when-new specs is paramount to keeping data results accurate over time.
Hope that helps.
Phil
Anyway, I didnt even think about other variances with the dyno but those wouldnt apply to a baseline and after gearing redyno unless the clean-up was in between.
Thread Starter
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
I wasnt looking for what it was from (kinda know that already); just looking for any numbers that people have obseved..... but thanks for input.
I was trying to keep away from having the thread deteriorating into a 'how a dyno works' thread.
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Le Mans Master
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From: Monroe Township New Jersey
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16
St. Jude donor in memory of jpee '14
Melting Slicks
Joined: May 2006
Posts: 2,891
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From: NJ..."the way I saw it, everyone takes a beating sometimes."
I actually recall asking this same question after my CoW 4.10s were installed. I believe you (Spin) estimated an 8-10rwhp loss. Just curious as to where you came up with that number?
Thread Starter
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Dave at Cartek didnt quote as high a loss but I think he was averaging the loss over a wider rpm band. His answer was a little more tech than I was looking for at the time. Peak readings are where the highest loss is read but the 4k-5k range may only be a few HP.
Safety Car
Joined: Aug 2005
Posts: 4,279
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From: North Strand, NMB, SC; Retired x 2 (US Army: 70-90 AD) (US Army: 91-16 DAC); yea, I'm old.
I had my '05 MN6 w/4.10s dyno'd when I got my tune in Gettysburg last month and it pulled 347.95 RWHP and 348.25 RWTQ. I never dyno'd the car before the 4.10s so I don't have anything to compare it against.
Le Mans Master
Joined: Jul 2005
Posts: 5,328
Likes: 405
Not really sure how you got a torque increase or how HP stayed the same...stranger things have happened I guess. Maybe there was something wrong with the 3.55 gears/gear setup that was corrected with the 4.10s.
Instructor
Joined: Dec 2004
Posts: 215
Likes: 0
From: NEW YORK
interesting topic
ive read on the forum that there would be a 10hp to lose on the dyno w the additions of 4.10's. However when i brought this up to the dyno shop owner he said the dyno "adjusts" or somthing to that nature and there wouldnt be any significant hp lose...like maybe 2-3hp. Im wondering...id like to compare to hp #'s to someone w/o gears as a benchmark to see if there is substantial difference????
Drifting
Joined: Jul 2003
Posts: 1,796
Likes: 1
From: Annandale VA
The dyno does adjust for the final gear ratio, but that doesn't mean that it still will not show a loss.
When I dynoed my car, I did one pull in 3rd gear (since that is what gear the car will be in as it goes through the traps), and one in 4th gear. There was about a 10 HP difference, if I remember correctly.
When I dynoed my car, I did one pull in 3rd gear (since that is what gear the car will be in as it goes through the traps), and one in 4th gear. There was about a 10 HP difference, if I remember correctly.
