[Z06] Disappointing dyno today
Thread Starter
Le Mans Master
Joined: Oct 2000
Posts: 5,474
Likes: 80
From: raleigh, nc
Disappointing dyno today
Today, I took my car to get dynoed since i never had it done since installing a DTE 4.10 differential and a borla catback.
Before i did those mods, i made 442rwhp and 403 torque on the dyno at Cartek
I about lost my mind when my best pull today was 421.2 rwhp and 380 torque. I didn't know where my torque was going to be, but i expect my hp numbers were going to be over 430rwhp.
The only logical thing i can think of losing the extra 9-12rwhp is that it was like 30 degrees cooler when it was dynoed at Cartek
Before i did those mods, i made 442rwhp and 403 torque on the dyno at Cartek
I about lost my mind when my best pull today was 421.2 rwhp and 380 torque. I didn't know where my torque was going to be, but i expect my hp numbers were going to be over 430rwhp.
The only logical thing i can think of losing the extra 9-12rwhp is that it was like 30 degrees cooler when it was dynoed at Cartek
Drifting
Joined: Apr 2000
Posts: 1,391
Likes: 4
From: St Louis MO
Re: Disappointing dyno today (Y2K253SS)
That's ghey!
I didn't realize that changing the axle ratio would change the recorded output/power. Then again, I don't know a lot about that kinda stuff. You sure do have a nice car, though! :cheers:
I didn't realize that changing the axle ratio would change the recorded output/power. Then again, I don't know a lot about that kinda stuff. You sure do have a nice car, though! :cheers:
Drifting
Joined: May 2000
Posts: 1,695
Likes: 0
From: Long Island NY
Re: Disappointing dyno today (Y2K253SS)
The only logical thing i can think of losing the extra 9-12rwhp is that it was like 30 degrees cooler when it was dynoed at Cartek
Le Mans Master
Joined: Nov 2001
Posts: 6,984
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From: Central Coast CA
Re: Disappointing dyno today (Jim Hall)
So you're saying by changing the rear end gearing that upped the rwhp? Correct me if I'm wrong but, I don't think that mod will raise the rwhp higher than the rated 405hp.
Le Mans Master
Joined: Jul 2002
Posts: 6,147
Likes: 32
From: Dallas TX
Re: Disappointing dyno today (Shylor)
So you're saying by changing the rear end gearing that upped the rwhp? Correct me if I'm wrong but, I don't think that mod will raise the rwhp higher than the rated 405hp.
Going from 4.10 gears will make you lose hp on the dyno.
Thats why he went from 442 to 421rwhp. However, I dont think it cause a loss of 21hp. Part of the loss might have been the warmer weather.
Thats why he went from
Race Director
Joined: Oct 2003
Posts: 17,821
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From: Clayton, NC
Re: Disappointing dyno today (Shylor)
So you're saying by changing the rear end gearing that upped the rwhp? Correct me if I'm wrong but, I don't think that mod will raise the rwhp higher than the rated 405hp.
I understand losing hp due the gears but didn't think it would be that much.
I also thought the correction factor was supposed to make up for the difference in weather/elevation...etc. on dyno's. Did they use the same exact factors as the dyno at Cartek and is it the same exact type of dyno? :confused:
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Race Director
Joined: Jun 2003
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From: Baraboo WI
Senior Member
Cruise-In V Veteran
Re: Disappointing dyno today (W!ngnut)
I would say the for one you are on a different dyno and you could be lower anyway and for 2 the temp difference will hurt youre HP.
Le Mans Master
Joined: Nov 2003
Posts: 8,308
Likes: 157
From: NJ
Re: Disappointing dyno today (W!ngnut)
Its the gears. I lost 19 hp with the gear swap and others have lost close to 20 as well. Dont sweat the dyno numbers. Your car will run alot faster now provided you get traction to the tires. Trust me, get some et streets and hit the track.
Thread Starter
Le Mans Master
Joined: Oct 2000
Posts: 5,474
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From: raleigh, nc
Re: Disappointing dyno today (Shylor)
Want to thank everybody for the support and good feedback from some of the members. I have been wondering why was going on with the car because it didn't have any Knock retard or anything. It was constantly added timing after 6 grand which is how the tune is setup for.
Air/Fuel ration was a little lean, but within tolerable limits. Most be the damn oxygenated fuel :D
Air/Fuel ration was a little lean, but within tolerable limits. Most be the damn oxygenated fuel :D
Race Director
Joined: Oct 2003
Posts: 17,821
Likes: 0
From: Clayton, NC
Re: Disappointing dyno today (Y2K253SS)
Want to thank everybody for the support and good feedback from some of the members. I have been wondering why was going on with the car because it didn't have any Knock retard or anything. It was constantly added timing after 6 grand which is how the tune is setup for.
Air/Fuel ration was a little lean, but within tolerable limits. Most be the damn oxygenated fuel :D
Air/Fuel ration was a little lean, but within tolerable limits. Most be the damn oxygenated fuel :D
Melting Slicks
Joined: Sep 2003
Posts: 2,458
Likes: 105
From: Northville Michigan
Re: Disappointing dyno today (robz)
Rob,
Thanks for the reply.
I have spent the past 7 weeks in a rear axle manufacturing facility, and there is no measurable difference in the friction that it takes to turn a 4.10 gear set versus the 3.31, 3.55, or 3.73 gear sets that his plant makes. So, I am not convinced that friction would be a cause of the horsepower difference.
I suspect that there is a computer logic error in the chassis dynamometer's computer.
:confused: :confused: :confused:
Thanks for the reply.
I have spent the past 7 weeks in a rear axle manufacturing facility, and there is no measurable difference in the friction that it takes to turn a 4.10 gear set versus the 3.31, 3.55, or 3.73 gear sets that his plant makes. So, I am not convinced that friction would be a cause of the horsepower difference.
I suspect that there is a computer logic error in the chassis dynamometer's computer.
:confused: :confused: :confused:
Drifting
Joined: Aug 2001
Posts: 1,903
Likes: 0
From: Oakhurst NJ
Re: Disappointing dyno today (Pumba)
Rob,
Can someone explain to me in technical terms how changing from 3.42 gears to 4.10 gears can cause a loss of horsepower?
:confused:
Can someone explain to me in technical terms how changing from 3.42 gears to 4.10 gears can cause a loss of horsepower?
:confused:
Drifting
Joined: Oct 2002
Posts: 1,823
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From: If you can see the car behind you, your not going fast enough
Re: Disappointing dyno today (kh24)
Its definatley the gears and the warmer weather doesn't help either...
Pumba...
Ask any tuner that has experience with 4:10s... They are proven to dynbo 10 -20 hp lower then 3:42s... go ahead ask LGM, Lingenfelter, MTI, A&A, ECS, Vette doctors, cartek, MTI, A.R.E... Its no new jersey conspiricy... (I can't spell dont make fun of me)
Pumba...
Ask any tuner that has experience with 4:10s... They are proven to dynbo 10 -20 hp lower then 3:42s... go ahead ask LGM, Lingenfelter, MTI, A&A, ECS, Vette doctors, cartek, MTI, A.R.E... Its no new jersey conspiricy... (I can't spell dont make fun of me)
Melting Slicks
Joined: Sep 2003
Posts: 2,458
Likes: 105
From: Northville Michigan
Re: Disappointing dyno today (NJ99FRC)
Alex,
Thanks for the note.
I am convinced that the Tuners that we all use see a 10 to 20 horsepower loss when a customer changes to a 4.10 final drive ratio on their Mustang or Dynojet chassis dynamometers. Does that mean I really have 420 RWHP in my Z06? Or, does it mean those Vette owners with other gear sets should subtract 20 RWHP from their numbers?
I am concerned because when we measure the frictional losses at the rear axle manufacturing plant where I have been working for the past seven weeks, there is no difference between a 3.31 or 3.55 or 3.73 or a 4.10 gear set.
I have watched as the Tuners I use enter my 4.10 gear ration into the chassis dyno's computer. I suspect that the computer has a logic error, and can't correctly convert the rear wheel horsepower for a 4.10, when compared to a 2.73 or 3.15 or 3.42 gear set.
Thanks for your thoughts. :seeya
[Modified by Pumba, 8:32 AM 5/8/2004]
Thanks for the note.
I am convinced that the Tuners that we all use see a 10 to 20 horsepower loss when a customer changes to a 4.10 final drive ratio on their Mustang or Dynojet chassis dynamometers. Does that mean I really have 420 RWHP in my Z06? Or, does it mean those Vette owners with other gear sets should subtract 20 RWHP from their numbers?
I am concerned because when we measure the frictional losses at the rear axle manufacturing plant where I have been working for the past seven weeks, there is no difference between a 3.31 or 3.55 or 3.73 or a 4.10 gear set.
I have watched as the Tuners I use enter my 4.10 gear ration into the chassis dyno's computer. I suspect that the computer has a logic error, and can't correctly convert the rear wheel horsepower for a 4.10, when compared to a 2.73 or 3.15 or 3.42 gear set.
Thanks for your thoughts. :seeya
[Modified by Pumba, 8:32 AM 5/8/2004]