HP Question
Team Owner
Joined: Jun 2001
Posts: 26,714
Likes: 344
From: Houston, TX
Re: HP Question (dm3557)
Oh, you had to open that can of worms. There is a formula, but you really must work the other way to first find out what the formula is. There is always controversy over the "loss factor". 15% on six speeds is pretty much accepted as the best number, but some will disagree. Don't forget, you must take rwhp and divide by .85. I have dyno'd my car, and 15% was right on the money, buy the way. Automatics seem to be less consistent. Also, normal variance between cars and dynos will cause differences. And every car has a different loss factor. Best thing is to take a number of readings on stock cars, and calculate an average factor.
Hope this helps. Be prepared for more and different answers. Believe whichever makes the most sense to you.
Hope this helps. Be prepared for more and different answers. Believe whichever makes the most sense to you.
Former Vendor
Joined: Nov 2000
Posts: 5,607
Likes: 1
From: Houston TX
Re: HP Question (dm3557)
My 2000 LS1 6spd is rated 345hp and it dynoed @ 305rwhp bone-stock. So...is it underrated by GM or does it only have a lost of 12%? You'll be the judge :cheers:
305hp / .85 = 358.8rwhp (using the 15% loss, it would be underrated by GM)
305hp / .88 = 346.6rwhp (using the 12% loss, it is right on)
305hp / .85 = 358.8rwhp (using the 15% loss, it would be underrated by GM)
305hp / .88 = 346.6rwhp (using the 12% loss, it is right on)
Drifting
Joined: Oct 2001
Posts: 1,366
Likes: 0
From: America
Re: HP Question (dm3557)
dm, figure 15% on 6 speeds, and divide rwhp by .85 = crank.......
On an automatic do the same, except figure a 20% loss.......(Hydraulics v.s. Mech).divide rwhp by .80............to get crank.........
And, yes.......to leaun's postulation.............ALL LS1's, and LS 6's are UNDERATED.......
My ' 01 Z, cranks out 347@ rwhp, rated #@ 385 Crank........
Do the math, and you will see, I am running close to 408 crank..........
This is nothing new, GM has done this for years.................
Hope this helps, and it holds true almost 100% of the time........ :yesnod:
On an automatic do the same, except figure a 20% loss.......(Hydraulics v.s. Mech).divide rwhp by .80............to get crank.........
And, yes.......to leaun's postulation.............ALL LS1's, and LS 6's are UNDERATED.......
My ' 01 Z, cranks out 347@ rwhp, rated #@ 385 Crank........
Do the math, and you will see, I am running close to 408 crank..........
This is nothing new, GM has done this for years.................
Hope this helps, and it holds true almost 100% of the time........ :yesnod:
Team Owner
Joined: Jun 2001
Posts: 26,714
Likes: 344
From: Houston, TX
Re: HP Question (ZO6LS6)
I hate to disagree with the post above that they are under rated, but. I have seen too many dyno runs that indicate that they are rated just about right for the 15%. Sure, there will always be someone that dyno's high and makes his own case, but most non-Z06's dyno in the very low 300's, and most Z06's dyno in the mid 330's ('01's), and '02's between 345 and 350. This indicates to me that the 01 Z06 is slightly underated, which 1/4 times also indicate. Other indication is that the correction factor may be closer to 14%. I have never seen a dyno run at the crank, so everyone is speculating based on rated hp anyway.
Drifting
Joined: Nov 2001
Posts: 1,448
Likes: 16
From: Humble tx
Re: HP Question (jschindler)
Jim
I have to side with the other guy. My 02 Z dyno'd bone stock at 354RWHP and that seems pretty much what I have heard. That puts the Crank HP at 416.5. But it depends on the factor, doesn't it? If you use 12% than the car is over-rated. Who really knows?
Rg :rolleyes:
I have to side with the other guy. My 02 Z dyno'd bone stock at 354RWHP and that seems pretty much what I have heard. That puts the Crank HP at 416.5. But it depends on the factor, doesn't it? If you use 12% than the car is over-rated. Who really knows?
Rg :rolleyes:
Team Owner
Joined: Jun 2001
Posts: 26,714
Likes: 344
From: Houston, TX
Re: HP Question (rfgoss1)
Jim
I have to side with the other guy. My 02 Z dyno'd bone stock at 354RWHP and that seems pretty much what I have heard. That puts the Crank HP at 416.5. But it depends on the factor, doesn't it? If you use 12% than the car is over-rated. Who really knows?
Rg :rolleyes:
I have to side with the other guy. My 02 Z dyno'd bone stock at 354RWHP and that seems pretty much what I have heard. That puts the Crank HP at 416.5. But it depends on the factor, doesn't it? If you use 12% than the car is over-rated. Who really knows?
Rg :rolleyes:
Did you get your Cam put in? I saw your car out there last weekend. I still want to get togeher with you. I'll try to call you for lunch, maybe in a couple of weeks.
Jim
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Drifting
Joined: Nov 2001
Posts: 1,448
Likes: 16
From: Humble tx
Re: HP Question (jschindler)
Absolutely, lets do. I am going HRP Sunday night to play a little if you are around. If you feel like going, let me know. I have the suite there and my wife and kids may come out to watch. YOu are more than welcome to use the suite if you want to come out. Email me if you happen to go.
rfgoss1@yahoo.com
Cheers
rg :cheers:
rfgoss1@yahoo.com
Cheers
rg :cheers:
Team Owner
Joined: Jun 2001
Posts: 26,714
Likes: 344
From: Houston, TX
Re: HP Question (rfgoss1)
Absolutely, lets do. I am going HRP Sunday night to play a little if you are around. If you feel like going, let me know. I have the suite there and my wife and kids may come out to watch. YOu are more than welcome to use the suite if you want to come out. Email me if you happen to go.
rfgoss1@yahoo.com
Cheers
rg :cheers:
rfgoss1@yahoo.com
Cheers
rg :cheers:
Drifting
Joined: Oct 2001
Posts: 1,366
Likes: 0
From: America
Re: HP Question (jschindler)
J, Not to be a hardhead.....but, I stand by the 15%, and 20% factor....
The local speed shop here..........goes by this rating system, and they have a sterling rep.........also, numerous Z28's & Z28 SS models have been dynoing at over 310/320.........stock..........all on a 248c.......
The motors are the same as in the standard C5's for all practical purposes.......
This GAME has been going on for the past 30 years........... :chevy
The local speed shop here..........goes by this rating system, and they have a sterling rep.........also, numerous Z28's & Z28 SS models have been dynoing at over 310/320.........stock..........all on a 248c.......
The motors are the same as in the standard C5's for all practical purposes.......
This GAME has been going on for the past 30 years........... :chevy