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new car HP rating? #761637 07/30/10 06:49 PM 07/30/10 06:49 PM
Joined: Jun 2006 Posts: 3,075 Eastern Ohio mopowergtx OP master
mopowergtx OP master Joined: Jun 2006 Posts: 3,075 Eastern Ohio	How do they rate the new Dodges horsepower wise? Is the numbers they are throwing out there flywheel or rearwheel horsepower? Like for examples my 2004 Dodge Ram 5.7 is rated at 345HP. Where is that 345HP number derived from? Back at the rear wheels through exhaust and running the belt for the alternator and water pump breathing through the stock air box? Or sitting on a run stand in the engineering dept. dyno room? Why I ask is I thought they went to rear wheel horsepower years ago but if thats so it sure doesnt add up on a ET calculator for my buddies 07 Ram 3/4 ton 4x4 from last nights trip to the dragstrip. He had a trap speed of 80 mph and we figure it to weigh 6500 with him in it. You enter 6500 lbs then 80 mph you get 260 rear wheel HP. You put that in the next line it spits out a 17.03 ET. His best run last night was 16.98 but he had several 17.04's and 17.1's. So dang that seems to really justify that calculators rationing. What do you guys think? ET calculator

Re: new car HP rating? [Re: mopowergtx] #761638 07/30/10 09:00 PM 07/30/10 09:00 PM
Joined: Jan 2003 Posts: 4,395 The Pale Blue Dot Skeptic master
Skeptic master Joined: Jan 2003 Posts: 4,395 The Pale Blue Dot	It's flywheel HP, as the saying goes " Your mileage may vary"

Re: new car HP rating? [Re: mopowergtx] #761639 07/30/10 09:09 PM 07/30/10 09:09 PM
Joined: Jul 2005 Posts: 707 California BigDaddy440 super stock
BigDaddy440 super stock Joined: Jul 2005 Posts: 707 California	Modern HP ratings are flywheel numbers, NOT rear wheel numbers. I believe I read just a few years ago manufactures were forced / agreed to assimilate on how they rate their vehicles' power, to obtain more accuracy across the board. Same with fuel mileage claims as well. Rear Wheel numbers are a fairly new (last 10+ years or so) way to easily gauge how much power an engine is putting out after the drive train has absorbed its toll. Manual trans and lighter duty rear-ends will absorb less than a stingy auto trans with a converter. I'd assume a Dana 60 takes more �oomph� to turn than a 8.75 too. Also torque / stall converters multiply torque, so real wheel torque numbers will be inflated some with an auto trans. There are three (maybe four) popular chassis dyno systems, with Dynojet being the most popular (industry standard). The numbers can be listed corrected and non-corrected. Non-corrected (SAE) numbers are what the car actually put out that day. Corrected numbers take into consideration other factors such as weather and issue performance number based on a correction factor, so that someone in Death Valley California in July can compare their numbers with someone is Denver Colorado in January. 1969 A12 Roadrunner 1970 Plymouth Cuda 1968 Dodge Dart

Re: new car HP rating? [Re: BigDaddy440] #761640 07/30/10 11:10 PM 07/30/10 11:10 PM
Joined: Jun 2006 Posts: 3,075 Eastern Ohio mopowergtx OP master
mopowergtx OP master Joined: Jun 2006 Posts: 3,075 Eastern Ohio	What was Chrysler using in 1978? They have my '78 318 2 bbl listed as 140 HP @ 4000 RPM torque 245 @ 1600 RPM. Flywheel HP? Using that calculator I posted with my race weight of 3960 with driver and my trap speed of 75 mph it gave me 130 rear wheel HP. The only thing that I have changed is removing the cat converter and installing mandrel bent 2 1/2" exhaust back from the stock Y-pipe through a Summit Turbo muffler out a 2 1/2" tail pipe. I removed the Lean Burn installed a Mopar Electronic Ignition with Taylor 8mm 50 ohm wires and a MSD Blaster 2 coil. Everything else is 100% stock. 2.4 geared 7 1/4" rear end also. When I put their estimated 130 RWHP in with my race weight it said I should run a 18.17. Best run of the night was right after dark and it was 18.17 Dang that came out pretty close.

Re: new car HP rating? [Re: mopowergtx] #761641 07/31/10 03:28 AM 07/31/10 03:28 AM
Joined: Jul 2005 Posts: 707 California BigDaddy440 super stock
BigDaddy440 super stock Joined: Jul 2005 Posts: 707 California	Its hard to say, but I'd assume 30-40 years ago HP ratings might have been less accurate than more modern rating systems. If your engine was putting out 140 flywheel HP you could expect to see 115 at the rear wheels. With your modifications and possibly a little more factory HP than advertised, your estimated 130 rwhp might be right on. If you indeed have 130 rwhp, you most likely have about 160 flywheel HP. Drive Safely 1969 A12 Roadrunner 1970 Plymouth Cuda 1968 Dodge Dart

Re: new car HP rating? [Re: BigDaddy440] #761642 07/31/10 04:19 AM 07/31/10 04:19 AM
Joined: Feb 2003 Posts: 21,318 Manitoba, Canada DaytonaTurbo Too Many Posts
DaytonaTurbo Too Many Posts Joined: Feb 2003 Posts: 21,318 Manitoba, Canada	The auto manufacturers have NEVER rated their vehicles or motors at power at the wheels or transmission. It has ALWAYS been power at the flywheel. The difference being 1971 and earlier was SAE Gross power. SAE Gross = no belt driven accessories, no air cleaner, dyno headers/exhaust system. 1972+ was SAE Net which had the engine running water pump, alternator, air cleaner and stock type exhaust system. This standard was brough into effect to more accurately reflect real-world performance. A few years ago they came up with a voluntary SAE Certified, which the dyno test is basically the same as a SAE Net test, but done at an independant 3rd party dyno/dyno operator so the test conditions can't be manipulated by the manufacturer.

Re: new car HP rating? [Re: DaytonaTurbo] #761643 07/31/10 10:48 AM 07/31/10 10:48 AM
Joined: Jun 2006 Posts: 3,075 Eastern Ohio mopowergtx OP master
mopowergtx OP master Joined: Jun 2006 Posts: 3,075 Eastern Ohio	Quote: The auto manufacturers have NEVER rated their vehicles or motors at power at the wheels or transmission. It has ALWAYS been power at the flywheel. The difference being 1971 and earlier was SAE Gross power. SAE Gross = no belt driven accessories, no air cleaner, dyno headers/exhaust system. 1972+ was SAE Net which had the engine running water pump, alternator, air cleaner and stock type exhaust system. This standard was brough into effect to more accurately reflect real-world performance. A few years ago they came up with a voluntary SAE Certified, which the dyno test is basically the same as a SAE Net test, but done at an independant 3rd party dyno/dyno operator so the test conditions can't be manipulated by the manufacturer. Ah. I see. So my minor modifications have improved upon the stock HP rating it would seem enough to make a difference where you could tell. Seat of the pants said it did a little bit. I didnt get a baseline last year when it was 100% stock. I wanted to do that this year before I installed the 2.94 8 1/4", stock 340 cam, and a factory cast iron manifold with stock '75 Thermoquad.

Re: new car HP rating? [Re: DaytonaTurbo] #761644 07/31/10 11:33 AM 07/31/10 11:33 AM
Joined: Nov 2004 Posts: 1,708 S. Il. U.S.A. 5spdcuda top fuel
5spdcuda top fuel Joined: Nov 2004 Posts: 1,708 S. Il. U.S.A.	As stated older cars were rated by gross horsepower #s which were often inflated even more than the lack of accessories would have accounted for. Only a handful of engines from that era had ratings that were close to reality. Early 340's being a good example. Late models from every manufacturer seem to be pretty close. Lastly the dyno #'s used by car mag's and most engine builders are much more like the old car #'s were, which is to say that after you pull it off the dyno and actually install it in your car the #'s will fall. Anyone wishing to have an engine dynoed would be wise to ask just which correction fact was used to determine the output. IMO dynos are a very useful tool for determining the effect of changes, but the actual number isn't all that important. In the end the only numbers that actually count are time slips. Vehicle weight and trap speed tells more about actual power output than dyno #'s that vary according to individual dynos and their operators.

Re: new car HP rating? [Re: 5spdcuda] #761645 07/31/10 12:45 PM 07/31/10 12:45 PM
Joined: Feb 2003 Posts: 21,318 Manitoba, Canada DaytonaTurbo Too Many Posts
DaytonaTurbo Too Many Posts Joined: Feb 2003 Posts: 21,318 Manitoba, Canada	Quote: Vehicle weight and trap speed tells more about actual power output than dyno #'s that vary according to individual dynos and their operators. Yup, that would be why I've often heard dynojet brand dynos referred to as ego-jet!

Re: new car HP rating? [Re: DaytonaTurbo] #761646 07/31/10 02:12 PM 07/31/10 02:12 PM
Joined: Nov 2006 Posts: 1,074 Manitoba Canada 67autocross super stock
67autocross super stock Joined: Nov 2006 Posts: 1,074 Manitoba Canada	The new 5.0 Mustang makes it's rated 412 hp at the wheels... A new iron curtain drawn across the 49th parallel

Re: new car HP rating? [Re: 67autocross] #761647 07/31/10 03:33 PM 07/31/10 03:33 PM
Joined: Nov 2004 Posts: 1,708 S. Il. U.S.A. 5spdcuda top fuel
5spdcuda top fuel Joined: Nov 2004 Posts: 1,708 S. Il. U.S.A.	The Mustang's 412 hp. is a flywheel rating. Now whether or not that 412 is conservative or not is another matter. I've read several magazine tests and the results are inconsistent. All of them were pretty quick and more importantly fast, but the times and trap speeds varied enough to make me wonder if some mags got a ringer to test. That used to be common place, don't know about now. What I do know is that every time a new model comes out, most of the magazines act as if they owned stock in the company. Probably best to withhold judgment until enough of them hit your local track to see what the typical one actually runs like.

Re: new car HP rating? [Re: 67autocross] #761648 07/31/10 04:57 PM 07/31/10 04:57 PM
Joined: Sep 2007 Posts: 14,889 up yours Supercuda About to go away
Supercuda About to go away Joined: Sep 2007 Posts: 14,889 up yours	Quote: The new 5.0 Mustang makes it's rated 412 hp at the wheels... I guarantee you that Ford does not claim that. I can also guarantee that the 412HP rating is exactly correct. HOWEVER, it may not be max hp either. Manufacturers, for a number of reasons, have in the past quoted less than maximum hp ratings. It's all in what RPM they are claiming the hp at. Which may account for certain chassis dyno's seeing 412 (or more) hp at the wheels. Enjoy it while you can cause soon someone (insutance, gov't, your mom, etc) will wise up and you will be paying for it. They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.

Re: new car HP rating? [Re: 67autocross] #761649 07/31/10 05:30 PM 07/31/10 05:30 PM
Joined: Jul 2005 Posts: 707 California BigDaddy440 super stock
BigDaddy440 super stock Joined: Jul 2005 Posts: 707 California	Quote: The new 5.0 Mustang makes it's rated 412 hp at the wheels... While the 412 HP is most likely under-rated, as preliminary dyno tests have shown, the 412 rating is a flywheel number. You can expect 375-385rwhp from Ford's newest pony. As far as dyno's not being useful other than measuring the effect of a modification vs a baseline run, is not entirely true. While there are differences between dyno outputs, baseline dyno pulls of production cars have shown a strong level of consistency between like cars on the same types of dyno systems across the country. Last edited by BigDaddy440; 07/31/10 05:34 PM.

Re: new car HP rating? [Re: BigDaddy440] #761650 07/31/10 06:10 PM 07/31/10 06:10 PM
Joined: Feb 2003 Posts: 21,318 Manitoba, Canada DaytonaTurbo Too Many Posts
DaytonaTurbo Too Many Posts Joined: Feb 2003 Posts: 21,318 Manitoba, Canada	Quote: While there are differences between dyno outputs, baseline dyno pulls of production cars have shown a strong level of consistency between like cars on the same types of dyno systems across the country. Which is why they brought in the voluntary SAE Certified rating system, so a manufacturer could say this is how much HP our car produces, compared to other manufacturers cars tested with the same 3rd party rating system. Probably the closest to a level playing field we will get for dynos. But in the end I agree with what's been said, it's the track times I care about.

Re: new car HP rating? [Re: DaytonaTurbo] #761651 07/31/10 06:26 PM 07/31/10 06:26 PM
Joined: Nov 2006 Posts: 1,074 Manitoba Canada 67autocross super stock
67autocross super stock Joined: Nov 2006 Posts: 1,074 Manitoba Canada	Quote: Quote: While there are differences between dyno outputs, baseline dyno pulls of production cars have shown a strong level of consistency between like cars on the same types of dyno systems across the country. Which is why they brought in the voluntary SAE Certified rating system, so a manufacturer could say this is how much HP our car produces, compared to other manufacturers cars tested with the same 3rd party rating system. Probably the closest to a level playing field we will get for dynos. But in the end I agree with what's been said, it's the track times I care about. The 5.0's are posting 12:30's at 110 mph with nothing more then slicks and must be at least 3800lbs, how much horse power is that at the flywheel? A new iron curtain drawn across the 49th parallel

Re: new car HP rating? [Re: 67autocross] #761652 07/31/10 06:36 PM 07/31/10 06:36 PM
Joined: Dec 2008 Posts: 459 pana illinois B bigblock4x4 mopar
bigblock4x4 mopar B Joined: Dec 2008 Posts: 459 pana illinois	Quote: Quote: Quote: While there are differences between dyno outputs, baseline dyno pulls of production cars have shown a strong level of consistency between like cars on the same types of dyno systems across the country. Which is why they brought in the voluntary SAE Certified rating system, so a manufacturer could say this is how much HP our car produces, compared to other manufacturers cars tested with the same 3rd party rating system. Probably the closest to a level playing field we will get for dynos. But in the end I agree with what's been said, it's the track times I care about. The 5.0's are posting 12:30's at 110 mph with nothing more then slicks and must be at least 3800lbs, how much horse power is that at the flywheel? doesn't really matter too much it's a ford.

Re: new car HP rating? [Re: bigblock4x4] #761653 07/31/10 10:58 PM 07/31/10 10:58 PM
Joined: Sep 2007 Posts: 14,889 up yours Supercuda About to go away
Supercuda About to go away Joined: Sep 2007 Posts: 14,889 up yours	Quote: doesn't really matter too much it's a ford. Them grapes sour or what? They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.

Re: new car HP rating? [Re: 67autocross] #761654 07/31/10 11:01 PM 07/31/10 11:01 PM
Joined: Nov 2004 Posts: 1,708 S. Il. U.S.A. 5spdcuda top fuel
5spdcuda top fuel Joined: Nov 2004 Posts: 1,708 S. Il. U.S.A.	110mph at 3800lbs. = 394.74 hp. at the wheels. Draw your own conclusions about the 412 hp. at the crank rating. As someone else said earlier if you want the rating to be conservative just read the #s at a lower rpm than where it actually maxs out.

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