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Brian024.7
Dodge Dakota
12/10/2001
13:47:03
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 Subject: Did dodge under rate the 4.7?
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looking at this dyno chart of a stock 4.7 takin from speedtweaks site...
210 hp and 285 lb-ft of torque to the wheels
if you figure a 15% drivetrain loss (which is usually the minimum loss) this would mean about 246 hp and 335 torque at the flywheel.
I'm very curious if dodge didn't under rate the engine to not take away sales of the 5.9
I know some engines are stronger than others, but thats a big difference (40 lb-ft of torque). Does anyone else have a dyno of a stock 4.7?
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Demon-Xanth
Dodge Dakota
12/10/2001
13:55:22
| RE: Did dodge under rate the 4.7?
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Sounds like what GM did to the F-bodies. They claimed 285 but pulled 265 when Hot Rod dynoed them, the Mustang's were rated at 215 and only pulled about 175. (this was LT-1 vs. 5.0). 70HP on paper grew to 90HP on pavement.
There is other little driveline tweaks that can be done to reduce loss and engines vary, two 4.7s can probably vary from 220-245HP based on small variances, with 230HP being the norm.
Might've even just been a good day.
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Anthony G
Dodge Dakota
12/10/2001
14:07:04
| RE: Did dodge under rate the 4.7?
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When my 2001 R/T was stock with 4400k on the motor it pulled a corrected 209hp 302tq in 90+ hot weather. The Dyno still adjusted it to a lower figure. -(20%)with the slush box auto :)
So 209hp and 285tq seems about right for the 4.7L,
I think Jeff's 4.7 stick pulled those numbers stock too or near stock.
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CThomp
Dodge Dakota
12/10/2001
14:23:27
| RE: Did dodge under rate the 4.7?
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So what is the average hp and tq loss for the 4.7. I'm definitely curious as to some real numbers. My 4.7 is stock but hopefully not for long.
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Anthony G
Dodge Dakota
12/10/2001
14:54:41
| RE: Did dodge under rate the 4.7?
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15% for 4.7L 5-speed stick
15%-20% for the 4.7L Multi-speed 45RFE automatic
20%-25% for 4-speed 46RE which is found on the R/T's
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Anthony G
Dodge Dakota
12/10/2001
15:16:45
| RE: Did dodge under rate the 4.7?
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Crank HP STOCK
15%
Stock Speedtweak Dyno 4.7L 240.35hp 327.75tq
Not sure what year this 4.7L is.
Either the 235hp version or the 230hp rated.
20%
My 2001 R/T 5.9L 250.80hp 362.40tq
My Windows sticker said, 245hp@4000 335tq@3200
Sounds like Dodge did a good job on rating HP figures but not torque.
As you can see the 5.9L only makes 10hp more than the 4.7L just like is states. But the torque doesn't compare. Also the 4.7L does have a better upper power band vs the 5.9L. Stock for Stock.
That's a good reason why the 4.7L are quick, so I hear. Nothing a good M1 can't cure for the 5.9L's. :)
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Duner
Dodge Dakota
12/10/2001
15:38:05
|  RE: Did dodge under rate the 4.7?
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I wish I would have gotten some dyno runs when my truck was still stock.
Brian 024.7 - how did you post that dyno curve? I didn't know we could include pics.
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CThomp
Dodge Dakota
12/10/2001
15:45:22
| RE: Did dodge under rate the 4.7?
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The 4.7L is quick. I'm having some traction problems though. Just put the check in the mail to get my 16x8 rims (up from 15x7). Some 255/65-16's with the active suspension set up should give me what I need. How else can you reduce the amount of loss to the wheels?
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Brian024.7
Dodge Dakota
12/10/2001
15:56:16
| RE: Did dodge under rate the 4.7?
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actually anthony, i think your figureing those wrong...
because you have a 15% loss or 20% loss, you have to subtract that from the BHP, but your adding 15% and 20% to the WHP, which is not the same thing. 245 hp - 15% is 210 hp.....210 hp + 15% is 240, get the picture? I've found that adding 18% usually does the trick though.
Duner, use normal html
< i m g s r c = " address " >
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Anthony
Dodge Dakota
12/10/2001
16:57:53
| RE: Did dodge under rate the 4.7?
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So you say -15% from Brake Horse power to get RWHP or +18% to Rear Wheel Horse Power to get BHP or Crank HP.
So for an automatic could I say, -20% BHP or +22% or +23% RWHP?
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Grady C.
Dodge Dakota
12/10/2001
18:55:15
| RE: Did dodge under rate the 4.7?
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CTHOMP, I think you are misunderstanding what getting power to the wheels means. Power loss is parasitic drivetrain loss due to friction and gear reduction. This is the 15% loss, 5spd. Getting power to the road can be accomplished by larger tires, suspension changes, etc. Wheel hop would be a traction limiter but have nothing to do with limiting "power". Things to increase power to the wheels, are lighter flywheel, aluminum driveshaft etc. Traction bars or stiffer springs, shocks will help you get more traction.
Grady
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SuperDak
Dodge Dakota
12/10/2001
21:40:23
| RE: Did dodge under rate the 4.7?
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if my 4.7 is 240hp that what make it just as powerful as the 2001 4.7 toyota tundra
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Matt Barret
Dodge Dakota
12/11/2001
08:20:19
| RE: Did dodge under rate the 4.7?
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That stock Dyno chart above belongs to me, I provided Bernd with it a while ago. So it is a 5spd truck, and its the 230 version of the 4.7L W/ 3 cats ! Brian you hit on something I've been saying all along, Chrysler purposely under rated the 4.7L, because the 5.9L was still in production. They had to make it a little under the 5.9L in the advertising or else they would'nt sell as many 5.9L trucks. I've posted those same numbers to the DML a year and a half ago, man those 5.9L guys did'nt like that! now 2 years later, the 4.7L has finally gained respect, deservingly so.
Matt Y2K-HEMI
'00 RC 4.7L 5spd
14.23 @ 94.49
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Anthony G
Dodge Dakota
12/11/2001
10:01:03
| RE: Did dodge under rate the 4.7?
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Message:
Why would any 5.9L owner be mad or DC LIE? The 4.7L still produces less at the crank than the 5.9L. Yes the 4.7L does have the same HP at the wheels, but only with the 5-speed and with less torque.
I've heard of some older 5.9L only making 190-195hp with 280-290tq at the wheel, but I don't remember who said it or ever seeing anything on it.
Being a 5.9L owner, I don't care if the 4.7L did make more, all the better to beat up on Chevy and Ford :) Or rice burning cars.
I love modifying my engine, the old push rod engines are easy. Now with the OHC 4.7, It would require somewhat more skill and tools that I'm willing to get. Let alone the cost of performance parts for it.
If the new 5.7L hemi can't push or pull the new R/T faster than a lighting, I'm not going to bother buying it. It's no way I'm cracking open that baby for more ponies.
Build a 5.7L Hemi Charger with a SuperCharger, then I'll would be happy. No Front wheel drive crap either. Mid engine maybe, lol
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Brian024.7
Dodge Dakota
12/11/2001
10:50:41
| RE: Did dodge under rate the 4.7?
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not to mention this 4.7 has the 65 mm TB, maybe I'll throw my truck on a dyno while its stock. See if the bigger Trottle Body did anything. But mines a Club Cab, so there would probably be more loss in the drivetrain due to a heavier(longer) driveshaft
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Brian024.7
Dodge Dakota
12/11/2001
10:59:49
| RE: Did dodge under rate the 4.7?
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I just really agree with Matt on this one. If you notice anthony you said your truck made 302 lb-ft at the wheels, and the 4.7 made 285, that is no where near a 40-50 lb-ft difference dodge claims. And are you sure your truck is rated at 335 lb-ft, I thought they were rated at 345 lb-ft.
I'm not trying to start a 5.9 vs 4.7 war, this is solely for the purpose of saying dodge under rates the 4.7.
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Matt Barret
Dodge Dakota
12/11/2001
11:14:29
| RE: Did dodge under rate the 4.7?
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Brian, Exactly... Well said, and yes the 5.9L is rated at 345 Ft.Lbs. And I'd be the first one to admit the 5.9L makes more TQ, but NOT 40 to 50 ft lbs more than the 4.7L, no way. I'm not interested in starting WWIII here, but I firmly believe (My Opinion) the 4.7L figures were purposely deflated, slightly, to not take away from the 5.9L.
If the stock TQ rating of the 4.7L is indeed 295 ft lbs. Then how is it a stock truck can pull 285 ft lbs to the rear wheels ? THATS A 4% drivetrain loss, hee heeee LOL, if you believe a Manual trans only has a 4% loss, I have some property I'll sell you.....
Matt Y2K-HEMI
'00 RC 4.7L 5spd
14.23 @ 94.49
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Brian024.7
Dodge Dakota
12/11/2001
11:23:46
| RE: Did dodge under rate the 4.7?
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Message:
property? is it ocean front property in arizona?
haha, sorry, had to say it
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Anthony G
Dodge Dakota
12/11/2001
11:28:07
| RE: Did dodge under rate the 4.7?
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Message:
Hey all I was saying is hp figures where about right on for the 4.7L vs the 5.9L Around 10-15hp at the crank difference. Not saying that 245hp for the 5.9L or 230hp for the 4.7L are correct. I do think there underrated.
As for the torque, 302 was avg. pull for my motor. I made sure it wasn't a glitch, no second gear spike. I did get 400tq+ for my second gear spike :) I guess that's why it barks when my truck hits second gear, that's if I get a good take off.
All I know is all 2001+ R/T's or anything equipped with the 5.9L gets the 245hp@4000 335tq@3200 rated engine, at least that what it said on my window sticker. 250hp@4400 345tq@3200 for last years.
I guess those pesky pre-cats really hurt the 5.9L.
-5hp -10tq -400rpm peak power.
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CThomp
Dodge Dakota
12/11/2001
18:25:57
| RE: Did dodge under rate the 4.7?
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I do understand the difference between the whole power and traction thing. I'm workin on the traction part right now. I was just wondering about reducing that 15%. No wif only someone would come out with a carbon fiber drive shaft. That would way next to nothing and be stronger than aluminum. I should have placed the wheel purchase at the end of that post. Just excited about geting them I guess.
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dog
Dodge Dakota
12/11/2001
22:45:05
| RE: Did dodge under rate the 4.7?
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Anyone consider that this was one dyno run? Dynos have a margin of error, and engines need to be run on same dyno under same conditions to really compare. IMHO
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Brian024.7
Dodge Dakota
12/12/2001
10:38:42
| RE: Did dodge under rate the 4.7?
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thats true Dog, but this is a difference in numbers that would not be just because of this certain application/dyno. If it was 5 hp, I wouldn't make a big deal out of it, but this is 15 hp and 40 lb-ft of torque were talking. That would never be just because of dyno error.
And we're not comparing this dyno run to any other dyno runs, we are comparing it to Dodge's specifications.
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Duner
Dodge Dakota
12/12/2001
12:28:23
| It should have been better from the factory!
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I just wish they would have put out the 4.7 with the power it was capable of to begin with.
They could have let it have the larger exhaust system from the R/T (high rpm power) and been more aggressive with the PCM timing (bottom end torque). All of the Mopar engines could benefit from a change to the return style fuel system (hot performance). What a difference these three things make......
With the reprogrammed PCM, a stock for '01 68mm TB, and Mopar Cat-back, my truck dynoed (cold/red curve) 233.1 hp and 313.0 ft-lbs torque. With the stock catalytic convertor the numbers at 6000 rpm were 175 hp and 150 ft-lbs torque. It slowed down dramatically when it got hot.
http://members.home.net/cartel5/duner/Duner47Dyno.JPG
After looking at the dyno sheet and trying to figure out why it slowed down so much when it got hot as well as how it dropped off the power past 5000 rpms, I made a couple of changes.
With the addition of a full 3" cat and also a fuel rail cooling system, the numbers were (hot/green curve) 242.2 hp and 322.5 ft-lbs torque. With the larger exhaust the numbers at 6000 rpm were 212 hp and 180 ft-lbs torque. The red curve is with the cooling system turned off, which shows just the exhaust gain.
http://members.home.net/cartel5/duner/Duner47DynoWcooler.JPG
Those numbers at that 6000 rpm range are very important. With the stock PCM, you can't even get to that rpm to make any power. When you can get there, you find that the stock cat is restricting the flow at higher rpms. So the PCM added the torque and rpm range. The fuel rail cooling system fixed the loss of power when hot and the larger exhaust fixed the drop-off in power past 5000 rpms.
These two sets of pulls were done before the turbo system was installed. These are rear wheel numbers.... if you do the math - you come up with flywheel numbers that look pretty good!
I don't see any reason why it couldn't have come from the factory that way!
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alex
Dodge Dakota
12/12/2001
12:28:51
| RE: Did dodge under rate the 4.7?
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Boys, Boys, Boys....
Let's look back at Mopar History for a second, shall we? The 426 Hemi was rated at 425 horsepower before all the SAE conversion crappola. That meant 425 hp at the crank and that horsepower rating was at something like 4400 rpm (I dont have the 60's literature in front of me). The truth was shrouded with "smoke & mirrors" for decades until the engineers began to loosen up and talk just recently. The street hemi WAS actually making 425hp at 4400 rpm, but the motor would wind up to 5500 rpm (or soemwhere up there). At that lofty rpm, it was actually making in the neighborhood of 550 hp. But that would have been a disaster trying to get insurance on a 550 hp street car, so Mopar under-rated it. Everyone here (except for Matt Barrett & a few others) has been taking the Mopar marketing numbers and alleged dyno graphs as the gospel truth. The marketing department probably doesn't even know what a dyno looks like. They made up a slick graph with an early engineering estimate of the hp for all the motors and then put together some pamphlets. Those pamphlets match the hp rating that's published on the window sticker, and everyone just believes it. Matt's truck made 209.9 on the dyno stock (that particular day) and if you account for approx. 15% drivetrain power loss, that's 241 hp at the crank. Since the 4.7 was replacing the 318 motor, they must have tried to make the hp figure similar, but they did not want to take away from the R/T (or 360) sales.
Bottom line: Factory horsepower ratings are more voodoo than science.
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pwhite
Dodge Dakota
12/12/2001
20:38:45
| RE: Did dodge under rate the 4.7?
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Duner can you elaborate alittle more about the fuel cooling system. Did you make some kind of return system to the tank. what kind of cat did you add. thanks.
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BLK00DAK
Dodge Dakota
12/12/2001
21:40:23
| 4.7 automatic dyno numbers
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Hey guys,I try to stay out of these 4.7 Vs 5.9 debates but I need to stick up for the 45RFE. I was looking through some old posts and found some dyno numbers for a 2000 4.7 auto. The only modification was a 68mm TB. 218RWHP 272RWTQ.
http://www.dodgedakota.net/boards/per/25.html
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Duner
Dodge Dakota
12/12/2001
22:59:41
| pwhite -
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The first set of dyno runs showed me how much power the engine lost when it got hot. I needed to find out why!
The whole reason for the cooling system is that the returnless fuel system allows the fuel to heat soak in the fuel rail. One side of the fuel rail gets new/cooler fuel while at the end of the line the fuel gets hotter and hotter. One side of the engine is getting more fuel than the other because of this temperature difference. That just kills the performance! I mainly did the cooling system and dyno pulls to verify the problem.
The fuel rail cooling system is a closed coolant system that circulates water. I used 3/8" copper tubing and zip-tied it against the top of the fuel rails. I used the same tubing to coil around the A/C drier canister in the engine compartment. When the A/C is on the drier canister is very cold. I use a cheap fuel pump to circulate the water from the drier coil of tubing to the fuel rail tubing. The entire mess is insulated to keep the system as cold as possible. A return system would probably work just as well.... without the added complexity of the pump and tubing. I plan on changing my fuel system to add a return to the tank in the future. The way my fuel system is working now (with the turbo and FMU system) it heats the fuel up even more.
The 3" catalytic convertor I used is a MorFlow. I don't really know anything about them other than that's what my exhaust guy recommended... and had in stock.
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