My friend had his Runner on a dyno, the model you bolt directly to the wheel hubs. He got 463hp @ 4,238rpm and 570lb ft @ 4,255 What could it be at crank? 440” 727 (Gear Vendor) 8 3/4” Waiting for the dyno sheet
70 W100 Power Wagon. 318 4-spd 70 Sport Fury 440 2dr HT 71 Duster 340 71 Charger Super Bee - 383/727 72 Charger "Sabotage" - 440/727 - Street/Strip 78 Warlock in beautiful patina
Re: RWH to crank?
[Re: HP2]
#2921166 05/11/2101:25 PM05/11/2101:25 PM
It all depends on how well the combo works together. My wife's motor made 535HP on the engine dyno. She ran a 10.82 at 3130lb race weight 3 weekends ago and according to Wallace Racing Calculator that's 488 RWHP. 10% loss according to that. I know of a few other engines that were ran on the same dyno and don't produce the ET that I think they "should" run. They are more along the 20-25-30% power loss.
Re: RWH to crank?
[Re: HP2]
#2921420 05/11/2110:22 PM05/11/2110:22 PM
There's no fixed percentage, changes with every vehicle variable, and so many variances between engine dynos and chassis dynos. Sometimes it's fun to do a negative dyno test on the dynojet to see what it approximates drivetrain loss as.
As mentioned there are a lot of variables to consider. Even so, when I'm looking for a ballpark estimate I use 15% loss for manual transmissions and 20% for automatics.
If a car makes 400rwhp for example, I do the math like this:
manual....400/.85 = 470 engine hp
auto........400/.8 = 500 engine hp
again just an estimate
Last edited by BigDaddy440; 05/12/2101:03 AM.
1969 A12 Roadrunner 1970 Plymouth Cuda 1968 Dodge Dart
RWHP will show different from tire design, pressure, size driveshaft angle ATF fluid temperature ATF internal parts (TH400 higher than PG, 518 higher than 904, etc.) stall speed hypoid angle (9" vs. Dana etc.)
Boffin Emeritus
Re: RWH to crank?
[Re: HP2]
#2921582 05/12/2111:22 AM05/12/2111:22 AM
My friend had his Runner on a dyno, the model you bolt directly to the wheel hubs. He got 463hp @ 4,238rpm and 570lb ft @ 4,255 What could it be at crank? 440” 727 (Gear Vendor) 8 3/4” Waiting for the dyno sheet
550 WAG. (Wild Ass Guess)
Obviously lots of variables but we've seen about 100 hp differential between rwhp and crank at that level.
I have zero interest in HP ratings anymore. We have used the dyno to tune and optimize a car and know what that translated to for on track performance but not really valid to compare it to others.
Last edited by GY3; 05/12/2111:32 AM.
'63 Dodge 330 11.19 @ 121 mph Pump gas, n/a, through the mufflers on street tires with 3.54's. 3,600 lbs. 10.01 @ 133mph with a 250 shot of nitrous an a splash of race gas. 1.36 60 ft. 3,700 lbs.
As mentioned there are a lot of variables to consider. Even so, when I'm looking for a ballpark estimate I use 15% loss for manual transmissions and 20% for automatics.
If a car makes 400rwhp for example, I do the math like this:
manual....400/.85 = 470 engine hp
auto........400/.8 = 500 engine hp
again just an estimate
I'd like to see engine dyno's instead of factory numbers, but the Factory ratings turn out like this, all over the map.
I have zero interest in HP ratings anymore. We have used the dyno to tune and optimize a car and know what that translated to for on track performance but not really valid to compare it to others.
I have learned the hard way that the numbers from a dyno may or may not be accurate This happened several years back when Dram Dan from FL was still alive and had question some dyno HP results on one of my motors from the local Studka engine dyno. I took my 526 C.I. 440 dyno mule from Madras, OR(2500 Ft. elevation) to Klamath Falls, OR(4300 Ft.) to a DTS engine dyno. I made no changes to the motor and it made 100 HP less on the DTS engine dyno that was less than a year old and was calibrated correctly I took the motor back and told the dyno operator about the differences between the two dyno and we ended up calibrated it and it lost 100 HP also There had been conflict between the former dyno operator and the dyno owner so it wouldn't surprise me that he had mess with it before leaving My message is don't worry about the net HP and torque, look at the differences between changes you make, if it is getting better your going the right way, if it is losing power go the other way
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
My small block lost almost 23% from the engine dyno to a chassis dyno. I wasn't really worried about the numbers, just the tune. It runs just a tick over 110 mph in the 1/8 so it makes somewhere between 300 and 1000 HP. LOL
My small block lost almost 23% from the engine dyno to a chassis dyno. I wasn't really worried about the numbers, just the tune. It runs just a tick over 110 mph in the 1/8 so it makes somewhere between 300 and 1000 HP. LOL
My friend had his Runner on a dyno, the model you bolt directly to the wheel hubs. He got 463hp @ 4,238rpm and 570lb ft @ 4,255 What could it be at crank? 440” 727 (Gear Vendor) 8 3/4” Waiting for the dyno sheet
My Coronet would make 475 at the rear tires and 550 at the crank when I had the 470 in it. That is with a manual transmission. An automatic transmission can give you some funky numbers on a chassis dyno depending on the converter. https://www.youtube.com/watch?v=xG3-_YJGdZ8
Re: RWH to crank?
[Re: HP2]
#2921754 05/12/2104:57 PM05/12/2104:57 PM
I forgot about those. My first chassis dyno experience was also on one of the dynapack deals that bolt to the axles.
I can't remember whether Blusmbl took that video or I did, but never in my life have I watched and listened to a 6 second video SO many times
Don't recall the number it made, 4-something, but I do remember the little things I wanted to experiment with were eye opening and I learned a little bit.
I do recall making more improvements, trying to head back to Matt/the same Dynapack, and Matt telling me to take a hike. He told me the screens were already flashing warnings during my last test, and that I needed to find a dynojet. So that was the last time I did that.
He should run it out the back door at the track for MPH, and then weigh it, and then use all the calcuators too.
It's fun bench racing to take a guess, but TBH I've usually just gone by the estimates of folks I respect and left it at that.
Rich H.
Esse Quam Videri
Re: RWH to crank?
[Re: ZIPPY]
#2921756 05/12/2105:04 PM05/12/2105:04 PM
I forgot about those. My first chassis dyno experience was also on one of the dynapack deals that bolt to the axles.
I can't remember whether Blusmbl took that video or I did, but never in my life have I watched and listened to a 6 second video SO many times
Don't recall the number it made, 4-something, but I do remember the little things I wanted to experiment with were eye opening and I learned a little bit.
I do recall making more improvements, trying to head back to Matt/the same Dynapack, and Matt telling me to take a hike. He told me the screens were already flashing warnings during my last test, and that I needed to find a dynojet. So that was the last time I did that.
He should run it out the back door at the track for MPH, and then weigh it, and then use all the calcuators too.
It's fun bench racing to take a guess, but TBH I've usually just gone by the estimates of folks I respect and left it at that.
Cooling water issue maybe? My friend has one, it; seen a bunch of 800-1000 rwhp cars.That was the first dyno I got to spend real time on,great for steady state tuning. Dynapack was a out of my financial league when I was dyno shopping.
Re: RWH to crank?
[Re: deaks]
#2921971 05/13/2103:58 AM05/13/2103:58 AM
I forgot about those. My first chassis dyno experience was also on one of the dynapack deals that bolt to the axles.
I can't remember whether Blusmbl took that video or I did, but never in my life have I watched and listened to a 6 second video SO many times
Don't recall the number it made, 4-something, but I do remember the little things I wanted to experiment with were eye opening and I learned a little bit.
I do recall making more improvements, trying to head back to Matt/the same Dynapack, and Matt telling me to take a hike. He told me the screens were already flashing warnings during my last test, and that I needed to find a dynojet. So that was the last time I did that.
He should run it out the back door at the track for MPH, and then weigh it, and then use all the calcuators too.
It's fun bench racing to take a guess, but TBH I've usually just gone by the estimates of folks I respect and left it at that.
Cooling water issue maybe? My friend has one, it; seen a bunch of 800-1000 rwhp cars.That was the first dyno I got to spend real time on,great for steady state tuning. Dynapack was a out of my financial league when I was dyno shopping.
No idea really, He ran the water the whole time.... I don't know what the issue was. I do remember seeing some red banners flashing across the screen but I don't know what any of it meant. Maybe a calibration thing?
Of course it's very possible the guy just decided he hated me and didn't need the money LOL. If that was true he was a good actor/it wasn't easily detectable.
It was no big deal to find another dyno shop but being that he was a friend of a friend/former classmate of Blusmbl, I wanted to keep giving him the work. That attempt was probably in 2003 or 4, I haven't spoke to him since/no reason.
Jake's (jake68 here) chassis dyno service is just fine, Gary has like a million years of Mopar experience, BTDT, so the change was not at all painful.
