2 different dynos,2 very different numbers.why?

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lil red said:
Good read fellas, lots here i didnt realize
I did QA work for a machine shop a couple years back (we actually had an old Heenan and Froude water brake dyno for our marine engine testing/calibration) and our mics / measuring equipment /manufactured parts were calibrated and kept in temp controlled environment as per ISO regs., so that (as yellow rose stated) the repeatability/reliability of the measurements were maintained to a small percentile.
my point is cant a dyno be calibrated for repeatability and wouldnt an owner want the equipment to be accurate? just wondering?
We calibrate everything in our current shop that does a quantative measurement - mics, surface finish testers, verniers, precision levels, electronic dials, weight dyno scales , precision squares, etc.

most pieces of precision measuring gear are calibrated or set to a known standard, micrometers, surface testers are first run over a known piece of surface finish to calibrate, electronic levels calibrated on a flat surface before use, hardness testers on a known rockwell hardness, blah blah

anyway isnt there a known resistance or baseline that an engine dyno would be first 'setup' to or calibrated to before an engine pull?
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Of course there is a calibration method for the dyno--it involves weights that induce a torque on the load cell. It's really simple and simple is elegant. J.Rob
 
lil red said:
my point is cant a dyno be calibrated for repeatability and wouldnt an owner want the equipment to be accurate? just wondering?
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Yes. They should be calibrated regulary for repeatability.
My impression is that accuracy between different types of dynos gets into some fuzzy areas because they don't all measure the same things in the same way. For extreme example with chassis dynos, the roller types calculate power from assumptions about momentum (increasing speed to overcome the mass, etc). How is that accurately compared to an eddy current? How about ones where strain gages are used and force is calculated from that, then torque then power?
I've noticed engine dynos can be run at different rates of increasing rpm. That plays a role too.
Tricky problem getting them to compare to each other.
 
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All good points....but like I have mentioned, some builders use them as a "sales tool" and that's what I feel is unscrupulous.
 
jdsduster said:
same 408 stroker.built by a very rep.builder.his dyno shows 498 hp.518 tq.the rings did not seal and he did not want to stand behind his work.engine biulder #2,torn engine apart and corrected the problem.his dyno shows 433 hp and 467 tq.wow,why the huge difference?thats 60 hp and 50 tq.both are engine dynos.can dynos be fudged to put out bigger #s
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Engine builder #1 might have pushed the engine to a higher RPM than builder #2 or whatever he did really made a difference.
 
mopowers said:
A bullshitter desperately trying to sell another engine to an unsuspecting customer wanting to tout a huge hp number at his local car show.
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Fortunately, that "we'll respected" bullshiter is out of business, so hopefully no more victims...
 
j par said:
What about yellow rose!? He seems to be the resident expert on damn near everything but hasn't been in a car on the Dragstrip since 2006?:poke:
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Yellow rose doesn't make a living off selling engines to people with a bullshit dyno sheet
 
replicaracer43 said:
Yellow rose doesn't make a living off selling engines to people with a bullshit dyno sheet
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Of course not! I would never implied that yellow rose would try and rip somebody off. But on the other hand I'd sure give him a hard time just for the fun of it!
I don't believe yellow rose would ever sell somebody an engine with a false Dyno sheet on purpose, but an oil leak.....:poke:
 
j par said:
Of course not! I would never implied that yellow rose would try and rip somebody off. But on the other hand I'd sure give him a hard time just for the fun of it!
I don't believe yellow rose would ever sell somebody an engine with a false Dyno sheet on purpose, but an oil leak.....:poke:
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You DO remember the "670 HP pro comp smallblock" thread don't ya?
 
As soon as I hobbyist or wannabe racer says the word Dyno, I can't stop laughing..
The word Dyno to me is almost like a punchline.
 
mopowers said:
A bullshitter desperately trying to sell another engine to an unsuspecting customer wanting to tout a huge hp number at his local car show.
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To be fair. I've seen more than an occassional instance where shop owners and even engine builders simply don't understand. What I'm saying is that its not always nefarious. Some of these guys are very skilled in machine work and assembly etc. Or they are good at running a business. That doesn't mean they know how to use dynos and other testing and development tools.
Some think because they can build a good engine, there's nothing more to know. After all, they've been successful, at least in some specific situations. So sometimes its ego, sometimes it not knowing what you don't know. Others its a business decision - for example deciding that 95% of the customers will not pay the money for the time it takes to highly develop or tune an engine - and nor will they ever know since few actually take it to the drag strip..

I'm not excusing these guys. I've been burned myself. Just saying we shouldn't lump them all together, especially when implying motivation. What they do is wrong, but the road to hell is paved with good intentions. At least some of it anyway.
 
Machine shop where I had my motor done but of course not dynoed LOL this is the sign that have above that room lol....
IMG_20180515_095234.jpg
 
When my engine dynoed it cost $450 for all day and the motor oil. Money well spent IMO and if I ever build anything else with some steam I'll do it again.

If it's an engine the owner built "torture chamber" is the right name for the cell! After priming and installing the distributor my engine fired right up, we set the timing and warmed it up. Then shut it off and checked the lash. The next time we fired it up and let it run for a few seconds, the operator looked at me and asked if I was ready, WFO and pulled to 7200. I'm not going to lie it made me a lot nervous seeing and hearing it, I'd never done that to a brand new engine.

My engine had an oiling issue on the passengers side rocker arms that I would've never heard if it had been started in the car and driven. On the dyno it could be heard and we shut it down to investigate, found the issue and fixed it and went on with the secession.

As has been mentioned it's a tool, some use it for tuning and some use it to make money off unsuspecting customers.
 
justinp61 said:
When my engine dynoed it cost $450 for all day and the motor oil. Money well spent IMO and if I ever build anything else with some steam I'll do it again.

If it's an engine the owner built "torture chamber" is the right name for the cell! After priming and installing the distributor my engine fired right up, we set the timing and warmed it up. Then shut it off and checked the lash. The next time we fired it up and let it run for a few seconds, the operator looked at me and asked if I was ready, WFO and pulled to 7200. I'm not going to lie it made me a lot nervous seeing and hearing it, I'd never done that to a brand new engine.

My engine had an oiling issue on the passengers side rocker arms that I would've never heard if it had been started in the car and driven. On the dyno it could be heard and we shut it down to investigate, found the issue and fixed it and went on with the secession.

As has been mentioned it's a tool, some use it for tuning and some use it to make money off unsuspecting customers.
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Yes the torture chamber as it's called LOL is an availability at my machine shop where they basically run it up past 7000 and torture it and see if it'll blow up? And of course they do all the stuff you said, but I would never pay for anything like that myself.
But also they provide a service for every complete motor that comes out of there. They put it on a machine that's full of breaking oil and they lock the block down and put a PTO to it that runs at about 400 RPMs. Also they obviously connect a full oil pressure to it and run the motor and adjust the valves and check all all pressures everywhere. This way when you get the motor the Rings are already seated mostly the valves are already adjusted and oil pressure has been brought up everywhere once already.
 
ou812 said:
For engine builders like myself and others, the Dyno is a great learning tool WHEN you compare that data with flow bench data, and real world at the track data...to customers the Dyno is a great way to get the engine broke in, check for leaks, fine tune the engine for the air it's breather on that particular day (baseline tuneup) and try a few things that might make more power like lash, timing, etc...saving some time at the drag strip possibly.
I've seen a poorly setup car (with incorrect front end alignment) make a good engine look bad...what do your calculators say about that???? Oh, NOBODY has a poorly setup chassis....LOL!
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Guilty. Had a 585-590HP 360 in my car about 7 or 8 years ago. Car ran 10.90s at 122. Front end was F'd up, brakes were locked up so bad you could barely turn the wheels, converter was F'd up, trans was slipping, fuel system was lacking. Fast forward to today, all those problems are remedied. The car runs 10.60s at 122 with a motor that makes around 520HP.
IMO dynos and flow benches are like homemade yard sticks.
 
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