VincentHill
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posted September 26, 2007 06:51 PM
DIfference between STD and SAE HP & Torque
Here is what I found and it is why I think people should use SAE! The STD is so that the Dyno Operator can make you feel good or make you think they did great work on your bike but SAE is the real world!
quote:
STD, or Standard correction factor. The Standard correction factor corrects the dyno numbers to the international scientific standard conditions of 59° F, 29.92" Hg barometric pressure, and 0% humidity. Since cooler air and higher air pressure both result in more air molecules entering the engine, an engine will produce more power under STD conditions than under SAE conditions.
SAE (Society of Automotive Engineers) correction factor. The SAE correction factor tells you what the power output would be if the temperature were 77°F, the barometric pressure 29.23" Hg, and 0% humidity. As such, the SAE correction factor is conservative compared to the STD (Standard) correction factor, and probably more closely reflects the amount of power will be produced under real-world conditions. For this reason, SAE is currently the most widespread correction factor used by auto manufacturers in rating horsepower and torque output
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supra5677
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posted September 26, 2007 07:37 PM
4.4% more in std
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VincentHill
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posted September 27, 2007 07:17 AM
quote:
4.4% more in std
I had been using 4.5% more! Either way it is not "Real World" as close at SAE is.
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Phantom13
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posted September 27, 2007 07:46 AM
Then there's the issue of the dyno itself.....
A dyno cant reproduce actual ram air or actual load produced by the rider/bike weight + wind resistance. So it really doesn't matter what correction factor is being used, you can tune for max power on the dyno and the minute you roll out in the "real world" you're not at the same A/F that you were on the dyno, especially at speed.
Dyno tuning is an obsolite method of tuning.... but it's a very easy and convienient way of tuning, not to mention a CASH COW! 99 out of 100 people would rather see a big HP number and have a slower bike than have a faster bike with a lower HP number due to it being tuned in the real world.
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TRNorBRN6001
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posted September 27, 2007 08:28 AM
I don't think dyno tuning is as obsolete as you say. Sure there are real world variables, but
with a good experienced Dyno operator and the average street rider it works well. For the more adventurous it gives a great base to work with, which can be fine tuned for the track or street situation.
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Phantom13
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posted September 27, 2007 11:48 AM
 Edited By: Phantom13 on 27 Sep 2007 12:54
Very true!
Like I said, it's convienient. For the average rider that's happy with being 90% optimized it's the best bang for the buck. For the guys who are looking to push the limits and get 100% out of their machine.... a dyno is not cost effective. A generic map provided by dynojet is sufficient for a base map to tweek. I don't know about you... but I wouldn't waste $300+ getting a custom map made on the dyno when I had to go back and retune it at every rpm/tp anyway.
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VincentHill
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posted September 28, 2007 05:19 PM
What I posted this for is the Fact that a lot of "After Market" Part suppliers use STD Numbers but do not say STD and then when they put the parts on the Bike and see a Lot lower numbers they are Dissapointed to say the least! Then people post HP Numbers and do not say that they are STD and the people with SAE Numbers think they are not making enough HP! It would be nice if Everyone reported in SAE
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kaw12
Expert Class
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posted September 28, 2007 05:46 PM
i just wanted to post what my dyno operator told me! He told me that sae was only used in elevation levels above 150ft. he told me that after i asked for the sae that we were only at 19ft. above sea level and that sae would be useless to me.. so does he know what he's talking about?
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VincentHill
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posted September 29, 2007 05:49 AM
quote:
i just wanted to post what my dyno operator told me! He told me that sae was only used in elevation levels above 150ft. he told me that after i asked for the sae that we were only at 19ft. above sea level and that sae would be useless to me.. so does he know what he's talking about?
He is Out of his Mind! Pure BS as far as I am Concerned! What does the difference between 59 degrees and 75 degrees temp have to do with Sea Level? The Inches of Mercury take care of the "Pressure" differences. He just got caught with his pants down and did not want to appear Stupid which now he has confirmed! At all altitudes and conditions either can be used and will show the differences in results
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TRNorBRN6001
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posted September 29, 2007 07:45 AM
Yep most people like to see big numbers. A large number of people that show numbers are
also not using pump gas and most times using O2 fuel.
Plus some dyno operators are able to manipulate the weather station to increase numbers as well. Hence, a Happy Dyno! The dyno weather station may be accidentally placed outside of the enclosed and airconditioned dyno rooms, or directly manipulated through calibration.
I guess it would be nice if there were more of a constant out there.
Just don't get any Factory Pro guys on here!
Kaw12, I can't figure that one out.....................as long as you feel your bike is running well and you are enjoying it, just have fun.
Remember though I am an Idiot and am just giving my two cents.
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VincentHill
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posted September 29, 2007 07:32 PM
Dr. Gary, Lose your new last line! No one is buying it! Plus you are giving at least 2 Bits Worth! Just hanging with The CHeeseman makes you unable to use that last line Period!'
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supra5677
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posted October 02, 2007 06:33 AM
just to play devils advocate whats the deal with factory pro?
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TRNorBRN6001
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posted October 02, 2007 07:50 AM
I don't know what the deal is with them, they can be sensitive at times. I do believe
that they adhere to a different equation to arrive at a given hp number. I can not
remember, but I think its around 15% or so less than SAE readings.
Entropy uses a factory pro guy in Houston (Andy), but neither of them are overly sensitive.
Just like anything they use it as a tool not the end all of everything.
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entropy
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posted October 02, 2007 08:56 AM
Edited By: entropy on 2 Oct 2007 10:20
In my experience
FactoryPro
- very repeatable hp & tq, different days, supposedly even different FP dynos (i never tested this)
- 4 gases logged (but not A/F)
- steady state load, much easier on motor (IMO)
- can simulate LSR pass; hold at WOT, 6th gear, 11,000rpm, 15sec or more if desired
but: you get single rpm points not a sweep, takes longer to get hp/tq info
Dynojet
- sweep at WOT kinda like 1/4 mi, fast to get entire hp/tq info
- get A/F, can related to on-bike logging of O2 sensor
but: hp/tq HIGHLY variable from day to day, dyno to dyno, e.g. by the time you change cams for a relative performace test, the weather can change enough to render the 2-3 hp difference due to the cam change "invisible".
IMO: Bottom line is that they are both are very useful tools.
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kllrvet
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posted October 04, 2007 06:44 PM
I love how everyone thinks dynos/operators are idiots. I guess you all are a tuning pro here...LOL
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entropy
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posted October 05, 2007 12:46 AM
quote:
I love how everyone thinks dynos/operators are idiots. I guess you all are a tuning pro here...LOL
kllrvet,
who said that???
(although in many cases it's true)
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Y2KZX12R
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posted October 05, 2007 03:13 AM
Edited By: Y2KZX12R on 5 Oct 2007 04:22
From what I've seen most of the dynojet dyno operators (8 around here) dont have a clue.
They just do what they have been tought by the dynojet tuning classes and dont actually know why there doing it.
None of these guys except for two of them have ever been inside an engine or even set cam timing on an engine.
But if you tell them the target a/f ratio you want they can get you there. Does that make them idiots? Not at all. The full understanding of the engine just isnt what they profess.
I have heard a few of them make some off the wall statements about which they no nothing about. But thats not just limited to dyno operators is it?
Vince, I've noticed everyone is quoting STD hp lately. A lot of aftermarket guys etc.
I guess it doesnt really matter its just correcting to a different set of operating conditions.
but it does add to confusion.
I hope someday the bike manufacturers start to quote SAE RWHP and wet "ready to ride" weights that actually mean somthing. They can still throw in the ramair hp number if they like.
After all you cant ride around without oil, fuel, etc. and putting the power to the ground with the countershaft sprocket digging into the pavement.
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VincentHill
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posted October 05, 2007 07:40 AM
Y2K When you are 100% correct on EVERYTHING! U Da Man!!
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Y2KZX12R
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posted October 06, 2007 03:48 AM
LOL, I just call it like I see it vince ... 
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psycho1122
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posted October 06, 2007 05:17 AM
My Dyno operator uses a "MJP" eddie current dyno. Along with the Heated Lamda O2 sniffer, he also utilizes a 4 gas. What I like to see is when he goes to the peak TQ RPM according to the base run and does a "steady state" under load and measures power output while adjusting A/F.
This process helps determine what a particular engine combo likes for A/F.
www.mjpdyno.com
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VincentHill
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posted October 07, 2007 04:00 AM
quote:
My Dyno operator uses a "MJP" eddie current dyno. Along with the Heated Lamda O2 sniffer, he also utilizes a 4 gas. What I like to see is when he goes to the peak TQ RPM according to the base run and does a "steady state" under load and measures power output while adjusting A/F.
This process helps determine what a particular engine combo likes for A/F.
www.mjpdyno.com
Those kind of Dyno's that pull the engine down until it cannot increase speed anymore Scare Me! They remind me of the Water Brake Dyno's that Puked a Lot of engines when operated too long!
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psycho1122
Pro
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posted October 07, 2007 05:51 AM
quote:
Those kind of Dyno's that pull the engine down until it cannot increase speed anymore Scare Me! They remind me of the Water Brake Dyno's that Puked a Lot of engines when operated too long!
Vince; Dyno's don't hurt engines, an engine with a weak link will be exposed!
If I go by what you are saying here, when I climb a 7% grade or more with my 07' F150 and I have it floored to the board, my engine would / should fail when I stop excellerating and actually start to loose speed?!?
No. I only have used up my avaliable power for the load given.
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Y2KZX12R
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posted October 07, 2007 07:11 AM
Edited By: Y2KZX12R on 7 Oct 2007 08:33
quote:
Vince; Dyno's don't hurt engines, an engine with a weak link will be exposed!
+1
I bet many of these stroker engines people are blowing up, they didnt use a rifle bore brush to clean the oil passages in the crank. I got quite a bit of CRAP out of the crank on mine from grinding it. Also, they need to be demagnatized. Mine had a hell of a field. Sometimes (many times) the cranks never get demagnatized all the way or at all after magnafluxing. Ever try and clean small very fine metal debree from a magnet? Cant be done. But the hot flowing oil sure as hell will clean it... right into your bearings.
Someday, I should write an engine assembly check list and do's and donts. It would scare the bagezzes out of some people who have built a bike engine, or any engine, from a so called "drop in kit". I hope no one is still "spining" piston rings on anymore. Theres so many boobie traps.
Theres really no such thing as a "drop in kit" you still need to check EVERYTHING. People supplying products are human and make mistakes, or forget, and some times they just dont know, or sometimes just dont care. The term "Drop in kit" makes me shiver.
Its all the little details that make a difference.
Nope, Its not the dyno.
Anyway... as long as your taking away enough heat under load a dyno isnt any different than on the road.
Pulling an engine back down thru the power band at wot doesnt do any harm to an engine.
We have a DTS engine dyno (waterbrake) and do sustained WOT tests all the time at different rpms for circle track engines. Watching the A/F ratio during a shift recovery test is also a tool for drag engines.
Now a bike dyno or a car chasis dyno is another story. When you are using the car or bikes coolant system to cool the engine oil and the engine it self. Without proper air flow and cooling on these types of dynos you can build up excessive heat in a hurry.
Having an air blower in front of a car on a chassis dyno isnt enough cooling to sustain wot for very long. You get heat soak and oil temps rise.
But like I said Our DTS engine dyno can hold a 1000-2000 hp engine WOT without over heating. The engine coolant and waterbrake water are the same. The tank is 1500 gallons (I think) and can be held at a constant selected temp in the tank by automatically adding city water and dumping to drain at the same time to keep the 1500 galons at the selected temp. Ususally 70-80 degrees. And you can run an oil cooler to maintain what ever oil temps you want.
We did some testing on endurance engines where they were run continiously for hours.
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