Dynamometer Types and Number Validity

RonA said:
I liked the Super Flow dyno that was over in Fortuna. Drive in the room, close the door and the big fans take care of the smoke. When that thing applied the load, you better be ready.
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Ron I hope one day you will like ours too. I wished it wasn't raining last weekend so that we could see your truck run.
 
In the end here, I think the point I invalidated from his original post is, in the case of a dyno, that location and weather matter. The dyno doesn't change enough to measure a noticeable difference (rollers expand or contract based on temp. Infact, wouldn't the measuring tape also expand too?)

However on a motor, the difference in oxygen, humidity, etc, etc, etc, content is significant enough to matter and show a measurable amount of difference if you are using un-corrected numbers. Hence the entire idea of of corrected data.
 
StrokerDude said:
so you're telling guy who started the thread that this thread is not about what he started it about.... Now that's smart.

And your comments regarding Fords... You're an ignorant a-hole... Crawl out of your little freakin hole and look at what Ford are accomplishing now!
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Alex 496HP is nice for a 6.0 but Ryan says until you break 500 we still have to call you Alexis:poke:.
 
Wrightman said:
Ron I hope one day you will like ours too. I wished it wasn't raining last weekend so that we could see your truck run.
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I've was on yours at Ponci's event. I liked it(it lets me win sometimes :hehe:).
 
JasonCzerak said:
In the end here, I think the point I invalidated from his original post is, in the case of a dyno, that location and weather matter. The dyno doesn't change enough to measure a noticeable difference (rollers expand or contract based on temp. Infact, wouldn't the measuring tape also expand too?)

However on a motor, the difference in oxygen, humidity, etc, etc, etc, content is significant enough to matter and show a measurable amount of difference if you are using un-corrected numbers. Hence the entire idea of of corrected data.
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And I will forever try to explain to you that in reality, just using uncorrected values from a Dynojet 248c will yield the most consistent results.

As in... I have gone back to the dyno weeks, or even months later and pulled numbers within 1hp of my last session on the same setup. I have noticed this when I go back to re-run as I was setup last time, and then make the change to see the difference.

I can't count the number of times on one hand that I've gone back and overlayed the new line right on top of the old one.

I have made over 130 pulls with this truck over the course of the past 7 or 8 years now. If there were something substantial to be seen with subsequent run consistency I imagine I would have seen it by now.

But that's just me. Course I might also be the only one that ever notices that 99% of the time you hear about joe-blow making a bunch more power than anyone else on a known setup, it's just always happening on a load cell dyno, not a 248c.

Anybody else ever notice that? Either that or he's dynoing the truck up at elevation and the correction factor is stupid high.

Maybe you would like to tell me why the trucks usually seem to dyno stronger at higher elevation than at sea-level when a CF is used. Am I the only one that would expect lower power output on the top of a mountain if anything?

Correction Factors are bs. A corrected number is not an ACTUAL reading. The engine did not ACTUALLY make that power. Maybe I'm the only one that has a problem with fake numbers?
 
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NickTF said:
Gm's dyno numbers are right on if not conservative in my experience with their gas motor vehicles. Ford, well, they are all over the place.
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I was gonna say that too, but figured it was more of a generalization than anything. And I didnt want Charlie to beat me up!
 
where is you local dyno? is it in a controlled room. same temp year round? same humidy for the most part if it's in a building? if so, I would expect and stand by your with in 1hp claim. now take that dyno and move it to 14,000 foot, in a room the same temp and humidy. you will dyno less. appl correction factors in both locations, in theory it should calculate out to the same

the entire point of correction factor is to allow though a basic math formula every one to compare results on a similular playing field. nothing more
 
After reading all the posts I decided to add my $.02......... I have dynoed hundreds of times at many different locations. What I can say about CF for our trucks is that they are way off! Dyno around SL and then go to Denver and give the rollers a spin, the CF will add a ton of power. Now if you do them both uncorrected the numbers yielded will be very close to the same. Temperature and humidity play a part but the altitude corrections are just inaccurate.

Dyno's (all of them) are good for one thing and that is measuring the power output of an engine. Now that being said one needs to use the same tool for the job to be able to accurately and consistantly have good data. So for me this means the same brand and model dyno (normally a dynojet 248c). This dyno has yielded very repeatable numbers from one location to another if no CF is applied. As long as you use the same brand and model dyno your numbers should be resonably repeatable. The key is a dyno is a tuning tool, use it to determine if changes you have made yielded the results you are looking for.

The engine only knows oxygen density and a turbo charger allows for us to keep the density at a specific level. Aircraft have used turbos for years to allow them to maintain a specific HP to a specific altitude. At some point the air becomes too thin and the turbos too inefficient to allow for a specific HP to be obtained but this is normally well above 5000'. Our atmosphere is about 1/2 density at 18,000' but the difference is not constant. The O2 density at 9000' is a lot more than 2X that of 18,000'.

So what does this all mean..... Well it means that altitude does play a role in HP even on our turbo charged trucks. But that role is very small until we reach an altitude that is pretty high and I really doubt there are any dyno shops at an altitude much above Denver's 5000+. So for me uncorrected numbers are the only way.

Doug
 
Jetpilot said:
After reading all the posts I decided to add my $.02......... I have dynoed hundreds of times at many different locations. What I can say about CF for our trucks is that they are way off! Dyno around SL and then go to Denver and give the rollers a spin, the CF will add a ton of power. Now if you do them both uncorrected the numbers yielded will be very close to the same. Temperature and humidity play a part but the altitude corrections are just inaccurate.

Dyno's (all of them) are good for one thing and that is measuring the power output of an engine. Now that being said one needs to use the same tool for the job to be able to accurately and consistantly have good data. So for me this means the same brand and model dyno (normally a dynojet 248c). This dyno has yielded very repeatable numbers from one location to another if no CF is applied. As long as you use the same brand and model dyno your numbers should be resonably repeatable. The key is a dyno is a tuning tool, use it to determine if changes you have made yielded the results you are looking for.

The engine only knows oxygen density and a turbo charger allows for us to keep the density at a specific level. Aircraft have used turbos for years to allow them to maintain a specific HP to a specific altitude. At some point the air becomes too thin and the turbos too inefficient to allow for a specific HP to be obtained but this is normally well above 5000'. Our atmosphere is about 1/2 density at 18,000' but the difference is not constant. The O2 density at 9000' is a lot more than 2X that of 18,000'.

So what does this all mean..... Well it means that altitude does play a role in HP even on our turbo charged trucks. But that role is very small until we reach an altitude that is pretty high and I really doubt there are any dyno shops at an altitude much above Denver's 5000+. So for me uncorrected numbers are the only way.

Doug
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pretty much the way i feel. i remember maddog telling me he NEVER trusted a CF over 1.04 ...at altitude. i believe him. since then, i only state uncorrected #'s , be it lower or higher than the correction itself.
 
My butt dyno is almost always 100% accurate. Altitude has very little effect on final output numbers but they can be altered if I'm trying to sell you a performance part or alcohol is involved while tuning. The only other issue I've had with it is if someone puts a "performance sticker" on the vehicle i.e. "JEGS" it's hard calculate the actual HP gain but we all know it's there.
 
Interesting. Having some trouble finding a stinking webpage that isn't a "forum" with any real data on SAE correction factor. As it sits, I'd have to say it's a made up term since it's un-google-able LOL

Who's dynoed an N/A motor in different locations? How accurate are thoese correction factors?

I've done some searching here and there on forums. There are folks that run slower on the hill then they do on the flat. sometimes .5 faster in lower elevation. I'm curious is these folks are like me, they run the turbo to the end of the map.

JetPiolot, you keep your turbo's in the middle of the map or push them to the edge?

The dyno is located in Elk river, mn with an elevation: 896 FT (273 M). There isn't much lower then that. I'll be on my way to Detroit are this summer and it isn't much lower then MN (600-ish feet)
 
How do you explains McRat's ET difference? MPH is hard to "cheat" with a bad 60foot, and that's clearly different as well.
 
If your trying to tune your truck to make more power any UNCORRECTED dyno will give you accurate gains or losses, as long as all the parameters are kept the same for the load type dynos. But if your trying to compare your truck to what everbody else in the country is making for hp a 248 Dynojet UNCORRECTED is gonna give the fairest playing field for everyone to measure up against bar none because of their consistancy.
 
Dockboy said:
Dyno on Dunbars 248C - 1800' SAE CF 1.04

758 SAE
729 Uncorrected

2 weeks later.........

Dyno at SGS Automotive 248C - 300' SAE CF 1.00

728 SAE
728 Uncorrected


:poke:
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The only point I'm curious about is, what Charles was talking about earlier. how well matched are your turbo(s) and how far are you pushing them? It's gota be connected to how some folks run slower in elevation.

Take top fuel, they run slower in Denver. Yes, their are not turbo, however, they do.

SAE is still a workable formula, just the exception is mostly true to turbo's.
 
JasonCzerak said:
How do you explains McRat's ET difference? MPH is hard to "cheat" with a bad 60foot, and that's clearly different as well.
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I don't doubt one bit that there is a difference in power output at sea level with cool dry air vs high elevation with hot humid air. No doubt in my mind it makes a difference. All i'm saying is that i think the correction factors that are built into the software programs on all these dynos are not at all accurate on our turbocharged diesels.

You will be much closer to the truth using an uncorrected number then you will be by using a corrected number. With our trucks, corrected = inflated IMO.

My .02

Chris
 
I'm new here but came across this discussion and felt an obligation to respond.

If? and I do mean IF? this is the same Charles from PSN be warned that responding to any of his posts is hazardous. He'll state some 20 paragraph nonsense disguised as fact that is so obviously retarded that you can't help but put him in his place.
As soon as you respond to him it's like a virus, he will attack you personaly hoping that it will be enough for you not to respond again.
If you do shoot back he will fill 30 paragraphs and possibly a couple charts, graphs and pictures he drew in crayon to prove his point.

My advice is don't respond, he's not capable of serious discussion and not smart enough to understand why he's wrong. Take this discusion. Is there anybody left on this planet that doesn't know that temp, alt, BP, and anything else can produce differing reading on any dyno? That's common sense and reason, Charles has neither.
I think of him as "Raymond Babbett" from the movie Rainman. While to an outsider he may show flashes of genious, $1000 cars and candybars get him every time.

Let's go home now Chuck, it's time for Wopner, you like Wopner, yes you dooo!
 
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