Over the last few months, I have seen some interesting results from a few different dynos in my area. One place is very optimistic, while the other, is giving a good bit lower than in the past. Examples:

A 347 foxbody dyno'd on "X" dyno, and made 447. A cam only LS1 dyno'd on "Y" dyno, and made 367. Both of these cars are manuals, and from a low roll, the LS1 with 80rwhp LESS, pulled the fox??

A heads/cam/sprayed LS1 car was said to dyno 690 on "X" dyno. I raced this guy with my car making in the neighborhood of 575, and from a 35 roll to 120-125, took the win two times in a row by a couple cars?

Then the final deal, is a lil Ford Ranger making 504 on "X" dyno, and losing to my car when it had only bolt-ons, making 354/373?

Something VERY strange is going on, with the higher reading dyno more so than the other one, although, the dyno that I and my buddies have been on, seems to be reading significantly lower than it has in yrs past.

While my car was stock, and dyno "Y" was new, it laid down 321/331, and ran high 12s. Now this past weekend, my buddy dyno'd his near stock 01 m6 camaro, and it did 292, BUT, this car went high 12s as well, with the best run being 12.81@108ish. I did the calculations, and with the same 60fts, my car would have went 12.78 to his 12.81, so the power should be nearly identical, and I know we are very comparable drivers.

Then there was an 04 GTO m6, that only made 280ish rwhp, and went 13.2@104. This is just weird to me.

The last thing, would be my car. It dyno'd at 446/411 a lil over a yr ago at the same place. I went back this weekend with the 292rw car, and mine went 430 Yet it still runs the same?

Now I understand dynos are only tuning devices, but what I am curious to know is how long is it until they need the calibrations checked? Or some re-calibrating, etc? How is that done?

 

You pose some very good questions bro. Maybe Louis at LG Motorsports, or Ron at Vengeance could chime in and give us some insight. Any sponsor though would be greatly appreciated.

 

Anything with a load cell must be calibrated often to account for drift and temperature.. which raises the question.. why does everyone think a mustang dyno is accurate or consistantly X% off from a dynojet.

 

I think some dyno's read glory numbers. I dyno over here at Baker engineering and constantly get realistic numbers. Every one else goes to the dyno's that read high. Why??? Cause they want really high numbers. The cars I tune around here always beat the cars with higher numbers down the track. I use SAE correction.

 

Unfortunatly a lot of people care about the numbers. If they go out and spend a lot of money on parts and installation, they want to know it was worth it. Even if that is just an illusion. Most people get away from the fact that a dyno really serves for tuning and diagnostic purposes. If you make a change, you want to know what that change did to the car. no matter how its calibrated any dyno will give you that information. The problem is that some people care TOO much about the end number.

The result of good tuning and dyno use is a fast time slip at the track, not a print out of what could be magic numbers.

 

Right On!

Unfortunately, I never dyno'd on a jet, Mustang only, so I really cant compare #'s. Some say 10%, 12%, 15% not sure. Its obviously important that either be properly maintained & Calibrated.. But how do you know for sure? Thats why I like to back it up with @ the track.

 

There are too many differences between a Mustang Dyno and a DynoJet to say it's a consistant percentage different. Our experiences show that at 400rwhp on our dyno (Mustang MD1100SE), the same car will have about a 6 or 7% higher number on a DynoJet. At 420rwhp on our dyno, a car will produce about 10% on a DynoJet. I personally have seen a car dyno 600rwhp on a Mustang dyno (MD1750SE) drive off, then go to a DynoJet and dyno 680rwhp without even cooling down which is a 13% difference. Now consider the differences in weight, and there's no way you can say a Mustang Dyno is X% off a DynoJet. Take into the account of some trucks I've had on our dyno. . .and the amount of loading the dyno produces luggs them down a lot due to their weight. A dyno number is exactly what it is, a number. Nothing more, nothing less. I've tuned cars that make 430rwhp, and yet run 10.65's at 3300lbs.

 

This is all good information. Keep it coming and I know I'll keep reading.

It would seem to me that the best way to find out if all of that hard-earned and spent money was worth it is to dyno your car right before the installation/tune, and then right after on the same dyno.

Even track conditions and variables can change enough from day to day to not give you an accurate read on how much you gained (have to figure in driver, temp and humidity, track prep, etc, which all changes daily). Always baseline before the modification and then dyno right after on the same dyno if you are able.

 

The way to avoid "dyno wars" is to baseline every customers car when it hits the door. We do this to show the customer the GAINS he got with our package Vs just big dyno #s.... Showing a customer that he picked up X amount of power/torque at x rpm over his old combo shows what his money did for him.

Our dyno has been said to be high by many people on the internet because of the #s we produce, BUT the locals around here always seem to be a lil upset when they stop by for 3 pulls compared to some of the other dynos in the area.

 

I made 470rwhp on a Mustang dyno and went 10.54 @ 130 in a 3850lb car

 

I made 544 rwtq on a Mustang Dyno and broke da 10 bolt. LOL

 

Just like they make 'vanity' sizes for women (call it a Size 4 when it's really a Size 6!), it sounds like some shops are doing vanity dyno numbers. We've suspected it for a while around here, so I'm glad this thread came up.

Jim

 

I understand that it's a tuning device, but, what is odd to me is how this dyno me and my buddies have been visiting isn't showing the type of results it did a yr ago. I was just curious of the calibration checks needed, and all that. There's just no way my car dyno'd 321/331 and ran 12.9s, and my buddies dyno'd 292 and went 12.8s. The same 60ft would put them within .003 of each other, and even the traps were close, no where near 29rw difference. I just don't think this dyno is reading the same as it has in the past.

 

In your situation, looking at dyno numbers vs. ET isn't a good comparison. Dyno numbers vs. MPH(figuring both of you are decent drivers) is a better one, but even then, you're comparing when your car was stock(how long ago was that) vs. what your buddy dynoed this weekend. Even with SAE correction I've seen the same car with the same mods dyno higher when it's cold vs. in summer heat. A lot of things affect the numbers, which is why I could care less.

Here's some personal instances I've encountered:

My car dynoed 333/345 with stock clutch and stock 16s. It now has a SPEC and 18" Z06s and 30k more miles. It would prob. dyno less but it traps 108mph vs. 105mph back when it it had the stock clutch and shitty tires on the 16s.

My best friend had a 347 fox that dynoed less than 400rwhp at the wheels(Bogarts and 28" ET Streets) and ran 6.8s in the 1/8th. On the 150 shot it made a tad bit over 500(can't remember exact numbers but it was between 500-525) and ran 6.08 and 9.55 in the 1/4.

Another one of my close friends had a 02 SS with a Vengeance 416 with TF225s that dyno'd 524rwhp with true duals, 6spd, 17x11 chrome ZR1s with 555Rs. 9" with 3.73s and steel DS. It went 7.35@101mph on a 1.8 60ft and granny shifting the ONE time it went down the track before he sold it. That was in a full weight fully optioned 02 SS on 17x11s with the shittiest drag radial you can run on a high HP car. It hurt a LOT of car's feelings that were making more "dyno hp", I can promise you that.

Dyno numbers ain't **** to REAL racers, they are for gettin' your **** running right so you can have a REAL number....a timeslip.

 

I know in the end its the slip that counts, I'd just like to understand it all. And yes, our mph was VERY close as well, and getting stock LS1s in the 12s should indicate we're pretty good drivers

 

If want to see real gains then use the same dyno all the time. Our dyno has been very consistant on the cars we do when they are redyno'd at another time. There are alot of shops that will spit out a magic # for a dyno sheet for a customer.Lets face it ,99% of the people that dyno want the highest # they can find to brag about. We are mostly a drag race shop so the dyno is just a tuning tool for us.The track shows what the car really does.

 

I agree with that, I prefer to dyno after each mod so that I can get a true gain result. Obviously, any suspension mod must go to the track or out in front of the crib.. LOL

 

I agree about the track numbers vs. the dyno numbers. But every one wants SAE Dyno numbers but no one wants Corrected track numbers. Here on the East Coast from SC to NJ we get great air and the tracks are mostly just above sea level. So our cars run great for the amount of power they are making. My car only makes 465/426rw SAE on a Mustang Dyno and ran 10.8's@130 on the first time out. It was actually making a little less then. Now take my car to LACR or Bandimere and see what happens. I would probably run 11.5's@125-7. I have seen the DA as low as -2,000 in the dead of winter here. Some tracks never see +2,000 on a good day. Why do you think all the best times for cars come from the East Coast in winter time. I think comparing track time is useless as well, unless you compare them Corrected. The day after I ran the 10.8s@130 I took the car to the dyno in the same weather and put down 465/430 Uncorrected and 460/424 Corrected. Last week in 20* cooler weather I went back to the same dyno and put down 486/445 Uncorrected 465/426 Corrected. So when I take my car to the track in like weather next time it will go at least 2 tenths and 2mph faster. The track shows your uncorrected hp/tq. My point is, like others have said, is to find a dyno and a track around where you live and do before and after testing on both. That is the only way you are going to be able to tell what is really going on. You will never race all the guys on the internet so don't worry about what they say. Just beat all the guys around you and you will know who is the fastest.

 

Another unappreciated factor to consider is I seriously doubt that many dyno's weather stations ever undergo any calibration, especially with atmospheric pressure and humidity.

Even the most expensive barometers are calibrated monthly. I've seen good ones be off .030 of an inch a year. Add that to being off 10-20% in humidity, and now your SAE readings are off as much as 5-10%.

While there could be numerous factors involved, that would be my hunch how the same dyno would begin to have erroneous readings over time.

I like the before/after concept of dyno testing. At least on that particular day you are pretty much assured of the gain/loss results.

No dyno expert, but testing a few dyno's up here at Mile High on hot summer days and bringing my own weather station along..a few times I saw variations in their weather data that made readings about 4-5% off.

In essence track testing encounters the same dilemma. That track time may simply just reflect how much air got into your engine on that particular day, which depends on air temperature, pressure, humidity, driver ability etc..

Something to consider..WeathermanShawn..

 

I don't think some of you understand, I DO use the same dyno EVERY time! The other "high" reading dyno is one some other people I know have went to.

Thanks for everyones replies so far.