Looking for other experiences.

I recently visited a shop with a dyno dynamics dyno and I was very disappointed. I've been in GM performance and tuning for years now and have gone personally on dyno tuning days everywhere between as far north as PA, as south as LA, and as west as KS. I've literally used several dynos between various dynojets and a couple of mustangs.

The vehicle I was tuning on this Dyno dynamics dyno was a box stock LS2 TBSS. I've done a ton of these as they are one of our niche markets and a personal favorite of myself. I know that a stock TBSS typically does between 288-310 rwhp depending on AWD/2WD and if the vehicle is a freak or not. This accounts for a reasonable amount of drivetrain loss.

You can imagine my surprise when I saw 244, 247, and a 255 whp number! I told the guy, listen.. I've done lots and lots of these and that number isn't right. He then goes on to tell me how inflated a dynojet number is. lets see...

250 (avg) /395 ~ 37% drive line loss
300 (avg) / 395 ~ 25% drive line loss

which seems more reasonable?

We all know that GM doesn't OVER rate engines. in fact I recently finished a LS2 destined for a boat on a superflow engine dyno. It dynoed 480 with a very small 222/222 cam. I don't think 400 even would be a problem with the stock cam



The kicker was the operator said "well what number would you like to see?" He then starts clicking up on the correction factor until the weather correction reads 1.14. That�s when it was time to go... Not only did the dyno produce very low and unrealistic numbers the operator had the easy ability to alter the numbers. How honest is your tuner/dyno operator? Unless you put the weather station of a dynojet in a oven you are getting a number. There�s no up arrow to click on the weather station!!!


The rep later called me and tried to explain the numbers to me. This is ridiculous.. We all know its a tuning tool.. but if you step on a scale all your adult life and know your weight would you buy some random person trying to tell you your real weight is 50 pounds heavier?

Heres the bottom line..

The dynojets I've used have reasonably added up to a realistic or believable number.

The dynojets I've used have all been extremely consistant within themselves and very consistent between different dynos.. Say 3% worse possible case and typically 1-1.5% or less. (4-6 rwhp on a 400rwhp car)

Dynojet does not allow for any quick modifications to a correction factor.. Dyno dynamics is playing with fire letting their operators quickly skew or alter numbers.



I own a loading dyno jet. It has been fantastic and it meets all my tuning needs. I'm able to load test vehicles, do steady state loading and RPM/MPH holding etc. The dynojet has fantastic resolution (contradictory to what the local dyno dynamics rep told me) and superb repeatability. If my dynojet was AWD I wouldn't have needed to visit this dyno dynamics. I tell you I wish I had that 2 hours of my life and $75 back.

 

All dyno dynamics read lower than dynojet. Those numbers sound reasonable.
You could of tuned the TBSS on that and went on dynojet to see everything is fine and making good power, power you expect.
I heard they are awsome dyno's though, with the ability to adjust load.

 

244-255 whp sounds reasonable on a vehicle rated 395 at teh engine?

 

I felt the same way when I dyno'd my TBSS on a Dyno Dynamics dyno. Bone stock it dyno'd 257 whp and 273 whp after my tune. Picked up a lot of mid range torque. The print out lines were very squirrely, and when I asked the operator why he said "All TB SS's do that." I'm guessing it's because I didn't pull the Stabiltrak fuse (even though it was disabled).

 

you mean 395FLYWHEELHP.

Im not saying its reasonable (this one does sound lower than normal) Im saying they are underrated but you can still tune fine. #s dont mean anything.


IE My bros stock evo IX rated at 300hp. Made 245whp on dyno dynamics. After tuning and air intake we made 315whp. Other evos IX's that are stock dyno around 270whp on dynojets and 330+ tuned respectively.


hope this helps.
moral: yes it will read lower but you can tune fine. Sometimes better than dynojet, for turbo cars atleast that need to stimulate LOAD.

 

BTW - A local 03 Cobra that dyno'd over 500rwhp on a Dynojet 248c, dyno'd in the 430 rwhp range on the Dyno Dynamics dyno.

 

So what about my analogy with a bathroom scale? Would you like one that was off by say xx%? Why not, you know it is off by xx%? You see what I mean?

Dynojets do have a loading option with a optional eddy current brake. I have one and its fantastic.

 

The Dyno Dynamics are well known for reading low. However they are as good as the others for tuning purposes. Looks like you learned something new.

 

You're obviously familiar with variablity and statistics.

What makes you so sure it isn't a statistical anomaly?

You're also comparing brand A to brand X i.e. different bathroom scales. You've also made an important observation, there is a difference in the algorithms between the two dynos.

I'd personally be more worried about the delta (difference) between your work pre and post tunning.

.02

 

I put my old 00 SVT Lightning on a DD once. It was running 15psi with full exhaust and 93octane tune. Put down 305!! That truck should have been damn close to 400HP 500TQ. I wont find myself on a DD ever again. I know they are tuning tools, but damn at least be close!

 

I have used Dyno Dynamics. I don't know how they sell them because of the low numbers. It makes customers unhappy. But those things can hold steady state like no other!

Quite mobile too.

Dyno pack is cooler if u have the cash.

 

I've used several as well and love the Dyno Dynamic's dyno. To me it is the best dyno I've ever used.

 

my experience with the dyno dynamcis are confusion. first i love it for the tuning purpose because you can load it and hold the rpm's where ever you want. however, the numbers are low. my outlook is that so my car showed less horsepower than someone elses car on a dynojet, lets race and see who wins. my tuner was pissed when my car made low numbers. he called me to race another guy at the track who had H/C like i do. the other car made about 50RWHP more than me and he couldn't touch me on the track. i had a full half a second on him.

 

I agree with Chad, I love the dyno dynamics dyno. It is the most accurate i have ever used and gains can be seen very quickly and repeatably. The holding load is good also.


A dyno is just a tuning tool to help us see improvements in a tune. ANY dyno can be modified to make any numbers you want. It is purely a tool to make us see if we gain anything in real life. If on a dyno jet or any other dyno, if you see a gain, then you are good.

Real life drag strip is the real only way to see if your final settings make a difference.

AGAIN who cares what the dynos say or make from one to another. If im out tuning at a remote shop, and a guy makes 300 hp on his initial pull and i make changes and it goes to 330, then i made 30 more hp on the vehicle no matter what the dyno it is on. Point is, you gain 30. Who cares if one dyno shows 250 or shows 300. The customer should be happy because there was a definate gain.

 

They are awesome dynos. sure the numbers are low but what you have to ask yourself is " do I only care about some inflated dyno #'s just to pump up my ego?" or " It hauls ***. " Personally, I love the fact that I can tell a guy that my car only made 550rwhp then when the tailgate drops the bullshit stops (pardon the redneck comparison)

 

Perfectly said.

 

It's been said many times but I'll reiterate, it's about the gains, not the overall number. Until people start yanking motors and dynoing them on an engine dyno, then putting them back in the car to get chassis dyno number who really knows the the drivetrain loss is? A mustang dyno actually has the capability to determine drivetrain loss or at least get you well into the ballpark. That's a test that would have to be repeated over and over for viable results, along with a ton of factors being controlled. You're talking about turning and SUV transmission, AWD transfer case, the differentials, and big *** tires and wheels. Maybe the numbers are slightly low but I'm willing to bet they're not that far off. Your comparison to the scale is irrelevant. The pound is a standard measurement of weight that has been in place forever. With cars and dynos, there is no standard as to how you calculate hp in a dyno. That's completely evident by the different methods used from different dyno companies. I haven't even seen good evidence to show the number of rear wheel hp it takes to move a car of given weight, with given drag down a strip to a certain mph. All the calculations I've seen seem to be back calculated into a dyno number anyway and the whole point here is that the overall dyno numbers are subjective. As for overall numbers, Mark Dobeck, the founder of Dynojet has been on record stating that there are fudge factors built into the Dynojet machines. Here's a good read http://www.hotrod.com/thehistoryof/1..._creation.html

I do have a question regarding the loading ability of dynojets and dyno dynamics. How do you determine the loads with this setup? Is it by information pertaining to the vehicle or just a load percentage that you manually control?
I know with my mustang dyno I enter information pertaining to the specific car on the rollers and the machine simulates the load for that car. I have the ability to manually control the load but how do I know what percent is correct.

 

And therein lies part of the problem. Aside from drivetrain loss, there should be no reason to enter in any factors pertaining to the vehicle. A 400 hp motor makes no less hp in a 4000 pound car than it does in a 3000 pound car. The dyno shouldnt care about aero drag, vehicle weight, nothing. You should not be able to enter in any calculations to alter the numbers. Thats my whole issue with the DDs and the Mustangs, and the Dynapacks.
We dynoed 3 cars on my DJ, and then later the same 3 cars on a DD.
One car dynoed right on.
One car dynoed higher on the DD than on my DJ.
The last car dynoed lower on the DD than on my DJ.
All of these cars have since then been dynoed on my DJ AGAIN, and ALL were within a couple % of the previous time on my DJ.
To me a dyno is a tool that needs to be more than anything REPEATABLE. And a dynojet is just that. I havent seen the same thing from the others. Maybe its operator error? Possibly, but that shouldnt be a factor. You shouldnt be able to, as the operator, cause higher or lower results. It should be an 'is what it is' situation.
As for tuning, and loading, I can do things with my 248 that most people say you cant do. Dont wanna give away and "trade secrets" but I will say I can load a car pretty good. I can dial in a VE table, that needs little adjustment if any once its on the street.
Just my .02, and thats about all it worth.....

 

Has anyone ever correlated their RWHP on the dyno to a track MPH? I know it is not exact, but it can give you a reasonable idea of how close you are.

-Geoff

 

Thats what I'm saying.. I literally stood right there and watched him move the number up and down.. Where is the honesty in that? First you have a ruler that doesn't measure real numbers (who says dynojet is inflated, the numbers come out to a normal and realistic loss) Then you say you can push the number up and down at the click of a mouse.

Now that ability is completely obvious becasue there was a shop with a DD that went out of business about a year ago. We have since baseline several from that shop 20-50rwhp lower than what thier "low reading" dd read.

I know tuning is just about seeing a gain.. but hell... I want a realistic number. That way you know if your doing good + you know if somethhing is wrong. Finally, I can't give that number to a customer.. no matter what I tell him he will think there is something wrong somewhere.