Dynos - what differences in brands?
 

I went to Exhaust Readers in Colorado Springs today to see what they look for while doing a diesel emissions test as my Oklahoma tag expires this month and I'll have to get a Colorado tag very soon. I told the guy there that I basically have a TST 10 plate but still have stock exhaust including the kitty. He checked under the hood to see if the break-away screw was still on the pump and said it was OK if it had been replaced - they basically look to see if the cat is still there (whether its working or not :)) and then check for opacity of the exhaust while running steady speed on a dyno at 60, 50 and 40 mph.

I then asked if they could use the dyno to see what the max power my truck produced as its currently setup and they said sure. I told him I thought it should make somewhere close to 300 HP and 700 TQ and was just curious what it actually measured on a dyno. Now his response to this is what surprised me. He said in all the years he's been testing diesels he hasn't seen ANY diesel pickups make more than 300, or just a little over at most, at the rear wheel - period! I asked what dyno they used and he said it was a SuperFlow unit, supposedly rated to test any vehicle up to 1000 HP.

Now, I started wondering, is the SuperFlow dyno that much different than dynos that are used other places, to the point that it produces much lower HP and TQ measurements than others? I tend to think it shouldn't be ANY different or at least not all that much.

So, to all you guys who've run your trucks on dynos or know about these things, what is your take on this? Is the SuperFlow dyno really different than others or is this guy full of you know what?

Steve

I dont know about the Superflow but a mustang dyno will read lower numbers than a dynojet.

The Superflow unit is supposed to be the end all to dynos...I think it is a load type, not the acceleration type:D

Depends on the actual model of course:)
Chris

I believe the SF901 is a load-dyno, but eddy-current.

Basically, the SF measures accleration rate (like an intertial), but it can vary the load that the truck accelerates against (which the Dynojets can't do).

So think of it as a Dynojet that you can change the weight of the rollers on the fly.

I could be totally wrong, as always.

BTW-- my truck did 390/918 on a DJ248C, and 349/904 on a SuperFlow. This was with the EZ and DD2s.

It feels stronger now with M4s and various ECM tunes.

jh

A Dyno with double rollers is the ONLY dyno to use.

similar to this one at this shop:

http://www.dynocomp.com/tuner.php

sensitivity and the ability to simulate loads is the only way to dyno.

Spinnin a large drum is, well, innaccurate.

The guy that runs this shop here in AZ owns a 80s dodge charger too.. cant beat that ;)

a true load dyno will give much lower numbers... John at Floor-It Diesel(Lawrence Kansas) has one and I believe it has been named "Heartbreaker" for obvious reasons.

Double roller dynos are ok up to about 400 to 450 hp. Above that, there is tire slippage and the readings get inaccurate. Two 8.5 inch rollers just can't hold the power and torque of these diesels, like a large single roller can.

An inertia dyno, such as the Dynojet, may not be the most accurate for our trucks, but its design allows it to certainly be one of the most consistant in readings form dyno to dyno. For a NASCARs, the Dynojet is very accurate, because it was designed to simulate their weight. The drum wieghs 3200 or 3500 lbs, I believe.

Loading dynos are ok for consistancy as long as the loading is the same from run to run and dyno to dyno. There is a local diesel shop around here which uses a Mustang dyno to sell its performance products. If you bring in your truck to them with brand X injectors, it's no surprise when you change over to their's there is a power increase. The Mustang readouts can be changed by changing the load.

Thanks for all the comments guys. I haven't taken Moby in for the sniff test yet but when I do and I get the dyno numbers from it I'll post what their system says the ole truck's power output is.

Steve

Do you know what thier rates are? I found some on the events page, but I'm curious about regular prices.

Randy

A LOADING dyno is the only piece of equipment capabile of actually being called a DYNO. The rest is an approximation of power and torque which come from timing the rate of RPM rise of a known weight of roller assembly.

The SF's are loading dynos. Whether they are eddy current or water brake does not matter. They measure torque phsyically with a toruqe arm and load cell. This is REAL torque. The different SF models just vary in how they dump the energy, either eddy current or water brake. The inertia only factors in if you are doing a ramp test, and the SF's can do that, but THEY STILL MEASURE REAL TORQUE, not like the other 'make the owner happy' inertia only units out there...

A LOADING dyno is a real DYNO, and you can bet your house on the numbers. It measures torque directly. Once torque is directly measured, HP is calculated by a formula which never lies.

Inertia 'dynos' are fantastic tuning tools and are used by lots of race teams, but they use them as a RELATIVE tool.

If your goal is to measure TRUE AND ACCURATE Torque and Horsepower levels, then there is only one DYNO... its a LOADING DYNO.

Just think about it... statements like " an X dyno allways reads higher than a Y dyno, and the Z brand dyno is usually in the middle...." is indicative how none of those brands are actually dynos, and the numbers they print out mean nothing. If you make a pull on an X dyno and then make a mod and go back to the same dyno to check the mod, then that's fine. They are only relative but the HP Torque numbers mean NOTHING.

If the brands X,Y and Z were all real dynos then each one would meausure within a few FT*Lbs and HP of the others, every single time, and those Torque and HP numbers would be REAL. Period.

Again, I think an inertia 'dyno' is a terrific tool, but it is CRIMINAL to call it a DYNO.



KP

for many of us, its just bragging rights. its just a number.

does it really matter where you sit as far as the number on a piece of paper? what matters is knowing that extra power exists on the street, strip, track, etc. by looking at the weight moved, the speed and times.

im guilty of it, look at my sig as i have HP/TQ numbers. but after dynoing, my truck wasnt any faster on the street it just allowed me to say i was at X hp and Y tq.

would i dyno again? yes, as i would like to find a load dyno.

but a load dyno (during a ramped run) should be able to load the truck to allow the RPM rise you see on the street in YOUR truck, not just some arbitrary load...that way you dont get overloaded or underloaded and should get the numbers you make when driving the truck. no doubt it would tough, as the dyno would need to speak with each different truck, capture their RPM rise during a WOT drive up to redline in some gear, and then replicate that on the dyno.

Can it be set to a lower resistance than a Dynojet...thereby yeilding higher hp #'s?

RJ

That's where I have to get mine sniffed every year. Your going to get 3 results back the 3rd number your going to get is the 60mph number but watch out if it goes into OD your numbers are going to jump big time or that's what I remember from last year. Nice people, they will calculate the numbers for you if you ask, they make no sence on paper, you have to calculate the rear tires, rear end and what gear the test was done.

Bill.

The NASCARs using the Dynojet would probably successfully argue against your statement - unless I don't know what the maeaning of DYNO is. The Dynojet was designed to simulate the weight of a NASCAR on level ground. Besides, hp is measured by the amount of work done. If you're accelerating a known mass through a given period of time there's no approximation of the amount of work done. It's a known factor which is as accurate as sampling rate of the computer taking the readings. What loading dynos are able to do is simulate different vehicle weights and climbing hills etc. and measure the amonut work being done which isn't necessarily in an acceleration mode.

Dyno and sniff test finally done
 

Hi all. I finally got the truck emission tested today at Exhaust Readers. I wasn't sure what the opacity results would be but suspected they might be a little high. Well, they were indeed high - too high to pass the test. :mad:

First of all, just a little data to let you know the test environment. They use a Superflow 601 load dyno. The state calls if a 'Light duty vehicle dynamometer lug down test". The truck is run at 40, 50 and 60 mph in direct drive gear - 4th gear in my case. My test results were as follows.

60 mph - 86% opacity
50 mph - 70% opacity
40 mph - 76% opacity

The tester wrote my year vehicle is allowed 35% max at each speed. Obviously it was WAY over that.

Now, for the power figures they measured. The HP figures were listed clearly on the test sheet but the torque figures are hard to figure out. You'll see what I mean below.

VehPwr VehSpd R1 Trg
297 60.4 2752
274 50.6 3033
222 40.8 3045

The HP numbers don't surprise me too much since I have a home-ground version of a TST 10 plate and only have a BHAF to help ingest more air and don't yet have a 4" exhaust to get the spent air out and all this using a stock HX-35. Can anyone shed any light on how these torque numbers can be used to figure a more typical torque like I see in most posts? I read these can be used, knowing the axle gear ratio and the tranny gear ratio used during the test. My axles are 3.54 and the tranny was in 4th (1:1).

Also, to continue the saga, I now have to figure how to get the opacity levels down so I can get new Colorado license plates. I went to one truck shop and their top diesel tech convinced me to buy a product called Pro Tec Diesel Fuel Conditioner. He showed me their sales brochure in which it shows a heavy duty diesel pouring lots of smoke out the stack before using the treatment and another picture after. The second photo showed almost no smoke. He claimed he uses this just about anytime a customer needs to reduce smoke and says he has several customers with heavy duty rigs that have used it to show DOT folks they've fixed their excessive smoke problem they got pulled over for. I haven't used it yet as I'm trying to get more info on whether or not it really does work as claimed before putting it in my tank. It's $30 for a 375ml can and the whole contents are supposed to be used in one tank of fuel. Anyone hear or know anything about this stuff?

Another idea I had was to find a stock plate and simply put a stock plate in for the test then swap back to my performance plate until the next test time. I found a plate that is supposed to be from a 95 CTD that I'll try. It doesn't have the same profile as my original plate but I figure I can use it, at least for the test, to get the results I need to get plates each time I need them.

So, there you have it. As always, any feedback on figuring "real world" torque as well as whether I should try this Pro Tec conditioner or not and any thoughts on using the stock 95 plate for testing will definitely be appreciated.

Steve