Ph4tty

I assume the torque peaked at a much lower rpm with this run?

CTD2001

Peak torque came on at 2200 Rpms, which sounds about right and peak Hp was made at 2500rpms and held there till at least 2865rpms because that is where the graph stops. Do my numbers sound like they are coming in at about the right RPM ranges for torque and Hp? I hope to get on a Dynojet on Friday.

DavidTD

That's right, it CAN'T be the trucks fault, It HAS the be the dyno's fault.

My 7740 pound 24v would make 28 psi max boost unless it had a trailer on it, then it would peak at 32 psi. Did it find more power because it was heavier?

Why is it one truck with BIG chargers can make full boost and another truck with smaller chargers cannot? Yep, got the be the dyno's fault.

I stand corrected, running in the wrong gear will manipulate any dyno just as not running full throttle will.

Heated air will show as boost. Meaning, hot air is big air. Did it make more power?

All I am trying to do here is let you know a dyno, no matter what type, is a tool and that tool is trying to tell you something. Those that listen improve, those that don't blame the dyno.

bmoeller

Stock governor springs really suck on inertia dyno as well.

Particularly when you are in direct. On the dyno where he was wanting us to run in direct, we were starting the run at about 45. I max out at 60mph (3k) with my 4.10s. We couldn't really get any numbers on it. I'd hit the governor at about the snap of your fingers.

Was on the dyno at IRP this year. Runs were in OD. Did a best of 363hp/793tq.

Governor cuts me off at ~2450 rpms.

DPS- You are right on.

streetsmoker

I agree 100% with you there and it's all I'm trying to say also. All a dyno does is give you a baseline of what it is doing at that moment all the stars align when they press the big green button.

Only thing I have to say on the load vs. acceleration dyno is this: an 18 wheeler with a 500hp/1500tq. Cat. would never achive good #'s on an acceleration dyno. Does that meen it doesn't have 500hp? No, it does (or should we say it has the locked up potential), the dyno will only record what the truck can produce under certain algorithms. There are certain applications where a load dyno is the only way to get accurate readings. The only true way, using an accelaration type is to have the part of the Dynojet program that monitors engine load, and applies an eddy brake to bring up load. I do agree however they are far more consistant, and user/idiot proof when going from one to another.

bmoeller

That engine needs to see the doctor. LOL Better be closer to 1850tq.

It wouldn't be the best way to dyno a truck that made to pull, but I think it would still get decent numbers on a inertia dyno. Test drove a truck with a pre-ACERT 550hp C15 yesterday. That thing is VERY strong. It is close to rivalling my Ram on acceleration. My Ram weighs ~7600# and that T-800 is probably closer to 17-18k.

Put the hammer down on both, and they move.

CTD2001

Dave i have a question for you, or for anybody, why did the guy want to make passes on with my truck on the mustang with the overdrive off? All other dynos i have been on, including yours dave was with the overdrive on. I had to ask him/convince him to make one pass with the overdrive on. He also would not make a pull in my buddies truck in 5th gear. Dave sorry i did not get on the dyno on Sunday, it started to rain and we ended up leaving.

DavidTD

He was actually correct. Load cell dyno's should be run in 1 to 1 ratio. I haven't done any testing on what the difference is between the gears on a load cell so I am just relaying what I have been told.

One of these days, I will haul my dyno to a load dyno shop and will do some cool testing. Helps me learn too and for me that's what it's about. When I type these messages, it's not to make anyone mad, or to make my dyno out to be better than X brand. It's to try and relay what I have seen first hand while among other experience, working with Jeff Garmon on my machine building some of the quickest diesel trucks in the country. We used to cuss my machine daily, but after test runs at the track proved the dyno was right, we finally gave in and made them perform better on the rollers. I actually love the Super Flow dyno. Probably the best unit IMO on the market. Not real good for mobile use but a great machine. Interestingly enough, every time I have done comparison's with one, the numbers have been the same.

I hear ya about the rain, was a bad thing for everyone. I hated to close up with over 20 people in line, but when I was told I had about 45 mins to get packed up before the bottom fell out...

CTD2001

Yeah, that would be great to do some side by side testing with your dyno and other dynos, maybe be able to find the pros and cons of them both. Yeah i was bummed about the rain would have liked to seen if my truck would have recorded on your machine. Since that time i was on your dyno, i have had my truck on two other ones and have not had any problem getting a read out. Are you making anymore trips up here to the northeast region again?

DPS

I would like to see some pulling setups run on both dyno's vs the race setups at the same time to prove the accuracy/inaccuracy which ever the case may be. I would bet that if all things equal the dyno jet will exactly match the load dyno on a race truck and will show a large gap on the pullers. Also if a turbo is matched properly as the boost rises hp should increase because it is a denser air charge, if not then yes it is just packing hot air.

CTD2001

I will be running my truck at an 1/8th mile track tomorrow, i have never raced before so i dont know how well i will do. Any guesses on what i might be for 1/8th mile times? I was told not to power brake it for to long at the start line because every second that i am sitting at the line making boost, i will be melting down first gear. Thanks

John_P

Good discussion on the two types of dynos. I agree that there are "pros and cons" to both of them.

FWIW though,......David D. and I have made "comparisons" at the Scheid Rally the last couple of years between his Dynojet and Scheid's Mustang 1250. As I recall, diesel trucks running below 400 H.P. were within 5% of each other on the two dynos. David does that sound about right? One factor on the Mustang 1250 (Dual Roller) is tire slippage when the trucks are way up on H.P. although the Mustang 1750 which runs a single roller (like David's Dynojet) does not seem to experience those problems.

Anyway, IMO the dyno is a good "tool" to help in evaluating H.P. and torque on our trucks especially when adding modifications and wondering how much power you may have gained from it.

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John_P

thekidfan

Many opinions as this is mine, either dyno can be manipulated by driver OR operator. When comparing Mustangs or Dynojets there are many different models for MANY different puposes make sure you don't group all of one type together. I don't like dynojets that I cannot achive full boost on, that means too small of rollers OR no eddie current.....there is a reason eddie current is a option on a dynojet, they cannot properly load a truck. I have dyno'd up to 200rwhp and 24psi of boost lower on a dynojet, I have seen firsthand where a quicker spooling truck will kill a slower spooling twin truck on the dyno now tell me how that can make sense. The biggest thing to concider is if you are serious about tuning your truck don't go to different dynos stick with one, and make sure you control the variables as best you can (ie: weather, gear selection).
And BTW Mr Dunbar I completly agree that from what I have seen the Superflow is the sweetest setup dyno there is. Only problem is there is so much information available from one you just need to find out how to get it from the darn thing LOL.

jughead

did the dyno thing a few years back with my 90. measly 221 hp. took it to dragstrip a few weeks later. something didnt compute that horsepower will not run mid 9s in an 8th or mid 15s in 1/4. truck weighs 6569. needless to say i gave up on them.

streetsmoker

Or how about when I was at Brians Truck Shop for his grand opening dyno day, and the "Holly Grail" dragster of the Powerstroke crowd "Snow White" was there. A bonafied high 10's, low 11's truck and everyone watched and laughed when he only put down 478hp on a Dynojet. Yeh sure ok something just ain't right there is it? As was mentioned earlier, the higher hp trucks with slower spooling turbos, just could not build enough boost to get good #'s. Brian immediatle put in a call to the vendor who sold him the thing and found out it didn't have the Eddy current installed as he ordered and didn't have the correct roller mass for his application. All the lower hp guys were pleased, and one even had a pull that was better than he was expecting. This one guy had an '02 7.3 and said he should be about 350-375hp and he wound up pulling down a 402!!! Yours trully could only muster 490/990 that evening Suposedly the second highest at the meeting (yeah rite, NOT!) top five sure, but there was two others who had more power besides Snow White, but couldn't make good #'s no matter what they or the opperator did.