Dyno didnt seem right...thoughts?

jlibert said:
Do you have any experience with dynojets? Brown's Diesel's 248 with semi-heavy rollers is very consistent--Less than 1% difference between runs. any more than 1% difference would be worthless. Your superflow with "A FEW % difference would hardly be considered consistent. That would be over 20 hp on most the trucks owned by members of this forum.

If runs are conducted in the same fashion every time, my truck can hit within 1 hp in three runs. Bring boost up to 10psi, 62-63mph and start the run. Same hp, same curve.

Your experience with dynojets is not consistent with what i've seen them do.
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You didn't ask the right question, and I wasn't specific enough.

We were carefully logging intake manifold temperatures and were getting 10 to 15 degrees hotter on each run, and as such the curves would drop a bit each time...like 5 - 8 HP each time.

That's because of the wicked load being applied for about 10 seconds total.

Have you ever run on a SuperFlow? For those who have never done it, you tell the dyno what rpm band you want to measure over. Since I have an auto, we needed to keep it from downshifting. For me, we ran from 55 to 95 MPH and this RPM band was wide enough to capture what we wanted in 1:1.

Anyway, you roll up against 55 mph and the dyno will not let the engine accelerate. So you go to max load right off the bat...the engine comes up on full boost and then you release it to scan over the RPM band for about 8 seconds. It can be made MUCH longer if you have the balls to do it (and the absorber is big enough and cooled enough). I have heard of guys going 30 seconds or more at full load, but it's rare.

Point is, the engines are worked very hard and make a lot of heat. UNLIKE your inertia roller where it's all over in 2 seconds or whatever. You're at max load for an eyeblink by comparison. And therefore you make nowhere near the load and nowhere near the EGT and coolant temps you do on the load cell rollers. So you appear to have a super-repeatable number....and you should! You're just zinging the motor a few times. How accurate is it? Who knows?

This is why people rarely see the EGT and boost they do on the street with an inertia dyno.

It's pretty much common sense.

If you want to prove to me that inertia units are the best thing since sliced bread, show me a regression curve where you have plotted your 1/4 mile trap speeds against your dyno numbers. I've never seen it done....and I have my guesses as to why.
 
Holy crap, I havent been on this forum for close to a year, and I see we still have 'dyno' threads.....:hehe::hehe:
 
the engine comes up on full boost and then you release it to scan over the RPM band for about 8 seconds. It can be made MUCH longer if you have the balls to do it (and the absorber is big enough and cooled enough). I have heard of guys going 30 seconds or more at full load, but it's rare.
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Anything much past 12 seconds makes the really scary smells on even a stock to mildly modded truck. The tests that make me close my eyes and pray are the ones were you take it to max rpms and pull it down to 1000-2000 rpm. :charger:
 
nwpadmax said:
You didn't ask the right question, and I wasn't specific enough.

We were carefully logging intake manifold temperatures and were getting 10 to 15 degrees hotter on each run, and as such the curves would drop a bit each time...like 5 - 8 HP each time.

That's because of the wicked load being applied for about 10 seconds total.

Have you ever run on a SuperFlow? For those who have never done it, you tell the dyno what rpm band you want to measure over. Since I have an auto, we needed to keep it from downshifting. For me, we ran from 55 to 95 MPH and this RPM band was wide enough to capture what we wanted in 1:1.

Anyway, you roll up against 55 mph and the dyno will not let the engine accelerate. So you go to max load right off the bat...the engine comes up on full boost and then you release it to scan over the RPM band for about 8 seconds. It can be made MUCH longer if you have the balls to do it (and the absorber is big enough and cooled enough). I have heard of guys going 30 seconds or more at full load, but it's rare.

Point is, the engines are worked very hard and make a lot of heat. UNLIKE your inertia roller where it's all over in 2 seconds or whatever. You're at max load for an eyeblink by comparison. And therefore you make nowhere near the load and nowhere near the EGT and coolant temps you do on the load cell rollers. So you appear to have a super-repeatable number....and you should! You're just zinging the motor a few times. How accurate is it? Who knows?

This is why people rarely see the EGT and boost they do on the street with an inertia dyno.

It's pretty much common sense.

If you want to prove to me that inertia units are the best thing since sliced bread, show me a regression curve where you have plotted your 1/4 mile trap speeds against your dyno numbers. I've never seen it done....and I have my guesses as to why.
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On a given truck -- say yours for example.

Would the hp / tq. numbers be any different on a superflow vs. a dj with heavy rollers?

I have no experience with superflows.
 
jlibert said:
On a given truck -- say yours for example.

Would the hp / tq. numbers be any different on a superflow vs. a dj with heavy rollers?

I have no experience with superflows.
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Depends on how good the tune up is. If the tune up is spot on they will read very close. I went 507 on a DJ 248 and 505 on a Superflow with the same tune. Where the Superflow shines is if your tune is not spot on. The first time I was on a DJ 248 (Dunbars dyno in 06) I dyoned 458. My power curve looked good but it leveled off at 2600rpm and held flat to 3200 then started back down. I messed with the tune alot from 2600 up but never made any headway. Got me down some. Then I dynoed on the Superflow. NWPADMAX was there. I dynoed on the best tune I had that was proven. The one that went 458 on Dunbars DJ. What I saw suprised me. I dynoed like 504. Wahoo!:rockwoot: But power was down and kind off flat around 2000rpm but really jumped up at 2600rpm and was strong from there on out. I simply had to much timing and fuel at 2000rpm to 2600rpm. I backed that off and got the curve looking much better. Dynoed 505. Went Iwent back to the DJ 248 it dynoed 507.:rockwoot: That is a good example of where a DJ 248 can decive you. Mind you this was with a stock LB7 turbo. Bigger turbos are more sensitive yet. That is where the Superflow shines. I am not knocking the DJ 248 at all but it can be decieving if things are not just right with your setup.
 
jlibert said:
On a given truck -- say yours for example.

Would the hp / tq. numbers be any different on a superflow vs. a dj with heavy rollers?

I have no experience with superflows.
Click to expand...


That's an excellent question and I think you're looking at it correctly.

Yeah, I believe a VERY heavy roller on a inertia unit could work....but I don't think anyone builds 'em that heavy yet. I was talking to the folks at Dynocom and they were talking about making a roller equivalent to a 7000 lb vehicle.
 
JOHNBOY said:
...Bigger turbos are more sensitive yet...
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I agree. The problem with many of the trucks on here are doing just that, with big singles.

Twins probably make the situation better.

And since the Cummins engines can't be "tuned" like a Dmax can with EFILive, the setups are almost always a heavy compromise. Getting the big ones lit on a non-load-cell dyno is impossible. Can you imagine seeing Cory Atley's truck on a chassis dyno? I don't think it would do anything but smoke the building out.
 
J Anderson said:
Anything much past 12 seconds makes the really scary smells on even a stock to mildly modded truck. The tests that make me close my eyes and pray are the ones were you take it to max rpms and pull it down to 1000-2000 rpm. :charger:
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You and I think alike....I have always wanted to do that one but haven't got the balls to do it yet on the stock internals.

I was wondering if you ever got nervous standing down there underneath my truck. I'm not quite comfortable with being on the lift, have to tell ya.

Where's my data files, John? :D
 
nwpadmax said:
That's an excellent question and I think you're looking at it correctly.

Yeah, I believe a VERY heavy roller on a inertia unit could work....but I don't think anyone builds 'em that heavy yet. I was talking to the folks at Dynocom and they were talking about making a roller equivalent to a 7000 lb vehicle.
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You have to get on a 248 with heavy rollers. I forget what Erick at Brown's said the wieght of the drums are, but it's not in pounds-- it's a term I've never heard before. You'd probably know it.

Anyway, I've been on several 224's, and even a mustang dyno. None of them loaded my truck the way this dyno does. I'd always see about 10 psi lower boost than I'd see on the street, and it would build much slower. At Browns, it comes on fast and I see exactly the same boost I see on the street.

Thanks for the insight on the superflow.
 
nwpadmax said:
You and I think alike....I have always wanted to do that one but haven't got the balls to do it yet on the stock internals.

I was wondering if you ever got nervous standing down there underneath my truck. I'm not quite comfortable with being on the lift, have to tell ya.

Where's my data files, John? :D
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Nah, I don't get nervous. Besides, I have really good insurance. (health and shop :) )

I almost have those data files finished. Another day or so.
;)
 
J Anderson said:
Nah, I don't get nervous. Besides, I have really good insurance. (health and shop :) )

I almost have those data files finished. Another day or so.
;)
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Cool. My junk is alive again so we need to schedule visit.:rockwoot:
 
kinda off topic but why does everyone hate dynocoms they load as good as not better then a superflow, after they are calibrated right they seem to be real close to superflows, but there are not many of them around from what I have seen at least not ones capable of running diesels with huge drums
 
If you guys want a real dyno number take it to a semi shop where they put it in a controlled room, run it up to max throttle, rpm, and start pulling it down till almost killing the engine then back off a **** hair (red one) and hold it for a set amount of time. This is how tractors are dynoed too.

I was told that the drums on Dunbars weigh like 6000 lbs. So if the drums dont weigh as much as the truck, it is not going to load it as hard as street accelerating right?

We dynoed my brothers truck on Floor-its dyno in coffeen Il and it was a dyno dynamics load cell dyno. I have had this up a long time ago but for this thread i will link it again.

YouTube - jeffs dyno

This was all stock motor with 300 marine injectors (40 horse), full cuts, gutted afc, no plate, 27* timing, CDS 5k springs and a silver bullet 66 and a stock fuel supply system. 525/ 10??

YouTube - jeffs dyno
Here is the one from Danville In at the hoosier blackout. Everything is the same except the injectors which are 5x18 dual feed customs and 22* timing
591/11??
Tim
 
so a superflow can load a truck harder then on the road? or more similar to a sled pull/or drag strip run?
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Yes and yes. I would have to look to be sure, but I think the spec on my dyno is that I can hold 1200 horse at a steady rpm for 8 minutes before the dyno overheats. If you have a truck that can stay together at that power level for 8 minutes, I would love to try it.

Cool. My junk is alive again so we need to schedule visit.
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Cool.
 
J Anderson said:
Yes and yes. I would have to look to be sure, but I think the spec on my dyno is that I can hold 1200 horse at a steady rpm for 8 minutes before the dyno overheats. If you have a truck that can stay together at that power level for 8 minutes, I would love to try it.



Cool.
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1200? i think im ~700 shy of that mark.... best I've done si 463 on a DJ

pending egts truck "should" stay toegether

need to setup an app as well here soon
 
kmkdiesel said:
kinda off topic but why does everyone hate dynocoms they load as good as not better then a superflow, after they are calibrated right they seem to be real close to superflows, but there are not many of them around from what I have seen at least not ones capable of running diesels with huge drums
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I've heard the same thing. Dynocom is rather new to the scene as I understand it and they don't have the numbers of units in the field as that of the other established brands.

I talked to them a bit and they seemed very open and willing to discuss a lot about the product. At the time they had both inertia units and load cell units.....and for the diesels they had a big absorber and a Really Big Absorber...they even sent me the absorption curve and it was into the thousands of foot pounds IIRC.

Maybe somebody got on an inertia unit and didn't like it, or it didn't match a DJ, or the operator could have been making mistakes. Someone here knows something about it since I've seen references to it.

Moonlight had one, I thought. Saw pictures of their truck on it anyway.
 
nwpadmax said:
I've heard the same thing. Dynocom is rather new to the scene as I understand it and they don't have the numbers of units in the field as that of the other established brands.

I talked to them a bit and they seemed very open and willing to discuss a lot about the product. At the time they had both inertia units and load cell units.....and for the diesels they had a big absorber and a Really Big Absorber...they even sent me the absorption curve and it was into the thousands of foot pounds IIRC.

Maybe somebody got on an inertia unit and didn't like it, or it didn't match a DJ, or the operator could have been making mistakes. Someone here knows something about it since I've seen references to it.

Moonlight had one, I thought. Saw pictures of their truck on it anyway.
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thats the one i am talking about it numbers were about 100 high at least at first then he got it calibrated right so its on now, it supposidly is the onlyone in the US with as big as rollers as it has, one other one in canada also. it will load enough for any truck to spool on it, actually if any thing it is low on its numbers now. I have ran on it over 100 times on a few different times from the first time i was like 550 hp then the second time with 100 more hp of mods and spraying a 175 shot nitrous i hit 582 this was the day he recalibrated it also the day al (summit) hit 1108 cr fuel only, then a little while later no spray just water meth and better tuning i was 563 on a superflow so i think the numbers are spot on
 
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