Competition Dynojet question

[Jim Fulmer]

Those of you that have dynoed more than the three time I have could you give me you opinion on the runs! Does going from 60-120 in 3 seconds sound a little too fast, and will any extra load help H. P. any or just T/Q.



Jim

 

[Jetpilot]

Jim,



Depends on what HP level you are running..... When I dyno mine it takes around 2. 5 seconds for a 750HP run. Some questions for you are what gear are you dynoing in? I assume OD due to your MPH. Also is you TC locked or unlocked? You will load the engine more and transfer more power to the tires in lockup. How much boost were you seeing during your runs?



Doug

 

[Jim Fulmer]

Hey Doug, yes I was in O/D with the converter locked, boost was at 56 and egt was at 1250... lol. H. P. was a sick 440, really expected over 450 as I know I have a fuel issue or lack of, Al and I talked this Morning about it and were now fuel planning.



Jim

 

[propuller]

when i ran on the dyno they ran what they called a inertia run only with no load on the motor. i ran with the overdrive off (3rd) & the converter locked. the first dyno was a land & sea & i made 435 hp & something like 800 ft lb. the second dyno was a dynojet & i made 438 hp & 890 ft lb. my question is will the power numbers change if they put a small amount of resistance on the drums. these figures were with dd3 injectors & no nitrous. thanks for the help. kurt.

 

[Bob Wagner]

test

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[propuller]

hey bob thats cool ill take one.

 

[Jetpilot]

I think edward wants one as well... ... ... ...



Doug

 

[propuller]

jetpilot thats a good one. ive seen the fun there havin on the dtt forum. ya gotta love it. kurt.

 

[TxDieselKid]

Originally posted by Jetpilot

I think edward wants one as well... ... ... ...



Doug

LMFO!!!

 

[Bob Wagner]

for charles

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[Jim Fulmer]

Great Bob now I have to get both and swap them out every day... .



Jim

 

[banshee]

Jim,



The three seconds from 60-120 on the Dynojet is way too fast to get a really accurate reading. Basically, the ramp rate for a Dynojet is way too fast to be used with our trucks. This is directly due to the fact the a Dynojet is a "passive" dyno. Most of the time your midrange TQ number is going to be soft because your turbo(s) aren't going to spool up in time to give you max boost at what should be your peak TQ rpm. When I dyno my Trans Am I use a Dynojet because I think it's very accurate for a gas engine, but not for our trucks. Why? The run for my car from 45-130 mph in 4th gear takes a good 20 seconds to complete, so the run can be seen as fairly static for each rpm (i. e. you have a slow rpm rise, so the motor is working as hard as possible to accelerate). As we all know, this just isn't the case with our trucks, and it's this fact that makes a mustang dyno a good choice for us. Your lower numbers are going to be seen as both TQ and HP... they are both related by RPM and the equation HP = TQ*RPM/5252. Extra load on the rollers will only help this situation. The extra load can come from an electric motor (such as the mustang) or in the form of heavier rollers. There are also water brake dynos, eddy current dynos, etc, but they're not as common.



John

 

[KatDiesel]

It kinda depends on the setup Jim..... my truck for example, last two Dynojets (TX & KC) I only show 445hp everytime, however that is the peak reading at 3400RPM! So obviously somethings amiss with that reading in my opinion because thats the same reading I had with HX35 and DDIII's. My run takes no longer then 4 seconds.

 

[Joseph Donnelly]

Kat, your readings indicate that you are using the "baby" Dynojet designed for ricers (low inertia. ) The NASCAR high inertia model minimizes the problem--peak hp will be at proper rpm. Actually what it does is allow the engine to build its hp sooner so not only will the peak be around 2700 for your engine, but it will be higher hp that what you saw at 3400.



I hope you can attand May Madness again this year and "get back" the hp those baby dyno's "stole!"

 

[KatDiesel]

Originally posted by Joseph Donnelly

Kat, your readings indicate that you are using the "baby" Dynojet designed for ricers (low inertia. ) The NASCAR high inertia model minimizes the problem--peak hp will be at proper rpm. Actually what it does is allow the engine to build its hp sooner so not only will the peak be around 2700 for your engine, but it will be higher hp that what you saw at 3400.



I hope you can attand May Madness again this year and "get back" the hp those baby dyno's "stole!"

Ya I know, they are 248C Dynojets but they have the "normal rollers" ... ... ... . least thats what they told me the model number was. Would hate to see myself on a 224.



Can you refresh our memory and tell us what the Nascar version rollers weigh?



John and myself already have plans to return, and we'll bring the missing hp and then some this year

 

[KLockliear]

The older 248C's had an inertia of around 60 slugs. The High Inertias are around 80 slugs and the DD versions (like DDP in WA has) has 100 slugs or so.

 

[banshee]

100 slugs is still only a little over 3200 lbs. That's a far cry from the 6500-8000 lbs that most of these trucks weigh. What you really need is a roller that is closer to the weight of the vehicle you're testing to give you a more accurate ramp rate and thus a more accurate reading.

 

[Jim Fulmer]

Thanks Guys, I have found out that Mustang guys are saying it's not accurate on there cars, so there is one other one here in town, inground and they said they can simulate anything I want from a set lbs load to a quarter mile run. I Guess I'll run on it and see what it does then go back to that one after the mods, hopefully I can make it out to MM and run on a real Dyno at DD



Jim

 

[KLockliear]

Originally posted by Jim Fulmer

hopefully I can make it out to MM and run on a real Dyno at DD

 

[TxDieselKid]

Originally posted by KLockliear

LMFAO!!!!