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Discussion Starter #1
Just back from Dyno day. Little disappointed in truck performance.

So what was wrong with the truck? Well I didn't know anything about this dyno but it works off acceleration inertia to get a reading. The truck had the road speed limiter still on so top speed was 95 mph (my Fault). When it hit 92 the fuel cut back and so did the hp reading. Second thing that was bad was we couldn't keep the engine in 5th gear. It would down shift automatically around 88 or 90 mph. Down shift would screw up the dyno and the reading would go to zip. Truck has to stay in drive or direct drive to make good numbers on this dyno. That killed us. Ended up running tow mode manual 5th gear to get it to read decent. Still couldn't get a good run.
Some guy said the trans has a mind of it's own and it's hard to trick.

Some one said the computer is still controlling the variable pitch turbo and it's hard to make lots of boost with it. We got 26 psi. And the last thing and (I presume) it's just new, the Bully Dog program didn't make a whole lot of smoke. Matter of fact it was lame compared to the other trucks there. Posted 371hp at the rear wheels.

Here is where the real trouble is and I need your help. Coming home power was down somewhat and throttle response was very poor. At 50 mph you could mash the throttle and it would take 2 1/2 seconds for the engine to respond. Other speeds not so much noticeable. It was if nothing was there. No nothing. Not even a hint if it was going to accelerate at all. I actually thought the motor had died when it first happened. Any ideas?
In the trade it's called no throttle response.

Hate that fly by wire.


I would like to thank Sun Coast Converters for putting on one excellent show. They had to do a lot to promote and set this up and they were some of the best people you would want to meet. They build the converters totally in house and everyone I met was absolutely great.
 

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371 is a good run, another guy on here got 360hp on performance setting. Which did you use?
 

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Discussion Starter #3
Run on a dyno you gotta go all the way - EXTREME setting
 

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Why didn't you just put it into manual mode?

I don't know what the trans ratios are but I'd think you want a 1:1, typically 3rd in most automatics.

I'm not a big fan of the fly by wire either, there is def a significant delay when you punch it.
 

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Why didn't you just put it into manual mode?

I don't know what the trans ratios are but I'd think you want a 1:1, typically 3rd in most automatics.

I'm not a big fan of the fly by wire either, there is def a significant delay when you punch it.
It's a 5-speed, 5th is overdrive. Shouldn't you be in 4th on the dyno?
 

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Discussion Starter #6 (Edited)
The dyno operator was doing the drive selection. I was just a bystander. I thought he knew what he was doing because I sure didn't. I feel like an idiot but that's what happens when your not prepared, even though I asked several people on what to do before I went. Just don't like a dyno that can't hold a load at a given speed. I take credit for some stupidness but the operator should have known.

5th and 6th is overdrive
 

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It's a 5-speed, 5th is overdrive. Shouldn't you be in 4th on the dyno?
I don't know about the Allison but almost every other transmission I have seen 3rd is always the 1:1, the 4th and 5ths are overdrives.

I would assume you put the truck into manual mode, get it rolling put it into 3rd and then stand on it until redline, but I have never dyno'd a Diesel.
 

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Fourth is the "dyno gear". It's one to one on the Allison.

Normally you lock out 5th gear (I guess with yours, you select 4M), get it going about 45-50 in 4th, then roll into it.

Good news? You have more than 371HP. If it pulled that before the limiter, you probably had more HP available.
 

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Concerning your lack of power...

Hmmm...

Is it still making good boost?
 

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Discussion Starter #10
Has good power for a stock 360hp. But ahh, it's set on Bully dog extreme right now. Boost is still there. I parked it and let it sulk. Maybe tomorrow I'll find out what's going on. No codes, just a dead throttle at 50 mph for about 2-3 seconds.
 

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Transmission or Engine might have "learned" strange behavior. I've have cars and trucks do funny things when they get off the dyno.
 

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Run on a dyno you gotta go all the way - EXTREME setting
That could be your problem.
Unless you used a Tech-2 to lock the tranny into 4th, you may have hurt the trans.
Take the BD Extreme, floor the throttle from a standing start, you WILL limp the stock tranny.

My '06 LLY with the BD on Performance put 350hp @ 679.9 to the rollers.

As far as the top speed and downshifting and such, again, you should have put it in "M" and set it to 4th... the engine will easily rev out under load in 4th without getting near to the speed limiter.
Both of my runs, the chart drops immediately at 3050, while HP was still building, so I'm assuming the cutoff was due to the ECM defueling. I thought the rev limtier was at 3400, but I've also heard that it's at 3100 :confused:
It's a 5-speed, 5th is overdrive. Shouldn't you be in 4th on the dyno?
'06 is a 6 speed, but yes, both 5th and 6th are OD.
 

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Discussion Starter #13
May way of thinking the LBZ isn't going to make good numbers on the inertia type dynamometer unless you you get the rev limiter on up there. Your always going to bump the limiter and of course it's going to start defueling when you need it most. The dyno is designed for more conventional type engines that stay locked up and are capable of sudden bursts of high speed. Think the LBZ maximum load rpm is 3,200 RPM with 3,400 max no load. It's now quite obvious to me the engine is going to peter out dam quick after 3,250 rpm. Sad part is, it's capable of a whole lot more.
 

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I would not say that it is the dyno operator. This might be just one of the 3 or 2 LBZ Dmax's that has been dyno'ed with them. I know when my LB7 it is in drive the whole time. They might not have it down with the new 6 speed yet or it could just be that new Alli 6 speed trying to learn Mine acts all kind of funny ways from driving, dynoing, to changing tuners. They do have a mind of their own.
 

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Discussion Starter #15
Maybe not the dyn-o operators but to post good numbers all the "good" trucks where going over a hundred miles an hour. Duramax LB Z in direct drive (4th) gear with the rev limiter in place is not going to achieve this speed if I am correct. So is this type dyn-o inherently a bad choice to show off a LB Z?

What's the deal with the abreviations? Like LB LBZ DYNO
 

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Maybe not the dyn-o operators but to post good numbers all the "good" trucks where going over a hundred miles an hour. Duramax LB Z in direct drive (4th) gear with the rev limiter in place is not going to achieve this speed if I am correct. So is this type dyn-o inherently a bad choice to show off a LB Z?

What's the deal with the abreviations? Like LB LBZ DYNO
I think it is intended to help the newbies and slow some of the what does this mean? posts.
 

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If you lock it in 4th gear with a TECH2 and lock the converter you will not hit the speed limiter. 3200rpm in 4th gear is just shy of 90mph.
 

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Discussion Starter #18
Took the bully dog program out and reset to stock. Everything back to normal. Thanks for the help!
 
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