Does anyone have dyno curves (rear wheel) for the LB7 and LLY stock (HP and torque). Also, the tuner boxes in safe-for-the-stock-tranny tune for the LLY. I miss my Cummins torque and wish to upgrade slightly. I was under the impression (according to the 590 ftlbs at 1600rpm claim) that my engine would grunt, but my SOTP dyno is missing the feeling of pull. Thanx Geo.

It's there, and in spades. The thing is, you need to step in deep to get it, and this is what makes the trans downshift. Adding a tuner or module Like the Diablo Predator or Edge Juice will allow more power with less pedal...

I know you sell both, Mr. Kenedy, but which would you recommend to an old standard trans driver as plug and play (no gages safe, no towing, no trans upgrade, lots of low rpm, below 2000rpm, driving). Still interested in seeing the dyno curves as it is all BS without proof (no problem seeing dyno curves on the TDR site). Thanx Geo.

My opinion:

Well... One thing you will find is that few Dmaxes are manuals, which will make collecting data more difficult. Your stock stick LLY Dmax has a lower power output than the Allison equipped models. They are only detuned through the PCM, so you can certainly make the same (actually more) power than the Allison trucks by changing the tune. In other words, you should have more RWHP all along the curve with a 50HP PCM tune than an Allison with a 50HP tune. This is due to transmission losses.

Torque is kind of a pointless number, what you need is low RPM HP. Err, which is the same thing! When guys with Allisons dyno, the readings usually start at 2000 or higher due to the gear spacing on the trans unless they can lock it into 4th gear.

A good "grunt" program for a bone stock LLY truck would be the TTS Tow "50HP" (although it made 65rwhp in mine). You won't know the truck is not stock except you have WAY more ompph, and you won't need to downshift very often on hills. No gauges necessary, no worry about hurting the trans, little smoke, and no bad behavior. Of all the LLY tuners I have tested, it's the most "drivable" tune. You won't win drag races against musclecars with it, but you will run door to door with vehicles like the Silverado SS, and few trucks will out pull you going uphill towing.

I would certainly ask this same question in the Manual Transmission forum to see if you can find someone who has dyno'd.

Either will do well. Edge is more aggressive in the pedal response, and will allow you to make smoke. The Predator is very clean except for the 100HP tune which still isn't bad.

The plots to follow show stock vs. KD exhaust. The "Stock Baseline" run is an LB7 belonging to another prominent member. This was with a performance exhaust and I believe intake already installed. The test speeds are slightly different, but they are pretty decent representations. The LLY isn't quite as consistent in the middle of the curve, but the point where the stock exhaust zigs and the KD exhaust zags is repeatable. Basically, the valley where the torque dips below 450 on the exhaust run occurs earlier, and is much less dramatic.

Thanks McRat (hope that doesn't mean what I think it means, think of your colesteral levels), but I should figure out how to show a signature without typing it each time. I have a 2004 D/A CCLTLB LLY 4x4 and after 32yrs of stick, I won't go back. The TTS tow sounds like what I want but (and I may be mistaken) I don't want to send my computor away to get programmed. I plan on harrasing GM till they get the engine management right on my LLY (martyr for the masses?), so I will need to have the ability to return my program to stock for the many visits to the dealer in the next year. After a 9in. scratch in the hood, diesel washed off undercoating on the frame, dent in the drivers door, and acid washed paint on the drivers door, I figure they can't do much more that will bother me. They will get my truck back next year on trade. I also have to say the more miles I put on, the funner the truck. Thanx Geo.

Top left corner of the screen on a blue bar it says "USER CP", in there you can change your sig.

If swapping PCM's is out, then I would recommend the LLY Predator. It is also very smooth, and has some interesting features (read trouble codes, eliminate top speed governor, read engine parameters, etc). And it's cheap.

If you really want to cause trouble, load the "100HP" tune and hang on. It appears to be more than 100HP, but I haven't dyno'd yet.

The Edge? It "should" work better on a stick than an Auto (I had some problems with drivability with an auto), but it is a little (very little) harder to install, more $$$, and can be switched "on the fly", unlike the Predator which requires a few minutes parked to change settings.

Thanx Mr. Kennedy and Mr. McRat. The dyno shows my SOTP dyno isn't too fat. The torque peak is closer to 1850rpm or higher and the curve isn't linear. That funny dipping is wierd. Do you think the turbo is "despooling" or the fuel is being cut back to save the trans? Is this the rpm where the LLY overheats when towing? My truck really feels weak to me because of dip in torque at 2250rpm. I mostly head into the mountains to snowmobile in the winter. To go up, I put it into 4x4 and T/H and the tranny hangs up at 2250rpm, engine rattles and fights back, till I throttle it harder. All this leads to the feeling of low power. This also noticeable as a lag in power when doing a roll on highway pass. The dyno also shows me why the LB7 feels to me to be smoother and more powerful. Does the Predator in a safe tune take that curve and straighten it out? If it does then a Predator, KD exhaust, Bilstiens, and a Fingers Stick (if I find out it does not lead to the engine management problems that I experienced, high fuel consumption, irratic acceleration, when I unplugged my EGR), will be ordered after Xmas (in case it gets lost in the rush). Thanx Geo.

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The LLY Predator on the 40HP setting puts a solid 100#/ft increase on the stock Dmax across the board. The curve is also smoother with the "shark fin" like the blue plot above hitting about 575lb/ft at 2100...

Thanx . Has anyone looked at the reason for the wierd spike in the LLY torque curve stock. I have not seen that kind of a curve in anything except a two stroke motor. Can excessive fuel (poor mileage) (smoke hidden by the cat and EGR function), combined with controlled (electronically not demand) boost, make this kind of power out of turbo diesel. Would less fuel below 2350rpm make more power, less heat, and possibly eliminate the surging (does a diesel surge from too much fuel or not enough, too much I think). The power boost from just an exhaust is huge (but peaky). Is the excess fuel moving out of the engine quicker? Still interested in why this well designed engine is acting so wierd. Thanx Geo.

There's a lot of management going on in the LLY, combined with an actively changing turbocharger...

I understand the LLY has a complex engine management system (lots of little glitches with original tunes and stock) but, the torque curve you posted, showed a hugh gain in torque (90+ftlbs) with just an exhaust change. This hasn't changed anything electronically except that the mass air flow sensor may compensate for lack of backpressure. My experience with Egr disconnect ( thought it would spool quicker, fuel quicker, more power) was not dramatic (in fact disappointing). This mod should have shown a bigger change than it did if the exhaust change is this dramatic. So I throw the ball out again, any of you performance tuners, can you give more insight into the disappointing torque curve (fluctuating) on the LLY, and the dramatic difference with the exhaust mod. Thanx Geo.

EGR is not active at WOT. You will see no performance changes on the dyno.

It would be interesting to see the torque and vane position plotted together.

My point, Fingers, was the exhaust change power increase would be felt at part throttle (more torque) and it didn't change things electronically. What did it improve? Less back pressure couldn,t provide that much of an improvement without the engine electronics helping it along. So, the reason I compared to the EGR mod was that they are both air flow management changes with relations to the turbo vane positioning and readings by the mass air flow sensor. Thanx Geo.

I really like to drive my LLY even with factory tuning. It doesn't have the mountainous spike in torque or the big end power like my 2002, but the torque is there, flat, and smooth. All tests were made at WOT under heavy load. The LLY tends to drive better with a less aggressive right foot...



I understand the LLY has a complex engine management system (lots of little glitches with original tunes and stock) but, the torque curve you posted, showed a hugh gain in torque (90+ftlbs) with just an exhaust change. This hasn't changed anything electronically except that the mass air flow sensor may compensate for lack of backpressure. My experience with Egr disconnect ( thought it would spool quicker, fuel quicker, more power) was not dramatic (in fact disappointing). This mod should have shown a bigger change than it did if the exhaust change is this dramatic. So I throw the ball out again, any of you performance tuners, can you give more insight into the disappointing torque curve (fluctuating) on the LLY, and the dramatic difference with the exhaust mod. Thanx Geo.

My point, Fingers, was the exhaust change power increase would be felt at part throttle (more torque) and it didn't change things electronically. What did it improve? Less back pressure couldn,t provide that much of an improvement without the engine electronics helping it along. So, the reason I compared to the EGR mod was that they are both air flow management changes with relations to the turbo vane positioning and readings by the mass air flow sensor. Thanx Geo.
I disagree geo, exhaust backpressure reduction has a huge effect on engine performace across the board regardless of electronics. And in truth, the EGR mods have near none under load.