I finally took the LLY over and ran it on the dyno to find out just what it was putting to the ground, and what I found was a little suprising...

The tests were run on a Mustang Dyno and I made 4 runs.
All runs made with T/H ON and 5th gear locked out

Since I put the Powershot Propane on I questioned how much power it added in comparison to the Edge on level 1. (I thought the Edge was doing more than the Propane)
The powershot is so smooth I really have never been able to feel as much seat of the pants grunt as the Edge on level 1 or 2. However the "wheel of truth" cleared up my misconception.

I have been running the Edge on level 1 and running Propane. It has always felt plenty powerful, But does not exibit any of the bad habits of running the Edge on the higher settings alone. It has the driveability of a bone stock LLY , But just has a lot more available power. (See dyno run 3)
Running it this way also doesn't feel abusive like it seems to be when you turn up the Edge to levels 3, 4 or 5.

Here are the results of my 4 runs

1, Stock 242.9 HP @ 3000 rpm 451.0 Tq @ 2500 rpm

2, Powershot only 305.0 HP @ 3000 rpm 600.3 Tq @ 2500 rpm
Gains over stock 62.1 HP 149.3 Tq

3, Powershot & Edge level 1 331.6 HP @ 2750 rpm 692.0 Tq @ 2500 rpm
Gains over stock 88.7 HP 241.0 Tq
Gains over propane alone 26.6 HP 91.7 Tq

4, Powershot & Edge level 5 390.5 HP @ 2750 rpm 818.5 Tq @ 2500 rpm
Gains over stock 147.6 HP 367.5 Tq
Gains over propane & level 1 58.9 HP 126.5 Tq

Note: I checked my Attitude monitor after every run but on run #4 it recorded about 50% backdown. I Don't think it was because of EGTs (I had the backdown setpoint turned to 1500, and the EGTs didn't go over 1420.)
Could I have been slipping the Allison while in 4th gear? Maybe that triggered the backdown?

What tranny mods have ya got?

No transmission mods so far.

I'm hoping it will live for a long time on the stock Allison.
This may be wishful thinking but here is the reason.
I don't normally run it Above Level 1 Edge with the Powershot on, (See dyno run #3) And I have never limped the transmission.

The other reason is because I think those Dyno #s are corrected for Sea level.
I live in Salt Lake City, Utah. 4,400 Feet above sea level.
We have a little problem with available AIR to feed our motors. So I kinda doubt My Allison is actually seeing quite that much power at any given time...

I will keep you all posted if I ever limp the trans, or get it upgraded.

dude you were so damaging your tranny right there. No more mods until you update the tranny.:badidea:

Did you get #s for just the edge , no power shot?
GREAT info otherwise!!!!!!!!!!!!!!!!!!!!1

Unfortunately no numbers for just the edge.
However an interesting note, If you look at the "stock" Dyno figures using 20% drive train loss
you come up with approx. 303 HP and 565 Ft lbs. And those were still with the Complete 4" exhaust. Looks like GM is a little optimistic with the stock numbers.

BTW one cool thing about the Powershot dyno curve is how smooth it is compared to the Edge curves. It doesn't do any of the big spikes. It just makes nice wide power curves. I did some 5th wheel towing this weekend and left the edge on level 0 most of the time. I couldn't have asked for better results.




Emerick, The transmission is fine. As I stated earlier I only run level 1 with the propane, and have never limped the Allison. That was the only time It has seen above level 2.

I'm pretty sure it would have made more power on level 5 with a built trans. (No back down) but numbers like that are hard on ALL of the trucks components and really have no practical use in the real world anyway. (EGTs become the problem)
It is still nice to see what it can do just for fun...

if i remember correcly my # where 242hp stock and 505 tq stock. thats back in jan

This is the first time I have had the truck on the Dyno.

I can't believe you put 390 horses to the ground and didn't limp your tranny! I'm not being a smartass, but you must have not done a 4-5 shift. That much power would have to smoke something on the 4-5 shift.

coyote, he said he had 5th locked out

Ah, so he did. My bad...still, it's not something I would have tried, but I don't have real big ka-honas then either. Bad **** always happens when I push the envelope too much.

:cool2: Wow, those are very good numbers! 331 hp of very driveable power!

:cool2: Wow, those are very good numbers! 331 hp of very driveable power!

Driveable power is the key!
The more I tow with The propane and edge level 1 the more I am learning about EGT issues!

For towing purposes I really don't need the Edge at all.
The propane will give all the power you can safely run on the big hills. (EGTs can easily hit 1300 Deg. just with propane alone) Plus I have the added benefit of extra towing range because of the extra fuel I am carying.

The extra power the Edge adds beyond the propane is great for short bursts. But I am finding it hits 1350 Deg. Really fast and must back down.

I am very happy with the Edge Attitude, Probably just as much for the built in Monitoring feature, EGT, & Transmission safeguards than for the total power it adds when towing.
I'm quickly finding that when towing big loads it can quickly become unuseable power.

BTW: When you are not towing, none of the above is nearly as big of an issue. These are the times when the Edge is worth its weight in gold.

Also BTW: When towing, even if only using Propane I would STRONGLY recomend an some sort of an EGT guage, Just to be safe.

how much was the propane kit alone and how much instaled

The Powershot alone is $649.
Then you would need a tank & installation.

I build a special tank setup that uses an aluminum diamond plate truck box that sits just level with the top of the bed rails. The box holds Four 4.5 gallon propane tanks.(18 gallons total) These tanks are held down using RV hardware like you would see in a travel trailer, or 5th wheel. Using a custom header I link the 4 tank outlets together before going into the powershot unit, which is also mounted inside the truck box.
Two hoses (1 for boost signal and 1 for propane) and a power wire leave the box.
No tools are needed to remove & fill the tanks.
I can build the tank setup for under $700.
Using this setup solves the problem of how to hide the propane kit when taking the truck into the Dealer. (The 2 hoses & wire can be fished back into the box and locked)
If you don't have a tonno cover and want the entire propane kit well hidden this is the way to go.

Once everything is mounted inside the box, The installation into the truck is really easy and is less than a 1.5 hour job.