Safety/reliability of 370hp tune (A1R)

[aw113sgte]

Going up a local hill I could do it at 45 with just frame rails. After adding habitat (20ft shipping container) and all the other stuff(eco hubs too) I was at about 25mph today(about 2 min at full throttle). This is a very steep hill, but still that's a big drop. Weight before was about 20k, weight after probably 30-35.

I have an ECU I've put the 370hp tune on (yes with copied config and injector trims). What I don't want is to have the egts too high and burn a valve.

I know people have been running this tune, but seems like very few in the 6x6, 30k+category.

 

[GeneralDisorder]

The M-ATV turbo is water cooled. To prevent oil coking. Mind you this was on a 25k lb MRAP running in the middle east and was not running quality synthetic oil.

That is the only difference between the 330 and the 370 tune. There is apparently no concern with EGT's other than as related to oil coking in the turbocharger. In my estimation the modern synthetic oils will handle this without issue. So far I've flashed a lot of trucks and so have others and there are no reports I'm aware of indicating it's an issue.

It is possible to acquire the M-ATV turbocharger and install it. There are a couple coolant lines that have to be added - one from a plugged port on the water pump, and then one to the engine block. I have a friend with a 30k lb MTV running the M-ATV crate engine and turbocharger and he has no issues.

I've been told the transfer case is a bigger concern which is why I'm running synthetic Dex VI and ECO hubs to cut the RPM in half.

I don't think it's an issue. Monitor EGT's and oil temp if you are concerned.

 

[Skyhawk13205]

Going up a local hill I could do it at 45 with just frame rails. After adding habitat (20ft shipping container) and all the other stuff(eco hubs too) I was at about 25mph today(about 2 min at full throttle). This is a very steep hill, but still that's a big drop. Weight before was about 20k, weight after probably 30-35.

I have an ECU I've put the 370hp tune on (yes with copied config and injector trims). What I don't want is to have the egts too high and burn a valve.

I know people have been running this tune, but seems like very few in the 6x6, 30k+category.

Allison has a doc showing the gross input hp is 330 hp for the 3700sp, I don’t really know if that means is that is the most HP that the transmission can deliver or if it is the most HP it can receive. I know there has been people who have done the 370 tune without problems. Even if that is the max HP, there is a safety margin built into the limits, I would imagine that 330hp limit would be set for a specific lifespan or mileage estimate.

 

[GeneralDisorder]

It's torque that is the limiting factor for transmissions - HP is a measure of work performed over time - torque breaks things directly while HP wears things out. And the 3700SP is rated for 860 Ft/lbs but according to people that have spoken with Allison this is a VERY safe "guideline" and they can easily handle 100 Ft/lbs over that spec. The 370 fuel map is 932 Ft/lbs. So an increase of 72 Ft/lbs of torque. Call them and ask if you don't believe my claim. I know several people that have done just that and all of them were assured they were well within the design limits. Remember the environment these trucks were designed for - Allison tends to be pretty cautious with their ratings anyway and it shows in their reputation for quality and reliability - they are widely considered to make some of the best automatic transmissions in use today. That would not be the case if they failed at 8% over their spec. You put something like that into service and you will have HUGE failure rates when they get abused by 18 year old kids that try to get them airborne (seen it) in the field and if you get an engine that for whatever reason is out of spec and throws down a bit more power - boost sensor out of spec, fuel pressure too high, etc, etc - engines can and do go beyond their rating when sensors drift and conditions like very dense cold air are present, etc. You HAVE to have some safety margin in design or you'll be put out of business by the warranty claims.

Again - LOTS of people have done it and it hasn't proven to be an issue. My truck is my daily driver and I've been accused of driving it "like a sports car"..... I own a performance shop with a chassis dyno so the reference makes sense in terms of other things I drive regularly. WOT is the order of the day in the LMTV because it's relatively a LOT slower than anything else I own. More fun than anything else also but the shine wears off fast cars after building them for 20 years.

This gets rehashed here and on Facebook over and over and over. End of the day - do what you are comfortable with. I'm not concerned about the transmission - if I break it I'll tear it down and fix it and find out what failed and hopefully upgrade it. But that is the perspective of a life long master mechanic and Motorpool veteran and this possibility doesn't scare me or give me any sort of pause. So everyone here needs to take their own risk aversion into account - don't rely I mine cause I have little.

 

[Ronmar]

In the end its a cat tune, so it is as probably as safe and reliable as any other cat product run at that level of output

How hard you run things ultimately comes down to you...

 

[Skyhawk13205]

It's torque that is the limiting factor for transmissions - HP is a measure of work performed over time - torque breaks things directly while HP wears things out. And the 3700SP is rated for 860 Ft/lbs but according to people that have spoken with Allison this is a VERY safe "guideline" and they can easily handle 100 Ft/lbs over that spec. The 370 fuel map is 932 Ft/lbs. So an increase of 72 Ft/lbs of torque. Call them and ask if you don't believe my claim. I know several people that have done just that and all of them were assured they were well within the design limits. Remember the environment these trucks were designed for - Allison tends to be pretty cautious with their ratings anyway and it shows in their reputation for quality and reliability - they are widely considered to make some of the best automatic transmissions in use today. That would not be the case if they failed at 8% over their spec. You put something like that into service and you will have HUGE failure rates when they get abused by 18 year old kids that try to get them airborne (seen it) in the field and if you get an engine that for whatever reason is out of spec and throws down a bit more power - boost sensor out of spec, fuel pressure too high, etc, etc - engines can and do go beyond their rating when sensors drift and conditions like very dense cold air are present, etc. You HAVE to have some safety margin in design or you'll be put out of business by the warranty claims.

Again - LOTS of people have done it and it hasn't proven to be an issue. My truck is my daily driver and I've been accused of driving it "like a sports car"..... I own a performance shop with a chassis dyno so the reference makes sense in terms of other things I drive regularly. WOT is the order of the day in the LMTV because it's relatively a LOT slower than anything else I own. More fun than anything else also but the shine wears off fast cars after building them for 20 years.

This gets rehashed here and on Facebook over and over and over. End of the day - do what you are comfortable with. I'm not concerned about the transmission - if I break it I'll tear it down and fix it and find out what failed and hopefully upgrade it. But that is the perspective of a life long master mechanic and Motorpool veteran and this possibility doesn't scare me or give me any sort of pause. So everyone here needs to take their own risk aversion into account - don't rely I mine cause I have little.

I think the 370 HP rating would only be an issue if you got a warrantied transmission from MTP or from Allison. Otherwise it should not be an issue, I would imagine a C6 thrust bearing, heat exchanger leak or thrown driveshaft would destroy your transmission long before a 370hp tune would do any type of damage. Most of those issue should have been resolved with the A1R aswell.

 

[Skyhawk13205]

Going up a local hill I could do it at 45 with just frame rails. After adding habitat (20ft shipping container) and all the other stuff(eco hubs too) I was at about 25mph today(about 2 min at full throttle). This is a very steep hill, but still that's a big drop. Weight before was about 20k, weight after probably 30-35.

I have an ECU I've put the 370hp tune on (yes with copied config and injector trims). What I don't want is to have the egts too high and burn a valve.

I know people have been running this tune, but seems like very few in the 6x6, 30k+category.

Adept Ape has a good video about EGT regarding CAT engines, it sound like his advice was to have a pre turbo pryometer with a max temp of 1400 degrees. It sounds like CAT did not have a hard spec for EGT my guess is that with all factors remain equal with a correct tuned engine the ECM should be able to determine the safe fuel schedule to prevent damage based on other values such as air charge, air temp, and mass air flow.

I know for aircraft turbine engines, the FADEC can maintain engine operation even with multiple sensor values missing by using a calculated value based on other functioning sensors. I assume that automotive and other FADEC engines systems have the same capabilities.

Life is short and the truck is funner to drive with more power, I have the 3126 and I wish I had the capability to get a 1078 to 370hpmax I can do is 330