[glamis_dave]

hey guys.....verified that i indeed have pmrs....and was thinking about this......it seems generally accepted that 400 hp is a limit on pmrs......my truck has dp 80 tow 4 in exhaust 35s and i tow heavy at 22,000 gross combined......my question...is this....if you build a pmr motor to 350.....then tow heavy like i do pushing up hills deep into it.....can you under those circumstances...exceep the stress levels of pmrs and fold a motor...ok ok you can ....but is it likley.....it seems to me that with all the weight you would in effect....be putting as much or more stress on them.....as it would building the motor to 400 hp.....am i makeing sense........................................................q2...also i dynowed 275hp but they couldnt tell me the torque anybody know what 250 hp is in torque...david

 

[gregrob]

sheesh

Lose the dots dude. NO ONE will read your threads if you leave them hacked up like that with all the gibberish.

I think you're asking if towing heavy puts more stress on your engine than a leisurely sunday drive, if so yes. Definitely.

Running an engine at peak output is ALWAYS harder on it than an empty load. Question is: how much is too much right?

I can tell you I've towed up to 24,000 GCWR and ran whatever speed I wanted, flogged it hard on the hills, done numerous foot to floor boosted launch street races (a lot), several sled pulls, and a handful of drag strip passes and I have yet to hurt my engine.

You can extrapolate torque from HP if you know at what RPM that HP was made, but that won't tell you what PEAK torque was unless you redo the whole graph, not a quick or easy process.

My suggestion to you, copy my setup and hope it lives. I'd say it will, but no one would gaurantee it.

Good, cylinder pressure tested tuning, and small (read stock) nozzles are the key in my opinion.
Let's compare Kainers vs Mad_matt as examples. I know both these guys and they're cool, I'm just making a point.

OK, Kainers, 434HP on a stingy dyno, beats the piss out of it everyday, almost 300K miles, still living and doing great.
STOCK NOZZLES

mad_matt, 412 HP, blew up weeks after installing injectors and big oil.
.0075 Extrude Hone nozzles (flow a lot)

Take it or leave it, but that's my theory. Keep the nozzle size down, ICP up to burn the fuel, and don't get greedy.
If you got enough money to make 450+ HP in a powerstroke, you got enough money to pull it down and do rods, and vice versa.

Hope that helps

 

[gregrob]

another thing to remember, torque is what hurts your rods, not HP.

 

[CSIPSD]

My set up for 80k... With water meth...

 

[glamis_dave]

ok loseing the dots,but i suck at spelling you have been warned. i was trying to get an anser to be a base formula,for the mods i could safely do....but maybe i should just ask the final question to all that is on my mind.....i like to push as hard on the pedel as i want,loaded-unloaded,so with pmrs,3.73,35s,towing 22,000 gc what mods are ok.my thoughts were big oil, and a fuel system of somekind and leave the rest stock.i appricate your ansers,but could you make them somewhat comprehensive-detailed.david

 

[glamis_dave]

sheesh kind like gregrobs first anser was.

 

[glamis_dave]

also didnt understand cylinder pressure testing ,and icp to burn all the fuel.sorry fo 3 in a row..

 

[bigrpowr]

pulling a load will work your mtotr harder, but it wont put more stress on i the internals. the fuel and air and timing will put the stress on the rods....stick near 400 and you'll be safe, no matter how much you tow or how you tow it.

 

[Slated4Greatness]

A word to the wise. There is NO such thing as guaranteed or indestructable in these engines.

Gooch even with $3400 Cunningham rods blew a rod (Part failure) at around 400 HP.

I cracked my block in 5 places (Yes, I was using LP) at less than 400 HP. Amazingly the PMR's in my engine were fine.

Many others have met the same fate..

If you modify it be prepared to fix the weakest link. Not to say that a basic intake and exhaust upgrade will grenade your engine but be realistic if you double the intended output of your engine be prepared to "Pay" the piper..

 

[CSIPSD]

A word to the wise. There is NO such thing as guaranteed or indestructable in these engines.

Gooch even with $3400 Cunningham rods blew a rod (Part failure) at around 400 HP.

I cracked my block in 5 places (Yes, I was using LP) at less than 400 HP. Amazingly the PMR's in my engine were fine.

Many others have met the same fate..

If you modify it be prepared to fix the weakest link. Not to say that a basic intake and exhaust upgrade will grenade your engine but be realistic if you double the intended output of your engine be prepared to "Pay" the piper..

You going to put the PMR's back in....

 

[southmike]

I am not sure you can hammer the pedal wideopen up a 6% grade
towwing 22k . seems like egts would spike, any you would have a cooked motor.

 

[gregrob]

Depends on the tuning.

 

[gregrob]

A word to the wise. There is NO such thing as guaranteed or indestructable in these engines.

Gooch even with $3400 Cunningham rods blew a rod (Part failure) at around 400 HP.

I cracked my block in 5 places (Yes, I was using LP) at less than 400 HP. Amazingly the PMR's in my engine were fine.

Many others have met the same fate..

If you modify it be prepared to fix the weakest link. Not to say that a basic intake and exhaust upgrade will grenade your engine but be realistic if you double the intended output of your engine be prepared to "Pay" the piper..

You mean clam?

 

[69W900A]

The truck I use to pull my toys with is a PMR truck and it has been around 300-325hp since about 10K miles. Hardly ever gets driven unloaded and the truck is always over-loaded. Generally 23,000 CVW and has been much higher. It'll see full throttle on long pulls all the time. Rye Grass hill is about 12 miles of 6 to 7 percent grade and with a heavy load it's full throttle most of the way.

The tuning is far more critical to longevity than towing. The engine will live a lot longer if you use it to tow than if you drive it 2 miles to get milk every night.

 

[imelmo]

hey guys.....verified that i indeed have pmrs....and was thinking about this......it seems generally accepted that 400 hp is a limit on pmrs......my truck has dp 80 tow 4 in exhaust 35s and i tow heavy at 22,000 gross combined......my question...is this....if you build a pmr motor to 350.....then tow heavy like i do pushing up hills deep into it.....can you under those circumstances...exceep the stress levels of pmrs and fold a motor...ok ok you can ....but is it likley.....it seems to me that with all the weight you would in effect....be putting as much or more stress on them.....as it would building the motor to 400 hp.....am i makeing sense........................................................q2...also i dynowed 275hp but they couldnt tell me the torque anybody know what 250 hp is in torque...david

If you're worried about it, get some forged rods. That's the closest thing to a guaranty you'll have.

 

[bigdjvp]

sheesh

Lose the dots dude. NO ONE will read your threads if you leave them hacked up like that with all the gibberish.

I think you're asking if towing heavy puts more stress on your engine than a leisurely sunday drive, if so yes. Definitely.

Running an engine at peak output is ALWAYS harder on it than an empty load. Question is: how much is too much right?

I can tell you I've towed up to 24,000 GCWR and ran whatever speed I wanted, flogged it hard on the hills, done numerous foot to floor boosted launch street races (a lot), several sled pulls, and a handful of drag strip passes and I have yet to hurt my engine.

You can extrapolate torque from HP if you know at what RPM that HP was made, but that won't tell you what PEAK torque was unless you redo the whole graph, not a quick or easy process.

My suggestion to you, copy my setup and hope it lives. I'd say it will, but no one would gaurantee it.

Good, cylinder pressure tested tuning, and small (read stock) nozzles are the key in my opinion.
Let's compare Kainers vs Mad_matt as examples. I know both these guys and they're cool, I'm just making a point.

OK, Kainers, 434HP on a stingy dyno, beats the piss out of it everyday, almost 300K miles, still living and doing great.
STOCK NOZZLES

mad_matt, 412 HP, blew up weeks after installing injectors and big oil.
.0075 Extrude Hone nozzles (flow a lot)

Take it or leave it, but that's my theory. Keep the nozzle size down, ICP up to burn the fuel, and don't get greedy.
If you got enough money to make 450+ HP in a powerstroke, you got enough money to pull it down and do rods, and vice versa.

Hope that helps

Which injector builder builds 180cc AA's, if I can recall stock are 160cc. I have been told that single shots make less cylinder pressures and will probably make an engine more liveable. I am also am PMR carrier undecided on which injector will best serve my purpose, which happens to be the love of hp and the need to pull heavy loads.

 

[gregrob]

Which injector builder builds 180cc AA's,

Me!

if I can recall stock are 160cc.

Stock AD's are 140


I have been told that single shots make less cylinder pressures and will probably make an engine more liveable. I am also am PMR carrier undecided on which injector will best serve my purpose, which happens to be the love of hp and the need to pull heavy loads

 

[bigdjvp]

What is the AA injetor out of and what made you use this injector.

 

[gregrob]

AA is out of a 94.5-97 power stroke

AA's are stock 90cc

AA's are single shot.

I used this injector because I wanted single shots, I found a good deal on almost brand new alliants, and they are cheap to mod if you DIY like I did.

 

[PowerstrokeJunkie]

I would stick with stock injectors on a PMR engine, do everything you can do other than that, and you'll be safe with good tuning.