Engine/Transmission (1994 - 1998) How much power before issues arise?

[RSchwarzli]

How much power is the motors good for before potential problems arise? Meaning will the motors life significantly be reduced etc.



Also once you have achieved higher power, as in now running twins above 500 HP, what are the disadvanteges. I have heard people refer to increased problems, needing more servicing and care, etc. What are these increased problems and what is needed in increased attention to the motor? Thanks alot.



Robert

 

[ndurbin]

When I was talking with the guy who built my transmission he said once I get over 450 hp when towing heavy I should manually shift my transmission (doesn't affect enigne life but is a disadvantage when at those power levels).



Nathan

 

[biggy238]

I think there are several people on here over 250,000 miles and pushing upwards of 300hp that haven't complained much.



The drivetrain is what goes at higher HP. transmission, Tcase, Rearend. I've seen 3 rearends give out this summer alone on local pulling trucks. Anything that the added torque can take a toll on.

 

[Vaughn MacKenzie]

I would say up to low-mid 300s HP given the same maintenance you won't shorten engine life, but certainly by the time you're around 500 or more there is more potential for something to go wrong that will shorten engine life. Every time you blow that head gasket things like mixing fluids, tearing into the engine, etc. are risks to the engine.



Another thing is the higher HP you run the less wear an engine can have before it becomes apparent it doesn't have the potential it once did, or things such as more oil usage or blowby become issues.



There's been a lot of guys on TDR running a lot of HP and getting a lot of miles, and I've seen others with pretty tired engines by 200k without running tons of power.



Bottom line is how hard you run it and how well you take care of it plays into how long it will last.



Vaughn

 

[RJPotts]

Absolutely.

Every engine has a finite life, it will die, its just a matter of when.

If you have a lower hp truck or even a stock truck you have to run it harder to even keep up with traffic than as compared to a modded truck. And, the more often you run an engine at peak volumetric efficiency (theoretically) the less time it will last.

It all depends on the driver. Say in a stock truck you have to use 70% of the engine's power about 90% of the time to do the same work that a modded truck does using 40% of the engine's power for the same amount of time. Even though the modded truck has more power, it's not using as much of its available power (VE), this makes it last longer.

-R. J.

 

[RSchwarzli]

Ok. That all makes sense meaning how hard/often the power is used. Question two then. What disadvantages are there to running high HP. Also Vaughn mentioned some potential issues. Are these problems common? I am building a 98 12V for the crew and am deciding on how much power to get out of the finished motor.

 

[Vaughn MacKenzie]

Some of the disadvantages:



Poorer daily driveability (big turbos don't spool as well).

More soot & smoke production

Higher EGTs which can become a problem if towing at high elevation or in hot weather

Likely have to change oil more frequently due to more soot

Lower fuel economy



If you set your rig up right you can have good power say up to upper 300 range without significant drawbacks, but as you go higher the more compromises you'll have to make.



Vaughn

 

[RSchwarzli]

Besides fuel economy and oil changes wouldn't twins take care of those issues?

 

[DieselRam30]

Besides fuel economy and oil changes wouldn't twins take care of those issues?

At least to some degree, yes. With a properly matched set of twins (properly matched is the key word), twins are a great solution. I'm not saying that only one twin setup works, I'm simply saying that the ones that are chosen based on expected use, HP level, etc. by people knowledgeable in turbos will work much better. But then again, twins may not be the best choice if you're staying around 300 hp. It all depends on how high you want to go.



The biggest drawback to putting together a high HP truck as far as I can see is building the drivetrain to handle abuse, especially the transmission.



Bottom line is it's always going to be beneficial to take care of your truck and not abuse it regardless of power level. And to make sure the truck (transmission) can handle the power level you want to create.

 

[RSchwarzli]

I see. The transmition is the weak link. I am doing a NV 5600, Dana 80, 98 12V 500-550 HP (still deciding on the power, as can be seen by the thread) installation. How does this trans then sound for the power? Is that good enough or is that still the weak link?

 

[bkroupa]

It's more in how you use/abuse it. The six speed can be broken with a stock engine, it could also live a long happy life with over 500hp on tap depending on what you do with the power/clutch/shifting technique. I'm running the original 133k clutch with a 10 plate etc & it works great, as long as I don't fuel it up until the clutch is seated. A "kid" could probrably toast my clutch in a few minutes with little effort, but I expect it to last me another year even with some merge lane discussions

 

[RSchwarzli]

Thank you very much for your time, patience and sharing your knowledge with me. The 2nd gen parts are a little new to me, hence the reason I have lots of questions. Thanks again.

Robert