posting again because i need an answer..



i’ve got stock valve springs in my truck and i’m running about 30-35lbs if boost with the stock turbo. on the fueling side i’ve got 50hp DAP nozzles and edge ez tune. i don’t even really get up to 3k rpms. i’ve seen companies say that 35lbs is the limit. is this true? should i upgrade the valve springs? if so, 110lb? 103lb?

 

On the 24V the valve springs are not problematic.
What you read is about 12V trucks with exhaust brakes, and you can buy the correct springs from Cummins.
I run a bit over 40 psi at 3.2k rpm with stock valve springs for more than 200 k miles.

 

so i’m fine with about 35psi on the stock valve springs? i have headstuds and heavy duty pushrods because i would hate to have any problems that could be prevented

 

Headstuds and a quality surfacing of the head and a good gasket are necessary for higher than stock boost.

The heavy duty pushrods do not seem necessary to me, but if they are heavier than stock you will need stiffer valve sprigs for high rpm operation.

Depending on the mileage of your springs it may be advisable to change them.

 

To add to what AlpineRAM has already mentioned, the 35psi limit you've heard about has to do with the efficiency of the turbo and intake airflow. Once you start going beyond 35psi with an HX-35 turbo you don't really gain anything. It's a turbo limit, not a valve spring limit.

 

I think you should change valve springs only if your engine works on really high RPM