My turbo never goes higher than 25psi. Is this normal?

[Jerryss2]

My turbo never goes higher than 25psi. (On dash gauge ). Is this normal?
im not having any performance issues.
2020 tiffin allegron RED with 360 cummins engine

[chuckftboy]

That is pretty normal. I have seen mine as high as 32 but I was in the Rocky Mountains and pulling one heck of a load. Most often I don't see over 25 psi.

[ernieh]

I can't tell you what's normal for an ISB, but my 380Hp L9 indicates 32# frequently and sometimes as high as 34#. Normal cruise, flat road, no wind around 18#.

[PKI]

Our 340 hits a bit above 25 on occasion - maybe 27-28. However, 25 is what we normally expect.

[scottlayden]

Similar type issue:

I have a 2006 Tiffin Phaeton with 26,000 miles on it I bought it a couple of years ago, but it's finally coming out of the shop following fixing stuff the inspector missed.

Sometimes, the engine feels strong, but sometimes I'll put the pedal down all the way, and there is little push. Eventually, things get up to speed, but it's not what I'd expect from a big turbo diesel.

Is this lag or lack of oomph typical?

[boldma]

My 2021 Tiffin RED 360/800 will typically see 26-27 lbs at 100% load, pedal down.

[SteveD]

Originally Posted by scottlayden

Similar type issue:

I have a 2006 Tiffin Phaeton with 26,000 miles on it I bought it a couple of years ago, but it's finally coming out of the shop following fixing stuff the inspector missed.

Sometimes, the engine feels strong, but sometimes I'll put the pedal down all the way, and there is little push. Eventually, things get up to speed, but it's not what I'd expect from a big turbo diesel.

Is this lag or lack of oomph typical?

You don't say what SIZE or BRAND of engine you have, but My 06 Phaeton with a Cat C7/350 only makes me feel 'push' (or pull) coming away from a standing start. Going down the highway on flat terrain I can tell I'm accelerating only if I'm down around 40 MPH ...and NOT climbing a hill. Most of the time, I feel NOTHING regardless of where the pedal is. It can be solid on the floor going uphill at 65.. 60.. 55.. etc - depending on how steep the grade is.


Is this your first motorhome? They are NOT 'made for speed'. Some very few will have enough HP and TORQUE to 'pull like a car'. I can live with all that, no problem.. but the MPG really makes my wallet hurt. I've tried running all kinds of different speeds and seem to always end up between 6 and 7. I AM towing a 28 foot enclosed trailer weighing in at ~7800 lbs but this Cat just isn't as 'good' as the Cummins in my previous (1994) RV that got 8-9 running the same speeds and pulling the same trailer to the same places (race tracks).

PS... add a 'sig' with your RV specifics for better answers to any questions you ask.

Steve
BTW.. my rig PSI maxes out at about 24 or 25.

[lllkrob]

Originally Posted by scottlayden

Similar type issue:

Is this lag or lack of oomph typical?

Unless you have over 500HP, yes it's typical.

[chuckftboy]

Checked mine on a run down to central Florida last week. At 100% load my boost hit 35 PSI. I was on a flat highway with the pedal down to the floor.

[scottlayden]

Yes, this is my first personal motorhome. Family has had for decades, but this is my first one where I need to know what I need to know. Thanks, Scott

[Crasher]

From my own personal experience, the smaller the engine size (CU IN) the greater the power lag, especially from a standing start. If you look at the power curve of different size diesel engines, you will see that the bigger blocks will reach peak torque at a lower rpm than the smaller block like the ISB. Until the turbo can spool up to speed to force in more air for combustion, the engine is starving. The larger 600hp ISX will reach peak torque @about 1100 rpm while the smaller 360 hp ISB won't reach peak torque till 1600 rpm. Hence, a bigger lag to get going. You just have to get used to where the power curve is for your engine and learn how to use it.

[John St Maur]

Originally Posted by scottlayden

Similar type issue:



I have a 2006 Tiffin Phaeton with 26,000 miles on it I bought it a couple of years ago, but it's finally coming out of the shop following fixing stuff the inspector missed.



Sometimes, the engine feels strong, but sometimes I'll put the pedal down all the way, and there is little push. Eventually, things get up to speed, but it's not what I'd expect from a big turbo diesel.



Is this lag or lack of oomph typical?

Hello, I have a 2008 Phaeton with the 8.3L and I have the same experience. It will feel strong and then other times feels like it’s underpowered. It has 57,000 miles on it.