How much boost

[slickest1]

How many pounds of boost should a ISC 8.3 350hp run at. Mine gets about 28lbs.

[Mr_D]

Quote:

Originally Posted by slickest1 How many pounds of boost should a ISC 8.3 350hp run at. Mine gets about 28lbs.

Our ISC had about 25-26, now have the Banks kit. It includes a new turbo housing and shows 34-35 psi.

[powerboatr]

32 is as high as I have ever seen it
mostly it runs at 26-30 on highway at 67 or so

[slickest1]

Ok thanks for the relpies. Mine at 28 is probably normal then. I used to drive big trucks and they usually ran 30 to 35 so it made me wonder if it was low.

[bocajojo4]

I have a1996 Monaco windsor 275 hp. I only get 6 pounds boost what could be wrong? Thanks bob

[spike45]

Quote:

Originally Posted by slickest1 How many pounds of boost should a ISC 8.3 350hp run at. Mine gets about 28lbs.

Cummins Engine Data sheet calls for maximum boost of 69 inches mercury, which is 34 PSI. Your boost is 57 in-Hg. Get the right hill and load plus ambient air temperature and you should see it higher. When ambient air temperature is higher than the rating air temp, the boost will be less as the hot air is less dense. Also, check your charge air cooler for obstruction to air flow, same issue can be caused by partially blocked radiator air through the fins on the core.

At this point, I do not think there is anything really wrong with yours and your boost gauge may not be that accurate as well. Get it calibrated against a compressed air source.

[spike45]

Quote:

Originally Posted by bobcat1941 I have a1996 Monaco windsor 275 hp. I only get 6 pounds boost what could be wrong? Thanks bob

Your ISB 275 should have 52 in-Hg, 26 PSI boost. First, check the boost gauge for accuracy by testing a compressed air source (10, 25, 30 PSI). Check the charge air cooler core for cracks in the inlet and outlet tanks. Check the connecting hose from the turbocharger outlet to the CAC inlet. Those should be orange silicon rubber hose with metal rings on the outside. The CAC cracks can be heard as the turbo will be pushing air out thus you should hear a whistle or loud 'hiss'. Does the exhaust have any black smoke? Are you the first owner or the second? As first owner, you should know if it is lacking power. If you are not the first owner or never had a diesel engine before, you are not sure what you are missing, right? After checking these out, and still no answer, you need to see if there are any fault codes on the ECM of the engine. Take it to Cummins distributor to learn that. If you do not desire to crawl under the hood or is it into?! Take it to Cummins.

[Parkerrs]

Quote:

Originally Posted by bobcat1941 I have a1996 Monaco windsor 275 hp. I only get 6 pounds boost what could be wrong? Thanks bob

Quote:

Originally Posted by spike45 Your ISB 275 should have 52 in-Hg, 26 PSI boost. First, check the boost gauge for accuracy by testing a compressed air source (10, 25, 30 PSI). Check the charge air cooler core for cracks in the inlet and outlet tanks. Check the connecting hose from the turbocharger outlet to the CAC inlet. Those should be orange silicon rubber hose with metal rings on the outside. The CAC cracks can be heard as the turbo will be pushing air out thus you should hear a whistle or loud 'hiss'. Does the exhaust have any black smoke? Are you the first owner or the second? As first owner, you should know if it is lacking power. If you are not the first owner or never had a diesel engine before, you are not sure what you are missing, right? After checking these out, and still no answer, you need to see if there are any fault codes on the ECM of the engine. Take it to Cummins distributor to learn that. If you do not desire to crawl under the hood or is it into?! Take it to Cummins.

Also we are talking about maximum boost here. Driving on a flat level road at a steady state of speed , say 60mph, you will only show 6-8 lbs. of boost. Maximum boost pressure occurs when the engine is fully loaded and pulling, such as climbing a steep hill and downshifting to keep the revs up or flooring it from a stand still.

[Triker56]

Quote:

Originally Posted by bobcat1941 I have a1996 Monaco windsor 275 hp. I only get 6 pounds boost what could be wrong? Thanks bob

Several things could be wrong.
Leaking CAC
Leaking Hose
Broken turbo blades
Badly cracked exhaust manifold
etc.

[mrschwarz]

The most I have seen is 28 lbs.

[slickest1]

Thanks for all the replies, good info!

[sdelerio]

or possible stuck wate gate valve on turbo