How does it work, Compressor to turbo connection

[dennis45]

Originally Posted by tednruthy

Looks to me like you are the closest of the 7 posts so far. I was just at the repair center and saw the hose that was blown off with the missing clamp. I do believe I know the difference between the compressor used for braking and suspension and the Turbo. The hose is off the compressor on the curb side of the engine well below the much larger CAC hoses that are on BOTH sides of the ISL engine. Street side hose from Turbo to CAC and curb side from CAC to engine intake I believe. These turbo hoses are HIGH up on the engine. The hose that is off is LOW and on the curb side and on the air compressor. Only about 2 inches in diameter. The clamp is gone but looks like there is about 5/8 inches where there is no dust but on this area also no sign of a tight clamp compressing the hose? Still waiting for hose install and test drive to be completed in the AM. Still waiting to award the prize for whoever can tell me what this compressor air has to do with the turbo boost.

D Lindy is spot on. The air intake hose for the compressor tees off the air intake line to the intake manifold. (The 4-5" line off the CAC) When the air compressor inlet hose fell off, it allows intake manifold air pressure to escape and thus no power.

[tednruthy]

John, I will take a picture when I get back to the coach. Be a few days. I'll try to get a pix of the other end of the hose also.

Ted

Originally Posted by PDR John

Glad to hear it's fixed. Interesting way to make sure air get to the compressor.

If you can, will you snap a photo of the hose. I washed my engine compartment yesterday, so I can see everything clearly.

Thanks for posting and clearing everything up!

[PDR John]

Thank you, it will be good info to have.

[twinboat]

Ok, the air compressors on some engines do use turbo charged air, for its intake. The intake valves still open and the boost air moves back and forth in the intake line. They put a check valve at the CAC tee, so no compressor air goes into the engine intake.
The boosted, compressor air doesn't overcome the discharge, check valves, until the intake valves close.

Retired and still learning.

[palehorse89]

I am going just to post to all, that I stand corrected and learned ....agian something I did not know or ever see......I looked at New Navistar engine's, 500 HP Mercedes engine in our Sterling, and a couple other Cummins engines , and finally, open the hood on my new 35 ton crane with a Cummins QSX in it......and found that the air compressor is fed off of the outlet of the CAC! then I asked a buddy of mine about it, he said Mack engine's started doing /using this setup years back........other than Mack engines, he personally had not seen it on other engines, but he knew of it. So anyway.......Again, sorry........, some are plumbed to the outlet of the intercooler's...........Learn something everyday..........I did not mention above, all the engine's I investigated today, my crane was the only one with this setup for the air compressor.......

[Flyin_lo]

Routing pressurized air to the compressor intake is pretty common on big trucks. On Caterpillar engined Logging trucks with air scales it was common practice to rev the engine with the retarder on to make the turbo spool up and make the air compressor build depleted air faster.