Engine/Transmission (1998.5 - 2002) are our engines turbonormalized ?

[Sageair]

On the turbocharged piston engined airplanes I fly I can get the same manifold pressure (boost) up to 17,000 ft m. s. l as I can at sea level. Does the turbocharger on my ETH work the same way?

 

[HVAC]

No

Not the way I understand it. The system in your aircraft is just trying to keep the power level the same as it is at sea level. So where your at altitude your engine doesn't suffer any performance drop off.



The turbo on your engine is going to make as much boost as your fueling level will support. At altitude you will see your performance fall off.

 

[ToolManTimTaylor]

Oh Ooh I know I think ( Don't shoot me if I am wrong)

For Every 1000 feet above sea level There is a . 5 LB loss for a Lb of boost at the same compressor speed. There yeah that's it

 

[A Johnson]

Not trying to start any kind of argument because I'm not an engineer and I don't know specifics, but here goes.



I have allways been told that turbo charged Cummins engines will not lose power untill 10,000 feet or so, do to the turbo spinning faster in the thinner air kind of a self compensating thing. It makes sense to me. I do know that high horespower Cummins engines use an ambient pressure sensor and will derate (cut fuel back)over 10,000 feet to keep the turbo from overspeeding.



Maybe some of these travelers, who have been over the real high passes will chime in and tell us what they actually saw on the boost gauge.

 

[jwinnie]

Any aircraft mech will agree. The waste gate in your airplane's turbo is operated by absolute pressure. the waste gate closes as manifold pressure drops below sea level standard. the waste gate in your CTD (I am only aware of the diaphram type) I believe measures differental pressure, meaning the waste gate is set to keep a certain pressure (somewhere around 20 psi in stock machines) above ambient pressure.



Hmmm... . It would be interesting jee wiz info to see some absolute pressure readings from inside the CTD intake



I hope I didn't start any :-{}

 

[Doubleclutch]

J. W- sounds like "normalizing intake manifold pressure to sea level with the turbo" I'll by it! Never flew a turbo charged plane but was always told that the turbo wasn't to make hp on the runway, only high above it. Thanks.

Greg

 

[jlccc]

High-Altitude Turbocharging

In his book, Turbochargers, Hugh MacInnes discusses "normalized engines" in aircraft service--chapter 14. This book is 160+ pages and is just $12 at Amazon.com--excellent book!

 

[Barry]

This is a timely subject with me having been in Colo. for 10 days. As we satt around the campfire pits with no campfire(burn ban) I was amazed at how many folks are SICK of their big gas motor homes. I began to explain to them that the V10 gas engine does have 300 HP on the beach at Galveston, Tx. on a 59 degree day. But coming thru a pass in Colo. that say is 8,000' elevation and 90 degrees has a DENSITY altitude of probably 11 to 12 thousand feet. At that level a gas engine(normally aspirated) is doing well to make 50% of its rated horspower! Now they were begining to understand why their 35' superslide big 'ole hog motorhome was gasping for air at 15 mph while us Cummins guys were 50 to 60 mph thru the same pass.

Let me reach back in the cob webs of my mind and see if I can get somewhat technical. "Turbonormalized" is a term I first ran into in the aircraft biz. (20 years aircraft dealer) The standard day benchmark is 29. 92 barometric pressure and 59 degrees. At sea level, this is where your normally aspirated engine is suppose to make ALL it's horsepower. AS you ascend (on the ground or in the air) the air becomes less dense with less o2 and you begin to loose horspower. The turbonormalized turbo kit is designed to maintain SEA LEVEL pressure up to about 10,000 feet. A johnson is correct in that 10,000 feet is where the bleed off begins to occur. The engines we have in our trucks(because of the turbo) can produce pressures far greater than the outside barometric pressure. (We have some members who's trucks will produce more pressure than that which is on the planet Pluto) Therefore, our engines are turbocharged and not just limited to "normalization"

An interesting side note to all of this is there has become great interest in the older lower priced diesel pusher motorhomes. Even the 190 Cummins units that folks use to shy away from are starting to have a market. Folks are just getting sick of these old and new gas hogs with no power. I am starting to pursue that market.

 

[Gary - K7GLD]

I realize other contributing factors apply - such as turbo housing size differences between various year model trucks - but I swear, my old '91 seemed to grt STRONGER up at higher elevations!



THUS, I was mildly surprised wnen my NEW truck showed signs of reduced power in some of those same hills... Maybe the smaller turbo housing on the new truck couldn't keep up the volume the engine wanted in high-demand situations? I didn't have the guages on yet at that time - and now have added the Comp and made the turbo elbow mod - will be interesting to see how the truck does with the trailer in higher elevations NEXT time we're out...