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  #1  
Old 12-29-2005, 12:54 AM
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Default Turbos for Normalizing

Hello,

I've been reading through alot of these posts and I have a couple of questions. I hope they don't sound too retarded, but I'm truly intersted. Choosing an engine for my project is many years away, and I started out with the notion that I would_not use a turbo on my engine to adhear to the KISS principle. Just another variable I didn't want to worry about. But over time, and reading alot of the posts/progress reports here I'm starting to see some distinct advantages, especially when combined with some of the other engine alternatives such as rotories. I live in outside of Denver at around 5500 ASL.

I've read elsewhere that using a turbo for normalization rather than increasing base HP will extend the life of the unit greatly. While this seems obvious to me why, can someone elaborate?

When normalizing for Altitude, can the boost be controlled automatically somehow to adjust for SL atmosphere?

Thanks in advance for any information you can throw my way.

Bart
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  #2  
Old 12-29-2005, 01:05 AM
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there is a thing you can bolt on and set to 2 psi and it will keep that.
the way it was explaned to me was you have sea leval hp lift off and you have sea leval hp at 10k,or in this case 2 psi at 10k and 2 psi at sea leval
as you desend down you don't have to un-bost(nodetination)KISS
some for get andhave full boost at landing
its a 800.oo doller part and i for get the name but they sell them at the airport. hope that helped



i needspell check on this lap top
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  #3  
Old 12-29-2005, 04:22 AM
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Quote:
Originally Posted by Steve parkins



i needspell check on this lap top
Try ispell http://www.iespell.com/ . It works within Internet explorer and has been helpful and non intrusive for the several months I have been using it. It ends the task of composing it Word then cut and pasting. It becomes a "right click" option. Very easy......when I choose to actually use it

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  #4  
Old 12-29-2005, 08:47 AM
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Hi Bart,
There are turbo experts on the forum who could answer this better than I, but here's the "layman's perspective".

There are 2 ways to control boost (that I know of). The first is a wastegate which allows the exhaust gasses to bypass the turbo. Usually these are controlled by vacuum from the intake manifold. If the pressure in the intake gets too high, then the wastegate opens and releases some of the exhaust gas to slow the turbine down and reduce the pressure. Some turbos (like the stock Mazda rotary) have a small internal wastegate that doesnt let enough gas bypass to do the job effectively. I proved this (again) yesterday. As I throttle up with the wastegate fully open the boost increases linear with throttle. When I reach 46 MAP (i.e. 30 MAP ambient + 16 boost which equates to about 8 PSI boost at sea level) I'm getting a lot of power. This is my normal max take-off boost. Yesterday, to test the turbo pipework, I gave it a little more throttle. Beyond 48 MAP you can see the boost start to "run away". A very tiny increase in throttle and the boost goes quickly past 50 MAP, power drops off and the beginnings of detonation are heard. I back off the throttle quickly when this occurs. This means that I have to be careful with the throttle during take-off. I can't just go to WOT (wide open throttle).

My new installation will have a 46mm TAiL external wastegate and a different "aspect ratio" between the turbine and the compressor to help control this. The $500 TAil unit will allow enough exhaust gas to bypass the turbine to prevent overboosting.

The other device I have is a blow-off valve in the intake system. If the intake pressure gets too high it overcomes a spring, pushes a plunger and lets some of the pressure out. This keeps the boost from the engine, but it doesnt stop the turbo from overspeeding.

Now, as you climb the ambient pressure decreases about an inch for every thousand feet. So at 5000' ASL you're ambient is about 25 inches of mercury and you need 5 inches to "normalize" - ie bring the engine to sea level power. 1 inch of mercury is roughly 0.5 PSI, so at 10,000 feet ASL you need 10 inches (or roughly 5 PSI) and so on.

Lets say you're cruising at 20,000' boosting 10 PSI. As far as the engine is concerned its happily driving along at sea level, and is producing full power. i.e. normalized. Not bad considering that a non turbo engine is at something like 75% power at 8,000' and is probably not even going to get you up to 20k at all. At 20k, however, the turbo is working fairly hard to give you all the air the engine expects at sea level. Now, if you want boost power at 20,000' you're turbo really has its work cut out.

so, normalization wont hurt the engine but, depending on altitude, it can still give the turbo some work to do. Compared with boosting at altitude, however, it's easy on the turbo. Does that make sense?

Turbos come in all shapes and sizes with different aspect ratio, trim etc. to allow for various circumstances. A turbo that works well on a car can blow itself to bits at 10,000'. (Ask me how I know this )

You may find this glossary of turbo terminology useful:
http://not2fast.wryday.com/turbo/glo...glossary.shtml

I'm sorry. What was the question?
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  #5  
Old 12-29-2005, 10:33 AM
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I have also "heard" that turbonormalizing can increase the life of an airplane engine. (air cooled)

The explanation that was given to me, that it pressurizes the rings, does not make sense to me.

My guess is, airplane engines are designed to run at 75%-80% power, forever, throttling back to save fuel will cause wear on the cylinders and shorten the time before TBO.

SO, by turbonormalizing you are running at the designed power level and the engine lasts longer.

The FAA has a procedure for commercial operators to extend the tbo, based on that operators operating history. the operator can run the engine 100 hours over TBO, have the engine torn down and inspected. Each time this is done successfully, the engine showing no detrimental effects of being run 100 hours more than the previously set TBO, the TBO for that owners fleet of that engine is increased to the new number of hours.

Continentals normal TBO is 1400 hours. My buddy tore one down and measured the wear after 2900 hours and he found nothing - no wear.

How the company operated the planes

towed to the runup area
runup performed and plane takes off promptly, no waiting for temps - oil preasure, check list and GO
cruise at 80% power
land and shut down, plane is towed to hanger

So in normalizing you are able to run the engine the way it likes to be run and it will run longer
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Old 12-29-2005, 11:21 AM
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Given the unknowns of cylinder, bearing and ring lubrication, generally the higher the average power setting, the lower the engine life will be. The higher the BMEP, the higher the gas loads on the rings, ring lands and bearings are.

While mechanical loads may be similar to an atmo engine, turbo normalizing does impose considerable extra thermal loads at altitude on an engine which is not adequately intercooled, especially true in the case of air cooled engines. If operated below 12,000 feet, this may be insignificant. Above 15,000 or so, maybe quite significant.

A proper wastegate as John describes cockpit controlled by a pneumatic or PWM electronic device will allow manifold pressure to be maintained as the aircraft climbs up to the engine's critical altitude. These range in price from $25 to $900 depending on features and sophisication desired.

John,

What are those fellows doing to your turbo, applying 14 layers of gold plating? I usually have my stuff from Turbonetics within 48 hours of ordering it. Hoping you would be flying it soon.
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  #7  
Old 12-29-2005, 11:35 AM
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Quote:
Originally Posted by Dust
My guess is, airplane engines are designed to run at 75%-80% power, forever, throttling back to save fuel will cause wear on the cylinders and shorten the time before TBO. Continentals normal TBO is 1400 hours. My buddy tore one down and measured the wear after 2900 hours and he found nothing - no wear.
Totally unrelated to this thread, but I've done a fair amount of work with air-cooled V-twin motorcycle engines. The advent of Synthetic oil has played a HUGE factor in preventing wear in those engines. Are synthetics being adopted in aircraft engine and turbo lubrication as well?
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Old 12-29-2005, 11:54 AM
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Quote:
Originally Posted by bart
I've read elsewhere that using a turbo for normalization rather than increasing base HP will extend the life of the unit greatly. While this seems obvious to me why, can someone elaborate?

Bart
MMMM, thought this was your question?
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  #9  
Old 12-29-2005, 12:03 PM
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I've been using Mobil 1 in race and street engines for almost 20 years now and I agree. This is magic stuff. Engines and turbos which would have failed with conventional oils last with Mobil 1. Longterm wear is almost unmeasurable is many cases. Equally magic for turbos where it eliminates coking failures common in the olden days. You can beat the crap outta engines, overtemp the oil big time and the engine remains mint inside.

This is a very good idea for auto engines, especially turbos. We break engines in on the stuff and have no issues using with 100LL and Decalin TCP lead scavenger. Change every 50 hours.
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  #10  
Old 12-29-2005, 12:24 PM
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Quote:
Originally Posted by Dust
MMMM, thought this was your question?
Sorry Dust, I was saying "my" comments were unrealted to the orignal thread...not yours!

Bart
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  #11  
Old 12-29-2005, 12:47 PM
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RVGuy, Why did Mobil1 pull out of the aviation market?? Were these real problems, or lawyer problems?

Waiter
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  #12  
Old 12-29-2005, 01:10 PM
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Mobil 1 was never offered for GA use. Mobil tried a synthetic AV oil which was removed from the market in about 2 years after multiple complaints about camshaft and lifter galling and corrosion and a class action suit brought against them if memory serves me correctly.

I'm not sure if it was ever proven that the oil was really bad. The chemists for Mobil stated it was superior in all respects to conventional aviation oils... but. From time to time, Lycomings have suffered spats of camshaft and lifter problems some apparently caused by improper metallurgy and heat treatment. Maybe the oil was just a scapegoat, maybe not.

Mobil had to fork out lots of dough to fix engines and that's the last we heard of this

For auto engines which don't seem to have camshaft and lifter issues generally speaking (forget Chev small blocks for a second here) Mobil 1 has proven to be far superior to mineral based lubricants and and are used extensively in Formula 1 and Indy Car engines. Thrashed at 19,000 rpm. Talk about high loadings.
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  #13  
Old 12-29-2005, 01:25 PM
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Quote:
What are those fellows doing to your turbo, applying 14 layers of gold plating? I usually have my stuff from Turbonetics within 48 hours of ordering it.
I don't know. Maybe they ran out of gold foil because of using it on the tree. Hopefully it'll be on the way soon. I was told a week or two a week or two ago. I still have to do something about a manifold. In the meantime, Bob's stock unit is behaving quite well (but I'm being nice to it).

Back on thread - I'm using Mobil 1 in my installation.
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