Sounds to me like you need to get yourself a wide band O2, that would make tuning your quad safer, quicker, and faster!!

There are two ways you'll know your turbo is to small, first if the exhaust side is to small the engine's power will fall off fast on the top end because your restricting to much of the exhaust flow. Second if the boost comes up then falls off and goes lower than you wastegate setting, the compressor side is to small for the engine. Since boost is basically a measurement of the air an engine can not consume, if the boost falls off it's because the engine is using it all up and then some, and the compressor can not keep up. There are many charts to give everyone a good idea of what housing sizes, turbines and trims to use on any given engine, you mentioned the maps with squiggly lines and such, those are the specific compressor maps for each compressor wheel. I can help you guys with that, it's easy.

Let's say we want to turbo charge a 3.0L engine, at 6,000 RPM and 10 PSI that gives us a pressure ratio of 1.68. Pressure ratio is calculated by this: atmospheric pressure (14.7) + desired boost (in our case 10 PSI)= 24.7. Now divide that (24.7) by atmospheric pressure (14.7)= 1.68. Now there are charts for this on the net but, I know that this engine will require about 25 lbs per minute of air, now take those two numbers, 1.68 and 25 lbs/min and click this link: TO4 50 Trim wheel

If you plot out those two numbers you will see that we are right in the begining of the sweet spot of compressor wheel, peak is 78% on this particular wheel, and what does this mean when you are running in this area? A happy turbo, no worries of compressor surge, since it is in it's peak efficient area the charge temps will be the coolest because your not overworking the turbo to make boost.

Hope this helps.


Later

 

LOL yeah a wide band would help. I have a standard one with the 1V O2 in my exhaust. I just don't have the A/F gauge mounted.

As far as sizing, the only thing is I don't know of too many different turbos for small engines. On cars you get a popular unit and can swap housings and all that easy.

My turbo is actually made for a 1.6 (or was it 1.8) Audo Turbo Diesel!
That's 1800cc's and my ATV is 350cc LOL!

But as I have found out, DEISELS use SMALL turbos in compare of GAS engines.


So far so good. Today I took mine out for some test rides. My Fuel Injection control board still laying under my seat. Surprisingly it hasn't broke something on it. Picture ---> http://www.paysonarizona.net/MyProje...ss000_5453.JPG

Copy and paste if the links are not working here!




Here's my injector upside down under the HUGE Holley Throttle Body off of a V6 Chrysler LOL! And also you can see the hacked in cam position sensor.---> http://www.paysonarizona.net/MyProje...ss000_5455.JPG





Here's a video of my home made fuel injection computer board and a LCD plugged in so I can adjust the fuel map. Real Player video ---> http://www.paysonarizona.net/Home%20...Programming.rm

I will be making a new control board encased and mounted to the ATV frame. And a smaller LCD I have mounted on the gas tank or somewhere with 5 or so buttons to view and adjust the fuel table.

It's kinda cool now. I don't have to use my laptop to adjust it. I made it in the program so I can adjust it ON THE ATV. I did have help from someone online learning to program this thing especially the assembler language I hated!





Here's two 3gp (cameraphone) videos of me riding. Sound is kinda crappy form that thing.

http://www.paysonarizona.net/Home%20...urboEFI_01.3g2

http://www.paysonarizona.net/Home%20...urboEFI_02.3g2

That gauge in the middle of the handlebars is a boost gauge [img]i/expressions/face-icon-small-tongue.gif[/img]

It's not perfect yet. But running at least as good as it ever did with the carb. And I ran out of Aviation gas a few weeks ago working in this thing. Today was on 89 octane or so. It never pinged thank God!

Actually, it's going nuts once in boost to where it revs to my valves float! I need aftermarket springs soon.

And I need to get rid of my STOCK muffler for something not so restrictive. I don't need ANY backpressure after my turbo. I bet I get a few more PSI without that muffler back there. I just don't want it TOO loud.

 

Okay from all that I have read is that on the oil drain from the turbo you do not want it to go below the oil level in the engine. That is what mine does. It actually drains to the drain plug on the bottom of engine. I have already had to much oil to the turbo and blown seals in the turbo, I have had a plugged oil feed to the turbo, fried it.....Is there a dedicated oiling system someone has tried so I can possibly eliminate these kinds of problems?

 

Where is your turbo. BEHIND the engine?

I thought about doing some dedicated oiling so I could put mine under my seat. But then didn't want to have to worry about that kind of stuff. And I figure I'm taxing my electrical running a fuel pump as it is and a oil pump would probably use more power!

My turbo is slightly HIGHER than my drain in FRONT TOP of my engine where I drilled a hole and threaded in a return line. When I accelerate or go up hill (which is when you will be spooling the turbo) the oil would drain even better in that case.

 

As you've found out, you have big problems. There is only a few ways to go on this deal.
1 Get the turbo up higher so it will drain above the oil line.
2 Get a pump (dry sump belt drive or electric) and pump the oil into the engine case.
3 Get a total dedicated system, (tank, lines, pump) and use this as your oil system.
All but the first have big problems to overcome.
As GraphiteDak has already pointed out, that is why most systems are up front and up high.

 

Well unfortunatly my turbo is in front and my gravity oil drain from the turbo is as low as the bottom 1/3 of the engine with barely enough slope in the large line to allow gravity to do its thing.....It has worked but it has also caused some problems. I have been thinking about making a new header pipe, mainly to get the placement of the intercooler up front but now I guess it needs to be done for possible oiling problems.
How much oil to the turbo is too much? I know they don't take much.

I have noticed I have alot of pressure pulses coming out of my crankcase breather tube/filter, I wonder if I could use this to make a scavenge pump type setup without using a actual electric pump......

 

The place where I bought the turbo from told me that the oil return was the key.
I am not sure how much oil I need to let go to my turbo, but I have a orifice inline with my tubing that feeds my turbo. When I first tested it, I had a clear return hose and I could see oil coming back to the engine frothy like the turbo guy said it would, so I know I have oil. I have a red high temp line on it now. SO I can't see it anymore. I also installed an oil cooler just before my turbo.
Most if my stuff is form the junk yard except the actual Turbo and the 2 BAR MAP sensor.

I also drilled into my crank case to get the oil back into it up high, just below where my cylinder jug bolts to the crank case. Maybe a higher port would help, but you may ned to move your turbo higher like you said.