Turbo Theories and Myths

[NM]

Had to start my own thread on this as I feel it is not my business to post in the Aero thread.

Who else thinks that Fred W should prove what he is saying. I want to see where a Aero turbo flows better at 8 lbs than Boondockers or TSS turbo at 12-13 lbs.

If this is fact...Aerocharger should have been using this factual information in their marketing efforts. I mean that would be something to brag about.

Lets see it Fred.

In my testing with a 2863 GTX vs an Aero 66, the GTX spooled faster and just kept pulling away. Both sleds at 8 lbs.

 

[go green]

Boondocker and TSS don't make turbos but the GTX 2863 or the 2867 is a better turbo than the areocharger 66 .

 

[WesG]

Been playing with calculations for awhile now. What is everyone using for VE for an 800cc two stroke?(I used 85% for my calcs) How about your calculated non-boost airflow(I came up with 195.68 cfm after VE and 230.216 cfm before VE)?

 

[NM]

Boondocker and TSS don't make turbos but the GTX 2863 or the 2867 is a better turbo than the areocharger 66 .

lol..ya ya.

I think the GTX turbo's are pretty hard to beat too, but we should give Fred the chance to back up his statements with some proof. Since he is the Canadian Aerocharger poster boy and all.

I had an Aero 66 on a HM kit and I will admit that it worked just fine, but not as good as the GTX. Both sleds had identical motors, clutching, tracks, and water to air intercoolers. We ran them against each other for at least 20 days and the Garrett worked better in every situation.

The other issue with the Aero is when they get tipped over or upside down you lose some turbo oil.

 

[1100]

Neil have you done any testing with the comp turbos?

 

[Adrenaline Addiction]

lol..ya ya.

I think the GTX turbo's are pretty hard to beat too, but we should give Fred the chance to back up his statements with some proof. Since he is the Canadian Aerocharger poster boy and all.

I had an Aero 66 on a HM kit and I will admit that it worked just fine, but not as good as the GTX. Both sleds had identical motors, clutching, tracks, and water to air intercoolers. We ran them against each other for at least 20 days and the Garrett worked better in every situation.

The other issue with the Aero is when they get tipped over or upside down you lose some turbo oil.

I can second that. I rode both these sleds at 8#'s boost. I found the Garrett to be more responsive, and far more linear power. I found the Aerocharger to be very peaky. I rode the Aero for two full days, the first 20 seconds on the Garrett I could tell it was much better. Its that noticeable IMO.

 

[rsaint]

Neil have you done any testing with the comp turbos?

I am putting a equal to gtx 3076 on a linderman 900 cat built to 1000 with neils boost it box.

 

[steveo10]

Garrett >Aerocharger

 

[1100]

Let me know how it works out. I cant wait for snow to do some more tuning on the 1000. You building off the zx chassis r saint. I plan to run mine the way it sits for the winter, If it works well I would like to do a bigger turbo and an intercooler, the year after.

 

[rsaint]

Let me know how it works out. I cant wait for snow to do some more tuning on the 1000. You building off the zx chassis r saint. I plan to run mine the way it sits for the winter, If it works well I would like to do a bigger turbo and an intercooler, the year after.

Will do hopefully this year.

 

[Aerocharger_Brad]

Sorry for not responding sooner.

1. An Aerocharger at 8psi cannot and will not flow more than a Garrett at 12-13psi. Flow is dictated by Engine VE, Turbine Size, Intercooler efficiency, Air Box design, Overall Engine / Kit efficiency. We have seen for many years, in many different applications that systems, not the turbocharger, have a wider range of efficiencies when flow is studied. Many of our customers experience the same performance increase at lower boost levels then Garret systems at higher boost levels. That statement is not claiming that the Aerochargers at 8psi flows the same as a Garretts at 12-13psi, but instead the overall system performs more efficiently.

2. When all things are correct and the application is proper we experience faster spool and larger top end power with the Aerocharger over automotive style turbo. In some cases one may be able to specifically chase one aspect and beat the Aerocharger performance but in general we have a good balance of performance and power. If the Power seemed “Peaky” a vane adjustment would be needed. Please watch the following video on how the adjust the vanes of an Aerocharger. Aerocharger Boost Controller.avi - YouTube Adjusting the vane allows the rider to tune the turbine to perfectly match the needs of the engine and the rider. This ability to tune the turbine is exclusive to Aerocharger. Proper fuel tune is also very important to drivability and must not be overlooked.

3. At sea level I use the following for the E-tec 800cc. VE 86%, ME 31%, AFR 13.5, 59F, 14.7Psig, 15.2 lbm/min. At 6.5K ft I see in testing. Boost 7.5psi, CFM 316, P/R 1.65, T1 36F, T2 142F, Post intercooler 56F, Exhaust back pressure 10.3.

4. FredW has no affiliation with Aerocharger other than being a critical yet happy customer. Check his earlier post.

5. When a sled is upside down a few drops of oil will come out of the breather vent. This is normal and of no harm to the turbo or engine.

In short as new companies come along they make alliances with others in the industry and have to separate themselves from the competition. There are exciting times ahead as this industry grows and the consumer has more choices. The additional competition will force all companies in the industry to move forward to produce the best possible product. Aerocharger is always looking to test and develop new products. Just a few weeks ago we even tried to purchase a Boost-it to test and also be able to support our customer(NM), who has sold it with our kits. We did think it was odd we could not purchase from a good customer but now we know why. This is a large industry and I wish Neil and Dave luck in their new venture.
Please come down to the Edmonton snow show and check out the product yourself. You can find our products bring offered by Mountain Magic and Absolute Power at the show. You can also see our products in the Ski-Doo booth with Andrew Dey (Engineer), Calvin Felker (Racer) and Carl Kuster (Racer, Dealer).

 

[1100]

You guys have any plan on producing a larger turbo anytime soon?

 

[Aerocharger_Brad]

1100,

Good question and as the thread title implies I think you are hinting at one of the biggest myths out there. We use a 66 series Aerocharger on the E-Tec 800cc with 66 being the frame size of the Aerocharger. Currently we inventory 3 compressors and three turbine sizes. We offer on the compressor side a 178%, 200%, and 224% and on the Turbine side we offer a .200, .250 and .300. Current production kits for the E-Tec 800 uses a 200%/.250 Aerocharger. From this you can tell we are in the middle of the trim sizes on both the Compressor and the Turbine.

Let’s talk about compressor matching and the myth behind it. For example, we can use 7.5psi at 6,500ft and with an intercooler we use 316cfm at 1.65 pressure ratio. A compressor map has efficiency islands - the center island is where the compressor operates most efficiently. What this means to the engine is that the charge air is at a lower temp compared to a charge from a less efficient island. On a 200% compressor the 316cfm and 1.65pr is in the center of the most efficient island. On the bigger 224% compressor, it would fall on the left side of the most efficient island. Now let’s talk about the Myth, a larger compressor flows more air. This is true, but who cares about what the compressor CAN flow. Let’s talk about what the engine DOES flow. The throttle bodies are a fixed size, and if you have 7.5psi of air feeding them they will flow 316cfm. The throttle bodies do not care if the pressure was created by a compressor 1 inch in diameter or 10 Ft. What does change is that on a larger compressor, the air will be hotter because the compressor is over sized and not operating in the most efficient island. Please also note that matching a compressor for a snowmobile is very different from sizing an automotive application. We consider the following when sizing a snowmobile turbo: clutch engagement, altitude, temp, and clutched RPM in addition to the standard criteria.

On the turbine side we have tested all three sizes and in some cases we use a different size then the production .250. The .200 turbine offers faster spool and is good for a hardcore tree guy or snowcross. The .300 offers a little top end power from reduced back pressure and would be my recommendation for someone who only does big pulls or a dash for cash. In the end, the .250 is the best choice and is used in 99% of the kits. From the race program, we have also developed turbine porting for all three sizes and will be offering this to the public later this year. In very limited production we will also offer a light weight Turbine wheel, which will reduce the turbine weight by 27% for even faster spool and efficiency. These are the things I love to work on with our race team.

 

[NM]

1100,

Good question and as the thread title implies I think you are hinting at one of the biggest myths out there. We use a 66 series Aerocharger on the E-Tec 800cc with 66 being the frame size of the Aerocharger. Currently we inventory 3 compressors and three turbine sizes. We offer on the compressor side a 178%, 200%, and 224% and on the Turbine side we offer a .200, .250 and .300. Current production kits for the E-Tec 800 uses a 200%/.250 Aerocharger. From this you can tell we are in the middle of the trim sizes on both the Compressor and the Turbine.

Let’s talk about compressor matching and the myth behind it. For example, we can use 7.5psi at 6,500ft and with an intercooler we use 316cfm at 1.65 pressure ratio. A compressor map has efficiency islands - the center island is where the compressor operates most efficiently. What this means to the engine is that the charge air is at a lower temp compared to a charge from a less efficient island. On a 200% compressor the 316cfm and 1.65pr is in the center of the most efficient island. On the bigger 224% compressor, it would fall on the left side of the most efficient island. Now let’s talk about the Myth, a larger compressor flows more air. This is true, but who cares about what the compressor CAN flow. Let’s talk about what the engine DOES flow. The throttle bodies are a fixed size, and if you have 7.5psi of air feeding them they will flow 316cfm. The throttle bodies do not care if the pressure was created by a compressor 1 inch in diameter or 10 Ft. What does change is that on a larger compressor, the air will be hotter because the compressor is over sized and not operating in the most efficient island. Please also note that matching a compressor for a snowmobile is very different from sizing an automotive application. We consider the following when sizing a snowmobile turbo: clutch engagement, altitude, temp, and clutched RPM in addition to the standard criteria.

On the turbine side we have tested all three sizes and in some cases we use a different size then the production .250. The .200 turbine offers faster spool and is good for a hardcore tree guy or snowcross. The .300 offers a little top end power from reduced back pressure and would be my recommendation for someone who only does big pulls or a dash for cash. In the end, the .250 is the best choice and is used in 99% of the kits. From the race program, we have also developed turbine porting for all three sizes and will be offering this to the public later this year. In very limited production we will also offer a light weight Turbine wheel, which will reduce the turbine weight by 27% for even faster spool and efficiency. These are the things I love to work on with our race team.

There are some good points Brad, but you should explain how a bigger turbo generates higher charge temps? Proper turbo size is more relative to altitude and engine load. As you know, the turbo's ability to move air can change significantly as you go up in altitude, and more importantly as engine load becomes increased.

The other thing I have seen you mention before is 02 values, and you think high 12s for the e-tech is acceptable for max horsepower, which is fine. Do you know where they make the max tourque?
If the guys that ride in Revy with 174 3 inch tracks were in the high 12's they would have some problems. People really need to know how these work in BC, because the race circuit really has no meaning in Revy.
We have the e-techs so they will start a long pull in the high 12's then creep down to low 12's to save the motor and create the most tourque. There is a noticible difference.

 

[Justin_sane]

I have been reading through this post and I had a few things I wanted to make discussion of...

I kinda disagree that sizing the turbo is different for a sled than a car (i mean, I agree it is different, being small displacement two stroke, vs a a 4 stroke car engine). But the general principles are the same arent they? the turbo is an air pump (as is the engine), spun by wasted exhaust energy (heat mostly, then pressure to a lesser extent). I dont feel that the issue is that a larger turbo compressor will increase the heat of the charge, more likely that you can get surging/stalling which can toast a turbos bearings/thrust bearing quickly. However a lot of compressor housings come with anti surge porting now which allow smaller engines to run much larger compressors without surging (like some of these car guys making 800+ hp on a 2L engine or even 1500hp on a 3L engine). Conversely an undersized compressor will choke causing it to increase in backpressure, overspeed at high rpm , blow oil seals, etc. In saying all that, imo there isnt really a reason to go with an overly large compressor on a sled anyways because even if you can spool it by a useable rpm, how much power is really necessary on a sled before you just flip over every time you nail the throttle. lol

Whats important and often overlooked is the Density ratio, which you mentioned in different terms i guess, by mentioning altitude and temperature. But those things are also of major importance to an automotive application as well.

Correct me if im wrong... I just wanted to join the discussion to learn more about sled applications

 

[Aerocharger_Brad]

NM,
I tried to explain why a turbo that is too big will have higher charge temps, but let me break it down at little bit more. I do love explaining this stuff so, here it goes and please anybody feel free to ask questions.

A compressor map is like a topo map. The top of the “mountain” is where you want to operate the turbo. Like a mountain there is a ridge, and as you go up in altitude or increase boost, you move along this ridge. You always want to operate as high on the “mountain” as possible. If the turbo is matched correctly you will always stay on the ridge as you change boost and/or altitude. By using a bigger turbo, you will be operating lower on the “mountain” than is best. The lower on the “mountain”, the lower the compressor efficiency. The lower the efficiency, the more heat the compressor makes at a given boost or pressure ratio. The higher the heat, the lower the air density is - therefore less oxygen to burn with the fuel. Less oxygen and fuel = less hp.

Engine load has nothing to do with compressor size as we do not care about compressor efficiency anywhere but 100% throttle on a CVT. A bigger turbo would only perform worse at less than 100% throttle, because it is even less efficient at part throttle then 100%.
With over 300 Aerocharged E-tecs, we can recommend 12.5-13 AFR - any more fuel than 12.5 and the E-tec is not happy. Your Pro will take more, but not the E-tec.

You said your AFR starts at high 12’s and creep down to low 12’s to save the motor... Does the boost-it box have a timer and add fuel as 100% tps is maintained? What if the pull is longer then you planed- does it keep adding fuel? We have run 30hrs straight at 100% with no issues. My guess would be your system is heat soaking and that is the cause of the creeping AFR. As the system heats up, the system has less oxygen and needs less fuel.

174 x 3 is a popular upgrade and we have many systems running this combination, including some in Revy without issues.

The race circuit is where I get to play with new technologies that do relate to back country riding weather at 11,000ft in Colorado or in Revy. Carl Kuster will be servicing and stocking kits at his CKMP in that neck of the woods. He puts on about 4k miles a year…lucky dog.

 

[Aerocharger_Brad]

Justin,

Thanks for joining. The major difference between a snowmobile and an automotive application is how I would plot my calculation on the compressor map. Back to the mountain on a topo, with a snowmobile I would plan to have max power and RPM on the peak of the ridge because the CVT is very good at maintaining RPM - let say 8200 RPM. On a race car, for example, I would plot max torque (3,500RPM) and redline (7,000RPM) and want to center this line on the ridge. So as we shift and go through the RPM range, we want to be in the best possible area on the map. Long and short- we want to operate the turbo in the most efficient range as possible for as long as possible.

 

[sledwhore]

I bought a aerocharger 66 that is used and am wondering if there is a way that I can configure it differently, like spin the top an bottom to align it to fit in the chassis better , is this something I can do myself or do I have to send it away, and also how can you tell what turbine is in it

 

[CrankShop910]

1100,

Good question and as the thread title implies I think you are hinting at one of the biggest myths out there. We use a 66 series Aerocharger on the E-Tec 800cc with 66 being the frame size of the Aerocharger. Currently we inventory 3 compressors and three turbine sizes. We offer on the compressor side a 178%, 200%, and 224% and on the Turbine side we offer a .200, .250 and .300. Current production kits for the E-Tec 800 uses a 200%/.250 Aerocharger. From this you can tell we are in the middle of the trim sizes on both the Compressor and the Turbine.

Let’s talk about compressor matching and the myth behind it. For example, we can use 7.5psi at 6,500ft and with an intercooler we use 316cfm at 1.65 pressure ratio. A compressor map has efficiency islands - the center island is where the compressor operates most efficiently. What this means to the engine is that the charge air is at a lower temp compared to a charge from a less efficient island. On a 200% compressor the 316cfm and 1.65pr is in the center of the most efficient island. On the bigger 224% compressor, it would fall on the left side of the most efficient island. Now let’s talk about the Myth, a larger compressor flows more air. This is true, but who cares about what the compressor CAN flow. Let’s talk about what the engine DOES flow. The throttle bodies are a fixed size, and if you have 7.5psi of air feeding them they will flow 316cfm. The throttle bodies do not care if the pressure was created by a compressor 1 inch in diameter or 10 Ft. What does change is that on a larger compressor, the air will be hotter because the compressor is over sized and not operating in the most efficient island. Please also note that matching a compressor for a snowmobile is very different from sizing an automotive application. We consider the following when sizing a snowmobile turbo: clutch engagement, altitude, temp, and clutched RPM in addition to the standard criteria.

On the turbine side we have tested all three sizes and in some cases we use a different size then the production .250. The .200 turbine offers faster spool and is good for a hardcore tree guy or snowcross. The .300 offers a little top end power from reduced back pressure and would be my recommendation for someone who only does big pulls or a dash for cash. In the end, the .250 is the best choice and is used in 99% of the kits. From the race program, we have also developed turbine porting for all three sizes and will be offering this to the public later this year. In very limited production we will also offer a light weight Turbine wheel, which will reduce the turbine weight by 27% for even faster spool and efficiency. These are the things I love to work on with our race team.

Brad, have you measure the pressure drop throught the throttle body's and reads after 8 pounds of boost, is it liner or compounding???

 

[jpgmtech]

In simple terms, peak compressor efficiency at target CFM is the determining factor for compressor size. Therefore larger compressor does not equal lower charge temps unless your compressor was too small to start with.