2016/17 AXYS MTNTK TURBO

[mountainhorse]

Noise is not a concern really... they are noisy machines, right.

Only a concern if it is damaging...or is an indication for areas of performance improvement.
At sled boost levels... I'm not really worried about breaking compressor wheels...so we can write off the damage category, leaving only the question of perf improvement.

If the flutter happens during part throttle... can be corrected easily and improvements made.

If the flutter only happens when the throttle is abruptly closed... nothing to do.

If it is surging too much... the spring may be too stiff for the application and is not relieving the pressure fast enough,
could also be related to wastegate response time (not fast enough to decrease energy to the turbine).

OR... as mentioned above: Is it the nature of an EFR turbo to make a 'flutter' noise because the air is returned directly
back to the inducer?

Surge is directly related to response... and I doubt you will keep surge from happening when you go from WOT to
full closed in an instant on ANY system.

Intake noise on a sled is accentuated by the fact that there is a pretty direct line for sound to travel to
the riders ears... with no other 'muffling' device between the source and the rider.

The question about the wastegate spring on the MTNTK setup, vs. diaphragm actuator on the factory configuration
(typical) is related to speed at which pipe pressure can open the wastegate in response to the speed of throttle operation.

Again... from reports on the MTNTK kit... customers are happy with them... but always things can evolve.

The mass of the turbine (or lack thereof) puts the EFR into it's own category... spool rates, up/down, must be great with this unit.

Not long before others are using the EFR's in the sleds... I've seen a mock up of one with external
wastegate for an AXYS running an EBC... I really enjoy seeing this stuff evolve !

Heck... less than 10 years ago.. we were just starting to see turbo kits for sleds being marketed
to the average consumer... things have evolved a LOT since then.



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[mountainhorse]

If it IS surge/chatter... then you can pick up performance (throttle response) by minimizing the surge and you will improve recovery time.... and the EFR is built specifically to have fast recovery... it would be a shame to not capitalize on that aspect.

As td points out... these sleds are running low boost relative to capabilities... so I'm not very concerned with the durability issues.... more related to optimizing what seems to be a great system... and everybody want the most out of the stuff we are putting on our sleds.

Since the spring provided in the MTNTK kits CRV is the Garrett supplied generic spring intended for the automotive (4-stroke) aftermarket... there may be some thing to pick up in terms of performance by changing the spring.

Heck.. how many people want to tweak the "good enough" clutching that comes with a turbo kit (or is recommended) to optimize performance??

Why not see if the chatter can be minimized by a changing a simple spring on the CRV and get slightly better performance ?

Here is a simple vid on youtube to help those that may not understand surge/flutter/stall....It actually shows what happens in this situation so you can see/hear it.

<iframe width="900" height="506" src="https://www.youtube.com/embed/FwzUffAuQyc?rel=0" frameborder="0" allowfullscreen></iframe>






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[inspector01]

Just throw a wheel speed sensor on it and find out for sure what's going on.

Edit: They already have a cheap, easy kit to setup on the EFR turbos.

 

[mountainhorse]

Yea, BW made it super simple to add a turbo speed sensor with the EFR line of turbos.

You would have to also have a data logger to interpret speed info within the window of BOV/CRV operation and the relationship in a graphical manner. Would the BD controller that comes with the MTNTK unit be able to output logs or would another module be needed?

It would be cool if Turbosmart also offered their adjustable dual-port CRV for the EFR's in a non vented design to return all BOV flow back into the inducer.

The 'dual port' references that besides venting back to the inducer, it also vents to atmosphere to give the woosh sound, not that the sound is a big deal to me... I wonder if this external vent would affect recovery time with such a low inertia rotating assembly of the EFR's. We don't have to worry about venting affecting the fuel system as sleds don't have MAF sensors.

Would be cool to fit this little sukker on the MTNTK kit as it would be easy to dial up or down the CRV spring pre-load.... with just a twist to fine tune.

Also... with a low boost system... and the relatively low lb/min demand of a CFi2 800 running at say 5-lbs at sea level (19.7PSI MAP). I'd really like to see MTNTK make a super simple NON intercooled system with the EFR that can keep the complexity and cost down. No intercooler, no extra tunnel cooler etc...

At that level of boost... we've seen systems that can provide ample power, in the 190hp range, at '5 lbs' on pump fuel and no fuss. That is adding about 50% more HP at elevation than other NA sleds. Pretty darn great IMO....

Pretty amazing what a properly sized, properly clutched, well controlled '5 lb' kit can do on the mountain.

Now that is a kit I'd like to see.

Sure, being able to add more boost is nice, but that also adds complexity with more components needed, and most likely will change throttle response....

If MTNTK can supply a kit with intercooler and additional tunnel cooler... for about $4000 USd ... what kind of price could they offer on a simpler '5 lb' complete system??




BTW: For those wondering EFR stands for "Engineered For Racing"(thx Tory) ... A marketing term that BW (Borg Warner) came up with... they wanted to combine features, technology and aesthetics into a nice aftermarket package. The EFR's come standard with Stainless steel turbine housings and have available, as an option, aluminum center sections to keep weight down.

Looks like Ford is incorporating many of these EFR features into their BW turbos in EcoBoost engines... I believe that the Focus-RS uses a BW EFR type of turbo in the factory offering... that Lightweight turbine really is THAT big of a deal !

Keeping in mind that a stock naturally aspirated engine is making maybe 110-120 hp at 10k feet.







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[tangerine_sky]

It's hard to find any information on the BullyDog GT unit... Seems like most info out there is about installing it in Diesel trucks and loading up a pre-programmed tune...

Turbosmart does offer a Kompact shortie that is completely recirculating.

I would think as long as there is still sufficient pressure between the compressor and throttle body that no harm would be done by venting to atmosphere.

Whether recirculated or vented to atmosphere, if the compressor to throttle body piping contains the same pressure in both cases I do not see an advantage to recirculating, especially considering the recirculated air will be hotter than air drawn in through the air intake. This is with respect to MAFless tuned engines only.

With that being the case, I would think whatever pressure relief method resulted in the quickest release of a sufficient amount of pressure to not induce compressor surge would be ideal.

 

[tdbaugha]

EFR stands for Engineered For Racing. Couldn't help myself mountainhorse. Haha

 

[mountainhorse]

Thats alright... I need to be kept on my toes.

Thats your only comment though??




Fixed it

Yea, BW made it super simple to add a turbo speed sensor with the EFR line of turbos.

You would have to also have a data logger to interpret speed info within the window of BOV/CRV operation and the relationship in a graphical manner. Would the BD controller that comes with the MTNTK unit be able to output logs or would another module be needed?

It would be cool if Turbosmart also offered their adjustable dual-port CRV for the EFR's in a non vented design to return all BOV flow back into the inducer.

The 'dual port' references that besides venting back to the inducer, it also vents to atmosphere to give the woosh sound, not that the sound is a big deal to me... I wonder if this external vent would affect recovery time with such a low inertia rotating assembly of the EFR's. We don't have to worry about venting affecting the fuel system as sleds don't have MAF sensors.

Would be cool to fit this little sukker on the MTNTK kit as it would be easy to dial up or down the CRV spring pre-load.... with just a twist to fine tune.

Also... with a low boost system... and the relatively low lb/min demand of a CFi2 800 running at say 5-lbs at sea level (19.7PSI MAP). I'd really like to see MTNTK make a super simple NON intercooled system with the EFR that can keep the complexity and cost down. No intercooler, no extra tunnel cooler etc...

At that level of boost... we've seen systems that can provide ample power, in the 190hp range, at '5 lbs' on pump fuel and no fuss. That is adding about 50% more HP at elevation than other NA sleds. Pretty darn great IMO....

Pretty amazing what a properly sized, properly clutched, well controlled '5 lb' kit can do on the mountain.

Now that is a kit I'd like to see.

Sure, being able to add more boost is nice, but that also adds complexity with more components needed, and most likely will change throttle response....

If MTNTK can supply a kit with intercooler and additional tunnel cooler... for about $4000 USd ... what kind of price could they offer on a simpler '5 lb' complete system??




BTW: For those wondering EFR stands for "Engineered For Racing"(thx Tory) ... A marketing term that BW (Borg Warner) came up with... they wanted to combine features, technology and aesthetics into a nice aftermarket package. The EFR's come standard with Stainless steel turbine housings and have available, as an option, aluminum center sections to keep weight down.

Looks like Ford is incorporating many of these EFR features into their BW turbos in EcoBoost engines... I believe that the Focus-RS uses a BW EFR type of turbo in the factory offering... that Lightweight turbine really is THAT big of a deal !

Keeping in mind that a stock naturally aspirated engine is making maybe 110-120 hp at 10k feet.







.

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[Iceman56]

Also... with a low boost system... and the relatively low lb/min demand of a CFi2 800 running at say 5-lbs at sea level (19.7PSI MAP). I'd really like to see MTNTK make a super simple NON intercooled system with the EFR that can keep the complexity and cost down. No intercooler, no extra tunnel cooler etc...

At that level of boost... we've seen systems that can provide ample power, in the 190hp range, at '5 lbs' on pump fuel and no fuss. That is adding about 50% more HP at elevation than other NA sleds. Pretty darn great IMO....

Pretty amazing what a properly sized, properly clutched, well controlled '5 lb' kit can do on the mountain.

Now that is a kit I'd like to see.

Sure, being able to add more boost is nice, but that also adds complexity with more components needed, and most likely will change throttle response....

If MTNTK can supply a kit with intercooler and additional tunnel cooler... for about $4000 USd ... what kind of price could they offer on a simpler '5 lb' complete system??




BTW: For those wondering EFR stands for "Engineered For Racing"(thx Tory) ... A marketing term that BW (Borg Warner) came up with... they wanted to combine features, technology and aesthetics into a nice aftermarket package. The EFR's come standard with Stainless steel turbine housings and have available, as an option, aluminum center sections to keep weight down.

Looks like Ford is incorporating many of these EFR features into their BW turbos in EcoBoost engines... I believe that the Focus-RS uses a BW EFR type of turbo in the factory offering... that Lightweight turbine really is THAT big of a deal !

Keeping in mind that a stock naturally aspirated engine is making maybe 110-120 hp at 10k feet.

I'd like to see that too... Just a 6 psi pump gas kit like everyone else is starting to do. No IC, no gauges, could even do a Reflash in house with the BD to save money, wonder how cheap they could get the kit?

IMO though the EFR is nice cause it has all these features, almost like making it a "Turbo Kit" in itself, but the actual performance of the turbo never lived up to the hype IMO. Everyone jumped on them right away and most all just went back to a regular old Gerrett, and Im not just talking about snowmobiles, the racing world too.

 

[tdbaugha]

Ok in the pursuit of the pinnacle of performance, the Mtntk kit would benefit from a traditional wastegate with electronic boost controller. With the Bully Dog reflash there is no way of doing that so they'd have to add additional electronics. Last I checked, HM Turbos was working on a different reflash in order to do boost control with the stock ECU. We're now into the second year of the Axys and they still don't have it figured out.

With regard to the CRV, I'm not convinced the spring is incorrect for the application or that the noise is compressor surge... It could be because the reference line is at the reed cage and there are a lot of intake harmonics in that area, ESPECIALLY when going from WOT and 8-10psi to TB closed. Your case pressure is going to be really high and the reeds are working 10x harder to keep that charge in the crank case. They may not be sealing completely and the pressure in between the reeds and TB is pulsating... Again, I'm not sure.

Adding external BOV's and wastegates I think would be fairly ridiculous in our application. The EFR wastegate is PLENTY big enough and is aerodynamically designed for the best performance. Look at how well all these new internal wastegate kits run. Externals look cool and allow you to run low boost in a garret style turbo because the garret internal gates are tiny. Same goes for the BOV, recirculating the pressurized air back into the compressor should help keep the spool up. I'd take a little higher heat with better response over lower heat and worse response.

 

[mountainhorse]

Tory,

Great discussion... and I truly appreciate that you are actually using the kit on your own sled ... and not a 'keyboard jock' like me here about the MTNTK kit.


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I agree, for our apps, the external BOV/Wastegates are a bit of overkill and wont add much, if any, to the MTNTK kit in context with the advanced design of both internal devices on the EFR in the first place. The EFR wastegate location and design will rival, IMO, most eternal WG's that are grafted onto the exhaust, in terms of performance for OUR needs. The EFR's internal wastegate is designed to flow really well and have excellent aerodynamics, head-and-shoulders above current internal WG designs on other turbos used on sleds that I've seen.

The spring controlled wastegate on the MTNTK EFR turbo keeps things simple and performs well from all reports I've heard. An EBC device would be nice to see if it could work and at what cost? Evolution of an already great product, sounds natural to me.

I also agree that the internal BOV on the EFR (CRV) is more than sufficient in size to handle the blow-off needed.... which is why I believe that there is a strong possibility of room for improvement in performance, if it is surge, like I talked about in the previous post on the other page [below] it would be great to find out if it is indeed stall or just operational noise. In the same way we are "searching for best performance" with efforts in clutching changes.

Same goes for the BOV, recirculating the pressurized air back into the compressor should help keep the spool up

Unless, surge is slowing the spool, detracting from this performance aspect.

For a new MTNTK product offering possibility... a "base' model kit.
I agree with Iceman, that with an ECU reflash and a "5-6" lb kit... no intercooler, no additional tunnel cooler. A simpler, lower boost potential, non adjustable, MTNTK kit could compete in price with any kit on the market... and making it the hottest seller in the Polaris segment IMO because of the features and performance.

If it IS surge/chatter... then you can pick up performance (throttle response) by minimizing the surge and you will improve recovery time.... and the EFR is built specifically to have fast recovery... it would be a shame to not capitalize on that aspect.

As td points out... these sleds are running low boost relative to capabilities... so I'm not very concerned with the durability issues.... more related to optimizing what seems to be a great system... and everybody want the most out of the stuff we are putting on our sleds.

Since the spring provided in the MTNTK kits CRV is the Garrett supplied generic spring intended for the automotive (4-stroke) aftermarket... there may be some thing to pick up in terms of performance by changing the spring.

Heck.. how many people want to tweak the "good enough" clutching that comes with a turbo kit (or is recommended) to optimize performance??

Why not see if the chatter can be minimized by a changing a simple spring on the CRV and get slightly better performance ?

Here is a simple vid on youtube to help those that may not understand surge/flutter/stall....It actually shows what happens in this situation so you can see/hear it.

<iframe width="400" height="225" src="https://www.youtube.com/embed/FwzUffAuQyc?rel=0" frameborder="0" allowfullscreen></iframe>

.

 

[gmustangt]

No negativy, just discussion.

Personally dont see the value in a BRV / CRV. I know the car world it is used as a quieter application.

When you close your throttle body , the demand for air at the compressor inlet drops as its not needed going out the other end.
So to reintroduce it when the demand is not there , there is not a gain.
Just the double heated air.
To split the finest of hairs your disrupting the flow at the compressor inlet , call it not noticable.

 

[mountainhorse]

Definately see your point... and weather or not the recirc is benerficial... hard to tell... too many variables.

Most recirc exists to get away from MAF/ECU calibration issues on pollution controlled cars.

IMO... Running that Adjustable DP CRV/BOV (above) would give you the ability to fine tune your BOV in very small increments to dial it in just right.
As far as I can tell that TurboSmart valve is the only one out there that is adjustable.


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[diamonddave]

Ok in the pursuit of the pinnacle of performance, the Mtntk kit would benefit from a traditional wastegate with electronic boost controller. With the Bully Dog reflash there is no way of doing that so they'd have to add additional electronics. Last I checked, HM Turbos was working on a different reflash in order to do boost control with the stock ECU. We're now into the second year of the Axys and they still don't have it figured out.

With regard to the CRV, I'm not convinced the spring is incorrect for the application or that the noise is compressor surge... It could be because the reference line is at the reed cage and there are a lot of intake harmonics in that area, ESPECIALLY when going from WOT and 8-10psi to TB closed. Your case pressure is going to be really high and the reeds are working 10x harder to keep that charge in the crank case. They may not be sealing completely and the pressure in between the reeds and TB is pulsating... Again, I'm not sure.

Adding external BOV's and wastegates I think would be fairly ridiculous in our application. The EFR wastegate is PLENTY big enough and is aerodynamically designed for the best performance. Look at how well all these new internal wastegate kits run. Externals look cool and allow you to run low boost in a garret style turbo because the garret internal gates are tiny. Same goes for the BOV, recirculating the pressurized air back into the compressor should help keep the spool up. I'd take a little higher heat with better response over lower heat and worse response.

Tory are you running any additional intake venting on your sled? I have solved 2 turbo sleds having surge issues with additional intake vents. These were on Pro's but completely solved and fixed the issue (when the stock intake plenum was being used.)


I think the lack of available airflow was choking the turbo.

After seeing the stock Axys plenum, I'd highly recommend it...

 

[tdbaugha]

Tory are you running any additional intake venting on your sled? I have solved 2 turbo sleds having surge issues with additional intake vents. These were on Pro's but completely solved and fixed the issue (when the stock intake plenum was being used.)


I think the lack of available airflow was choking the turbo.

After seeing the stock Axys plenum, I'd highly recommend it...

Yes we are running fire n ice vents. And I removed the sound damping material from the stock intakes.

 

[tdbaugha]

EFR's come with the light spring and they do offer a 66% stiffer spring as an option. For grins I think I'll try their stiffer spring.

http://www.forgedperformance.com/store/product.php?productid=21569&cat=2493&page=1

"This item is not required based on HP or boost level - most applications work fine with the standard CRV spring. For applications that have an open CRV during part throttle cruising in high vacuum (Audibly loud, such as stock engine Subaru WRX/STI with EFR6758) or if surge is present while lifting the throttle - this stiffer spring may be the solution."

 

[mountainhorse]

It might be worth a call to Borg-Warner EFR tech line and ask an engineer what the BOV pressure rating is with both springs.

The EFRs were built for the car world with higher volume intake tracts and a higher lb/min ratings.


Just pondering here.

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[mountainhorse]

Tory

I saw you posted up a compressor map of the EFR in your other thread

What "island" is the MTNTK kit running on??


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[mountainhorse]

If the heavier spring makes it chatter more... You will know it is not inducer noise from recirc flow...

If it makes it less... Hmm

It might be that for the EFR to be tailored for the 800 CFI it maybe possible that it needs a lighter spring
than the standard spring issued with the turbo for the larger charge tract, higher lb/min automotive apps ???









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[tdbaugha]

If you go by the rule of 9.5-10.5 hp for every lb/min, then you get this:

What you really need is a speed sensor on there. Then you can see how much you're pumping. This is just a guess taken from the 4-stroke world.

 

[mountainhorse]

Tory,

Which EFR turbo and trim is being used in the MTNTK kit? (what Map are you showing above?)

Is your system making positive manifold pressure (>14.7PSIa) at engagement?

Does MTNTK have any tables on lb/min demand at consistent manifold pressures for the 800 AXYS engines over the RPM range while pressurized?
It would be nice to see what these engines "need" in terms of mass/flow/pressure.


Also... Have you put a vacuum gauge at the reed vacuum reference point to see what it is reading at idle?
Then see what vacuum is required to begin to lift the CRV... set the spring pressure at just slightly above that
and you, IMO, will have an optimized BOV-circuit for your configuration.

It is nearly impossible to get rid of some flutter when you chop the throttle..but it's good, from a performance perspective, to try to minimize it.



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