I also resized the Pr chart I found for the RHB5 series as well as RHC6 (My GM3):

 

matt- I'm not sure how you factored in RPM but your Pr are off. You have 12 psi at 1.9 Pr which 12 psi is 1.81 Pr. Looking at the rest they're a little off as well. Pr is calculated by boost pressure+14.7/14.

The map is broken up in groups of 5 and groups of 10. Your 7.5 mark would be 1.6 Pr which is roughly 8.8 psi.

If you look at my spread sheet on my web page, you would understand that the rpms represent the amount of air in m^3/min our engine takes in. That plot i made was specificaly for the f2T. An engine at a specific rpm will take in the same VOLUME of air at any boost pressure.

Yes, Pr = boost pressure+14.7/14. On your map you are using boost numbers strait from the turbo. In my spread sheet it says to input the amout of boost you want to see on your gauge, which is not the same as the boost from the turbo. My sheet has a field for pressure drop across the ic and piping(i used 1.5 as the pressure drop). So my formula is:

[boost(12) + 14.7 + ic pressure drop(1.5)]/14.7 = 1.918367

You add the pressure drop to the boost you see at the gauge b/c the the turbo is actualy puting out more boost than the gauge reads (unless you gauge is tied in at the nozle of the turbo - i hope not)

any more questions?

O BTW - my spread sheet also converts m^3/min to cfm. Not to mention that it already outputs in in m^3/min so no conversion is needed for IHI maps - thats why i made it in the first place.

 

Fair enough.



I also did the same thing with the T Bird, and as it appears, up to 14 psi is where the turbo is most efficient as it pushes roughly 264.8 cfm at 76% compressor efficiency:

At 18 psi, it would be pushing roughly 317.8 cfm at roughly 72% efficiency but is also at the choke line.

The choke line is described as the maximum centrifugal compressor volume flow rate that is normally limited by the cross section at the compressor inlet. When flow at the wheel inlet reaches sonic velocity, no further flow rate increase is possible. the choke line can be recognised by the steeply descending speed lines at the right of the compressor map.

This is a case where bigger isn't always better. You've already seen my comparison of the T Bird wheel and Vj11 wheel. This is a case where people think that the turbo is bigger so "I must be able to push higher boost" They forget that just the same as other turbos, the larger turbo is capable of flowing the more at less boost.

Case in point the T Bird is capable of 264.8 cfm at 14 psi and 76% efficiency where the Vj11 is capable of 264.8 cfm at 18 psi and barely 70% efficiency, it is also at the choke line at that point. The T bird on the other hand is capable of 320 cfm at 18 psi but is on the choke line itself.

So as far as sizing wise, you should yield the best results at between 8 and 14 psi at roughly 76% efficiency and 14-16 psi puts you in the 74% catagory but you'll probably find that 14-15 psi feels best.

 

I really wish this all made sense to me.
I can semi-under stand it.
It pretty much outlines.

Stock Turbo - no higher than 16 PSI.
Based on the plot. 15.5.

The HP #'s are a little off.

 

I really wish this all made sense to me.
I can semi-under stand it.
It pretty much outlines.

Stock Turbo - no higher than 16 PSI.
Based on the plot. 15.5.

The HP #'s are a little off.

It's all math and theory, not absolute as there are plenty of variables. But the stock T Bird hybrid pushes at 14-15 psi what the Vj11 takes roughly 18-20 psi to do.

The way that this was explained is that-"The compressor in the Probe and MX6 is biased toward elimination of surge and high pressure ratios at relatively low flow. It is rated for 300-325cfm, about the same as a DSM T25, but it can actually put out 325cfm at a pressure ratio of 2.7 (23-25psi of boost)"-which doesn't mean that you should go that high. I changed some numbers around because the person who explained it had the numbers a little higher than they should have been.

Look on the right side of the VJ11 map (the choke line) and you'll see that if you went further, that it could make it this high. However, if you look at my last dyno sheets you'll see that the Vj11 made about 2 hp per lb of boost increase. This is a case where the T Bird would have probably made the same numbers on a minimal 14-16 psi. There have been plenty of people who have run 200+ hp with 16 psi on the T Bird, it took me 20-22 psi to get 195hp on the Vj11. This could have been a complete disaster on the dyno.

This could also be a reason that Terri (MSGT-R) pulled such low numbers on the dyno (140hp) with a T Bird, stock air box with filter and stock boost solenoid. She'd in theory only be pushing what the T Bird is capable of at 8 psi where the Vj11 would be at around 10-12 psi. She didn't have a boost guage hooked up so nobody has any idea what boost level she was at. For all we know she could have been at 6 psi.

The compressor in the thunderbird turbo coupe is biased heavily toward flow and much less for "high" pressure ratios - it actually is outside of spec at anything above a 2.4 pressure ratio (wheelspeed exceeds design limits) This is one of the reasons people with the tbird IHI turbos complain that they "blow up" if you run more than 16-18 psi.

At 18 psi it is capable of 320cfm, but it is on the choke line. It is for this reason that it should be kept less than 16 psi rather than boosting it to 18 psi thinking that you must be able to because it is larger, and asking for your money back when it is your own fault.


Look at this for more insight on flow of our motor:
http://www.mx6.com/forums/showthread.php?t=107278

 

any more questions?

I also made 176.6 HP at 4,370 rpm at 10 psi:
http://www.mx6.com/forums/showpost.php?p=1245612&postcount=56

Your plots say 174HP at 4,500 rpm. Regardless it is all theory and there are too many variables.

 

At 18 psi, it would be pushing roughly 317.8 cfm at roughly 72% efficiency but is also at the choke line.

so do you know what that means?

So as far as sizing wise, you should yield the best results at between 8 and 14 psi at roughly 76% efficiency and 14-16 psi puts you in the 74% catagory but you'll probably find that 14-15 psi feels best.

So are you saying when ever i run 14-16psi i'm at 74%?? - b/c thats what it sounds like. hmm... you're missing something.

 

Mr.Jason - the hp numbers are off. In the thread sick took that map from I state that they are nimbers based only on the amount of air coming in the turbo - i do not take in consideration the change in VE of the engine through the rpm's. I simply use a flat VE of 85%

 

so... its open sick. Are you still going to finish?

 

test post

 

test post

 

Matt- I'm also curious where you got your 1.5 psi of pressure drop at the intercooler? Every reference I have seen for the MX6/Probe intercooler (which is not many) and I believe was posted by magik8 or SleepCounter showed less than a 1psi drop from if any at all.

I got curious today and hooked up three McMaster/Carr vaccum/boost gauges plus my Autometer which is tapped at the dynamic chamber behind the throttle body.

I tested one gauge at the turbo outlet line to boost solenoid, one after the stock bypass before the intercooler, and one after the intercooler on the way to the throttle body and went for a drive.

I had 10 psi on all 4 gauges with no kind of drop whatsoever.

Now keeping in mind that you did no actual testing, rather just threw a number in and called it a day, this says one thing and one thing only. Your calculations are flawed.

This isn't a perfect world and all of this isn't even an absolute, it would be impossible to say that it was as there are so many variables. But, you can cut down on the variables if you don't add in your own variables.

As said, I got 10 psi on all 4 gauges. How much did you get?

 

AR ratio = (atmospheric pressure 14.6 x boost pressure)/(atmospherice pressure 14.7)

 

AR ratio = (atmospheric pressure 14.6 x boost pressure)/(atmospherice pressure 14.7)

Dood, WHAT are you talking about? AR and Pr are two entirely different things. A/R is the area of the scroll divided by the radius from the center of the scroll to the shaft centerline.

PR, is the ratio of the air pressure at the discharge opening divided by the ambient air pressure at the inlet, P2C/P1C.

The equation is set up as 14.7+boost pressure/14.7

 

The 1.5 psi was just a worst case scenario ic - if you want to use a different pressure drop you can simple change that value in my spread sheet. 1.5 is just what most sites (that i've seen) use in their formula. Now to say my "calculations are flawed" it a true statement - but all these calculations are flawed, b/c as you said the world is not perfect.

I do find it efficiencies though that there was 0 pressure drop from the outlet of the turbo to the tb.

So sick, are you still going to discuss how the efficiencies will change with rpm and that 16 psi at 4.5k is "good" but soon after its not?

 

So sick, are you still going to discuss how the efficiencies will change with rpm and that 16 psi at 4.5k is "good" but soon after its not?

You're forgetting one major reason why Matt, the wastegate itself. The stock wastegate is set to start opening at 8.5 psi and Mazda insists that it never see's anything over 14 psi to avoid a loss of function. This was set up as a safeguard against warranty claims for the turbo and for the motor/the car in general.

Going by that, and going by the fact that I have driven with 18 psi on the stock turbo, it doesn't last long, in fact tapers off right away regardless of which rpm.

The wastegate is set low for a reason, longevity.

Now that being said, I can't think of a single person on MX6.com who has ever swapped their wastegate for one which started opening at a higher psi than 8.5, say 10-12 psi which would have a range of 16-18 psi as a total amount it should ever see.

The turbo itself isn't so much of the problem as the wastegate wasn't intended on seeing 16 psi, 17 psi, 18 psi. I've gone to 20-22 psi plenty of times with the stock turbo and never blew it up, thats not to say that this is a good thing to do, but it is still functioning fine. The problem with going that high is that you don't have boost for long with the stock wastegate.

If you know anything about turbos, you know that when you raise the boost, it's a good idea to also change the wastegate otherwise you're stressing more parts than you need to. Hitting a wastegate with twice the amount that is is intended to see stock isn't a good idea. You'll weaken the spring, possibly rip the diaphragm, and then it will open at 2 psi (random number) instead of the stock 8.5...then where will you be?

I'm not suggesting that everyone run right out and install a 12-14 psi wastegate, but that nobody ever has on this forum therefor always complains that the vj11 isn't efficient past 4,500 rpm (like you) when the reality is that the wastegate has already started dumping boost 1,500 rpm ago due to the 16-18 psi you've thrown at it.

If you've ever checked your boost gauge on a dyno, you'd see that on stock boost the turbo will hold fine most of the way to redline, but it doesn't take much more than 8.5 psi for your boost to start tapering off. Change it to 18 psi and you'll barely have 18 psi for 1,500 rpm.

In short, you cannot blame the vj11 for the inefficiency when there are other culprits involved in the inefficiency. Change your wastegate to one of a higher psi and you'll likely see better results. I've done it multiple times just never with the MX6. I've done it with the vj11 but this wasn't on the MX6.

 

ummm... the exhaust side (never mind the wastegate) has nothing to do with the efficiency numbers on the compressor map (that is why they call it a compressor map ) But for the sake of truth I have to ask you what you think you boost controller does...

[off-topic]

The waste gate starts opening at some point between 0 and 8.5 psi. At 8.5 psi it already is open as much as it needs to be for the turbo to maintain 8.5 psi. The only time your waste gate actuator will "see" above 8.5psi is if you out flow the waste gate port and and thus make more boost than intended by your boost controller. In theory, your boost controller should bleed of how eve many psi you want to run minus 8.5. So if you want to run 12psi the boost controller is venting 3.5psi from the wastegate actuator pressure line - so your wastegate actuator will never see more than 8.5psi (unless you out flow the waste gate port) [/off-topic]



I guess i over estimated your understanding of what i meant by efficiency. I am talking about the efficiency of the compressor which is listed on the map, NOT the efficiency of the whole turbo. What i'm trying to get you to explain is how you can say things like "14-16 psi puts you in the 74% category."



You can't say things like that b/c the compressor map obviously uses 2 variables to map points. When you map the boost number it gives you an entire range of efficiencies. The efficiency is then based on the amount of airflow through the compressor.

What determines the amount of air flow through the compressor? - 2 things, rpm and boost pressure. So when you say that "14-16 psi puts you in the 74% category." you MUST state an rpm as well. 16psi puts you in 74% from about 3.7k to 4.6k but then it quickly goes to the "maximum permissible speed line" line by 5k rpm.

All i'm trying to say is that when you quote efficiencies you need to quote psi AND flow (putting the flow as an rpm number makes it much more useful b/c it actually means something.)

 

ummm... the exhaust side (never mind the wastegate) has nothing to do with the efficiency numbers on the compressor map (that is why they call it a compressor map )

It most certainly does. Regardless of the numbers on the map, the turbo can not perform to it's potential, or can be overworked past it's limit. This is the responsibility of the wastegate both ways. It was set at 8.5 psi and set to work withing parameters for a reason (longevity) by a department which spent many more hours of R&D than you or I have on our calculators. Just because the amount that it is set at works well for higher boost, doesn't mean that a higher setting wastegate actuator can't be used to gain results (within reason)

But for the sake of truth I have to ask you what you think you boost controller does...

The factory boost solenoid divides boost pressure between all three places, the solenoid inlet to the wastegate, and the solenoid inlet to turbo inlet. The solenoid inlet sends pressure back through the turbos inlet. The lower nipple of the solenoid is normally open almost all of the time via a 12v source. When knock is detected, the knock sensor and KCU send a signal to the ECU which cuts power to the boost solenoid allowing the compressor line to go directly to the wastegate. This gives you somewhere in the neighborhood of 2.2 psi decrease and as much as 6º retard of timing.

The waste gate starts opening at some point between 0 and 8.5 psi.

Your wastgate must be fux0red. Mine doesn't move until 8.5 psi.

At 8.5 psi it already is open as much as it needs to be for the turbo to maintain 8.5 psi.

I take it you've never checked to see how much more the actuator will move with more than 8.5 psi? Have you checked at all?

I'll tell you this: The stock wastegate actuator will move the control rod roughly 1/8" at 8.5 psi and the number goes to roughly 1/4" with 10-12 psi and can't go much farther than 1/4" due to the length of the rod. if you've ever tested this, which you haven't, then you'd know this instead of speculating.

The only time your waste gate actuator will "see" above 8.5psi is if you out flow the waste gate port and and thus make more boost than intended by your boost controller.

Like all of the guys buying crappy boost controllers on eBay that have their adjustments as 20 psi or infinity psi?

In theory, your boost controller should bleed of how eve many psi you want to run minus 8.5

Agree'd but only if you're talking about a bleed valve.

So if you want to run 12psi the boost controller is venting 3.5psi from the wastegate actuator pressure line - so your wastegate actuator will never see more than 8.5psi (unless you out flow the waste gate port)

You mean like the guys with crappy eBay boost controllers with adjustments as 20 psi or infinity psi?

I guess i over estimated your understanding of what i meant by efficiency.

You're preaching to the choir Matt. I understand perfectly.

I am talking about the efficiency of the compressor which is listed on the map, NOT the efficiency of the whole turbo. What i'm trying to get you to explain is how you can say things like "14-16 psi puts you in the 74% category."

Again Matt, I told you that the only thing I had done thus far was Pr and flow conversion.

You can't say things like that b/c the compressor map obviously uses 2 variables to map points. When you map the boost number it gives you an entire range of efficiencies. The efficiency is then based on the amount of airflow through the compressor.

No, really?

What determines the amount of air flow through the compressor? - 2 things, rpm and boost pressure.

No, really?

So when you say that "14-16 psi puts you in the 74% category." you MUST state an rpm as well.

No, really?

16psi puts you in 74% from about 3.7k to 4.6k but then it quickly goes to the "maximum permissible speed line" line by 5k rpm.

Which is dictated heavily by the wastegate. You can't have rpm on the compressor wheel if you don't have rpm on the turbine. I hope you don't think the highest the turbine can/should spin is 5,000 rpm?

All i'm trying to say is that when you quote efficiencies you need to quote psi AND flow (putting the flow as an rpm number makes it much more useful b/c it actually means something.)

No shizzle Sherlock, I told you a couple PM's ago that I hadn't finished. I haven't finshed because 1) I haven't cared enough 2) I haven't cared enough 3) I haven't cared enough. You plotted rpm on your chart already and they won't be much different. Plotting them again would be pointless. If you care enough, then take the charts and do it yourself.

 

It most certainly does. Regardless of the numbers on the map, the turbo can not perform to it's potential, or can be overworked past it's limit.

did you mis this: "the exhaust side... has nothing to do with the efficiency numbers ON THE COMPRESSOR MAP"? When IHI made those maps they most likely didn't even use an exhaust side - those numbers discribe how well the compressor can compress with out adding to much heat.

Your wastgate must be fux0red. Mine doesn't move until 8.5 psi.

So Corky Bell was wrong when he said that the problem with wastegates is that they have to start opening before the turbo reaches the desired boost pressure and thus wastes energy that could be used for spooling?

I take it you've never checked to see how much more the actuator will move with more than 8.5 psi? Have you checked at all?

I'll tell you this: The stock wastegate actuator will move the control rod roughly 1/8" at 8.5 psi and the number goes to roughly 1/4" with 10-12 psi and can't go much farther than 1/4" due to the length of the rod. if you've ever tested this, which you haven't, then you'd know this instead of speculating.

did you read what you quoted? I never speculated anything about how much it opened, i said it opens how ever much it needs to. I never said it couldn't open more. But from your tests it seems that the wastegate will see more than 8.5 psi more often than I thought b/c when the wastegate is not fully opened it will get outflowed earlier - but the fact still remains that the wastegate will only see more than 8.5 psi if the wastegate is can't control the boost (boost creep)

Like all of the guys buying crappy boost controllers on eBay that have their adjustments as 20 psi or infinity psi?

There aren't too many boost controllers that work with wastegates that do not bleed off pressure from the signal line running to the wastegate.

Quote: Originally Posted by n2o_matt
16psi puts you in 74% from about 3.7k to 4.6k but then it quickly goes to the "maximum permissible speed line" line by 5k rpm.

Which is dictated heavily by the wastegate. You can't have rpm on the compressor wheel if you don't have rpm on the turbine. I hope you don't think the highest the turbine can/should spin is 5,000 rpm?

Forget about the exhaust side, the wastegate does control the speed of the compressor by maintaining a boost pressure, but we can find this speed by determining how much air must be taken in for the turbo to maintain that boost. And you keep sayin you know this stuff but if you did you would know that i don't think that the compressor can only spin 5k but that when the the turbo is trying to maintain 16psi and the engine is flowing 9.5m^3/min, the compressor is spinning past its "maximum permissible speed line."

But back on subject, since the wastegate has nothing to do with the info on a compressor map...

If you care enough, then take the charts and do it yourself.

Sure i can plot points but i can't explain the answer to my question:

What i'm trying to get you to explain is how you can say things like "14-16 psi puts you in the 74% category."

 

So Corky Bell was wrong when he said that the problem with wastegates is that they have to start opening before the turbo reaches the desired boost pressure and thus wastes energy that could be used for spooling?

Did Corky Bell ever test your wastegate? I tested mine, it doesn't start opening until 8.5 psi. Did you miss the part where I talked about swapping wastegates for one that starts opening at a higher psi?

more often than I thought

So, you admit that you never tested it.

but the fact still remains that the wastegate will only see more than 8.5 psi if the wastegate is can't control the boost (boost creep)

Or if you're trying to boost your turbo to 18-20 psi.

There aren't too many boost controllers that work with wastegates that do not bleed off pressure from the signal line running to the wastegate.

A good ball and spring works great, except when the maker drills a huge hole so that it becomes a ball and spring bleeder valve that spikes to infinity psi. This is the reason you have to be so careful using eBay for boost controllers.

Forget about the exhaust side, the wastegate does control the speed of the compressor by maintaining a boost pressure, but we can find this speed by determining how much air must be taken in for the turbo to maintain that boost.

Wrong, the turbine maintains an RPM, the compressor maintains a pressure based on the turbines RPM.

And you keep sayin you know this stuff but if you did you would know that i don't think that the compressor can only spin 5k

How do I know what you think in your head, I'm not a mind reader. You could be so cocky that you would think that, but you'd be wrong.

but that when the the turbo is trying to maintain 16psi and the engine is flowing 9.5m^3/min, the compressor is spinning past its "maximum permissible speed line."

So keeping in mind that every 10lb/min is roughly equal to 144.7178 cfm we can safely say that you're wrong. Check "your own" spreadsheet and you'll see yourself. Sure 9.5m^3=335 cfm but you're talking like VE is an absolute which is isn't. There are too many variables for you to say things like 215hp at 18 psi and 4,200 rpm.

BTW- Why doesn't your sheet stop at 6,000 rpm instead of the 7,000 rpm that you have which skews results? Or did you not do that spreadsheet yourself/steal it from someone else?

But back on subject, since the wastegate has nothing to do with the info on a compressor map...

You keep bringing up the compressors efficiency but fail to realize that the wastegate is resonsible for its downfall. Again, I'm not saying that everyone should go out and install a 16 psi wastegate, but if you installed one within reason, you'd see better results without grenading it based on your findings of "maximum permissable speed" I'm not saying that that doesn't exist because it certainly does, only that your numbers are off.

Sure i can plot points but i can't explain the answer to my question.

I already told you that.

What i'm trying to get you to explain is how you can say things like "14-16 psi puts you in the 74% category."

Do you argue with the teacher in school too?

EDIT: Matt-Happy now?:

http://www.mx6.com/forums/showthread.php?t=107278

 

Wrong, the turbine maintains an RPM, the compressor maintains a pressure based on the turbines RPM.

Thats the same thing, look:

boost pressure controls wastegate ---> wastegate controls turbine rpm ---> turbine rpm controls compresor rpm/boost pressure

So... the wastegate maintains a set boost pressure.

Quote: Originally Posted by Matt
but that when the the turbo is trying to maintain 16psi and the engine is flowing 9.5m^3/min, the compressor is spinning past its "maximum permissible speed line."

So keeping in mind that every 10lb/min is roughly equal to 144.7178 cfm we can safely say that you're wrong. Check "your own" spreadsheet and you'll see yourself. Sure 9.5m^3=335 cfm but you're talking like VE is an absolute which is isn't. There are too many variables for you to say things like 215hp at 18 psi and 4,200 rpm.

You've lost me. Take your finger and put it on the 9.5 mark on the flow scale of the T-bird map, then slide it strait up to the 16psi mark. Its past the "maximum permissible speed line" isn't it? How is that wrong?

I don't know why you are bringing the hp numbers back into it when I have stated multiple time that they are not accurate numbers. They represent the amount of air the compressor is flowing in a easier to grasp way. The numbers are not acurate b/c they do not reflect the change in VE of the engine or the change in effiency of the turbo. If you notice, the plots where the engine and compressor are in a good efficiency range, the numbers are pretty close.

BTW- Why doesn't your sheet stop at 6,000 rpm instead of the 7,000 rpm that you have which skews results? Or did you not do that spreadsheet yourself/steal it from someone else?

Why not go to 7k? How can that skew results?? I added a couple more just for the sake of having them - other people can use this spread sheet you know - maybe an FE3? Its Now your accusing me of stealing it b/c i added room for 1,000 more rpm?!

Do you argue with the teacher in school too?

you are far from the teacher on this subject.

EDIT: Matt-Happy now?:

yes.

 

You've lost me. Take your finger and put it on the 9.5 mark on the flow scale of the T-bird map, then slide it strait up to the 16psi mark. Its past the "maximum permissible speed line" isn't it?

Nope, not yet.

How is that wrong?

Because it isn't past it yet, close, but not past it.

Why not go to 7k? How can that skew results??

Because the chart gives results with 7,000 rpm being the max rpm which skews results. I don't drive my car to 7,000 rpm, do you?

other people can use this spread sheet you know - maybe an FE3?

And their redline IIRC is 7,000 rpm? Ours is 6,000.

your accusing me of stealing it b/c i added room for 1,000 more rpm?!

No, I asked you stole it.

you are far from the teacher on this subject.

Never said I was. I asked if you argue with the teacher in school too.

 

Because it isn't past it yet, close, but not past it.

you're gonna argue with me over 1mm? Ok, if you go to 5,010rpm then you are over.

Because the chart gives results with 7,000 rpm being the max rpm which skews results. I don't drive my car to 7,000 rpm, do you?

What?! The chart could list rpm's up to 20,000 and it wouldn't change anything - it just tells you how much air the engine would require at that rpm.

where does it say anything about 7k being a max??

I asked if you argue with the teacher in school too.

Only if they are wrong or don't give all the information needed for me to understand.

 

Bump

for good info