For those who think turbos are ALWAYS efficient
02-17-09, 08:12 PM
#26
From the Garrett Turbo site:
For giggles and grins:
The Choke Line is the right hand boundary of the compressor map. For Garrett maps, the choke line is typically defined by the point where the efficiency drops below 58%. In addition to the rapid drop of compressor efficiency past this point, the turbo speed will also be approaching or exceeding the allowable limit. If your actual or predicted operation is beyond this limit, a larger compressor is necessary.
The Choke Line is the right hand boundary of the compressor map. For Garrett maps, the choke line is typically defined by the point where the efficiency drops below 58%. In addition to the rapid drop of compressor efficiency past this point, the turbo speed will also be approaching or exceeding the allowable limit. If your actual or predicted operation is beyond this limit, a larger compressor is necessary.
02-17-09, 08:55 PM
#28
Relevant numbers can be used to compare anything.
Assuming the numbers for the OEM turbo we are discussing are accurate, then it is valid to compare the OEM turbo with aftermarket turbo.
02-17-09, 10:30 PM
#30
The Firestarter
don't forget manufacturing cost, i am sure some corners were cut and expensive stuff was tossed before real production was done in 1985. S4 and S5 turbochargers were probably one of those short cuts to higher profit..... But thats just pure speculation on my end.
02-17-09, 10:36 PM
#31
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If stock units are based on effeiciency than Mazda failed with that turbo. Maybe as the entire system they hit a home run but as far as that turbo, it seems like a waste.
Perhaps Mazda had other considerations when they chose to use that particular turbo. Emissions for one we all know drives corporate decions as does reliabilty. Perhaps they thought that this turbo in particular was the best COMPROMISE of everything. We all know that's what the automakers do, compromise to get the best of everything. Every manufacture does it. Look at Jeep for example, tell me the WK is not a full out compromise between a decently capable off-road rig and a smooth supple Benz on the inside. What about the XJ's and all the wranlgers. A few inches of lift and some bigger tires and damn, but they wouldn't sell as many. So they compromised
/late night ramblings
Perhaps Mazda had other considerations when they chose to use that particular turbo. Emissions for one we all know drives corporate decions as does reliabilty. Perhaps they thought that this turbo in particular was the best COMPROMISE of everything. We all know that's what the automakers do, compromise to get the best of everything. Every manufacture does it. Look at Jeep for example, tell me the WK is not a full out compromise between a decently capable off-road rig and a smooth supple Benz on the inside. What about the XJ's and all the wranlgers. A few inches of lift and some bigger tires and damn, but they wouldn't sell as many. So they compromised
/late night ramblings
02-17-09, 10:49 PM
#32
They only had a power goal of 175 hp back when they were developing the TII which isn't much. I have no idea why they chose the setup they did other than the fact that the compressor wheel probably already existed and just happened to give them the power number they desired. Max efficiency probably wasn't a consideration. Hitting the power goal was and they did. It's not hard to do but it's hard to do that poorly and still justify it as a safe success.
FWIW: The whole intent of this thread wasn't to directly compare superchargers to turbos. The point was that I've seen people talk bad about superchargers, specifically roots blowers, on the grounds that they aren't as efficient as turbos. I've seen people say that turbos are always more efficient and hence better. While I'm not making a case for a supercharger even though I do like them in some ways, I am saying that no a turbo is not always efficient and not always necessarily better than a supercharger. A stock TII is proof.
FWIW: The whole intent of this thread wasn't to directly compare superchargers to turbos. The point was that I've seen people talk bad about superchargers, specifically roots blowers, on the grounds that they aren't as efficient as turbos. I've seen people say that turbos are always more efficient and hence better. While I'm not making a case for a supercharger even though I do like them in some ways, I am saying that no a turbo is not always efficient and not always necessarily better than a supercharger. A stock TII is proof.
02-17-09, 11:11 PM
#33
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I don't have numbers on anything else. I got these off of old papers I found while cleaning the house. I've got stacks of rotary related papers going back to the early 80's and this was a part of them. Apparently someone did some testing and research when the TII first came out. I wish I could take credit for it but I can't. It's still good info to know though and since I've never seen it anywhere else online I thought I'd share it here.
That should have clued you in to the fact that you have bad information, lol.
02-18-09, 12:04 AM
#34
I'm not going to get into some pissing contest debate or provide sources of anything as it's just not worth it. I'm not making claims on it based off of some wild theory. I'm just passing on old info that I've got. That's it. No I didn't make it up! Believe it or don't. I could really care less. I'm not one to say it's wrong and quite frankly neither are you regardless of how smart you 'think' you are. You only either have to believe it or not. It's obvious which side you take. I didn't even have to share it. I just thought it would be interesting to some as lots of old info before the days of the internet never gets seen. I never intended it to be a source of ridicule by the naysayers. What did I really expect though? It happens. Moving on...
02-18-09, 12:45 AM
#35
O_o
some one sounds defensive. Evil will probably back me up when saying that EVERY thing looks different on paper than how it turns out *some things more so than others*. info like this is easy to manipulate, record improperly, ect.
No two cars are the same at that. I've seen two stock cars with about 5k miles on them same model, trans,diff, tires, ect. one hit 14% higher on the same dyno.
Hell you want to make your car look like a hp pimp. Run on a 40ºF day when a high Pressure front is rolling past and ask them to turn off SAE correction, can have upwards of 15% more power. numbers are just that... numbers. Don't need to get mad over some one who thinks there wrong.
some one sounds defensive. Evil will probably back me up when saying that EVERY thing looks different on paper than how it turns out *some things more so than others*. info like this is easy to manipulate, record improperly, ect.
No two cars are the same at that. I've seen two stock cars with about 5k miles on them same model, trans,diff, tires, ect. one hit 14% higher on the same dyno.
Hell you want to make your car look like a hp pimp. Run on a 40ºF day when a high Pressure front is rolling past and ask them to turn off SAE correction, can have upwards of 15% more power. numbers are just that... numbers. Don't need to get mad over some one who thinks there wrong.
02-18-09, 01:22 PM
#37
The Firestarter
But you are right about just being calculated numbers, The compressor map is the data of the sample representing the general population of those turbos. Although not every same identical turbo will put down the same numbers that the map gives us, but it will be relatively close assuming that the sample population was large during the calculation.
If that compressor map data given was just 1-5 turbo samples the margin of error to represent the population would be too high and wouldn't be very accurate. But...we just kinda assume and trust that it is accurate.... And a 49% peek Efficiency is pretty ******* bad, which we can safely assume that the population range is pretty low..probably 55%-58% tops.
As far as the argument about efficiency levels of traditional roots blowers vs turbochargers (let alone stock TII turbos), its kind of a give and take situation and there is no real definite answer to it as there are to many variables to consider including the; applications, design, technology, grade material, age etc. And since none of us (i would assume) are veteran engineers or professionals in that field its harder to gather the right accurate data to devise an comparison and contrast..... But its still ok to speculate the differences.
02-18-09, 01:41 PM
#38
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Rotary God, could you scan that paper you were talking about. As a fellow information **** I like to keep things like this in a file for future reference. I just want to see it. Is a compressor map a part of it?
02-18-09, 02:50 PM
#40
I understand the efficiency numbers you are talking about but I think when people say turbos are more efficient, they are talking about the flywheel power lost to operate the pump/compressor to create a specific amount of boost.
Interesting information none the less (even if there are no sources cited)
Interesting information none the less (even if there are no sources cited)
02-18-09, 06:56 PM
#41
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I will send $100 to the first person who posts a legitimate turbocharger compressor map produced by the manufacturer which clearly shows the peak thermal efficiency island labled with a number lower than 65%.
02-18-09, 10:34 PM
#42
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Hey guys.
I am not here to say hybrids are the "best of" or the "beat all" of turbochargers. It is bang for the buck, 100% bolt on, increase of HP the easy way. When you have strict emissions and visual inspections for state regulations that keep you from "going single", there aren't really any options. Racing classes will also bump you up classes for single turbo conversions. You don't want that unless you are one bad ***! Anyway, thats where BNR comes in. Making altercations to improve design, flow and reliability are my 3 biggest concerns. 412 RWHP sequential, 426 RWHP non sequential on the FD stage 3's isn't too bad. That is around the limitations for pump fuel for a reliable B engine and plus you maximize your power band with the small turbine housings and short manifold runners. The FC stage 4 generated 403 RWHP. And that powerband averaged 400 RWHP from 6-8K RPM. When you stop making power after so much boost, that is the point at which you have excedingly too much back pressure in a hybrid. The FD turbos find that mark at around 18 psi of boost which is around 420-425 RWHP on a properly modified and tuned RX7.
I am planning on hitting 425 RWHP (fingers crossed) in my T2 on a S4 based hybrid and a street ported 13BT. I have something in the works and I will try breaking the current record of 403 RWHP held by a BNR customer in vegas! If it makes 410 RWHP I will fine with that as well
.
Bryan@BNR
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I am not here to say hybrids are the "best of" or the "beat all" of turbochargers. It is bang for the buck, 100% bolt on, increase of HP the easy way. When you have strict emissions and visual inspections for state regulations that keep you from "going single", there aren't really any options. Racing classes will also bump you up classes for single turbo conversions. You don't want that unless you are one bad ***! Anyway, thats where BNR comes in. Making altercations to improve design, flow and reliability are my 3 biggest concerns. 412 RWHP sequential, 426 RWHP non sequential on the FD stage 3's isn't too bad. That is around the limitations for pump fuel for a reliable B engine and plus you maximize your power band with the small turbine housings and short manifold runners. The FC stage 4 generated 403 RWHP. And that powerband averaged 400 RWHP from 6-8K RPM. When you stop making power after so much boost, that is the point at which you have excedingly too much back pressure in a hybrid. The FD turbos find that mark at around 18 psi of boost which is around 420-425 RWHP on a properly modified and tuned RX7.
I am planning on hitting 425 RWHP (fingers crossed) in my T2 on a S4 based hybrid and a street ported 13BT. I have something in the works and I will try breaking the current record of 403 RWHP held by a BNR customer in vegas! If it makes 410 RWHP I will fine with that as well
.Bryan@BNR
205 640 1193
02-19-09, 04:44 PM
#45
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Brian if u can pull 425 rwhp out of a stock framed turbo you are the man.
Ill be posting up my stg 4 #s in a couple weeks I hope to break 400rwhp with my supporting mods.
James
02-19-09, 04:47 PM
#46
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idk about reliabilty but you sure altered and improved design and flow in my book lol i only need 2 more years to put it to good use lol and I see u changed my favorite picture around alittle, what going on with that?
James
02-19-09, 05:42 PM
#47
"your turbo source"
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Yup I am serious about this stuff.
The job has to be done right w/o cutting corners. Reliability is number 1 in my book. I hate redoing work so you do it right the first time and you don't have to worry. I know the older I get, the less I want to work on them. Maybe I am just around them too much and a little burned out
I didn't mean to throw in the sales pitch earlier. Thats not really my style. Each rotating component and both turbine and compressor housings have their effiencies. All of which work together. Say I put a standard T3 turbine wheel with a 60-1 compressor wheel, you would be limited to the turbine wheel which would only allow you around 250 HP. you can change that turbine to one the spins the same RPM and has similar flow charactoristics as the 60-1 and gain 150-200 HP just with the right turbine wheel. Same goes with housings. To small you choke, too big its lazy. It all is about an even flow in and out of the turbocharger to make power. You don't have enough coming out, that is when the housing or turbine wheel doesn't flow enough. When the compressor is getting sucked dry and the boost falls off up top, that tells you that the wheel just doesn't flow enough volume to keep up with the engine or there is an increased amount of back pressure between the engine and turbine that pushes on the wastegate valve and your boost drops.
Bryan@BNR
02-19-09, 06:32 PM
#48
The stock i/c isn't terribly efficient at rejecting heat at 68% but it could be worse. It's got a pretty high pressure drop. 1 psi is acceptable under normal conditions for an intercooler and that's what the stock one is with the stock turbo at stock boost levels. It's adequate for stock and that's about it. Of course upgrading to a more efficient one with less flow restriction is going to be better. However since it does do something, it can still be used for a while. I'd argue that you could get away with it up past about 250 hp or so but above that you should really consider changing it. That's just a number I'm throwing out though.
I for one think that the turbo should be addressed first though as 49% peak efficiency is horrible no matter how you look at it. Keep in mind the turbo isn't always in it's peak efficiency area and is almost always below it. If you could replace the stock turbo with one that was say 70% efficient, that's a very big deal. A BNR hybrid would do a good job on the compressor side but the exhaust side is still pretty restrictive. Fixing anything is better than doing nothing and the BNR's can do pretty well for those wanting more but not 400+. Keep in mind that the more restrictive the exhaust side, the more likely an engine is to detonate so ultimately above a certain point this should really get some attention too.
I for one think that the turbo should be addressed first though as 49% peak efficiency is horrible no matter how you look at it. Keep in mind the turbo isn't always in it's peak efficiency area and is almost always below it. If you could replace the stock turbo with one that was say 70% efficient, that's a very big deal. A BNR hybrid would do a good job on the compressor side but the exhaust side is still pretty restrictive. Fixing anything is better than doing nothing and the BNR's can do pretty well for those wanting more but not 400+. Keep in mind that the more restrictive the exhaust side, the more likely an engine is to detonate so ultimately above a certain point this should really get some attention too.