For giggles and grins:

 

not to sound like an ***, what-so-ever, but how can one compare a stock turbocharger to an aftermarket supercharger?

 

The not-sounding-like-an-***-back answer would be one word: Numbers.

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.

 

its just based on efficiency and power goals.

aftermarket is just mainly power. stock units are based on efficiency. simple.

 

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.

 

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

 

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.

 

FYI the numbers you have are wrong, and turbochargers are in fact more efficient than traditional Roots blowers. The new Eaton TVS blower is the first Roots-type supercharger that I am aware of reaching centrifugal turbocharger efficiency levels.

That should have clued you in to the fact that you have bad information, lol.

 

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...

 

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.

 

they are calculated numbers. thats why you have a compressor map. temperature isnt a factor.

 

In normal driving situations however i am sure altitude and ambient temperature do play a factor in functionality of those turbos.

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.

 

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?

 

Good thread, Rotarygod! Very good thread indeed!

 

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)

 

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%.

 

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
205 640 1193

 

nice sales pitch.

and um... this is the second gen forum, whats with this single turbo conversions stuff?

 

Damn bro u guys must be serious about this! The last time I got into an altercation it sure as hell wasn't to improve design, flow and reliability.

 

Brian makes hybrid turbos specifically for our cars. Its basically the stock turbo on steroids.
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

 

Derek,
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

 

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

 

Bryan, could you comment on the exhaust side being restrictive and what could be done to free it up, factoring in spool time and compressor output, as well as engine reliability due to exhaust restrictiveness?

 

I under stand this. My point is in the second gen forum there is little point to talk about "going single" or "single turbo conversions."

 

Man what a mess. One of these days I am going to have a shop make the stuff for me. Anyhow I was making a joke about "altercation" when he meant alteration. I was just being a smart ***.