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Originally Posted by sixshooter
(Post 17565)
https://www.miataforumz.com/attachme...ine=1344450813https://www.miataforumz.com/attachme...ine=1344450813
Compare these two compressor maps carefully. The concentric curves (ovals) delineate changes in efficiency, or the ability to move and compress air without turning the mechanical energy into heat. Higher efficiency means more power and less heat waste are created. Operationally, you ideally want to function in the middle island of greatest efficiency, but our engines are not constant speed so they trace a line through the graph during operation. At a pressure ratio of 2, which is roughly 15 psi, the greatest efficiency that can be achieved by the 2554 is ~70% and most of that operational area is between 17 and 24 lbs/min of airflow. Remember, airflow is what makes horsepower because air mixed with fuel makes horses. Twice as much air equals twice as much fuel equals twice (roughly) as much power. If we look at the second map, it has a sizable island of 76% efficiency at the pressure ratio of 2 line, which is considerably higher efficiency. And it maintains 75% efficiency or greater at an airflow of around 23 to 32 lbs/minute of airflow, a much greater amount of air. So we are seeing 25% more airflow at the same pressure with 7% greater efficiency. That is a win-win. It also means the air volume that is generated is cooler which is also beneficial to make more power in your engine. The same 2871 is capable of maintaining its 75%+ efficiency all the way up to ~39 lbs/min of airflow and do it at up to 26 psi. Maintaining efficiency as the pressure and flow gets higher is where the engineering really makes the difference. Digging into the big versus little comparison, you can see that the 2554 at a PR of 2 (15psi) is hitting 24 lbs/min maxed out in the 70% efficiency range, but at the same efficiency level the 2871 can hit 24 lbs/min at a PR of 1.5 or about 7.5 psi -- Same airflow, same efficiency level, half the pressure. So we have a bigger turbo at half the pressure making same horsepower. This is why guys who know a thing or two think other guys are idiots when they ask "How much boost you runnin'?" without knowing how large the turbo is. Knowing how much boost someone is running without knowing anything else literally tells you nothing. Does this help at all? It definitely gave me a better idea of turbos, but I had to read it twice haha :D |
Originally Posted by djshoester
(Post 17576)
This was an awesome post! Where did you find the diagrams?
It definitely gave me a better idea of turbos, but I had to read it twice haha :D |
Originally Posted by RedTurboMiata
(Post 17580)
Lots of time spent researching turbos trying to decide which one you want, And the people on miataturbo
Though it seems like miataTurbo is not as active as a forum..or perhaps that is just me not really checking out the forum fully yet. I am bouncing between this one and miata.net doing research =) |
The compressor maps are all over the internet. It just takes time studying to determine how to read them and how to apply what you are reading to what you are trying to accomplish.
Miata dot net is pretty vanilla on good information. The real meat and potatoes are found on miataturbo.net but they aren't kind with new guys asking the same basic questions over and over. They have a good DIY FAQ and they expect you to read it. There is more good info on that forum than anywhere about performance and power. They work on their own cars and tend to be innovators. They want the cheapest way to do the best job every time and that usually means DIY. I'll try to point you in the right direction if you have any questions. You can always post them here and we can point you in the right direction or answer it outright. |
Yea, I enjoy Miata.net for all the questions that us new guys keep posting up cause it helps my research =) I also like this forum for the threads that are already here and I would say your guys' vetern inputs haha
I will definitely look into miataturbo now for more research and DIY things. It is super exciting to just learn all these things. Thanks for all your help and willingness to help! |
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Hey another Nissan to Mazda converter. Your coupe was so clean man, nice fitment, Bricks and my favorite two tone combo... well yours kinda is, lol. Here was my Hatch:
https://www.miataforumz.com/attachme...ine=1345880145 My Miata is also Red, as yours is. Lookin' forward to seeing where this goes. I didn't catch when skimming your thread, are you going to be drifting your Miata at all or will it be strictly DD. |
Miatas don't make nearly as good a drift car as the 240 because of the very short wheelbase and the lower polar moment of inertia. They are therefore much more difficult to maintain a drift angle with and are more suited to rapid changes in direction (road coarse). It can be done but the difficulty level is much higher than in a car more suited to the task. Even the 2nd gen RX7 was much better for drifting because of it's longer wheelbase.
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Originally Posted by sixshooter
(Post 17760)
Miatas don't make nearly as good a drift car as the 240 because of the very short wheelbase and the lower polar moment of inertia. They are therefore much more difficult to maintain a drift angle with and are more suited to rapid changes in direction (road coarse). It can be done but the difficulty level is much higher than in a car more suited to the task. Even the 2nd gen RX7 was much better for drifting because of it's longer wheelbase.
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