Splain-Nation- By Bro.D

PJ McCoy

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Red98422
My cfm calculated out to 1072cfm.
So I looked through the catalog to find a turbo that had a density ratio between 1.41-1.68 these are for low boost.
Remember, I'm a noob at turbos, so I used those numbers with a range from 53-74 lbs/min mass A/F. The density and Lbs/min is what I used to find a turbo that had good efficiency numbers. Also Looks like I could be in the 600-720hp range.
Am I on the right track here?
PJ
 

PJ McCoy

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First off I would like to say, well damn look at that screen shot. Couldn’t have timed it better myself :laugh:.




a lot of what you are talking about is in the realm of “advanced understanding” and nothing wrong at all with those questions!

boost should by all means be taken seriously, however if you aren’t pushing the envelope to the bleeding edge you can take the worry down a notch.

as I understand it the boost does “cushion” to a small extent but what is worrisome is that it is also attempting to compress a greater amount of volume in the same speed, which can be stressful to the bearings as the see a greater load/time.

now for the super tricky stuff, boost actually will work better with less exhaust overlap (gotta keep cylinder fill) so there are cams specifically made for boost by turbo vs boost by supercharger. I wish I could be more detailed than that but I am still learning myself.

something I believe gets overlooked and or misunderstood is judging boost based on PSI. What we should really be talking about if CFM.

I get that the industry standard is psi, it’s just bothered me as depending on the housings you could be running the same psi but two totally different flow numbers and backpressure.

also @PJ McCoy and @5one9. You should both begin studying back pressure and it effects. Also a lesson in turbo sizing would be a great help as well. The math can be difficult, but it’s worth it to know so you can plot your own numbers without relying on a computer app.
LOL, RED, I saw that screen shot and had to double take that "THING" In her hand!!!
 

smalltruckbigcid

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First off I would like to say, well damn look at that screen shot. Couldn’t have timed it better myself :laugh:.




a lot of what you are talking about is in the realm of “advanced understanding” and nothing wrong at all with those questions!

boost should by all means be taken seriously, however if you aren’t pushing the envelope to the bleeding edge you can take the worry down a notch.

as I understand it the boost does “cushion” to a small extent but what is worrisome is that it is also attempting to compress a greater amount of volume in the same speed, which can be stressful to the bearings as the see a greater load/time.

now for the super tricky stuff, boost actually will work better with less exhaust overlap (gotta keep cylinder fill) so there are cams specifically made for boost by turbo vs boost by supercharger. I wish I could be more detailed than that but I am still learning myself.

something I believe gets overlooked and or misunderstood is judging boost based on PSI. What we should really be talking about if CFM.

I get that the industry standard is psi, it’s just bothered me as depending on the housings you could be running the same psi but two totally different flow numbers and backpressure.

also @PJ McCoy and @5one9. You should both begin studying back pressure and it effects. Also a lesson in turbo sizing would be a great help as well. The math can be difficult, but it’s worth it to know so you can plot your own numbers without relying on a computer app.

Drive pressure in a turbo engine is important. That's the pressure above the piston to the compressor housing on the exhaust stroke. Equal to or less than boost pressure is good. When it's greater than boost pressure efficiency drops and heat and egt's go up.

Gale banks has a lot to say about using air density instead of boost pressure. Check his YouTube videos out
 

PJ McCoy

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Drive pressure in a turbo engine is important. That's the pressure above the piston to the compressor housing on the exhaust stroke. Equal to or less than boost pressure is good. When it's greater than boost pressure efficiency drops and heat and egt's go up.

Gale banks has a lot to say about using air density instead of boost pressure. Check his YouTube videos out
Thanks I will. Its been a very long week!! Sorry it took so long to reply.
PJ
 
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