Danbonzo
New member
Not to be argumentative but A+B+C=$! lol
Exhaust Back Pressure
- Thread starter powerstrokedub
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Not to be argumentative but A+B+C=$! lol
White_monster
Active member
Hahaha. Well put my friend.
Erikclaw
Active member
Very true, I should know. Or should I say I will find out.
White_monster
Active member
It's possible Erik.
Erikclaw
Active member
Lalalalalala I can't hear you!
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but boost is only a measurement of restriction. lbs/min , how many times the air is compressed, discharge air temps, etc. for example, high powers make the same amount of boost as stock turbos, except they are well within their maps at the same psi, 50-52... but make WAY more bp than stock turbos, with the same stock fueling. lbs/min are the reason. boost, i dont believe is directly related to drive pressure. i think the more we constructively discuss this, we can get somehwere. it is very thought provoking. i like it.
Erikclaw
Active member
That makes sense, flowing more air through the same restrictions (heads) etc would cause bp to increase. It seems to come to bp being the one factor that can start the chain of events that cause a hg to fail.
I need to think on this some more but boost and back pressure are directly related, but not at the same time.
Alot of times you will find that some turbos make high back pressure and low boost, other times you will find that turbos make low back pressure and low boost, other times you will find that turbos make low boost and still make tons of power.
Its hard to explain, and i really need to think of a good way to put it.
But stock turbos is a good example of how 50 psi of boost doesnt mean your making a ton of power, when a set of max or high powers almost dont make any more boost than stock turbos, but they do make more power... its all about the same pressure, with lower temperatures outlet of the turbos, still hard to explain so i will try to find a way to explain it.
Erikclaw
Active member
What? Care to explain that better? LOL sorry. Was wondering when you were getting in this.
Think of air and how much it would weigh if you could put it on a scale
a turbo that puts out 87lbs per minute, think of 87 lbs in a flat rate shipping box
Now take a turbo that puts out 105lbs per min, and put that in the SAME flat rate box
Sitting on the table the boxes look the same right? So you think ok, same amount of air in each box, until you pick it up off the table and realize that there is more air in one box than the other, and not necessarly any higher pressure from one to the other, so put a boost gauge on both boxes and they both read 10psi, now hook a straw into the box and start breathing the air from the box, i bet you get light headed from the 87lb per min box first....
TERRIBLE way to put it, but its all i can come up with... im going to bed
a turbo that puts out 87lbs per minute, think of 87 lbs in a flat rate shipping box
Now take a turbo that puts out 105lbs per min, and put that in the SAME flat rate box
Sitting on the table the boxes look the same right? So you think ok, same amount of air in each box, until you pick it up off the table and realize that there is more air in one box than the other, and not necessarly any higher pressure from one to the other, so put a boost gauge on both boxes and they both read 10psi, now hook a straw into the box and start breathing the air from the box, i bet you get light headed from the 87lb per min box first....
TERRIBLE way to put it, but its all i can come up with... im going to bed
Jeff@Spartan
New member
Hasn't it been proven time and time again that stock trucks with a tuner, intake, and exhaust make more power than an equivalent truck plus an EGR delete w/wastegate? I have never seen a set of gated stock turbo's make more power than a non-gated set of stockers. If it has happened (fuel only), please educate me.
and to add to that, some turbos are rated in cfm, so take that box and make it 1 cubic foot, now pass 1000 of thoughs boxes past the mail man and ship them
one set of boxes is going to physically look the same size and they will be
but weigh each box and charge by the pound, now you realize that it was cheaper to ship the air from the 87lbs per min turbo...
and we havent even talked about what temperature the air is inside the box
one set of boxes is going to physically look the same size and they will be
but weigh each box and charge by the pound, now you realize that it was cheaper to ship the air from the 87lbs per min turbo...
and we havent even talked about what temperature the air is inside the box
I dont know if its been proven, aka running a truck with a gate, and then running the same truck with the gate blocked.
I dont know what the stock turbos flow lbs per min wise but i think stock turbos at sea level are at the edge of the map, but not as far over the map as we have thought, i did the math awhile back on stock turbos and each turbo works at a 2.5 pressure ratio, which in most cases isnt that bad, but i dont know how far out of the map they are for air flow honestly, so im not sure HOW far they are out. I do think there would be some gains to a bigger turbine wheel on the LP turbo instead of a gate, reason being is you want to use ALL of the exhaust energy that you can to help drive the turbo's Thats why the tow power x turbos are such a great idea IMHO
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dont worry jeff, you're the king. but that topic has very little to do with this conversation, other than the possible fact the maps of the stock turbos like back pressure. a single with less total cfm than stock turbos, with no gate make more power than your setup (corsili) , different combo's, different maps, different results. there is no easy answer. my truck made more power, consistently with an egr and a gate. nothing even close to your miracle setup, that noone has even come close to matching.
Ipkyss
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Maybe we can add in a little more info towards controlling the bp. I have a few things I don't fully understand yet.
In most all cases. (I believe) A wastegate is used to control BP, which is used to directly control the amount of boost a vehicle makes. The wastegate uses a boost reference to fine tune it.
On our trucks. The wastegate has nothing to do with boost, yet still uses a boost reference to adjust it. I feel like it should be using ebp for a reference. I know the wastegate handles a ton of heat already, so I don't know if that would hurt it or not. It seems like it would help control bp better.
Starting to feel like just as soon as I get everything just right with the stock turbos, I will be getting something bigger. Waiting to see a price for these tow x turbos.
In most all cases. (I believe) A wastegate is used to control BP, which is used to directly control the amount of boost a vehicle makes. The wastegate uses a boost reference to fine tune it.
On our trucks. The wastegate has nothing to do with boost, yet still uses a boost reference to adjust it. I feel like it should be using ebp for a reference. I know the wastegate handles a ton of heat already, so I don't know if that would hurt it or not. It seems like it would help control bp better.
Starting to feel like just as soon as I get everything just right with the stock turbos, I will be getting something bigger. Waiting to see a price for these tow x turbos.
Jeff@Spartan
New member
Not sure what you're talking about, but ok....
I wasn't referring to my truck. Yes....my truck makes good power on stock turbo's, but there are a lot of other trucks making good power on stock turbo's....with no wastegate. I have never seen a gated set of stock turbo's do well on fuel. Maybe it has to do with gate tuning, but I think drive pressure is part of the reason these trucks make such good power tuner only. Who knows, maybe I am crazy....:shrug:
And I don't have a miracle setup. Just a really light crew cab with good tuning.
Wastegates do use back pressure for a reference to open the gate... every time you make back pressure there is pressure on the valve trying to unseat it but the spring holds it shut depending on the spring it usually holds it shut until boosted is added to assist the gate open.
Boost is fine to open the gate. Its filtered clean air. Not sooty exhaust and its all a dial turn away for making perfect back pressure.
Boost is fine to open the gate. Its filtered clean air. Not sooty exhaust and its all a dial turn away for making perfect back pressure.
powerstrokedub
New member
Wow this thread really took off. Really great info in here. I have been trying to read up as much as I can on this topic but there is a ton of arguments about cause and effect, its really confusing actually.
