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Discussion Starter #1
For the guys that have backpressure sensors, is there any correlation to Co2 vs backpressure vs boost as backpressure exceeds 1:1?
 

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Montgomery Ragland
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Well I just looked over some logs real quick but here are some ruff numbers from my junk. Modmotor 88mm 1.15A/R

WG spring. 13.3map , 21bp = 1.58/1 7400rpm
3psiCO2. 16.1map , 22bp = 1.37/1 7600rpm
6psiCO2. 18.9map , 25bp = 1.32/1 7800rpm
9psiCO2. 19.4map , 30bp = 1.55/1 9200rpm

Thats all I have at the moment, just changed springs to a lighter one and no testing yet.
 

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im still learning the ams. but the guy i work with, he has told me that it takes alot more co2 once u start getting up in the boost. i know one guys car was around 60psi of co2 to make 30lbs boost.
 

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mine is very close to what i put to the gate 5lb spring plus 24 on the gate gets me right at 27 pounds.

mark
 

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Discussion Starter #6
I'll get my data tomorrow but I think 25# + a 4# spring made 25# of boost. 45+4 made 42.
 

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My gates have 6lb springs, if I put 10 on the ams its 16lbs of boost, 15 on the ams and 21lbs of boost, 22 on the ams is 28lbs, thats the highest i've been so far. At 20lbs of boost I have 18lbs of back pressure in the exhaust.
 

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Phil... howdy brother....

Mine doesnt make much sence that im runnign a really soft spring, but when i had the 6psi springs on them - the gates were were progressive when you added co2.

Ie, before I would add 10lbs, and it would be 16lbs boost.

Now i i have 3lbs springs and add 16lbs, and still dont see 16lbs..???

I think its got a lot to do with how well your gates seal as well.... hmmmm

Pete.
 

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Custom Engine Shop
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As stated the there doesn't seem to be a standard of base vs boost. Too many variables in the design of most turbo headers/crossovers/wastegate/ect... placements.

Like Seb stated, add pressure till you hit the number you need.
 

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I was running a 5# spring last year. I would make 8 psi MAP on spring
from there it went one to one until around 15 psi map with 7 psi co2.
when I went from 15 to 18 psi MAP it took 6psi co2.
It may have been back pressure building but it may have been leaking boost, but I never got to pressure test it.
 

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Montgomery Ragland
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Well I just looked over some logs real quick but here are some ruff numbers from my junk. Modmotor 88mm 1.15A/R

WG spring. 13.3map , 21bp = 1.58/1 7400rpm
3psiCO2. 16.1map , 22bp = 1.37/1 7600rpm
6psiCO2. 18.9map , 25bp = 1.32/1 7800rpm
9psiCO2. 19.4map , 30bp = 1.55/1 9200rpm

Thats all I have at the moment, just changed springs to a lighter one and no testing yet.
Here are some numbers from my stuff with the lighter spring, which I like much better.

WG spring. 4.2map , 7bp
16psiCO2. 16.4map , 22bp
20psiCO2. 20.4map, 30bp
 

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Here are some numbers from my stuff with the lighter spring, which I like much better.

WG spring. 4.2map , 7bp
16psiCO2. 16.4map , 22bp
20psiCO2. 20.4map, 30bp

Damn its hard to believe that the backpressure gets that high that quick with the 88 and the big AR..

Is it still pretty responsive? what are some details on the setup?
 

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many , many things can change the ratio. The ratio isnt important. Increase the target pressure unit you get the boost you want.
Yep, i think thats the case.... Try untill you get the right numbers your chasing...

Let us know Phil....

Pete.
 

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1 lb spring + 22 psi co2 = 17 psi
1 lb spring + 30 psi co2 = 20 psi
 
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