dastinker8

umm.. i got different calculations...

10+14.7/14.7 = 1.68 Not 1.78.

Also According to excel sheet that i made up.. a

1.6l Engine at like 82% efficency yields a flow at 7k 162cfms approx 111hp. (Crank)

Using a turbo sppoled up at 10psi.. on a 1.6l @ 7k rpm usin
550 Rankin turbo intake temp
Using a FMIC
average of about 75-80% efficient at 10psi at 7k
your expected flow rate would be 235-280cfms. approx 165-195hp(85-100%effecient)
using density ratio of about 1.4
you get around 24-28lbs per min.

Also at the lower rpm you would be higher. so your scale is a little off.
Just thought you might wanna take that into consideration.
Brian

RJwaggs

Didn't catch the PR error. I think the difference in calculations htough is coming from a difference in VE at differetn rPM's. I don't think it is published, so yall very well could have guessed two different numbers.

fastcivicboy

In the thread above yours the user linkmustang uses 50 trim t3's .42 .48 on his twin turbo mustang. Those are what your looking for. I hate the filter flange but you have to work with what you got if you get one.

Premium Dude

dastinker8, I did the calculations using two different methods.
The first method was by hand, and I would round every answer to 1 decimal place. With this method I had the pressure ratio you calculated, of 1.68. However, my air flow numbers where something like 5.5lb/min at 2000 and 16.5lb/min at 7000.
The second method was using an excel sheet provided on the stealthmode performance site. I agree that the pressure ratio is a bit odd, but it's not severly off. As for the air flow, it says that it is calculated based on formula's from the book "Maximum Boost". I think the air flow results are very accurate, because they pretty much match mine, even though I rounded a lot.
You on the other hand calculated air flow of 24-28lb/min. I dont know wether this is because you used different variables, or wether you skipped the step for corrected air flow, because to me that seems a little high. But I'm no expert, so I would love for someone to confirm this.
And RJ, thanks for all your help. Does anyone else have any input on this? Can someone tell me where I might be able to find a 50 trim t3, or wether I should just go with a 45 trim .42/.48, or a 60 trim .60/.48?
Thanks.

JDMFantasy2K

how come you haven't done any calculations with something bigger? I ran a 60 trim and i absolutely loved it.

dastinker8

The way i calculated was for 83%VE effeciency of the engine at 7000k RPM
When your stock. Highest effeciency your gonna get is about %85-90
But when you have 10psi flowing through your effeciency of the engin rasies to 100% +
VE = (cu.in * rpm)/3456
85% = VE *.85

p2/p1 = PSI+14.7/14.7

Deg R(inlet) = Air temp+ 460

p1 = Atmospheric Presure

t2 = p1 + (p1 *(-1 + (outlet pressure / inlet pressure)^.283))/turbo effeciency

Density = T1/T2 * P1/P2

Airflow w/turbo = Airflow wo/turbo * Density

n(lbs/min)= P(psia) x V(cu.ft./min) x 29
(10.73 x T(deg R))



These are some of what i used to calculate. when i did yours at 7000 rpm i used turbo eff. of .75
VE of 83. 10psi.. 90degre F inlet temp.

I came up with 24-28lb/min.
235-280cfms.
165-195hp(85-100%effecient)
Depending on your system you can get higher effeciency like i said above.. 100%+ . which would give you a little bit more flow which = a little more power..

D16 w/ 10psi = around 180-220HP

RJwaggs

Maybe 83% at redline is a little high... I know for 302's, when redlining the VE is horrid, like 55%.

dastinker8

The flow curve VERY closely follows the tq curve. so look at most boosted d series dynos. Close to redline the tq usually only falls of about 20-30hp from max if they have a good setup that can flow the air. So take max 200hp theoretical tq should be about 150... tq = hp x 5252/rpm. Take a d series engine. Maybe a max tq of 160-165tq

165 to 150 is about a %10 percent loss. so if the engine at 10psi got to an effeciency of 100% creating a max tq of 165-160 then at redline the effeciency would only drop 10-15% giving you a tq output of 150.(85%VE) This is for the d series engine. Ok so take the lower flow number thats still 4lbs higher then what he got.

Look at a dyno of the bigger engines 302.. There tq is really high at low rpm then when they get to redline there tq falls off drastically... like 100ftlbs or more...ive seen worse. Remeber tq curve follows the flow curve... Thats why on bigger engines that cant flow the air.. their really ineffecient at high rpm.. Really good at low rpm but not up top.

Brian