Furlanetto

So I would like to be able to calculate the amount of pressure needed to make X horsepower. It's impossible, but if i have reference numbers for a particular setup can i figure it out?

Right now my power output for by setup (B18C1, 9:1, with PTE 5731E) is 300HP on 10 PSI (24.7 PSI in absolute pressure) at the wheels. With the same turbo is the power/pressure relationship linear in absolute pressure units?
Absolute=Gauge Pressure+Atmospheric Pressure. Atmospheric pressure is approximately 14.7 PSI.

So if i make 300 HP on 24.7 PSI absolute, if the power/pressure relationship is linear I could calculate the pressure needed to produce 400 HP with the same turbo. For example if I want to make 400hp:

(400HP)*(24.7PSI)/(300HP) =32.9 PSI absolute = 18.2 PSI needed to make 400whp. It's simply a ratio of HP to absolute pressure.

My main question is does this relationship work with the same turbo.

My intuition would say it does work since the pressure is proportional to the amount of moles of air entering the engine ( n=PV/RT) which correlates to the amount of heat/power generated. Now does the practical side agree with this? (tuners)


I could also understand how it is not linear since more pressure= more heat which means less moles of air thus leading to less power than calculated in the example.

OneBadTurboCRV

It isn't impossible in the slightest. You are calculating HP and NOT WHP. You have the engine calculation side of things but you need to plot some compressor maps. You are better off just going with the tried and true setups that have been tested. Just because it works on paper doesn't mean it directly translates into the real world. Too many variables to be considered to be exacting. You can get in the ballpark with XX% of error with computing.

Flow won't be linear since the compressor maps are practically never linear. Since you have a manufacturer that doesn't have compressor maps this whole conversation is a waste of our time. Don't try to reinvent the wheel and just looks for similar builds to yours. I guarantee you there are multiple... People have been boosting Hondas for decades, nothing new.

Schister66

As OneBad said, the relationship isn't exactly linear. You have to plot the flow rates on the compressor map (non-existent, but could use a .57 trim garrett as an analog) and figure the relative efficiency of the compressor. Where you fall on the map dictates if you make 10hp/psi or 12hp/psi ... obviously those are made up numbers, but you get the idea.

Research a few .57 trim Garrett setups and see what they make. You will be within a few % of those. Again, there are 100 other variables to consider so look at other setups as a guide, not as fact

NotARaCist

iTrader: (1)

Read this. Then read this. Then read this. If, after reading and understanding all three of those, you still don't know why what you want to do doesn't work, then you're beyond help. Turbo math is not simple, linear math.

Furlanetto

Cool, thanks guys for the input! Looks like i'll do some reading about the maps NotaRacist.
I'm currently studying electrical eng so i know nothing about fluid dynamics, but the math should be fine.

I really like the idea of comparing with similar setups, i just want a ballpark idea for the next waste gate spring.

Schister66

Or buy a boost controller and skip the planning, but it is nice to have a benchmark