I'm a moron

Re: whats to come

i have a question bout your equation tho. ok small turbo and big turbos have different sized wholes of where the compressed air comes out the compresser housing(do you get what im sayen) so are you baseing the volume of air the block (183ci) has in it at 20 psi or are you using some specs you know bout the holset hx35 it self. IT seems your using the engine block to calculate the estimated denstity/volume of air would/should be in the motor at 20 psi. and i think i just answered my own question. so i can use this equation no matter what turbo i use

Re: whats to come

Your holset is going to flow Lbs/Min at a given boost pressure. Find a map, and i'll show you the equation for that.

Re: whats to come

Ok one more question then ill leave you alone in your experiance what would the best tuneing for what i want to do or what ive listed above? NISTUNE ROMULATOR MEGASQUIRT? MY ecu is a 1984or85 but my car is a 87 na2t Same o2 sensors correct.

Re: whats to come

Sorry bro, I find myself asking the same question. I'd say give nistune a shot. I am stuck between 2.

Re: I'm a moron

http://www.cumminsforum.com/forum/gener … g-l-2.html

half way down the page is the map explain

Re: I'm a moron

IS volumetric efficiency of 85% pretty accurate or were you just using it for the example? but wouldnt the volumetric be way above 100% due to forced induction and get greater and greater as boost was raised.

Re: I'm a moron



So now that we know how many lbs/min this turbo flows at 15 PSI or a PR of 2.02. And you probably want to hit full boost by half of your red line so 3250 right?

You have to do the CFM equation of the engine for 3250 and 6500.
- - - - Math Time - - - -
295.5 CFM @ 3250 and 590 CFM @ 6500.

Now you have to convert CFM into Lbs/Min. This is done by dividing CFM by 14.27.

295.5/14.27=20.7 Lbs/min 590/14.27= 41.34 Lbs/min

So now you have the 3 Magic numbers.

1 - Your PR of 2.02, which is the Left side of the Turbo Map.

2 & 3 - Your Range of full boost action from 20.7-41.34, which is the lower numbers on the Turbo Map.

If you go outside of those circles to the left, you have gone past the surge Limit. That is bad. Now it is your turn. Just match the numbers up and see if they fall into the map. So tell me, does it seem to work?

Re: I'm a moron

yes? maybe! what do the numbers on the bottom represent ?

Re: I'm a moron

that is what the PR is for, at 20lbs boost (PR 2.36) with a VE of 85% you motor will be 200.6% efficient per stroke.

Re: I'm a moron

so it it like connect the dots go up 2.02 and over to 20.7 thats one dot then from there you move over to 41.34 then draw a line between the 2 and thats your line and if doesnt fall inside of the map your surging? but what does 20.7 and 41.34epresent?

Re: I'm a moron

the lb/min your motor is flowing at 3250 and 6500 rpm

Re: I'm a moron

Yeah. A Dot at 20.7 and 41.34 w/ a line fromt 2.02 all the way across.

Re: I'm a moron

so lets say your motor somehow reved to 13000 rpm then the you motor will flow is 82.68lb/min and that would be out of the efficiency range of the turbo.

the turbo is not spinning at the same speed even if it is boosting 20lbs all the time. the turbo first has to match the cfm for the motor at a certain rpm, then has to make pressure ontop of that. so its easy to see how you can run out of efficiency

Re: I'm a moron

wow im a dumb ass i just got it ,wow thats so simple its converting it back a forth that got me ok kool. so this map/turbo should work just fine then right!

Re: I'm a moron

woops i didnt see he converted to lb/min, i corrected my posts