VE Issues

IggysPiggy · #1 (**permalink**) 07-17-2008, 04:31 PM

Hey I am looking to calculate my VE for my 2004 grand prix gtp. Now I have the equations, I understand how to do it for an NA car (done it before) but now how do I go about factoring my sc's boost into the equation. (I have books and have read them so please no go read post's). I am new to this stuff so any and all HELP is appreciated. I can't dyno it (ridiculously expensive up here) but I know your Highest VE is supposed to occur at peak torque, am I safe to assume that is correct? I probably would be safe to assume 83-93% peak VE but I do not know at what point (RPM) it occurs.

Can I possibly pull off my sc belt and take the reading that way....?

Please If I am way out to lunch here please be nice,

Cheers, Jesse

IggysPiggy · #2 (**permalink**) 07-18-2008, 07:46 PM

Come on guys no one? All I need is an idea lol I just need a couple of maf readings at dif. rpm points but I dont want it cluttered by boost....

Is the removal of the SC belt a solid idea...?

nuclearxp · #3 (**permalink**) 07-18-2008, 09:16 PM

Does this help?

Gary's HP Tuners Basic Tuning 101

IggysPiggy · #4 (**permalink**) 07-21-2008, 07:34 PM

Ah It didn't help but damn it was a good read (makes me want to buy HPT). I appreciate you trying to help. Do you know if its ok to pull my sc belt off and run the engine with out it...? I refuse to just give up there's a way to do this yet.

nuclearxp · #5 (**permalink**) 07-21-2008, 08:28 PM

Did I miss you saying why you want to calculate your engine VE so badly?

IggysPiggy · #6 (**permalink**) 07-22-2008, 01:20 PM

haha I probably did not say why realistically (from the old ladies point) there is no reason (shhh

) but I am reading a set of books (street turbocharging, turbo basics, advanced tubo setups...) and they have all the calcs in the book and I wanted to apply it to something I have. I want to do all of it for my 3800 (I need my VE so I can plot compressor maps) and I have started with this car and now I am half way through and im stuck lol.(I refuse to just give up that is not an answer lol)

All this is doing is helping me learn about turbos and the way they are sized, trim options and how they affect boost...etc

I know it seems dumb but it keeps me busy

Cheers, Jesse

nuclearxp · #7 (**permalink**) 07-22-2008, 02:02 PM

VE of a supercharged motor != NA != Turbocharged to my knowledge.

If you're looking to find a compressor map based on your current motor I don't think you'll get it by calculating VE.

Last I knew turbo compressor maps key off of pressure ratio and airflow (volume). I would think you should be calculating how much (volume) of air your motor is moving now, then from there determine how much more you want to move to make a given power level (i.e. 40lb*min of air is said to be ~ 400whp). Pressure ratio is the equivalent amount of boost (I believe you must add absolute pressure to your desired boost to get it to the pressure ratio).

Does that make any sense?

IggysPiggy · #8 (**permalink**) 07-22-2008, 02:59 PM

no no I see what your saying but I am trying to do all the equations based off of my car that is all and one is for calculating VE. I hate doing anything half a**ed most of the book is done i have pages and pages of numbers but the one page marked VE is sadly unfinished. I look at it like tuneing your car half way whats the point?

I will admit I am new to all this but what I am trying to do is learn. I may just have to pick a dif car to do the VE equation for but I will look at it and it will nag me if you know what I mean.

Cheers, Jesse

nuclearxp · #9 (**permalink**) 07-22-2008, 03:17 PM

I'm going to have to back out of this discussion, as I still don't get what it is you're trying to do......

I don't get why you're trying to "factor in your supercharger's boost".... Are you trying to determine what effect it has on VE in respect to the motor naturally aspirated?

You ask if you can pull the SC belt off and test it that way? Well what does that mean? You can't leave the whole SC on and expect that running it with the belt off will give you it's effect on efficiency. You'd still be trying to suck air through the supercharger and make the air force the rotors to turn thereby completely ruining your VE calculations. If you're seriously only trying to calculate your blowers effectiveness on VE then MAYBE you could remove the rotors and block the back end off and run without the blower but the tun would be off anyway that would STILL throw your calculations off.

It seems

Quote:

Hey I am looking to calculate my VE for my 2004 grand prix gtp.

was your "quoted" goal... but your car already has an entire VE table (accessible via HP Tuners). Why are you trying to calculate it over again? Just for fun? Please clarify if this is what you're getting at.