What is the volumetric efficiency on a stock F22A4 block and what can I do to increase it?

 

What RPM are you shooting to build for? You need to know this in order to figure the VE for that specific range.

 

I am shooting for the 3,000 to 5,200rpm range, and I want to know what the VE is at that range stock.

 

In order to figure out the specific VE for that RPM range you also need to know the CFM of your engine at that RPM.

I'm away from my house right now so I don't have any MAP/CFM numbers with me but here is the formula for figuring out VE.

VE = 3456 x CFM (critical for VE)
------------------------
135 (CID) x 4200 (Mid RPM range)

I would think that a turbo would be a quick way to get 100+% VE at those ranges. Or a P&P head and intake manifold along with a cam with a bit more lift. If your looking to raise your VE and stay with stock internals your best bet would be a good flowing I/H/E combo.

 

According to the VE calculators I've been using, the F22A4 only needs 283CFM @ 6,100rpms flow rate to run at 100% VE or 190CFM @ 4,200rpms to run at 100% VE. Those calculators measured the airflow by calculating three numbers: Engine displacement, maximum safe RPM (or shift point at WOT), and intended Volumetric Efficiency (in my case 100%), then it calculated the airflow required to reach that VE.


Modified by otacon122 at 4:55 PM 2/16/2008


Modified by otacon122 at 4:55 PM 2/16/2008

 

If you know the actual engine torque @4200 you can figure the CFM and VE for your displacement. Or you need to measure the actual CFM in a closed system going to the engine.

 

Here is what I got for a Stock F22A4. This is only a virtual engine dyno.... The numbers could be off a bit, remember this is to get a rough idea on where your sitting.

RPM-----CFM-----VE%
4250-----161-----86%
5250-----180-----96%
<FONT COLOR="darkred">5750----218----97%</FONT> Peak Tq @ 120
6250-----199-----97%
<FONT COLOR="darkred">6750----149----97%</FONT> Peak Hp @ 153
7250-----275-----91%
8250-----312-----80%

I couldn't find the stock cam specs so I used these specs
Lift Int .411" and Exh .410"
Dur Int-238, Exh 248
Intake manifold estimated at 4248cc's from the back of the throttle plate to back of the valve. W/CAI - Headers w/stock exhaust.

 

This does help. I had no idea the K&N air filter boosted efficiency that much at top end. I did some calculations of my own, and here is what I came up with: At peak power (5200rpms) for an F22A4 (139CID) engine, in order to maintain 96% volumetric efficiency, the entire intake system must be capable of flowing a minimum of 217CFM. In order to maintain 100% VE @ 5200rpms, the entire intake system must flow a minimum of 226CFM. At 100% VE, expected horsepower is 224hp.


Modified by otacon122 at 7:37 AM 2/17/2008

 

Those are some pretty high HP numbers just from doing VE%'s on paper. Now the question is how do you get those VE & CFM numbers off of your computer screen and converted to Tq & Hp at the crank of your engine.

FYI, An F22A4 with a stock stroke of 95mm and a bore of 85mm gives you 2156cc or 131.56 CI of displacement aka 132. It doesn't seem like a big difference but it will factor into your end results. Unless you are running your numbers for an 87.5mm bore. That will give you a 139CID F22.

As I mentioned in my PM your stock IM & TB is more than capable of flowing those CFM numbers on paper. It's everything else that comes into play now. Your intake and exhaust port flow, valve size, cam specs ie. valve lift and duration not to mention timing. These factors are some of the physical aspects that will make or break whether or not you get too 100% VE. There are also atmospheric principals that may help or hinder your quest for 100% VE as well.

Anyone else care to expand on this discussion...join in....I don't think i have read many H-T threads on Volumetric Efficiency.... And it's been a wile since I tinkered with it for my build.