Volumetric Efficiency

[BigAL]

So I have a question, is it common for engines to work at greater than a 100% volumetric efficiency? I ask this cause when going over my dyno results it shows that the highest Volumetric Efficiency I had was 112.8%. Is this something normal that you'd see?

[dieselgeek]

Yep, that's normal (edit - seeing a VE over 100% using typical measurement or calc methods).

[Barry Donovan]

a real backyard way to verify the number..
if your base engines max torque on regular fuel is a lower rpm than that is written by the maker..

Adding a map sensor to an old subaru has max torque at 2000s instead of 2800. That is an example of gaining on VE.
..and of course natural can go beyond. VE is just a number comparing to a standard set in the beginning of testing...comparing to itself makes the most sense right?

[BigAL]

Yep, that's normal (edit - seeing a VE over 100% using typical measurement or calc methods).

Ya I was just wondering, because a lot of the CFM calculators for sizing carbs gives examples of VE at 80-90% for street motors and 90-100+% for modified/race motors, so when I saw that mine had a peak of 112.8% I was a little surprised. My dyno results are from 4500-7000rpm and my average VE was 111.3%, so if that is normal, what is considered high, like what's the highest VE you've seen?

[dieselgeek]

Ya I was just wondering, because a lot of the CFM calculators for sizing carbs gives examples of VE at 80-90% for street motors and 90-100+% for modified/race motors, so when I saw that mine had a peak of 112.8% I was a little surprised. My dyno results are from 4500-7000rpm and my average VE was 111.3%, so if that is normal, what is considered high, like what's the highest VE you've seen?

It's likely your engine WAS over 100% at peak VE if the parts were picked right. That's what all the stuff you've read about peak depression during overlap, wave tuning, etc. are about - increasing torque by maximizing VE. Get it all set up right and it will reward you. Work hard at it, and you can spread that performance over a wider RPM range - it gets exponentially harder to do the wider you try to make the RPM range, hence the strange intrigue of Engine Masters.

The EFI stuff I use, it also estimates VE but since we use non-lab-grade sensors and actuators, there is going to be a few percent error. The best EMC engines I've worked on, showed a VE of around 110-115%. My guess is the difference between a standard hot rod engine and a max effort EMC engine is going to be maybe a 5-7% spread based on power numbers, that last 5% is the real challenge IMO.

[BigAL]

I do have to say doing that motor really got me addicted to the dyno, right after I was done I wanted to build another motor just to see what kind of power it will make, thus the reason I'm building that blown 496. It really is a lot of fun. I get my distributor next week which is the last part I'm waiting for and then I'm hoping to drop off the motor with Rick by the end of November, really excited to see what this one does.

[Bob Holmes]

Very addictive, isn't it?

[dieselgeek]

I do have to say doing that motor really got me addicted to the dyno, right after I was done I wanted to build another motor just to see what kind of power it will make, thus the reason I'm building that blown 496. It really is a lot of fun. I get my distributor next week which is the last part I'm waiting for and then I'm hoping to drop off the motor with Rick by the end of November, really excited to see what this one does.

If you want to have real fun at a dyno session, bring AS MANY parts as you can possibly test, and a plan to test them, in the time you've reserved. Bring a few mechanical friends as your pit crew.

Crazy things I have seen that people did not expect to see:

Changing collector volume pick up peak 40hp at BES (on a 700hp engine, that's huge)
Going from no carb spacer to a 1.5" spacer picking up also 40 peak hp (Dalquist on his 565" engine in the latest Vizard book) (bigger spacers started losing power)
A little grinding on a TB-to-intake transition picking up a whopping 150hp (on a 1100hp N/A engine, still huge gains!)

In order of importance based on what I see - start in this order:

Exhaust
Intake
Ignition timing
AFR
Cam profile/choice
etc.

hugest gains are always on intake and exhaust tuning, testing. If you can bring a couple different intakes, do it! in the end you will find a combo of parts that in now way would you have guessed to be "the best combination" but it will make more power where you want it. The more you test, the better you'll do.

[Deaf Bob]

I remember reading that VE would never reack more than 80% due to the way the internal combustion engine was designed.. That hose nbrs could only be acheived on the dyno and never in the real world driving times.. Now I see 100%+ VE, I wonder what VE is seen on the street?

[Barry Donovan]

I remember reading that VE would never reack more than 80% due to the way the internal combustion engine was designed.. That hose nbrs could only be acheived on the dyno and never in the real world driving times.. Now I see 100%+ VE, I wonder what VE is seen on the street?

the speed of timing, for regular people comfort would drop it. else there is no excuses.
Just setting a spark off at the right time creates a draw through squares, circles, ovals, whatever is flowing air.

I went as dieselgeeks list by nature, a lot of people do. Transitions in porting has always been my fun...timing exactly right is the real win...does not happen enough, not even by factory.
the engine retarders..all for comforts.

A v8 has to be crammed precise like every counterbalance for the counterbalance for the counterbalance... like cat chasing its own tail.

Some engines, like the boxer, reveal the truth of cutting back on purpose: by nature they'd smack your head off the seat. I have witnessed the onsanity on air flows...most often losing venturi tightness anywhere creates just another weirdo to chase around in circles.

Everything can be 100+, as the real bad ones, people don't even run them. the worst is the 70s stuff...and then that old article with a 40 year old boost setup conquers that one too.

it is fun, don't even need a dyno.
if you have a throttle for the throttle beyond a choke...you just might be playing with more than a hundred.

another simple hint you are winning VE. You cut back on fuel settings for the same mileage... because air is moving. That is for carbs...but you may get the idea.

I started off with the 90hp 4.1L, the 200 ci six, the chevettes..this little subaru, all those doggy ass 305 chevies.. and the most frustrating was a 301 pontiac at 130hp. What the hell did they do to go that runted?

I learned it, and it is a surprise to teeter totter the same consumption to nearly a double in power...a lot of chores.
Nice to see the v8s in the 700hp natural today.

An illusion comes from the v8 crowd, it is displacement related.. but that is what makes pros and amateurs divide a line. I see the crank as hopeless..always will. Have fun anyway, we are just a small paragraph in histories book.

[BigAL]

Very addictive, isn't it?

it sure is Bob, the fact that I basically just threw together a 355 with off the shelf Ebay parts for a quick build to put an engine in my Monte that was reliable and it did so well on the dyno really blows my mind. I know it seem crazy but I really think all the debating I've done over the years with you guys has given me a good perspective on picking the right combo of parts to make good power. Though I have to credit a lot of it to using the AFR heads, and that AFR Titan Intake and the Total Seal Rings, along with having a great engine builder build the motor for me. Also I used a nitrous profile camshaft from Comp, it's really not that big, but it doesn't have to be with the low lift flow numbers those AFR heads have.

Link to Cam specs.

http://www.summitracing.com/parts/cca-08-303-8/overview/