Coreyc619

there are VE formulas if you google. but those are THEORY.. like based on your displacement your theoretical VE could be... in any specific instance it must be measured.

nitromethane doesnt have anything to do with VE...? sure you can add nearly 9x as much fuel/same volume of air but.. how does that affect VE?

DREAMZ28

iTrader: (1)

I would imagine you could use any fuel and the VE would be virtually the same. VE is basically just measuring how much power the motor is making versus how much it should theoretically be making, IF im not mistaken. Don't blow up if my idea on this is wrong though, I am only 15.. Still waiting on some educated ls1tech'ers to drop by and share knowledge.

1989GTA

"The graph I posted on my 402 was with some 1-7/8" American Racing F-body Headers that have a nice merge collector with a "velocity spike". It actually showed a significant gain in the touque output and VE over the 1 -7/8" dyno headers we started with when I dynoed."

Your test shows how important a well constucted set of headers is and especially the collector area. Also the entry into the header from the head. That is the first time I have seen a dyno chart with the VE posted along with it. Thanks for the interesting post.

Coreyc619

that was my point.. what would the fuel have to do with it..?

thats not really what VE is. its more like how much air its moving, which is related to power production but not directly in every case. extrememly efficient engines that take advantage of pressure wave tuning on the intake AND the exhaust side can be more than 100% efficient. theres the cliffs notes. google the rest, or goto hardcorels1.com and read the stickies/posts by oldsstroker

dont confuse him with his son sstrokerace.. his posts are generally a waste of time to read.

NVmyVETTE

VE isn't about power. It's volumetric efficiency or air flow potential. Each cylinder holds x amount of air. At 100% VE the cylinder is moving the exact amount of air as the cylinder volume. Above 100% means it's above capacity and below 100% is less.

What fuel you're using is more of a power thing. Based around timing/cylinder pressure/air flow inside the cylinder (combustion chamber shape and swirl).

VE is more or less airflow per cylinder and can be measure on a flow bench without even using fuel.

DREAMZ28

iTrader: (1)

Ok I understand it now..

So basically VE is just how much air the motor or cylinder is sucking in compared to its actual volume.

I mostly understand how the "pressure waves" in the exaust port can occur, but I've never heard of them occuring on the intake side.

JonCR96Z

iTrader: (33)

The air is flowing down the runner and into the cylinder then all of sudden the valve closes the air has to stop abruptly and it creates pressure waves in the intake.

That is where tuning intake runner length and valve timing really come into play.

grb

A spacer under a carb. often adds power. I assume this has nothing to do with VE. BUT, what would be the effect of adding a 1" spacer between the HEADS and the INTAKE. Would it effect power in any way? Would it make any difference at all? It couldn't possibly reduce power could it??

If it would make any difference let's say the intake is a FAST and the engine is a solid roller 427 ci. To really complicate matters would this mod. effect a super charged engine in the same way as an NA?

NSSANE02

iTrader: (14)

You couldn't put a spacer under the intake due to the angle.

grb

I've got two spacers on mine (L & R) that adapt the FAST intake to the C5R heads. One inch thick aluminum and fairly well port matched.

NSSANE02

iTrader: (14)

Seems to me if you space the intake at all it creates an odd angle from the intake to the head. Because the intake would have to go straight up but the runner is still coming down at the same angle, as is the head port so the spacer would have to go straight down from I.D. to I.D. to match the ports. Maybe I'm thinking about it wrong.

grb

It did raise the height of the intake. One inch, so the hood wouldn't close which resulted in a hole being cut in the tunnel for clearance which allowed raw gas type fumes into the car. Not fun! A Hogan or Wilson sheet metal intake would have been cheaper, better and cost less!!

irocz2173

Just finished an airflow class here at Ferris State University. To better answer the OP's question, yes a VE of more than 100% is very easily attainable. To be exact 130% is the max theoretical VE by using both the intake and exhaust pulses. On the intake side the first pulse is not usable but it is generally accepted that the second pulse is the most desirable. It has the most positive pressure and as long as the intake valve opens at the right time. As previously stated intake runner length plays a major role in which pulse you can utilize and at which RPM it is most effective. The exhaust side also uses pulse but they are negative pressures. The first pulse is the most desireble in this case. Header design plays a major role as you may imagine. Primary lengths can be determined by an equation that I have but dont know how in depth you want me to get. When designing the headers, it is possible to create an over-scavenging effect. This is when the negative pressure actually pulls some of the fresh air fuel charge out the exhaust, increasing brake specific fuel consumption(BSFC). Well I gotta run to my next class but I hope this helped. It really is amazing how in depth you can get when discussing airflow through an engine.

grb

Now that's a great answer. BUT, it makes me wonder how on earth does an engine designer, much less a builder, determine when and where these pulses are which would have a great effect on the cam, intake and header design? And wouldn't changing one of these parts effect the entire engine?

HUNTER02SS

iTrader: (24)

When he had this combination built back in 04, there was no intake available with C5r style intake ports that just bolt on other than a custom sheetmetal intake, which would of cost ALOT more than a set of spacers that he had made..

HUNTER02SS

iTrader: (24)

lmao!!!

grb

Check with Wilson and Hogan. They both would make a great looking, sheet metal that would flow better for less than $3,500 in '04. That same intake today is around $2,500. Why in God's name would an intake mfg. invest in the equipment to build a hand full of intakes. Think man!

HUNTER02SS

iTrader: (24)

If a Hogan or Wilson custom sheetmetal intake is so much less expensive, than a FAST and a set of spacer's, why didn't you just go that route??
Obviously you didn't THINK MAN?????

irocz2173

Yes, changing just one of these components would change the characteristics of the entire engine. This is why people always say you need to make each component work with each other. Cam selection is one of the most important parts to an engine and can really improve performance if valve timing is properly selected but a header swap could negate any performance gains if it is not matched to the setup. I cant comment on the engine designer aspect of your question but I hope to be one within the next two years. Any openings in the GM Performance Division? I only wish... Obviously countless hours go into designing the engines we use everyday to meet a certain goal. Though this goal may not be the most performance oriented, it is designed to work well from the factory and last.

grb

I would think GM has advanced computer programs that can pretty much determine the proper parts that will produce what they are looking for including fuel mileage and emissions.