750 Brawler vs 650 AVS 2 at the track, right OOTB !

[Hysteric]

My guess most of this carb sizing crap comes down to guy's not or poorly tuning.

Not the case at all. On a 800HP plus race engine some one very knowledgeable had to decrease the overall induction (carbs) size to gain back what they lost when they made changes to improve airflow.........because the new combo diminished the vaporization rate (gas conversion) he needed to get it back and a set of smaller overall carbs is what did it.

 

[273]

It's crazy to come any conclusion other than both carbs did very well under the circumstance.
Not definitive proof of anything.

 

[318willrun]

I guess my assessment, as well as my friends from the track is this:

• Brawler wasn't a surprise as it was basically the same as the 4779 Holley DP it replaced. I was impressed at how well it work, and I mean it was flawless 100% from every point, right out of the box.
• The AVS did impress me because my friend and I BOTH thought I'd loose about 2 mph on the big end, and it did not give up anything.
• The AVS appears to be a nice carb for the 384.00 shipped to your door price. HOWEVER, of the 2 carbs, I was surprised that it was the AVS that started some hard and actually died after a burnout.

 

[318willrun]

AND... for the giggles... the AVS sounds Just Like a Thermoquad with the air cleaner off... that back air door

 

[Hysteric]

The AVS appears to be a nice carb for the 384.00 shipped to your door price. HOWEVER, of the 2 carbs, I was surprised that it was the AVS that started some hard and actually did after a burnout.

It shouldn't which means you need to figure out what's wrong with it. My guess would be to check the float levels first.

 

[318willrun]

It's crazy to come any conclusion other than both carbs did very well under the circumstance.
Not definitive proof of anything.

Agreed. Fully tuned, which carb might light what spacer, etc.. hard to say where these would end up. I can tell as crisp and clean as both these carbs ran, there wouldn't be a ton left in the tune to find.

 

[273]

Not the case at all. On a 800HP plus race engine some one very knowledgeable had to decrease the over carb size to gain back what they lost when they made changes to improve airflow.........because the new combo diminished the vaporization rate (gas conversion) he needed to get it back and a set of smaller overall carbs is what did it.

What is over sizing exactly?, other than testing which works best for particular purposes, it's all guesstimation, carbs don't flow a certain amount of air they all basically flow whatever amount of air you draw through them, different carbs have different amounts of restriction kind of like headers. to be continued.

 

[Hysteric]

It's crazy to come any conclusion other than both carbs did very well under the circumstance.
Not definitive proof of anything.

And yet 318willrun clearly believed otherwise:

The AVS did impress me because my friend and I BOTH thought I'd loose about 2 mph on the big end, and it did not give up anything.

Funny that isn't it. The general misconception is a bigger carb will always make more power.

 

[318willrun]

And yet 318willrun clearly believed otherwise:


Funny that isn't it. The general misconception is a bigger carb will always make more power.

What I should have done, is run a vacuum gage inside the car and see what it did under WOT. That could have been interesting.

 

[Hysteric]

What is over sizing exactly?, other than testing which works best for particular purposes, it's all guesstimation, carbs don't flow a certain amount of air they all basically flow whatever amount of air you draw through them, different carbs have different amounts of restriction kind of like headers. to be continued.

Smart people at the top of motorsports don't guess they test and test and test.

What I should have done, is run a vacuum gage inside the car and see what it did under WOT. That could have been interesting.

That's exactly what you should do. Vacuum aids vaporization and if an engine needs more vacuum to convert more of the fuel to a gas that's a burnable state then guess what happens?

Look at the 400 cube ford that ran best with a 650 and ask yourself why did it make most power with 5.5 inches of mercury @ the top end?

 

[273]

Smart people at the top of motorsports don't guess they test and test and test.

That's my point your assumption is the 750 too big neither carb has been fully tested on another thread your telling guy his 950 on a healthy big block is too big without any real proof.

According to the so called carb formula cid x rpm / 3456 x ve% = carb cfm, which would be 450-550 cfms for most 360 making peak power with 4500-5500 rpm. So basically every 4bbl 360 and under is over carb. including the 650 avs.

 

[318willrun]

We'll continue to make "improvements" to the car. A lot of thought has gone into the car so far. Remember, it's first goal was to run 13.9X's with 2.45 gears, stock converter, factory smog heads, factory exhaust manifolds, at about 3500+ lbs at the start line and it did it. We have plans, and this car is just going to keep getting faster.... but as for now, it's best is a 12.86.
AND... Hats off to the 904 - hanging in there all these years with no shift kit or anything (we have a plan for that too)

 

[Hysteric]

That's my point your assumption is the 750 too big

No that's yours and other peoples assumptions. I just point out the obvious disparity between peoples statements and the real world. A milder engine can tolerate a bigger carb.........Why is that?

You think that Big Block is healthy.......

According to the so called carb formula cid x rpm / 3456 x ve% = carb cfm, which would be 450-550 cfms for most 360 making peak power with 4500-5500 rpm. So basically every 4bbl 360 and under is over carb. including the 650 avs

You're the only one saying that.

 

[273]

And yet 318willrun clearly believed otherwise:


Funny that isn't it. The general misconception is a bigger carb will always make more power.

You maybe right in this case and fully tuned the 650 could be the best or even a 500 might be better or maybe a 850 might be the fastest or even 1500+ cfm tunnel ram might be the quickest combo who knows, your making a broad assumption without much info/testing.

But what we do know in general 750 has proved itself as a good general purpose performance carb that has worked from stock to fairly wild. And generally a 650 is more than enough on the mild side.

 

[Rat Bastid]

You maybe right in this case and fully tuned the 650 could be the best or even a 500 might be better or maybe a 850 might be the fastest or even 1500+ cfm tunnel ram might be the quickest combo who knows, your making a broad assumption without much info/testing.

But what we do know in general 750 has proved itself as a good general purpose performance carb that has worked from stock to fairly wild. And generally a 650 is more than enough on the mild side.

You’ll never convince Hysteric that he’s wrong on carb sizing.

Issue number ONE is you can NOT judge the airflow of a carb based on its CFM rating. That’s crazy.

He also is a one trick pony when it comes to tuning. He thinks “vacuum” is the only way to get proper fuel homogeneity.

He also refuses to grasp the fuel he gets down under is far different than what we get here so he fails to admit that tuning here doesnt have to be exactly what he thinks.

He is unteachable. And a one trick pony.

 

[Hysteric]

You maybe right in this case

Only in this case I'm sure......

Issue number ONE is you can NOT judge the airflow of a carb based on its CFM rating. That’s crazy.

What does this have to do with the fact that even 318willrun and his mate can obviously tell the difference in sizing between the 2 and expect the bigger carb to make much more power. Surely the 750 holley clone flows more than an annular 600 edelbrock. There's clearly a difference..........

He thinks “vacuum” is the only way to get proper fuel homogeneity.

Um.......every engine needs vacuum to assist in VAPORIZATION which is not HOMOGENIZATION. Maybe if you understood the difference you wouldn't make such an *** of yourself.

He also refuses to grasp the fuel he gets

LIQUID FUELS in general need to be vaporized for them to burn correctly. Maybe the engines and fuels you use defy the laws of physics? Variations in the Hydro Carbons used and Distillation Temps mean different fuels require different amounts of energy imputation to achieve this(conversion to gaseous state). Hope this helps you better understand what Vaporization is and why you need it.

Wikipedia "Vaporization"

Vaporization (or vaporisation) of an element or compound is a phase transition from the liquid phase to vapor.

 

[Rat Bastid]

Only in this case I'm sure......


What does this have to do with the fact that even 318willrun and his mate can obviously tell the difference in sizing between the 2 and expect the bigger carb to make much more power. Surely the 750 holley clone flows more than an annular 600 edelbrock. There's clearly a difference..........


Um.......every engine needs vacuum to assist in VAPORIZATION which is not HOMOGENIZATION. Maybe if you understood the difference you wouldn't make such an *** of yourself.


LIQUID FUELS in general need to be vaporized for them to burn correctly. Maybe the engines and fuels you use defy the laws of physics? Variations in the Hydro Carbons used and Distillation Temps mean different fuels require different amounts of energy imputation to achieve this(conversion to gaseous state). Hope this helps you better understand what Vaporization is and why you need it.

Wikipedia "Vaporization"

No **** Sherlock. I get it. You don’t. You have a one track mind.

 

[MopaR&D]

Um.......every engine needs vacuum to assist in VAPORIZATION which is not HOMOGENIZATION. Maybe if you understood the difference you wouldn't make such an *** of yourself.

Vacuum helps but it's not needed if the boosters are the right type (annular or triple-stack and/or at least sharpened lower edges), short-side radius in the intake port has the right contour and the port velocity is decent for the intended application (displacement and RPM range). I haven't seen one in person yet but direct-injection engines don't have a SSR because its sole purpose is to shear the wet flow in port-injected/carb'd engines. That's actually the most critical thing, much more than vacuum unless we're talking strictly street engines at part-throttle.

 

[pittsburghracer]

Vacuum helps but it's not needed if the boosters are the right type (annular or triple-stack and/or at least sharpened lower edges), short-side radius in the intake port has the right contour and the port velocity is decent for the intended application (displacement and RPM range). I haven't seen one in person yet but direct-injection engines don't have a SSR because its sole purpose is to shear the wet flow in port-injected/carb'd engines. That's actually the most critical thing, much more than vacuum unless we're talking strictly street engines at part-throttle.

I gotta tell you I got a little excited reading this post. Short side radius, contour, port velocity, displacement, and rpm and in one carb post. I think I need a nap after reading this.

 

[MopaR&D]

I gotta tell you I got a little excited reading this post. Short side radius, contour, port velocity, displacement, and rpm and in one carb post. I think I need a nap after reading this.

Lol I'm pretty much just summarizing what I learned after watching and reading some stuff mostly by Darin Morgan and combining it with my experience in CFD and fluid flow from engineering school. I wish I had more hands-on experience in this realm but there's only so much time in the day...

 

[318willrun]

The car still has the 100% factory fuel delivery system which is the factory 5/16 fuel line and the over the counter factory replacement mechanical fuel pump. No, I don't have a fuel pressure gage so I don't know what it runs for fuel psi

 

[318willrun]

Lol I'm pretty much just summarizing what I learned after watching and reading some stuff mostly by Darin Morgan and combining it with my experience in CFD and fluid flow from engineering school. I wish I had more hands-on experience in this realm but there's only so much time in the day...

• The combustion chamber engine has been studied, and there is not a lot we don't know about them. However, our approach is the difference... at least my difference with this car.
• We all have our beliefs or likings, and I spent too many years looking for evidence to support my theories. I think this is where too many get hung up on, evidence to support personal theories. Sure, in general, throw a bigger cam, better heads, 4bbl, gears and converter at a car and go faster.
• What changed this time is I cleared my mind to a white sheet of paper and said to myself "capture evidence, even if it testifies against my theories". While there may be some truth (or even a lot of truth) in folks argument, evidence can be missed because of "support of theory". I know this lives in my past.
• "Theory" for years said a J-head 340 with 3.55's from the factory would destroy a low compression smog 360 with log manifolds with 2.45's in a heavier car, wouldn't be a race. A laugher in fact. I was in that crowd too, years ago. But when I set theory aside, followed evidence, I ran a better time and mph with the LC 360 and log manifolds, with 2.45 gears.

 

[MopaR&D]

• The combustion chamber engine has been studied, and there is not a lot we don't know about them. However, our approach is the difference... at least my difference with this car.
• We all have our beliefs or likings, and I spent too many years looking for evidence to support my theories. I think this is where too many get hung up on, evidence to support personal theories. Sure, in general, throw a bigger cam, better heads, 4bbl, gears and converter at a car and go faster.
• What changed this time is I cleared my mind to a white sheet of paper and said to myself "capture evidence, even if it testifies against my theories". While there may be some truth (or even a lot of truth) in folks argument, evidence can be missed because of "support of theory". I know this lives in my past.
• "Theory" for years said a J-head 340 with 3.55's from the factory would destroy a low compression smog 360 with log manifolds with 2.45's in a heavier car, wouldn't be a race. A laugher in fact. I was in that crowd too, years ago. But when I set theory aside, followed evidence, I ran a better time and mph with the LC 360 and log manifolds, with 2.45 gears.

My 5.9L Magnum short block with ported open-chamber Edelbrocks "should" be soft on the bottom end with only 9:1 compression... I had the cam custom-ground by Racer Brown and it's not a problem, granted it has a converter that stalls around 2600 RPM but still. It would be better with closed-chamber heads and zero-deck pistons but that wasn't in the budget.

I love gaining knowledge and thinking about the theory but I also try to stay realistic and work with what I have/can afford and most importantly, what my actual goals are. I didn't need a super-dialed perfect combo for competitive drag racing, just something with good HP and torque to push the car around a road course.

 

[a-bodyguy]

My 5.9L Magnum short block with ported open-chamber Edelbrocks "should" be soft on the bottom end with only 9:1 compression... I had the cam custom-ground by Racer Brown and it's not a problem, granted it has a converter that stalls around 2600 RPM but still. It would be better with closed-chamber heads and zero-deck pistons but that wasn't in the budget.

I love gaining knowledge and thinking about the theory but I also try to stay realistic and work with what I have/can afford and most importantly, what my actual goals are.

150 shot fixes that and the verter will stall@3k

 

[pittsburghracer]

150 shot fixes that and the verter will stall@3k

Bla bla bla aaa