Don't read if you're close minded

[Mean416]

So, he does the tests without much discussion about the whys. My guess is that the vac secondaries aren't opening up on that 750.

I also suspect outright airflow, annnnd....airflow characteristics....are better in the dominator vs a similarly sized 4150.

Is the dominator also possibly better at atomization? Could this also be about evaporative cooling?

 

[Ant]

I do have my opinions and I believe if one carb made more power everywhere than the other carb like how the dominator did in the video, then the street manners will depend on the setup and tunability ( if I'm wrong, please correct me).

As for those CFM calculators and formulas for carb sizing for street engines, I believe they give something to work with, but that something is not good enough for me to work with. I may have a flawed perspective, correct me if I do, but it's based not only what other people wrote, do and claim, but a little bit on my experience with my Ferd at the dyno tuner. 302 Ford truck making more power everywhere when we experimented with the air filter. The shop owner/engine tuner who also claims to be an engineer said that the motor will benefit from a better induction setup, with maybe a CAI and a bigger throttle body. Wait! I know that is not a carb, but according to the calculators the ford 302 would need a 500 550 CFM carb. Ok, this where my thought process may get flawed, I might be comparing apples to oranges. The factory Ford dual throttle body flows at about 680CFM from what I can find and we are finding that the engine wants more air. So a bigger throttle body is recommended. Ok, so a bit bigger is better, so why is it fine for normal street driving? It's the tune. Well, it does have efi, so the ecm copes with the different driving conditions based off of the data from the sensors. Now a carb is different because the atomization of fuel happens there first and the venturi speeds up the air going in, but based on what I cand find, more WOT CFM does not make it worse all the time and it's design, setup and tune mostly is what I believe. Do I believe that there is to big? Yes, but I hope that I am in the ball park of what I need not trusting those calculators and not getting a smaller carb.

So... I agree with Eric and
I agree with 318WillRun

As far as low-end vs CFM's (rating at least.... ).....
In the worst-case scenario (meaning highway gears, stock converter).... my 360 Duster 60 ft the best with the 750 DP Holley and 750 DP Brawler. I tried a 600 eddy, 650 AVS II, 770 VS. As far as Double Pumper's and more CFM rating killing low end on a streetcar with stock converter (or next to stock) and highway gears just isn't the case in my opinion. I believe it's in the tune.

 

[Hysteric]

What a worthless test.

A proper test would have been 3 carbs built by Mark Whitner just varying sizes and get him to tune them for that engine.

 

[273]

Yes cause he should of spent a bunch of money on a little curiosity test.

 

[Hysteric]

You mean investing in properly built and set up carbs from some one who actually has an Idea is a waste of money?

 

[273]

You mean investing in properly built and set up carbs from some one who actually has an Idea is a waste of money?

Yes, do you think he's that interested in this test?

To spend a bunch of money, time and effort more than he already did. I doubt it but who knows maybe this is just the beginning and he's gonna do a 100's carbs on 100's of engines and thousands of dyno hours to get to the bottom of this. Possibly but I doubt it, more than likely they had some time left on the dyno session and decided to try a few carbs. I'm sure he sorry the test didn't live up to your standards, seems like few can.

 

[Hysteric]

I'm sure he sorry the test didn't live up to your standards, seems like few can.

Real testing involves controlling variables. Its not a meaningful tests its just entertainment. Draw whatever conclusion you like.....its meaningless.

 

[273]

Real testing involves controlling variables. Its not a meaningful tests its just entertainment. Draw whatever conclusion you like.....its meaningless.

Doesn't stop you from using the same example of a car going faster with a smaller carb over and over and over etc.. again trying to make your point. No one is saying these videos are absolute proof of anything.
But you don't like them cause they question you philosophy of strangling the hell out of your engine.

 

[MILO]

Hmm I guess we know the video was for chevy engines

 

[Mean416]

Hmm I guess we know the video was for chevy engines

Actually I would argue the video was for air pumps.

 

[Hysteric]

Doesn't stop you from using the same example of a car going faster with a smaller carb over and over and over etc..

You mean the test where they dyno tune the carbs on a chassis dyno then take them to the track to see how they actually perform?

Was it the test where the engine ran fastest with 5 inches of vacuum at the top end with all those pumping losses?

Why did it run fastest and idle best with the smallest carb and 5 inches of vacuum?

 

[273]

You mean the test where they dyno tune the carbs on a chassis dyno then take them to the track to see how they actually perform?

Was it the test where the engine ran fastest with 5 inches of vacuum at the top end with all those pumping losses?

Why did it run fastest and idle best with the smallest carb and 5 inches of vacuum?

That's one car, doesn't mean the results for that car is universal to every one else's car. It's interesting but you would need a few thousand more examples, to offset the last 65 years or so of racing and hot rodding.

 

[Hysteric]

That's one car, doesn't mean the results for that car is universal to every one else's car. It's interesting but you would need a few thousand more examples, to offset the last 65 years or so of racing and hot rodding.

I've provided enough examples of "supposedly" flow challenged engines that make more power than people claim they should whether they were under headed or under carbed because they utilize the oxygen they get. What you fail to grasp is to use the oxygen the fuel needs to be in the correct state........

Combustion science has come a long way in the last 50 years.........you can stay in the 1970's if you like.

 

[273]

I've provided enough examples

Like 2-5 lol

of "supposedly" flow challenged engines that make more power than people claim they should whether they were under headed or under carbed because they utilize the oxygen they get.

No your haven't, you think you have cause you strawman everyone's argument.

What you fail to grasp is to use the oxygen the fuel needs to be in the correct state........

You don't even know what I grasp, cause your not looking for honest discussions, you just look for threads to interject your strawman arguments.

Combustion science has come a long way in the last 50 years.........you can stay in the 1970's if you like.

I was a child in the 70's

 

[Hysteric]

I was a child in the 70's

Nothings changed.....

 

[Bewy]

Touche...

 

[RAMM]

What a worthless test.

A proper test would have been 3 carbs built by Mark Whitner just varying sizes and get him to tune them for that engine.

I agree and I'm kinda surprised he didn't verify the secondaries were opening. I've found a ziptie zipped around the secondary door opener rod with the tail sticking out gives you a nice visual confirmation if they are even trying to open. It really doesn't matter either way because I know and Eric knows that even if they were fully open that vac secondary carbs are inferior to any dbl pumper on the dyno. J.Rob

 

[RAMM]

Wasn't this article was it:

How to Pick the Best Carburetor for a Street/Strip Car

No it isn't the same one but it is interesting. If you read between the lines its clear they didn't really have the time to dial in the other carbs at all. It appears the 650 just happened to be closest/rich, which makes sense because it is the smallest and it would be nice and fat due to the enormous signal as evidenced by the 5.5" Hg at WOT. That's way too much and the carb with the -1.7Hg would have been the victor given a little fattening up. If we extrapolate this article out and follow the zero vacuum logic then a larger and larger carb should have swung the needle the other way. We'll never know. J.Rob

 

[Spadman]

do you think any of that was a function of people not understanding or having the ability to tune the TQ?

not questioning the veracity of them going faster with the smaller carb, but merely wondering aloud if it was just because it was so new that the secrets had yet to be unlocked.

I don’t remember it as being swapping TQ for AVS off a 440; but swapping an AVS from a 440 replacing the smaller AVS that was stock for a 340 really made a difference you could feel. Been there, did that.

 

[junkyardhero]

I don’t remember it as being swapping TQ for AVS off a 440; but swapping an AVS from a 440 replacing the smaller AVS that was stock for a 340 really made a difference you could feel. Been there, did that.

yeah, my lizard brain thought: 340=TQ rather than: oh, an early 340 would have an AVS and swapping that one for an AVS unit off a 440 would make sense.

a whole hear hoof beats and thinking zebras when it was donkeys around the corner instead.

 

[Hysteric]

No it isn't the same one but it is interesting. If you read between the lines its clear they didn't really have the time to dial in the other carbs at all. It appears the 650 just happened to be closest/rich, which makes sense because it is the smallest and it would be nice and fat due to the enormous signal as evidenced by the 5.5" Hg at WOT. That's way too much and the carb with the -1.7Hg would have been the victor given a little fattening up. If we extrapolate this article out and follow the zero vacuum logic then a larger and larger carb should have swung the needle the other way. We'll never know. J.Rob

My view is a little different. Looking at the incrementals it was quicker everywhere except the 60ft. The fact that its was able to do that with 5.5 inches of vacuum tells me that engine needs vacuum to aid it in the vaporization department as he's running pump fuel which has higher temp fractions. I've seen 4 inches of vacuum at the top end take off 4 tenths and 5 MPH on a combo that didn't open the secondary's due to a linkage issue.. Not so this car so there's more in play than simple airflow. For me its a good example of the chemistry involved in combustion.

Having to fatten up an engine could be viewed as needing more of the lighter fractions of the fuel blend to help out the burn as they vaporize much easier because there isn't enough vaporization taking place in the intake tract and on the compression stroke to gas the liquid sufficiently.

 

[Newbomb Turk]

My view is a little different. Looking at the incrementals it was quicker everywhere except the 60ft. The fact that its was able to do that with 5.5 inches of vacuum tells me that engine needs vacuum to aid it in the vaporization department as he's running pump fuel which has higher temp fractions. I've seen 4 inches of vacuum at the top end take off 4 tenths and 5 MPH on a combo that didn't open the secondary's due to a linkage issue.. Not so this car so there's more in play than simple airflow. For me its a good example of the chemistry involved in combustion.

Having to fatten up an engine could be viewed as needing more of the lighter fractions of the fuel blend to help out the burn as they vaporize much easier because there isn't enough vaporization taking place in the intake tract and on the compression stroke to gas the liquid sufficiently.

What it told me was they didn’t do much tuning and the car was a sponge.

A perfect example of time slips being useless.

If they put the engine on a dyno, they’d KNOW how much power each one made.

Then you go to the track and sort out the car.

Pretty much a silly test.

 

[Killer6]

To cure curiosities & answer the question, the HP Holley 4150 series carbs are rated at 2"Hg, not 1.5"Hg. The 1000 HP is really ~=an 870cfm std. Double Pumper. The one on the 455 Olds I built has one, with annular boosters, not drop-legs. Runs & drives like a pup.

 

[TT5.9mag]

I think Eric’s test was absolutely worthwhile. Was it scientific? Nope. Did it follow some methodology that engineers or engine builders would have followed? Nope. What it did represent was what probably 80% of the market would do at home on their own pile of crap hot rod. “I put a 750 on it and it slowed down”. Never checking for secondary activation or even WOT. Even walking around at a track I am amazed by the lack of knowledge people often have when asking questions about THEIR setup and how little they know about tuning it.
Eric’s test demonstrates how and why rumors or myths start about nonsensical crap in the automotive world and others regurgitating it. If your junk is faster with 5” vacuum at WOT you have a serious tuning problem.

 

[273]

Funny in the Article they still picked the 750 ultra, the 750/850 ultra made most peak power at lower rpms so at least on top end there more efficient, they didn't really tune the 750 and 850 ultra at the track so who knows how far off they really are, they speculated the 650 would be most streetable.

And in the end they picked 750 ultra and even if the 650 is being more effective with atomization, vaporization and whatever the 750 ultra can't be that far behind since it's putting down similar results without that much effort. So say the 650 is even better at being more effective with atomization, vaporization etc.. (speculation) It really didn't account for much in reality, they still preferred the 750 ultra overall. Not greatest example of proof for the small.