500 cfm carb horsepower

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500 cfm carb horsepower

Post by Racer18 » Wed Apr 10, 2019 4:27 pm

What is the maximum horsepower a 500 cfm 2- barrel carb is capable of? No power adders, gasoline, real world. Anything goes- roller cam, lightweight everything. Gauge legal carburetor- 4412 holley specs.

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Re: 500 cfm carb horsepower

Post by PackardV8 » Wed Apr 10, 2019 4:54 pm

Yes, No, Maybe.

The 500 CFM on a 2-bbl is rated at three inches of vacuum. However, lets imagine one on a 600" big block tunnel ram which might be capable of sucking that little 2-bbl inside out. Suppose it's now at ten inches of vacuum; yes a lot of restriction, but still developing substantially more horsepower than would the three inches on a 350".

So, it depends.
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Re: 500 cfm carb horsepower

Post by Racer18 » Wed Apr 10, 2019 5:26 pm

I guess my question is what is the horsepower limit at 500 cfm? Is there a formula? Meaning if 500 cfm of air and the corresponding amount of fuel were being consumed, what numbers is it technically possible of producing?

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Re: 500 cfm carb horsepower

Post by In-Tech » Wed Apr 10, 2019 5:29 pm

I've made 540hp, 4.155x3.25, 16.2:1, Roller cam, ASCS spec heads, dry sump, gauge legal 4412. That was ~8" vacuum @wot.

https://www.ismasupers.com/ These type of cars, 360 2bl back in the 90's. 72% left side weight, I drove one a couple times, once on a 1/3 mile track and once on a 1/2. What a blast, nothin like goin into 3 on the outside and hoping the guy you are passing doesn't wash out. :shock: :lol:
Heat is energy, energy is horsepower...but you gotta control the heat.
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Re: 500 cfm carb horsepower

Post by PackardV8 » Wed Apr 10, 2019 8:00 pm

I've made 540hp, . . . gauge legal 4412. That was ~8" vacuum @wot.
Racer18 wrote:
Wed Apr 10, 2019 5:26 pm
I guess my question is what is the horsepower limit at 500 cfm? Is there a formula? Meaning if 500 cfm of air and the corresponding amount of fuel were being consumed, what numbers is it technically possible of producing?
Again, not enough specificity to accurately answer; one must define how the 500 CFM is measured; see one example above. If an IR intake running essentially unthrottled, 500 CFM is different than a 500 CFM 4-bbl pulling 1.5 inches or your 500 CFM 2-bbl @ 3 inches or his 540 hp @ 8 inches.
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Re: 500 cfm carb horsepower

Post by Bazman » Wed Apr 10, 2019 8:22 pm

In-Tech wrote:
Wed Apr 10, 2019 5:29 pm
I've made 540hp, 4.155x3.25, 16.2:1, Roller cam, ASCS spec heads, dry sump, gauge legal 4412. That was ~8" vacuum @wot.
That's stout. Based upon the normal range of 1.5 to 1.6cfm per hp that 500cfm carb was able to suck in 810-860cfm. That much vacuum at WOT could suck a canary out of its cage from the next room :lol:

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Re: 500 cfm carb horsepower

Post by In-Tech » Wed Apr 10, 2019 8:26 pm

Yeah Jack, I get what you are saying, I was just posting a hp number for comparison.

Asking for an equation that probably does not exist, it might as well be internet folklore but I heard this before the internet :lol: ..."Every cfm you can gain on a guage legal 4412 is worth 1-2hp"

Bazman, I tried some other cam combo's that could get more WOT vacuum (as much as 12-14") but I couldn't control the fuel curve. :cry:

I would bet Camking and others here can chime in on 4412 hp levels.
Heat is energy, energy is horsepower...but you gotta control the heat.
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Re: 500 cfm carb horsepower

Post by mag2555 » Thu Apr 11, 2019 6:38 am

I have seen a 421 cid trip power motor make 325 hp on just the center 1 3/8" 435 cfm GM Carb and GM cast Intake , when it topped out at 472 hp with all 3 Carbs open and this was by no means a race motor.
I would say that with a 500 cfm Carb and less cid this this example that 450 hp could be had .

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Re: 500 cfm carb horsepower

Post by Ken_Parkman » Thu Apr 11, 2019 12:35 pm

A more relevant question may be how much more power would the __________ combo make with an optimized carb over the 2 bbl.

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Re: 500 cfm carb horsepower

Post by Krooser » Thu Apr 11, 2019 1:50 pm

Bazman wrote:
Wed Apr 10, 2019 8:22 pm
In-Tech wrote:
Wed Apr 10, 2019 5:29 pm
I've made 540hp, 4.155x3.25, 16.2:1, Roller cam, ASCS spec heads, dry sump, gauge legal 4412. That was ~8" vacuum @wot.
That's stout. Based upon the normal range of 1.5 to 1.6cfm per hp that 500cfm carb was able to suck in 810-860cfm. That much vacuum at WOT could suck a canary out of its cage from the next room :lol:
My ex could suck the chrome off a Peterbilt bumper...
Last place in the B-main is better than anyplace in the grandstands...

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Re: 500 cfm carb horsepower

Post by In-Tech » Thu Apr 11, 2019 1:55 pm

Krooser wrote:
Thu Apr 11, 2019 1:50 pm
Bazman wrote:
Wed Apr 10, 2019 8:22 pm
In-Tech wrote:
Wed Apr 10, 2019 5:29 pm
I've made 540hp, 4.155x3.25, 16.2:1, Roller cam, ASCS spec heads, dry sump, gauge legal 4412. That was ~8" vacuum @wot.
That's stout. Based upon the normal range of 1.5 to 1.6cfm per hp that 500cfm carb was able to suck in 810-860cfm. That much vacuum at WOT could suck a canary out of its cage from the next room :lol:
My ex could suck the chrome off a Peterbilt bumper...
We all(or most of us) have ex's stories. :lol:
Heat is energy, energy is horsepower...but you gotta control the heat.
-Carl

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Re: 500 cfm carb horsepower

Post by CamKing » Fri Apr 12, 2019 10:29 am

In circle-track trim, we normally see with a 4412 carb
Low 400's with a hydr flat tappet cam, and 2 plane manifold.
High 400's with a mech flat tappet cam, and single plane manifold
Low 500's with a roller and single plane manifold.
These are normally in the 10:1 to 12:1 range for compression. If you could get the compression up, you'll make more.
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Re: 500 cfm carb horsepower

Post by cgarb » Fri Apr 12, 2019 1:17 pm

If you have all that extra vacuum and could jet for it.... wouldn't a big vacuum leak somewhere in the intake manifold give a few extra CFM. Like a lean out valve you could open once you got it up and going. Probably not exactly class legal though.

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Re: 500 cfm carb horsepower

Post by PackardV8 » Fri Apr 12, 2019 1:38 pm

cgarb wrote:
Fri Apr 12, 2019 1:17 pm
If you have all that extra vacuum and could jet for it.... wouldn't a big vacuum leak somewhere in the intake manifold give a few extra CFM. Like a lean out valve you could open once you got it up and going. Probably not exactly class legal though.
The Cup guys were there the first time restrictor plates were required. As one might imagine, there have been dozens of ingenious methods of leaking air below the plate.

Toyota had a great and undetectable method of cheating around the restrictor on their WRC turbo cars.
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Re: 500 cfm carb horsepower

Post by Racer18 » Sat Apr 13, 2019 11:31 am

Cam King- those numbers are what we have been seeing as well. I do have a 415 with your cam, flat tappet, single plane intake that made 515. Reason for my question is that I dynoed an engine for someone and it made 440 with a 4412, pulled it and put on a 750 cfm carb and it made 495. Customer was extremely disappointed in the numbers because his engine builder told him it was 600 hp :^o :lol: with a 4412 at that LOL

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