Re: A ? about flow numbers
[Re: dodgeboy11]
#595869
01/27/10 06:21 PM
01/27/10 06:21 PM
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Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
BradH
Taking time off to work on my car
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Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
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Quote:
... but you can just about guarantee 1.75 hp per cfm in a street application and closer to if not more than 2 hp per cfm on something more racy.
Like you said, there are really way too many variables to take into account. I've seen about 2 HP / cfm on something that was already starved for air, but also seen it drop down to about 1 HP / cfm for an application that was already closer to optimized. 
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Re: A ? about flow numbers
[Re: BradH]
#595870
01/27/10 08:01 PM
01/27/10 08:01 PM
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Joined: Feb 2003
Posts: 12,675
Columbia, CT
moper
I Live Here
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I Live Here
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Posts: 12,675
Columbia, CT
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assuming the engine package already works (meaning it's all matched) and assuming the cfm is as a result of better port design than strictly larger volume, then a jump that large would require a new cam, prob convertor too. You're talking over 15% better on a port that flows 300. A larger percentage on worse flowing port... I would consider the " 2hp/cfm to be a very general guide for possibility of output, not a given.
Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
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Re: A ? about flow numbers
[Re: moper]
#595871
01/27/10 08:18 PM
01/27/10 08:18 PM
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Joined: Nov 2003
Posts: 6,293
Rock Springs
Bob_Coomer
master
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master
Joined: Nov 2003
Posts: 6,293
Rock Springs
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Well A moderate 493 inch RB engine with 11:1 compression had a set of 440-1 heads that flow in the 320-330 range. I had the heads CNC ported and on the same bench now flowed 380 cfm or so. I added a good size Solid roller cam (near .800 lift) to take advantage of the large flow numbers. The car picked up .5+ seconds and right at 10 mph in the 8th mile.
Of coarse the power gain/et gain was NOT all due to the flow alone, the cam switch helped some too. At least 25HP, maybe more.
So... were are talking a high 10 second ride that run low 10's high 9's in the 1/4 mile.
In the same situation of the engine was in a dragster running low 8's. The same changes might have only shown a tenth or two tops.
So just to many variables to account for.
[color:"red"]65 Hemi Belvedere coming soon [/color]
[color:"#00FF00"]557" Indy engine 1.07 60ft 144mph in the 8th 2100 lbs package [/color]
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Re: A ? about flow numbers
[Re: dbran451]
#595872
01/27/10 09:54 PM
01/27/10 09:54 PM
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Joined: Mar 2008
Posts: 307
OH
TheBlackCar
enthusiast
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enthusiast
Joined: Mar 2008
Posts: 307
OH
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Quote:
As it's cold outside and I'm thinking again and that's dangerous, was wondering how much ET a person would pick up by increasing the cfm's by say 50 if everyting else remains the same???
Your 10.004 will now be a 10.002. 
It's rough gettin that three digit pass, huh, Dave? Save the money that your thinkin about putting in those heads and bring me the motor and I'll help you kick that door open...without the 50cfm.
If not, then expect the 50 cfm to not help too much on ET but a little on mph, which is already down a little.(ie other issues) Too much emphasis on flow #'s around here, remember, torque is ET and HP will show on MPH.
Either way, Good Luck
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Re: A ? about flow numbers
[Re: TheBlackCar]
#595873
01/28/10 12:37 AM
01/28/10 12:37 AM
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Joined: Mar 2008
Posts: 553
Kentucky
clovis
mopar
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mopar
Joined: Mar 2008
Posts: 553
Kentucky
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Its interesting to go over to the Wallace Calculators and just play with all the formulas for head flow and HP. Most of the time you will not get the same answer twice, when using the different formulas. By the formulas it doesn't seem to take a tremendous amount of flow (260-70) to get a car fairly deep into the 10's, weight pending.
'75 Plymouth Duster
Phase I 451 906/590/2-660 10.75/126
Phase II 451 Stage VI/590/1050 9.82/135
Phase III 383 906/Victor-Pump gas 11.30/119
"For by grace you have been saved through faith. And this is not your own doing; it is the gift of God,"
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Re: A ? about flow numbers
[Re: dbran451]
#595874
01/28/10 01:55 AM
01/28/10 01:55 AM
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Joined: Jan 2003
Posts: 6,591
Canton, Ohio
Sport440
master
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master
Joined: Jan 2003
Posts: 6,591
Canton, Ohio
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Quote:
As it's cold outside and I'm thinking again and that's dangerous, was wondering how much ET a person would pick up by increasing the cfm's by say 50 if everyting else remains the same???
If its 50 CFM more then the engine needs or can consume with its current combo. Then the extra 50 cfm will net you 0. HP.
It could even hurt performance by reducing the port flow velocity.  mikie
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Re: A ? about flow numbers
[Re: dbran451]
#595875
01/28/10 02:12 AM
01/28/10 02:12 AM
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Joined: Jul 2004
Posts: 19,318
State of confusion
Thumperdart
I Live Here
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I Live Here
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Posts: 19,318
State of confusion
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What`s your combo now just out of curiosity. I went from well ported 906`s and a solid cam to home ported rpm`s and a solid roller w/the same 12.11 comp. and picked up a half second and 5+ mph.
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: A ? about flow numbers
[Re: TheBlackCar]
#595876
01/28/10 02:03 PM
01/28/10 02:03 PM
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Joined: Nov 2003
Posts: 654
ohio
dbran451
OP
mopar
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OP
mopar
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ohio
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Your 10.004 will now be a 10.002. Save the money that your thinkin about putting in those heads and bring me the motor and I'll help you kick that door open...without the 50cfm. If not, then expect the 50 cfm to not help too much on ET but a little on mph, which is already down a little.(ie other issues) Too much emphasis on flow #'s around here, remember, torque is ET and HP will show on MPH. Either way, Good Luck
Jeff thanks for the offer to kick the door in but I like opening my own doors,just curious what MPH do you think I should be at as the car is pretty consistent 10.0car @132-133 mph
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Re: A ? about flow numbers
[Re: dbran451]
#595877
01/28/10 10:01 PM
01/28/10 10:01 PM
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Joined: Jan 2003
Posts: 6,591
Canton, Ohio
Sport440
master
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master
Joined: Jan 2003
Posts: 6,591
Canton, Ohio
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Quote:
Your 10.004 will now be a 10.002.
Save the money that your thinkin about putting in those heads and bring me the motor and I'll help you kick that door open...without the 50cfm.
If not, then expect the 50 cfm to not help too much on ET but a little on mph, which is already down a little.(ie other issues) Too much emphasis on flow #'s around here, remember, torque is ET and HP will show on MPH.
Either way, Good Luck
Jeff thanks for the offer to kick the door in but I like opening my own doors,just curious what MPH do you think I should be at as the car is pretty consistent 10.0car @132-133 mph
Not Jeff, But Your right there IMO with MPH.
My Lickity Split Chassis Efficiency charts says a 10.00 car should have incrementals something like this.
1.37 60ft. 6.33 1/8 mile 10.00 @ 134.5 MPH
So your close IMO. Probably a little soft on the launch. Whats your flow numbers now.
A 50 CFM increase on a already Performance head is huge IMO mike I say shave it .010 and you will have your 9.975346852 ET  
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