Author Topic: Is there a "rule of thumb" for HP vs intake flow for heads?  (Read 1377 times)

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FERoadster

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Re: Is there a "rule of thumb" for HP vs intake flow for heads?
« Reply #15 on: August 05, 2020, 10:37:04 AM »
Doug yes. I bought the basket case 60 Vette in 1977 for $2400 and it has a new interior carpeting instrument panel etc.
It was taken all apart by my 2nd cousin who gave up on it and moved to Florida. Never saw or heard from him since.
I've been offered crazy money for it but it would cost me a lot more to  get a Cobra or an equivalent sports car. I've got a 1969 Mustang 9" that is the same width as the original Vette axle. The Mustang II is a tubular A arm setup by Fatmans that was in my 56 Ford PU that I ended up scrapping. (Michigan Rust victim)

Here is  a picture of the engine compartment. Huge empty space just waiting for the FE.

Richard

Chrisss31

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Re: Is there a "rule of thumb" for HP vs intake flow for heads?
« Reply #16 on: August 05, 2020, 10:41:13 AM »
Payback for all the LS powered Mustangs.  Love it!!

jayb

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Re: Is there a "rule of thumb" for HP vs intake flow for heads?
« Reply #17 on: August 05, 2020, 10:48:06 AM »
Richard, have you seen the old Hot Rod article where somebody put a 427 FE engine in a 64 or 65 Corvette?  Somebody here probably has a copy...
Jay Brown
- 1969 Mach 1, Drag Week 2005 Winner NA/BB, 511" FE (10.60s @ 129); Drag Week 2007 Runner-Up PA/BB, 490" Supercharged FE (9.35 @ 151)
- 1964 Ford Galaxie, Drag Week 2009 Winner Modified NA (9.50s @ 143), 585" SOHC
- 1969 Shelby Clone, Drag Week 2015 Winner Modified NA (Average 8.98 @ 149), 585" SOHC

   

thatdarncat

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Re: Is there a "rule of thumb" for HP vs intake flow for heads?
« Reply #18 on: August 05, 2020, 12:09:43 PM »
Richard, have you seen the old Hot Rod article where somebody put a 427 FE engine in a 64 or 65 Corvette?  Somebody here probably has a copy...



Kevin Rolph

1967 Cougar Drag Car ( under constuction )
1966 7 litre Galaxie
1966 Country Squire 390
1966 Cyclone GT 390
1968 Torino GT 390
1972 Gran Torino wagon
1978 Lincoln Mk V

Royce

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Re: Is there a "rule of thumb" for HP vs intake flow for heads?
« Reply #19 on: August 05, 2020, 12:41:02 PM »
I was there at Jay's for that dyno test of the 6x2 intake.. I think with about 2 weeks more carb fiddling linkage engineering and cam changes we could have knocked the Perfomer RPM off it's perch  Jay cut it short due to the potential fire hazard of 6 leaky Holley 94s.  Would love to rerun it with a sextet of brand new Stromberg 97s.. Let's see   that's about 4k worth of carbs  lol
1955 Thunderbird Competition Coupe Altered Chassis "War Bird" 383 Lincoln Y block 520 hp
1955 Thunderbird 292 275 hp Y Block
1956 Ford Victoria 292 Y block
1956 Mercury "Thumper"433 cu in 445 hp Lincoln Y Block
1957 Mercury 2dr Wagon "Battle Wagon" drag car  Currently engineless,  Boss 9 transplant coming soon.
1957 Thunderbird Glass body Tube Chassis drag car 333 cu in 500 hp Ford Y block
1958 Mercury Monterey  430cu in 400hp 3x2 Super Marauder
1961 Starliner 390/375 clone
1960 Starliner 352/360hp, real one
1966 Falcon Pro Touring project

My427stang

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Re: Is there a "rule of thumb" for HP vs intake flow for heads?
« Reply #20 on: August 05, 2020, 01:00:16 PM »
That 6X2 intake did a lot better than I thought it would, peak power with that intake was almost as high as the top intakes.  It lagged a little in the midrange, but still a really good intake.


I was there at Jay's for that dyno test of the 6x2 intake.. I think with about 2 weeks more carb fiddling linkage engineering and cam changes we could have knocked the Perfomer RPM off it's perch  Jay cut it short due to the potential fire hazard of 6 leaky Holley 94s.  Would love to rerun it with a sextet of brand new Stromberg 97s.. Let's see   that's about 4k worth of carbs  lol

I would stay I stand corrected, but better would be "I fell over in amazement"  that's cool and suprising!


Doug yes. I bought the basket case 60 Vette in 1977 for $2400 and it has a new interior carpeting instrument panel etc.
It was taken all apart by my 2nd cousin who gave up on it and moved to Florida. Never saw or heard from him since.
I've been offered crazy money for it but it would cost me a lot more to  get a Cobra or an equivalent sports car. I've got a 1969 Mustang 9" that is the same width as the original Vette axle. The Mustang II is a tubular A arm setup by Fatmans that was in my 56 Ford PU that I ended up scrapping. (Michigan Rust victim)

Here is  a picture of the engine compartment. Huge empty space just waiting for the FE.

Richard

Richard, that's going to be awesome.  I am not one for Chevy punishment, but I love the idea based on how a big FE will run.  Thant's a cool machine!
---------------------------------
Ross

- 70 Fastback Mustang, 489 cid FE, Victor, SEFI, Erson SFT cam, TKO-600 5 speed, 4.11 9 inch.
- 71 F100 shortbed 4x4, 461 cid FE, headers, Victor Pro-flo EFI, Comp Custom HFT cam, 3.50 9 inch

FERoadster

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Re: Is there a "rule of thumb" for HP vs intake flow for heads?
« Reply #21 on: August 05, 2020, 01:42:01 PM »
Royce and others: The Stromberg WW flows about 20% more than the 97. They are carbs that came out in the late 50"s or early 60's. My first one was on a 1965  2 ton GMC 305 CI V6 (can't remember the Cubes) but the carb was really smooth. Since then I've collected more then 20  complete WW's and have somewhere near 10 new ones. I usually pick them up for around $20 each. I've also got near 10 parts carbs.
A few years ago I posted CFM rates for 94's 97's and WW's on here.  I'll see if I can find the post
Richard

Here is the post

Jay and others: Did some searching  on HAMB  for a short time today and looked for CFM data on 94's
Here is my preliminary finding. First off. 2bbl carbs are rated at 3" vacuum where 4bbl carbs are at 1.5" so I'm including some # for each.
The Holley-Ford carbs are designated by the venturi size in decimals of an inch. ie 94=.94, 81, 48 and Stromberg 97 as well .97

So flow ratings are as follows

Carb Model    CFM@3.0"  CFM@1.5"

94                   251            176
81                   192            135
48                   250            175
LZ                   229            160
ECG                264             185

Strom 97         214             150
Strom WW       357             250   not sure of which venturi size 2 variations one @ 1.125 and another @ 1.1875



« Last Edit: August 05, 2020, 01:48:59 PM by FERoadster »

frnkeore

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Re: Is there a "rule of thumb" for HP vs intake flow for heads?
« Reply #22 on: August 05, 2020, 03:42:43 PM »
Is your 6x2 manifold a 3 bolt or 4 bolt flange?

If 3 bolt, the 2100 Holley, with a 1 1/16" venturi ( a 94 but, with 1 1/16 on the side) would be best. If it's a 4 bolt, the WW's are much lighter but, the Rochester, 2CG carbs, offer 350 and 500 cfm @3".

BTW, the Stromberg 48, has a 1 1/32" venturi. The 48, comes from the Ford part number 48- of 1934. Harder to find and more expensive, only used 2 years.
« Last Edit: August 05, 2020, 03:46:29 PM by frnkeore »
Frank

WerbyFord

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Re: Is there a "rule of thumb" for HP vs intake flow for heads?
« Reply #23 on: August 06, 2020, 10:22:33 AM »
Royce and others: The Stromberg WW flows about 20% more than the 97. They are carbs that came out in the late 50"s or early 60's. My first one was on a 1965  2 ton GMC 305 CI V6 (can't remember the Cubes) but the carb was really smooth. Since then I've collected more then 20  complete WW's and have somewhere near 10 new ones. I usually pick them up for around $20 each. I've also got near 10 parts carbs.
A few years ago I posted CFM rates for 94's 97's and WW's on here.  I'll see if I can find the post
Richard

Here is the post

Jay and others: Did some searching  on HAMB  for a short time today and looked for CFM data on 94's
Here is my preliminary finding. First off. 2bbl carbs are rated at 3" vacuum where 4bbl carbs are at 1.5" so I'm including some # for each.
The Holley-Ford carbs are designated by the venturi size in decimals of an inch. ie 94=.94, 81, 48 and Stromberg 97 as well .97

So flow ratings are as follows

Carb Model    CFM@3.0"  CFM@1.5"

94                   251            176
81                   192            135
48                   250            175
LZ                   229            160
ECG                264             185

Strom 97         214             150
Strom WW       357             250   not sure of which venturi size 2 variations one @ 1.125 and another @ 1.1875



Great chart!
Similar data in Tex Smith's "the complete (old) Chrysler Hemi" by Ron Cerdano.
It lists those same carbs but not the "WW".
Seems the "WW" was uised quite a few years -
My scroungy data shows venturi & throttle sizes & cfm at 3" Hg of
1.08 x 1.436 256cfm
1.18 x 1.436 287cfm
1.24 x 1.436 294cfm
1.31 x 1.562 356cfm (a guess on that last one, but that' where I get flow of 356cfm at 3" Hg)
Since you have so many WW's, wondering if you can confirm if these or other sizes actually existed & when.

WerbyFord

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Re: Is there a "rule of thumb" for HP vs intake flow for heads?
« Reply #24 on: August 06, 2020, 10:37:17 AM »
Here is my cam card.  engine is a +030 427 with a 3.98 crank  Cam purchased new from Gene Kitchen about 8 years ago. I bought it primarily due to the larger exhaust potential for 100% street driving in a car right at 3000# with a 4.57 gear and wide ratio toploader. Intake will be the 6X2 Edelbrock with Edel. heads and 2.19 valves .  Heads flowed 306 at 600 lift.

Hope this helps with  the 2X HP rating

Richard

More to the original question:
I Gonkulated your buildk using the same carbs Jay used in his dyno tests I think, 2110 Holleys at 185cfm each at 1.5" Hg. At 1110cfm total plenty of air!
Gonkulator says
Torq 514 at 4400
Powr 546 at 6500

Now, on the heads:
Cut intake flow by 10% => down 14hp
Cut exhaust flow by 10% => down 16hp
Cut BOTH by 10% => down 23hp
I think engines always want more flow- - just not necessarily more port area.
For example, let's de-stroke your engine with a 390 crank, down 23cid.
Results:
Torq -23 ftlb about as expected
Powr -8 hp
So those extra 23cid only gain you 8 hp on top. Not enough airflow, but that's not unusual.
As you add inches, most engines gain torque 1-for-1 or so, but only gain power at 1/4 to 1/2 hp/CID - yours is about in the middle there.

Big Ford power in a little 60 Vet - should run good!

C6AE

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Re: Is there a "rule of thumb" for HP vs intake flow for heads?
« Reply #25 on: August 06, 2020, 10:37:29 PM »
This is a great project, Best Corvette ever!
Please keep us informed of your progress?

FERoadster

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Re: Is there a "rule of thumb" for HP vs intake flow for heads?
« Reply #26 on: August 06, 2020, 11:23:09 PM »
Frank: my 6X2 is the 3 bolt version but the WW throttle  shaft on the drivers side hits the VC so I've got spacers. A novel thought I've had is to turn the drivers side carbs backward and use a bell crank with  the top pushing and the bottom pulling in that way both would open with no issues and all linkage would be between the carbs. (a much cleaner install). I will have to figure out how hard the pedal pressure will be and balance springs.
A picture of the intake with carbs in the normal positions. Planning on using 2 sets of FE 3X2 linkage for progressive action.
When I finish my 1948 Continental in a few months I'll start a member project thread on the Vette.
Richard
« Last Edit: August 06, 2020, 11:27:18 PM by FERoadster »

Falcon67

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Re: Is there a "rule of thumb" for HP vs intake flow for heads?
« Reply #27 on: August 07, 2020, 09:59:19 AM »
I use the 1 x Time Slip method.  (MPH/187)^3 x Weight =  1/8 mile RWH.  Then swag some bogus drive train loss percentage to get flywheel, more or less.

frnkeore

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Re: Is there a "rule of thumb" for HP vs intake flow for heads?
« Reply #28 on: August 07, 2020, 12:55:11 PM »
I'm from a different era, 6x2 wasn't uncommon, in the late 50's threw the 70's. I feel in love with multi carb engines (more than 3) in 1959. I lived on a rural road with a straight stretch of at least 1.5 miles. One day a '32 or '34 Ford coupe, made a run on my street. It had a nail head engine, with 6x2's and I'll never forget the sound of the carbs, as it pasted me.

In those days, most where called "log" manifolds. You could even by kits, with a piece of round tubing, intake flanges and tubing, to fit the flanges, then weld it together.

In 64/65, I had a 410 MEL, I bought a 6x2 manifold for it and two sets of 348 Chev tri-powers to put on it. I was going to put it in my '60 Galaxy, to replace the 352 but, I got drafted in '65 and while I was in the Army, my dad hauled the engine off, for scarp. I kept the manifold for a long time after that but, threw it in the scrap pile, at work, in '76 when I moved out of SoCal.

Did Jay have that 6x2 ported in his test? If not, I bet a good porter could take it up a notch or two, on the manifold test scale.
Frank