just how good a stock 2v head is

L

lyonsy

Well-known member
ok come across this today after searching for like 12months
on this site under the 2v alloy it has the flow figure's for a stock 2v cast iron head.
nown when i first seen these i gone nice but that later heads must be better..... i was wrong
stock slow if avible otherwise stage 1
4L ef falcon ohc stage 1 porting
C.F.M. POT. HORSE POWER C.F.M. POT. HORSE POWER
0.100" 34.67 89 24.26 62
0.200" 75.42 194 46.27 119
0.300" 111.65 288 68.08 175
0.400" 134.54 347 87.85 226
0.450" 139.30 359 93.34 240
0.500" 140.22 361 98.28 253
186 holden red engine stage 1 porting
C.F.M. POT. HORSE POWER C.F.M. POT. HORSE POWER
0.100" 28.97 74 29.13 67
0.200" 52.80 136 45.43 117
0.300" 71.99 185 54.64 140
0.400" 87.85 226 63.81 164
0.450" 94.28 243 71.68 184
0.500" 97.49 251 73.43 189
rb30 vl skyline
C.F.M. POT. HORSE POWER C.F.M. POT. HORSE POWER C.F.M. POT. HORSE POWER C.F.M. POT. HORSE POWER
standerd stage 1
0.100" 29.86 77 25.65 66 30.65 79 27.16 70
0.200" 63.55 163 50.35 129 65.20 168 54.03 139
0.300" 86.66 223 58.33 150 88.73 228 69.93 180
0.400" 94.92 244 58.33 150 99.04 255 71.68 184
0.450" 98.01 252 58.33 150 101.79 262 71.68 184
0.500" 99.04 255 58.33 150 105.23 271 71.68 184

vn 5L v8 heads widly considerd the best manufacture produced head in australiaby hands down nothing comes close
C.F.M. POT. HORSE POWER C.F.M. POT. HORSE POWER C.F.M. POT. HORSE POWER C.F.M. POT. HORSE POWER
standerd inlet ported stage 1
0.100" 37.72 129 38.76 133 32.00 110
0.200" 75.93 261 79.81 274 62.37 214
0.300" 103.16 354 108.56 373 80.38 276
0.400" 121.74 418 127.85 439 92.79 319
0.450" 127.24 437 135.91 467 97.18 334
0.500" 129.30 444 141.57 487 99.93 343
0.550" 134.11 461 147.24 506 102.13 351

oh but wait what about the 2v well nigh on 20years earlyer ford had betterd it.

Intake
100= 36
200= 68
300= 91
400= 98
500= 103
600= 105

Exhaust
100= 63
200= 101
300= 133
400= 155
500= 156
600= 156

i still havent managed to find a xflow but think 4L with worse flow again
so my orginal thoughts after seeing the 2v for the first time was this thing has awsome inlets.
but now i find that even the exhaust flow well enough to beat every engine here and everyone on the list that decided to open
here's the source
http://www.freeflowcylinderheads.com.au/
 
:wink: Good information, buddy. 8)

Until people read the fine print, a lot of people will go off half cocked. Even if the flow at half the likely valve lift is really poor, the Internet, advetising or book figures favour the highest flowing head. No matter how jerry rigged or downright corrupt the basic figures. You've seen it with Hosepower figures in every Aussie magazine since 1993, and every cfm figure since about 2000, when people started forgetting the basics. I suspect the honest ones, such as COME Racing, forced the beat up kings to hang themselves in there own delusions. 90% of what I read in any given publication is utter rot unless there are some real simple questions to ask, ones the Mike from Classic Inlines had to remind everyone of back in 2004 when people wanted a 274 degree cam which had better 50 thou figures, or 2V heads which flowed more CFM at 500 thou, when what benfited the customer was better 250 thou figures, not peak flow.

Irony is, it's the Yanks, once the talk-up kings of the Draft Horsepower lobby, have set some really simple baselines when talking cfm. They say four key things


Peak flow is irrelevent unless

a) the pressure head is defined (Unlike carbs, which tested at 1.5, 2.0 or 3.0"Hg, heads are tested at 10, 25, 28 inches of H20, which is 0.73, 1.85, or 2.06" H20, and conversion between them is the square route of the algeriac difference. This messes with peoples head, and smart ass head grinders use it to there advantage :wink: )

b) realistic gross valve lift at the valve is defined, and

c) some assessment the ports intake cc's from the intake gasket to the valve is defined and

d) some assessment of flow at half the likely installed lift is defined. A valve is only open at full lift once, but is at half lift twice, and the bulk area under the curve flow is what produces useable power and economy on the street.


Prety good advice

As an example, I can make, say, a small daimeter intake stock Falcon AU 4.0 head outflow a 351C 351 head by just grabing some figures at 28inches of Mercury and compare them with , say, the flow rates at 10 inches of Mercury for the 351 head. If I use the later AU VCT cam and 1.9:1 rockers, verses a set of 1.73:1 rockers, you can see no apples verses apples in the comparision, and I can manage the results to work in my favour to any engine I pick. Cam duration and lift on the stock Cleveland was 256 degrees and lift at the valve was really low compared to an XR6 VCT. Yet they both had similar quarter mile times when in 1570 kilogram manual Falcon sedans

Incidently, if you find the 1980 Modern Motor magazine with a silver XD Falcon ESP on the cover, I think the factory figures for the first Alloy Head show peak flow of 145 cfm at 25"Hg at stock lift with the factory 256 degree cam, yet the 250 2v has been known to do 175 cfm at 25"Hg, at 0.500". See, different figures are useless if they are not qualifed by inlet runner cc, lift, pressures and an idea of a realistic valve lift. The brake specfic fuel consumption on the stock iron 250 2V is pretty crock in comparison to a 4.1 alloy head; for each Horsepower, the 2V uses more fuel than any Alloy Head or Alloy Head II with the same carburation. Even 1/4 mile times bear this out... a light weight XY or XA 2V Falcon 250 wilth 2.92:1 diff is only able to do a 17 second quarter mile. 1320 to 1365 :wink: :wink: kilos. The much heavier 2-bbl Weber 4.1 XE Falcon does 17.6 yet weighes 1435 kilos and runs a 2.77:1 diff.

In truth, both Alloy X-flow and Iron 2V heads flow a similar amount as there is a huge rocker ratio gain on the X-flow (1.73:1), a much small rocker ratio (1.5:1)on any 2V, each has a different stock lift, almost half an inch difference in port diameter.


The real reason the 2v is so good is there are now some good FE V8 rocker gear which can create Cleveland style lift of up to 1.8:1 , and its got awesome, huge 42 mm ports where as the very biggest iron X-flow had 35 or 40mm modified, and about 33 mm in alloy head form.
 
xecute":2pne6bz1 said:
The real reason the 2v is so good is there are now some good FE V8 rocker gear which can create Cleveland style lift of up to 1.8:1 , and its got awesome, huge 42 mm ports where as the very biggest iron X-flow had 35 or 40mm modified, and about 33 mm in alloy head form.
Click to expand...

Interesting, please expalin......
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Roller Rocker ratio for some stock and crazy FE Edlebrock 427 heads is indeed 1.76:1 from Harland Sharp . Erson's Billet Roller is 1.76 too, Part #: E918502. These can fit the 2V head with a little work. If your hugry for lift...


Getting back to those four points on flow...


2V ports are not the biggest in the business since, at 2.15 sq in, they are just short of the Chrysler 265 Hemi's 2.7 sq inches at the gasket face by 20% or so.

Compared to the early 4V HO Cleveland 351 and Boss 302, the 2V's are small, 3.3 sq in at the gasket face, 50% smaller.

What is amazing is that a tiny little Iron or Alloy X-flow can get as much air flow with a itty bitty 1.5 sq in port, well over 40% down on the 2V, and 88% smaller than a 265, yet get close to similar power. That's becasue they had ex Repco and race engineers who found that shape was more important then proportion. A 15% greater rocker ratio helps evey time the valve is open, a 50% greater port size is only of benefit after 3500 rpm.

In its bare, unported form, the new alloy 2V is the culmination of the old school bigger is better idea which gave us the 265 Hemi, 302 Boss and 351 Cleveland, merged with some really trick LS-1 style mixture motion and shaping. So pretty soon people will find that they will be running really mild cams and getting huge performance with no modifications. Any porting done will hurt the torque and maximum power unless its done with a CNC machine and a flow bench. This is the case with the iron 2V as well, its ports are sooo big that its almost like what happened in the 1969/70 TransAm races with the Boss 302...they went better when the intake ports were epoxyied up!

Even the stock iron 2v is an animal compare to the stats on any X-flow head.


As for the 2v valve gear, well its straight 427/428 FE. The FE is still an amzingl throwback from the 60's that has never really died in the US...its still got heaps of reallt hard out gear there for it. Cobra 427, KR 427, later GT40's and Mirages, ThunderBolt rip offs and the use of 390 engines right up to 1976 in trucks ensured its survival. With the 2V, even if its got just adjustable solid shafts from a 144/170 or early 200 or plain vanlia non adjustable, its very, very ridgid FE rocker gear, and there are some very special Edlebrock rockers which a 1.76:1 on the FE. On a six, they may only give 1.65 or 1.7, but there are a few Mini Cooper style tricks (like 30 thou offset bushes) can bring that ratio up to 1.8:1 or more, and give an insane amount of lift with a very mild cam profile. Remember, one of the four conditions is what happens at the valve. Since Edlebrock started making alloy FE 427 heads in 2000, the amount of performance with stroked FE blocks has gone up to 460 Lima V8 territory. Lets understand this. Edelbrock tools up for an FE engine which sold for 18 years from 1958 to 1976. Possibly 20 million around. Then they tool up for the tiny amount of really hot total Perfromance Fords, maybee only 5 000 ever in existance. Yet we have 20 million old 144/170/187/188/200/221/250 sixes around in junkyard form, using an amalgam of big ports with modern flow techniques, with just one ballsy investor who liked what he saw on 12000 2V 250 engines from 1971 to 1973.

So it will be with the 2V, its going to revolutionise bolt up equipment industry, because it gives a state of the art head on a base of 20 million junkyard engines world wide. Each part of the four steps is covered.

Flow rate is defined
a) the pressure head is defined
b) realistic gross valve lift at the valve is defined
c) assessment the ports intake cc's from the intake gasket to the valve is defined
d) assessment of flow at half the likely installed lift is defined.

Each of these four has aftermarket development from the most advanced flow benches in the world chomping away at getting more power. Developments from Fords hottest big block FE are coming right into the alloy 2V. That's not the case with the X-flow.
 
ok here's what iam understanding.
the xflow has a much better port design in mixing the fuel along with chamber design
ok which head has the best of the xflow charicter.
also the rocker ratio has me pegged but here's my understanding the bigger the ratio the quicker the mid action of the open and closing occurs so like a big roller when you have a soild.
and the new alloy 2v should be the best of both the xflow and the 2v with the big ports and better airflow.
so if you happen to get a alloy 2v and fitted the largest valves then offset bush some big lift rockers to give somewhere in the region of 1.8 or better rocker ratio a set of tuned length extrators and see what this 4bbl manfiold will be and you should be chasing 350hp from a 250 and 380 or so from a 221?
 
i'm no expert but must agree on the inlet port size for the 2v heads (iron-orig aussie)
reading david vizards tome from the early seventies 'theory and practice of cylinder head modification'
he says inlet ports dia should be approx 0.82 to 0.85 of the valve dia-
the 2v has 1.68' valves as std and approx same size inlet ports ( 1.65")

so not sure what ford was up to when they did them cause according to mr vizard the valve size should be almost 2" for the 1.65" port ( which i think is valve size the aussie valiant/chrysler 265 hemis had approx).

maybe xrcute can comment if vizards ratios is still valid almost 37years later

brett
melbourne
 
To answer the question, yes, the proportions are still valid today.

There is a caveat. The rule is valid for 2 valve per cylinder heads, and valid only when the inlet and exhast size are optimal for best cfm. The ideal port can be very, very small (like the last Alloy Head XF unleaded X-flow) but have huge intake and exhast valves.

Additionally, Vizard agreed by his figures that when modifying any head, attempt to get the exhast to flow 65 to 80% of the intake flow. Mick Webb siad its not what goes into the engine that makes it thin or fat, its what comes out yer bum.


Lift and port area or carb/throttle body size are restricted by cost, casting limits, or rules, you have to go to NASCAR/AVESCO or Mini 7/850/ 1000 cheater cams, which make more power right on the rev limit, by having no over-run.(Normally, power hapPens at 90% of the maximum safe rev range. In the 7500 rpm NASCAR and AVESCO maximum power is at the maximum safe rpm. These formulas limit revs as well as a lot of other things.

GM's power plants are designed by ex race engineers on retainers to the General. They understand that port area and valve size are restricted by lots of issues like bore size, exhast valve diameter, and that cam duration for emission has to be below 270 degrees, or additional measures have to be kicked into play to kill of NOx and Volitile Organic Compounds. The squeaky clean production LS-1 (Holden GTS 300) that got 400 hp got it at well over 6000 rpm. The dirty, pre emissions 4-bbl Phase 3 351C 4V HO Cleveland got 360 hp at 5800 rpm. The LS-1 can rev to 6600 from the factory. The stock factory Clevo is not safe above 6200, but race built, it will rev to 7200 rpm if you take brave pills. The ports on the Cleveland were giants. The effective or equivalent port size of the LS-1 was very, very small. Forget the talk about the cathedral port EFI, the head was necked to a very small size just before the valve, less than 80% of the valve size.


How and what proportion intake to exhast valve size that gets that is up to you. There are cam pattern and lift options, even different inlet and exhast rocker ratios, there are many ways to skin a cat. Therefore the inlet port size can vary quite a lot because so can the ideal intake valve size. An example is how drastically Davids first 1970's edition of patterned hi performance Mini heads in his first Mini book varied in the 15 years before the second edition book in 1984. The ideal valve size to port size and shapes varied immensly. They were siamesed ports, but the degrees of accuracy vary a lot. My favorite was that the stock Pinto 2000 (Cortina/Capri/Sierra/Pinto) had heads with 32 mm (1.26") ports, and they were way to big with 1.64's, and 1.75's and were only any good when welded up and profiled to an apple port design rather like the 2.8 Chevy V6. The square inches per valve size for sucess are Chrylsers. 2.7 sq in is an effective round port of 1.85", all for a 1.96" valve in a 3.91" head.

Proportions ratios are
Inlet port Xsect Area , Equivalent diameter, Valve size, Piston Size

Ford Falcon 2V 250 2.15 port area:1.65 equivalent port diameter:1.64 valve:3.68 piston. Port area is 101% of the valve size, great unmodified for a big cammed fire breathing Ford.

Ford Falcon 4V 351C HO 3.30 port area:2.05 equivalent port diameter:2.19 valve:4.00 piston. Port area is 95% of the valve size, great unmodified for a big cammed fire breathing Ford. 350 hp net at 5800 with the mild 300 degree, 0.5" lift cam.

Chrysler Hemi 265 2.7 port area:1.85 equivalent port diameter :1.96: valve: 3.91 piston. The port size is 94% of the valve size. Okay for 320 hp net with over 300 degree cam and 0.5" lift

Ford Cortina 1.25 port area :1.26 equivalent port diameter:1.64 valve:3.575 piston.The Cortina port is too big for the nature flow of the head, even though the port size is only 76% or (0.76 of the valve). It's passible at 72% (0.72). Okay for 155 net hp or so with 295 degree cam and 0.45" lift.

Ford Falcon XF 4.1 1.33 port area:1.3 equivalent port diameter:1.81 valve:3.68 piston. 72% of the valve size is about right for 196 to 206 hp net with 280 degree cam and 0.450" lift.

My personal take on Vizards council was to make certain the intake and exhast function properly within the exhast flow 80 to 65% flow of intake limits. Oversize the exhast as much as possible, but don't go up on intake diameter unless you can keep to the 82 to 85% valve diameter rule.

The way to blance all these strictures is to do what all good sensible , well trained engineers have done Civil, Structural, Roading and Mechanical engineering since the dark ages. Run three scenarios, least cost, Rolls Royce, and some intermediate type. You 'horse trade' on the specific details. In a Ford engine, its cam profile on lift and exhast, duration, lobe centre, overlap, rocker ratio on inlet and exhast, port area, flow on intake and exhast in cfm, and end up with something that gives the best results without breaking the bank. You can do it electronically with a Dyno package, or use the vast experience form engine builders who test and then race the engines they make, or you do it your self, and hope your assumptions were based on the facts.


With the 2V, the engine was designed by Ford Australia engineers, and then tested by a few brought in people from Repco, Rolloy and some other experts. The 2V was a stock cam engine with just headers and a blQQdy good intake. The latest 2v has been further pefected by a brief by the best American engineers, and the reworked into existing historical Aussie production by engineers who have done Holdens similar 12 port alloy red, blue and black alloy heads. These engines have never had the port area of the 2V, nor the abilty to run the vlave sizes the alloy 2V does. We are at 308 V8 Holden valve sizes here, well up on the early X-flow's, and you can decide what you want to do.

Again, I'll predict making a 2V work is more a cam issue than porting a head. It's almost perfect!
 
To explain what i am doing might help I have a 250 2v I will be running on a 250 american block. I want to maxamize to exhaust flow and thought that by increasing lift on the exhaust side this would increse output. Can you use the FE rockers on the exhaust side and stock rockers on the intake side? I will be running stock intake valve size and 1.46 exhaust valves {144 intake valves}. What do you think?
 
I don't have specific details, but it sounds like a good idea if it yields the right flow figures to balance those massive 2V intake ports. Just remember the many ways to skin a cat!

The Falcon Six Performance book should outline the general details on running changes to the 200 and 250. Actual ratio of 1.76 FE rollers on a small six is likely to be 1.65 or so, due to minute geometric changes with rocker shaft bolt to valve pivot centres, but its certainly going to yield a big increase in lift at the valve compared to the stock set-up. The exhasts are restricted on 2V's only in proportion to the intake ports, its not a bad flwing exhast with a set of headers and a good tail pipe. Lift can make up for any situation where there's less than 65% inlet flow at the exhast port. So can a dual pattern cam, so can basic porting and flow benchwork. You can even weld the exhast flange in the restricted ports 1 and 6, and grind out the exhast ports and any extractor mated to it to a much large size.

You've got to do the checking from the supplier, but like most companies, Ford attempts to save money on inventory of parts, and it only changes something to save money. I think there was a change to rocker shaft oiling at some stage between 1969 and 1974, and the shaft diameter chnaged too, but you can swap parts with ease if you do your homework.

I'm off to the tech section, not really wanting to hijack a good thread :oops:
 
well found some more info out looks like all those flow figures or at least the ohc nes where done @10in of water
the 2v was done @28 of water i beleave
 
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