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Author
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Topic: 351C 2V/4V heads.......CFM vs. HP/Torque
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DutchD58
Gearhead Posts: 142
From: West Milton, OH
Registered: Jul 2000
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posted 11-25-2001 10:22 AM
 
For the last year or two I've been mulling over the approach for a street oriented Cleveland build-up for my Torino. For my own reasons, I favor the Cleveland over the Windsors or Big-blocks. I've also settled on building a stroker, probably a 393C. What I was still not sold on, however, was whether to use ported 2V or fairly stock 4V heads for my horsepower and torque goals (420-450 HP and maximum available torque from the combo) and to try and keep it under 6500 RPM's. It's no secret that the stock 2V heads offer better throttle response and torque down low and are good for about 350HP, but I could never find anything that could quantifiably tell me what the HP potential was for a set of properly set up 2V heads So, for a different perspective, I posted a question at another board that produced some interest and answers that you may find eye opening or re-assuring, depending on where you're coming from. I intentionally, initially, asked the question pertaining to a heads' flow as it relates to HP in such a way as to try and not bias the responses due to someone's preference for Windsor or Cleveland power, and was very pleased with the answers. As you sift through the debate (and it got a little heated), there's some good information, proven formulas and a few links that you may find useful in making a decision. I know it did for me!
Below are the links to the discussion and a few others that may be helpful, too. Kevin http://www.fordmuscle.com/boardpower/discussion.cgi?forum=1&discussion=4523 http://www.bgsoflex.com/auto.html http://www.waldens.com/waldens/fmotorsp.htm http://www.powerheads.com/ProductDetails.asp?product_id=6
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mj
Journeyman Posts: 3
From:
Registered: Nov 2001
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posted 11-25-2001 12:58 PM
for your heavy car i would use the aussies
but
if you have a few sets of closed chamber 4vs kickin around use them as it will be cheaper
cant remember if you are an auto guy, if so high stall is in your future
seems you are overthinking this street engine.
[This message has been edited by mj (edited 11-25-2001).]
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badazzcougar
Gearhead Posts: 132
From: Seattle
Registered: Oct 2001
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posted 11-25-2001 06:54 PM
How do the cleveland heads compare flow wise to say small block chevy heads or good factory windsor heads. the 2V and the 4v versions.
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SteveLaRiviere
Administrator Posts: 48752
From: Saco, Maine
Registered: May 99
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posted 11-25-2001 07:12 PM
This should help. It's from the Dec. '99 Mustang & Fords magazine: 
They have a mistake in their chart -- the exhaust valve for a 351 Cleveland 4V head is 1.71", not the 1.67" valve they have listed.
Also, the 351 Cleveland 2V valves are 2.04" intake and 1.65" exhaust. '70 Mustang Mach 1 M code 351C 4V/FMX/3.25 open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC
My Photo Page
Christmas shopping? Why not use the Mustangsandmore.com Bookstore? [This message has been edited by SteveLaRiviere (edited 11-25-2001).]
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DutchD58
Gearhead Posts: 142
From: West Milton, OH
Registered: Jul 2000
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posted 11-25-2001 10:56 PM
badazz, the 2V heads (Aussie or American) will apparently equal or better the stock 4V heads, up to .500"-.550" lift when set-up with larger valves and ported. Couple that with the smaller ports' higher velocity (torque) and you get the best of both worlds, up to a certain point. The link to "Powerheads" below will give you an idea of what many have been able to typically achieve with a modified 2V head. With approximately 240 CFM @ .550" the 2V heads SHOULD be capable of supporting something around 490 HP. And that's N/A with no power adders!
mj, I will probably run the Aussies. While you'll NEVER hear me say "money is no object", since this is a long term investment for me I do expect to spend more than if it were just a basic re-build and warm-up. Yes, I'm gonna run a C-6 with an aftermarket torque converter and some steeper gears. I know a C-4 would be faster, but again, I'm building for the long haul. As far as overthinking it goes, I don't look at it that way at all, I just want as clear a picture as possible before I lay down any money.
Steve, do you have any of the older (late '70's- early '80's) SuperFord mags? I seem to recall some articles with flowbench comparisons between the 2V/4V heads, stock vs. ported. Used to have 'em, but that was at least 4 kids and two wives ago!Kevin http://www.powerheads.com/ProductDetails.asp?product_id=6
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badazzcougar
Gearhead Posts: 132
From: Seattle
Registered: Oct 2001
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posted 11-25-2001 11:38 PM
say I were to pick up a set of aussie heads for racing and had them cut for 4V valves. Ive got pop up pistons which would kick my compression up to 12.5 to one or so. How much power is that extra 2.5 points of comression going to give me? I assume I'd have to go to a wilder cam to take advantage of the extra compression. Or would I just be better off going with a set of quench 4 v heads? Also I understand the 4V aussie heads were really on a 302 . Is that 302 crank available? Was it a cleveland based engine or windsor like the US? did it use 351 pistons and longer rods? Sounds like a screamer. [This message has been edited by badazzcougar (edited 11-25-2001).]
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Clevo377
Gearhead Posts: 312
From: Blackburn, Victoria, Australia
Registered: Nov 2000
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posted 11-26-2001 04:30 AM
I'd go with stock (or just cleaned up) 4V. Pick a mild (214/224) cam and 850 Holley and you'll make 400Hp at around 6000rpm, Thats what I did  Stand on the gas down to 1800rpm and the tires lite up (with a stick shift and 3.5 rear)Paul
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mj
Journeyman Posts: 3
From:
Registered: Nov 2001
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posted 11-26-2001 02:43 PM
I am no aussie expert, but the aussie didnt answer iti understand the 302c to be a long rod short stroke with unique pistons in a 351c type block.
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SteveLaRiviere
Administrator Posts: 48752
From: Saco, Maine
Registered: May 99
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posted 11-26-2001 06:21 PM
quote:
Originally posted by DutchD58:
Steve, do you have any of the older (late '70's- early '80's) SuperFord mags? I seem to recall some articles with flowbench comparisons between the 2V/4V heads, stock vs. ported. Used to have 'em, but that was at least 4 kids and two wives ago!
I may have, deep in my cave. I'd need a safari to go hunting for them... ------------------
'70 Mustang Mach 1 M code 351C 4V/FMX/3.25 open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC
My Photo Page
Christmas shopping? Why not use the Mustangsandmore.com Bookstore?
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DutchD58
Gearhead Posts: 142
From: West Milton, OH
Registered: Jul 2000
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posted 11-26-2001 08:18 PM
badazz,
There are others here who could answer this better than me, but if you had a 400 HP, 10:1 motor and raised the CR to 12.5:1, with no other changes, I think that would be good for another 25 or so HP.
Kid Vishus (Rob) could probably tell you a great deal about the 2V heads in a race motor. I seem to recall he's gone as fast as 10.4 with a high compression motor running on alcohol, and spun it to well over 7000 RPM.kevin
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DutchD58
Gearhead Posts: 142
From: West Milton, OH
Registered: Jul 2000
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posted 11-26-2001 08:21 PM
quote:
Originally posted by SteveLaRiviere:
I may have, deep in my cave. I'd need a safari to go hunting for them...
Hey Steve,
I'd be more than happy to be your gunbearer on that one.......... kevin
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futurattraction
Gearhead Posts: 108
From: Iowa City, IA
Registered: Oct 2001
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posted 11-26-2001 08:40 PM
badazz,
The Aussie 302C heads have a tighter chamber than our U.S. 4V quench heads. A guy on the 335 series board discovered that his pop up pistons interfered with the Aussie heads he got. As mj said, the Australian 302C was a 351C-based block with a 3-inch stroke crank and 6.03 rods. Scott
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Clevo377
Gearhead Posts: 312
From: Blackburn, Victoria, Australia
Registered: Nov 2000
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posted 11-27-2001 01:48 AM
****** 302C *******
230Hp@5000rpm
300Lbs@2600rpm
4" bore x 3" stroke
6.03" rods
9.4:1 CR
small port
58cc chamber
2.04/1.65 valves
Paul
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Clevo377
Gearhead Posts: 312
From: Blackburn, Victoria, Australia
Registered: Nov 2000
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posted 11-27-2001 01:57 AM
Oh, 302 Cranks are VERY common here. Just recently threw one out (kept the heads though  ) From what I know they're not that strong. Most people go for the 3.5" crank...more cubes.Paul
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