Cam Tech

frnkeore

frnkeore

Well-known member
I thought I'd start a new thread on cams for the V8, rather than add more to the other thread. But, this will apply to all engines, including, OHV and the L head 6.

There is a lot to cam selection and there are many cams to choose from. Even though the cam is the heart of a engine, the cam can't do everything for a engine. It can only allow the port to try to fill the cylinder, with fuel and air.

The V8's biggest problem is the port. It's way to small for any serious HP. The stock diameter of it, is 1.312". It takes a LOT of porting to just enlarge it to 1.38.

I don't know the specifics of the porting work, of the flow test I'm posting but, it has 1.6 valves and is the only test that I've been able to find It seems to have been done in the best way possible for the V8.

144 cfm, isn't very much flow, at all. A OHV SBF with aluminum heads, can flow double that, w/o a problem. A well designed OHV port, can deliver 2 - 2.2 HP per cfm, for a V8. It is my opinion, that the flathead V8, can only deliver 1.4 - 1.6 HP per cfm and that is regardless of how many CI it has. If it was a OHV engine, that 144 cfm, would only get you 288 - 317 HP max, regardless of the displacement.

Does anyone else have any flow tests for a stock or ported engine? As a guess, I think a stock port, would be in the 110 - 120 cfm range, with a good valve job.

The cfm flow, works with the displacement. It takes more duration to fill a larger cylinder than a smaller one hence, the reason why one cam can't work, with all engines. So, it takes more duration to completely fill a larger cylinder.

HP, is a product of BTU's and BTU is a product of how much air and fuel, your able to burn.

A engine is a air pump and will produce so much air per revolution. The bigger the cyl, the more air but, if you spin a smaller cyl, at a higher rpm, you can attain the same volume as a bigger cyl. BUT, in either case, you have to have a hole, big enough to allow the cyl to fill so, the port is the limiting factor on HP. The undulations that a L head has, limit flow, so the flathead, can never keep up, with a OHV engine.

I have a lot of detailed cam info to post on old and currently available cams but, I can't add the L100 to the comparisons, w/o the advertised or the .015 cam lift duration. I have the .050 info and lift but, I need the .015, seat to seat or advertised duration to do it. Can anyone help with that?

I also will be posting a way to, advance and retard a cam, accurately.

More to come.
 

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I have done hundreds of flow tests with various port/head/relief configurations. Your numbers are strong representatives. It is allot of work to get 150CFM @ 28". There is a point at which the valve can be completely removed and no flow increase detected. Without finding my records I seem to recall the stock flows to max out at 90 CFM. If I get in the mood I will try to find my notebook.
 
Yes, I've been working on a new port for the past few years and came up with a method of removing the bowl under the valve to eliminate turbulence at hi flow. unfortunately my flow bench is long gone. i'm now working on improving the port. An interesting cylinder head is the 96 chevy smaller valves greater flow more HP????? The block is 258ci.
Gramps
 
Ol' Ron said:
Yes, I've been working on a new port for the past few years and came up with a method of removing the bowl under the valve to eliminate turbulence at hi flow. unfortunately my flow bench is long gone. i'm now working on improving the port. An interesting cylinder head is the 96 chevy smaller valves greater flow more HP????? The block is 258ci.
Gramps
Click to expand...

LS series motors use smaller valves I believe. Totally different animal than a flathead, but...
 
Tim, sometimes you have to look outside the box, nover know what you'll find. I'm sour someone had tried EVERTHING to improve the flathead. I look at JWL's input and say. "Good idea". At my age I can only wonder id we missed something. So I came up with a "BOWL" remover. Will it work?? I don't know?? might, might not. I'll post a picture of it and when the engine is done we can dyno the engine and find out??
Gramps
PS Fantastic information here, Makes that 200 hp flathead even harder to find.
G
 
Ol' Ron said:
Tim, sometimes you have to look outside the box, nover know what you'll find. I'm sour someone had tried EVERTHING to improve the flathead. I look at JWL's input and say. "Good idea". At my age I can only wonder id we missed something. So I came up with a "BOWL" remover. Will it work?? I don't know?? might, might not. I'll post a picture of it and when the engine is done we can dyno the engine and find out??
Gramps
PS Fantastic information here, Makes that 200 hp flathead even harder to find.
G
Click to expand...

Totally agree. When you look at science breakthroughs, a lot of advancements came by numerous attempts at improvements or going against the norms.
 
Frank there's a small group of like minded serious flathead Ford V-8 power producing guys. Each of us never accepted the idea The V8's biggest problem is the port. It's way to small for any serious HP. Now serious horsepower means different things to different people.

First I realize to the purist having 85 to 110 HP is more than enough. Then there's the guys who are happy with the thoughts of 150 to 200 HP. Then there's the forced induction crowd who expect 225 to 300HP the last two groups I'm part of for sure.

Then there's the small group I referenced to at the beginning who expect and get well above the 350 HP range. Some of us still use the original port layout of the production block I fall into that category.

I can't add anything to your port flow numbers since I have never taken the time to flow my ports. However I'm interested in the numbers you posted and anything else you add. If I can locate anyone in my area whos willing to work with me on testing ports maybe I can add something in the future.
Ronnieroadster
 
Some bench racing thoughts, if I may: Flow benches measure a steady flow of air, BUT it does not work that way in a real engine. Every time the intake valve closes, airflow completely stops at the underside of the valve and stays stopped during the compression, power and exhaust strokes. Since air has weight, it also has inertia and continues flowing into the port from the intake manifold and "piles up" behind the intake valve. These changes in velocity and pressure of the air/fuel mixture cause reverse pressure waves to travel back up the port into the intake manifold. Then the intake valve opens and the mixture behind the valve has to accelerate from a dead stop to enter the cylinder. Remember, the mixture is never "pulled" into the cylinder, it is always "pushed" in by atmospheric pressure (the air entering the carb).
Question #1: How much does this "start-stop" phenomenon of air flow affect the CFM readings of the flow bench?
Question #2: Is it better to enlarge the bowl as much as possible to "store" the incoming mixture until the valve opens, or better to shape the bowl to maximize flow once the mixture begins moving? (Probably some of both).
 
40 Deluxe, I think you have a good reason to believe this. I have the same feeling and for years felt the same way, however, one engine i built over 1400 miles by phone, made me think I might be wrong. The engine was that of Richard Koncs. AS his engine was going together, he asked about the ports?? I said, for your application I said "forget about it "
Several years later I had a chance to drive it. 276, l-100, hcheads and 500cfm carb and stock ports and valves. Y-5/4.10.
Bought the revs up, dumpt the clutch, poundes second. And the 3800 lb car supprised the sh#@ out of me.. 5 grand aall the way,
Not bad for stock valves and ports.
Gramps
 
Thanks for starting this thread! I love it when you guys start talking engine mods, especially cams & I try to absorb all the information!
 
I really know nothing about how to port a flathead. All I know is that you do not have much to work with! The 1.312 factory port is very limited, even to how large to can take it. I would be surprised if you can safety enlarge it to 1.44. There is water above it. The radius of the port, doesn't lend itself to being able to even see what your doing and getting 8 ports the same...... good luck.

I do believe you can work the bowl and valve guild area, successfully, that and a good 5 angle, valve job will increase flow but, by how much, I can't say.

There are many talented people in high performance engine building but, since the end of the '60's, not many of them work with the FH. If this engine were still popular in racing, I think port work, would have advanced to much higher level. The more minds, the more advancement.

In addition to what 40 Deluxe brings up, there is also overlap that has to be dealt with. Some amount of overlap is good, as it continues to draw on the intake port at higher rpm but, I suspect it's less desirable on a L-head engine. Here is where a dyno would be most helpful.

Regarding lift, it isn't needed much for the V8 and can have negative results if, after some point, the flow becomes turbulent. If it doesn't, even if the flow stops increasing, you'll still get more "area under the curve", with the higher lift.

Increased compression, will always create more HP, if you can get it. That is also hard to come by, on these engines. I spoke before about, what is called dynamic compress ratio, it the actual compression event, after the intake valve closes. Static compress ratio, as we all know, is the difference between the cyl volume and the cyl head volume but, that cyl leaks, until the intake is fully closed. The charts are increase duration, L to R. Note the LSA, ICL and overlap.

In the charts I'm posting all the engine sizes are the same, 3 5/16 x 4.0 (275.69 ci) and all static C/R are 8.70.

I would also, like I said earlier, like to do the L100 cam and if I can get that info, I'll also post the HV 12 cam (I have the specs for it) and some other lower duration cams.

Thank you all for your input, especially John and Ronnie.

Tomorrow, I'll explain a way to advance and retard a cam, accurately.
 

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40 Deluxe said:
Some bench racing thoughts, if I may: Flow benches measure a steady flow of air, BUT it does not work that way in a real engine. Every time the intake valve closes, airflow completely stops at the underside of the valve and stays stopped during the compression, power and exhaust strokes. Since air has weight, it also has inertia and continues flowing into the port from the intake manifold and "piles up" behind the intake valve. These changes in velocity and pressure of the air/fuel mixture cause reverse pressure waves to travel back up the port into the intake manifold. Then the intake valve opens and the mixture behind the valve has to accelerate from a dead stop to enter the cylinder. Remember, the mixture is never "pulled" into the cylinder, it is always "pushed" in by atmospheric pressure (the air entering the carb).
Question #1: How much does this "start-stop" phenomenon of air flow affect the CFM readings of the flow bench?
Question #2: Is it better to enlarge the bowl as much as possible to "store" the incoming mixture until the valve opens, or better to shape the bowl to maximize flow once the mixture begins moving? (Probably some of both).
Click to expand...

Your correct in the idea of the valve being closed has now created in a way a reverse flow situation. In a performance application the intake manifold design can take advantage of this reverse velocity so you now gain increased port flow. The Tunnel Ram design is the solution.
Ronnieroadster
 
This is a attempt to enlarge the smaller text.
 

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That didn't seem to work, if anyone would like full size copies, give me your Email and I'll send them.
 
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