HP & Torque For Various Cylinder Heads

[Bob Bidonde]

The dynamometer figures that follow where cherry-picked from the internet some time ago, and I did not make note of their sources. The figures are at the flywheel, and running with modern gasoline. From my notebook:
4.2:1 Compression Stock Head: 38 HP & 130 labs-ft Torque;
5.5:1 Current Hi-Compression Head: 47 HP & 141 lbs-ft Torque;
6:1 Current Hi-Compression Head. 58 HP & 146 lbs-ft Torque.


The best bang for the buck is the currently available 6:1 compression cylinder head.


If you have later / more accurate figures, please post them.

[Purdy Swoft]

What about Charley Yapps Lion head ? I believe that the lion head is around 6.5 or near compression ratio . I would think that charlie's head produced the most horsepower gain .

[denis4x4]

Probably the best head is Larry Brumfield’s. However, it looks like Jim Brierley’s new head is a contender.

[Purdy Swoft]

I wouldn't trade my Brumfield heads for a Snyder six to one head !!! The Brumfield heads are no longer available . I would think that the Snyder six to one head is now the best bang for the buck if an original appearing cast iron head is preferred .

[BRENT in 10-uh-C]

Bob, I suspect you found that info on Dennis & Beth Piranio's website. When I was still in high school, I wrenched on a top alcohol dragster that we match raced on the same circuit that Dennis' fielded a alcohol funny car on. Dennis was a good engine man back then, and I would expect his numbers are close.


Speaking of a good engine man, the Snyders 6.1 head was actually flogged by Bill Stipe, ...and based on some personal conversations with Bill, not to disagree with Purdy's statement but I would personally put one of Don's heads up against one of Larry's old heads. The thing we must all realize is that dynos are meant for giving comparisons of items on the same dyno, -and not for comparing numbers from two separate dynos. Machine calibration, ambient temperatures, altitudes, barometric and humidity levels can alter readings between machines where the data is not really accurate for comparisons.

[denis4x4]

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Bob’s Numbers don’t have info on intake, exhaust, ignition or cam specs. The A in my avatar was run on the chassis dyno during the Speedster Reunion two years ago and produced 59 HP at the rear wheels at 3200 RPM. Your guess is as good as mine as to the HP at the flywheel.

Brent is right on regarding comparing HP ratings on various dynos. I know for a fact that HP figures can be set to reach a predetermined number for advertising and editorial purposes.

Flywheel or rear wheel HP numbers are based on a lot of factors....bragging rights is the end result in most cases

[Railcarmover]

Dyno readings are what they are,a test engine under fixed conditions..competitors talk about turbulence and flame travel.Fact is compression increasing and additional fuel help a model A engine,add mechanical ignition timing and make the exhaust breathe better and all four upgrades help one another,fuel. compression. timing. exhaust. doesn't matter who provides what,as long as he brings it.

[Marshall V. Daut]

Since the mid-1990's when I was upgrading my various Model A's for cross-county driving from Arizona to Iowa and back on vacations, I experimented with several different higher compression cylinder heads. By achieving more horsepower mostly through cylinder head upgrades and secondarily through carburetion improvements, I was able to whittle the 1450 mile trip down from 2 1/2 days to just over one day (27 hours), driving straight through, stopping only for gas and the call of nature. Without a better cylinder head than the original one, this significant time reduction would not have been possible. Because I did not stop to sleep during the trip, it was imperative that I reach my goal (on a limited vacation schedule from work) as soon as possible before dozing off at the wheel. I made this trip numerous times over the period of 31 years (1973-2004), almost every trip with a different cylinder head for comparison, sometimes more with the same head. So, I think I can speak from practical experience about what worked best for me in terms of cylinder heads. Camshafts, carburetion, valve size and gearing tested could fill another thread some other time.
The heads I tested included a milled stock Model "A" head, the 1932-34 Model "B" head, the 1931 Model A Police head, Brumfield's standard 5.9 head, an aluminum Thomas head, both the 5.5 and 6.0 Snyder's heads, the 7:1 CR Super Brumfield head and the Riley Two-Port 7:1 CR repo OHV head. All had their pluses and all had their minuses, ranging from cost to expected improvement and reliability.
Predictably, the most disappointing of the bunch were the milled Model "A" and Model "B" heads. There was no improvement felt at all with the milled Model A head. Maybe the dyno would show an improvement, but I am talking about FEELING the difference on the road, which is really all that matters, isn't it?
Using the Model "B" head (with the "C" embossed on it) with only a mild increase in compression and no major combustion chamber improvement, not much gain was experienced for the money spent on acquiring the head, a new head gasket and rebuilding the special three-bolt hole water pump, which always seemed to fail. I would recommend neither a milled "A" or Model "B" head for sustained long distance driving, if one wants to experience noticeable increased performance.
At the other end of the spectrum were the Super Brumfield and Riley Two-Port heads. These were far superior to the other cylinder heads I had driven. It's probably not really fair to compare an OHV conversion to a flathead because of the difference in breathing capabilities. Our Model A engines are just big air pumps: the more air you can force into the cylinders and then force back out, the more power you'll make. An OHV has a distinct advantage over a flathead in this regard and should outperform a flathead of the same compression ratio, which my two heads were. On my trips using both heads, the same downdraft carb, headers, Aires muffler, similar camshaft grind profiles and a Mitchell overdrive leveled the playing field. In other words, the cylinder heads were the only major difference. The Riley probably made more raw horsepower, but contrary to all expectations, I would say it was almost a draw between the two in terms of performance on the road. There were many steep mountains to climb in northern Arizona and in central New Mexico, and both heads performed brilliantly in pulling power, very rarely needing to go back down to second gear, even on the steepest mountains. Acceleration when needed to pass trucks at 65 MPH on level interstate highways was instantly on tap with both heads. Miles per gallon were roughly similar. In short, the R2P OHV was not a clear winner over the Super Brumfield head in any facet of driving. For the money difference (roughly $400 versus $2750 in the late 1990's), the Super Brumfield was the better way to go, exotic though the R2P is, looking like a million dollars with its polished dome valve covers. I still drive the Super Brumfield head year-round without ever having suffered a single blown head gasket, whereas I went through five using the R2P in the first two months, finally buying an expensive solid copper gasket, which held. Guess which one of these heads I consider more reliable, let alone the better bang for the buck!?
I am not rebutting what others have written here so far about their experiences or preferences in terms of cylinder heads, nor would I expect them to rebutt what I have experienced. We know what we know from experience. My point in making this long post is that one must be careful not to lump comments about Brumfield heads into a single one-size-fits-all category because there were TWO Brumfield heads that should be considered. Of course, most guys opted for the less expensive Standard Brumfield, which is where most comments originate, from among those owners. To say "the Brumfield head did this or that" on dyno without specifying that it's the Standard 5.9 Brumfield being cited is unfair. To make such statements more complete and accurate, it should be stated that the STANDARD Brumfield head was tested and that a Super Brumfield would have undoubtedly resulted in higher HP and torque figures. Nice as the Standard Brumfield is, it is easily surpassed by the Super Brumfield in my opinion. It may be a moot point now to make a distinction between the Snyder's heads and the Standard Brumfield, since neither the Standard nor the Super Brumfield head is being manufactured for sale anymore. But there are plenty of them out there in Userland that when one becomes available new or used, it is quickly snapped up. Doesn't that tell us something about their desirability right there?
If the argument comes down to which head is better - the Snyder's 5.5/6.0 flavors or the Brumfield Standard - I still feel the Brumfield gives a better boost (torque) in third gear than either of the Snyder's heads. That place in the power curve is the weakest in Model A's and the reason we hold up traffic behind us until speed has increased in high gear. The Brumfield Standard head was and is the clearly superior in this area alone. Once again, however, unless the Standard Brumfield head goes back into production again, this discussion is purely academic. We are now left with only the two Snyder's heads, which I do feel are a big improvement over the stock Model "A" and "B" heads. But if push came to shove and one of these were lying next to a Standard Brumfield head for sale, I'd pick the Brumfield every time. And, no - I am not a salesman for the Brumfield Company, nor have I ever met Larry Brumfield personally. I just believe in endorsing a good product when I find one for the benefit of others.
Marshall

[Joe K]

And you can ask the cop who pulled over Marshall for speeding in his Model A what his opinion was of the head Marshall was driving. Isn't his name mentioned somewhere Marshall?

Sorry. Another Marshall story I remember.

Joe K

[Marshall V. Daut]

Ha, ha, ha! Ya' got me there, Joe! Yup - a highway patrolman pulled me over for speeding in my '29 Cabriolet IN THE MOUNTAINS while going uphill near Heber, Arizona. That was with the Riley Two-Port head. 'Might just as well have been the Super Brumfield flathead, though. They both pull nicely up hills. GREAT torque!
Fortunately, the highway patrolman only gave me a warning citation that day. Whew! Had he written me up for how fast I was REALLY going, I'd still be sitting in a Heber jail cell.
Good memory, Joe! But not such good memories for me: I blew three head gaskets on that trip alone. Getting pulled over for speeding was the highlight of that trip!
Marshall

[updraught]

Is Tod selling the Winfield head?

[duke36]

There has been some discussion and posting about whether babbitt bearings can over time sustain a high compression head ratio > the 5.5 or 5.9... any thoughts ?

[Terry, NJ]

First, I want to thank Marshall for his report! He brought many subjects to light that I really didn't consider, Yet!

Secondly, as far as the journals go on a A engine, Just looking at them tells me they are too small! Yet, I don't hear of many A engines failing because of that aspect. Yet , being conservative in most things, I would never put the higher end heads that Marshall mentioned (Lion, Brumfield, Thomas, Riley) on a car that I was going to drive 2800 miles round trip in. But he is doing it and it seems to be working. But if I did it, I'd be like Lindbergh when he flew across the ocean, Counting the Power strokes and wondering how metal could take that much punishment!
Terry

[BRENT in 10-uh-C]

Originally Posted by duke36

There has been some discussion and posting about whether babbitt bearings can over time sustain a high compression head ratio > the 5.5 or 5.9... any thoughts ?

Most of the rumors regarding babbitt not being able to withstand higher compressions ratios can easily be dispelled by asking this. What kind of compression ratios did early diesel truck engines have that also used babbitt for bearings? If the babbitt in those early truck engines failed prematurely due to high compression, do you think the diesel engine would have been considered successful back then?


IMO, 99% of the ones that complain about babbitt failures with high compression are choosing to overlook poor craftsmanship as the culprit.

Originally Posted by Terry, NJ

Secondly, as far as the journals go on a A engine, Just looking at them tells me they are too small!
Terry

Terry, compared to other engines, Model-A/B journals are anything but too small!

[Railcarmover]

To maximize bearing life full flow oil filtration and avoiding spark knock is important.The effect of spark knock on bearings increases with higher compression.Folks who want the power but look original with the 5.5 or 6 to 1 head and use an A distributor risk accelerated bearing wear due to detonation.One thing I'm not convinced about is the value of a counter balanced crankshaft vs the dynamic balanced crankshaft in the Model A.Does anyone have hard evidence of increased life vs cost? my gut says it doesn't pencil out..

[ryanheacox]

Originally Posted by BRENT in 10-uh-C

Terry, compared to other engines, Model-A/B journals are anything but too small!

The engine rebuilder I used also had an early 20's Overland (I think) in for a rebuild and compared to those journals the A's look massive.

[Marshall V. Daut]

Terry and others -
I didn't mention the type of bearings in my engines because I was trying to keep my previous post short (Ha, ha, ha!). Nor did I mention that some of the trips were made with "A" blocks and some with "B" blocks, and yet others with an "A" block featuring Model "B" crank and rods. Both the engine block type and bearing selection would have extended my post beyond the two or three sentences that comprised it.
The meat of this thread concerns various cylinder heads and the increased performance they supply, or at least that's the direction it was taking. So, I limited my comments to which cylinder head worked better for me. But for the record, the higher compression heads were run on engines with inserted rods and mains. In the mid-1990's I just wasn't having good luck with local Babbitt pourers in the Phoenix area after Clayton Halfin passed away. One disastrous trip ending in the New Mexican desert made up my mind to switch to insert bearings. Although I can't lay any engine failures directly at the doorstep of Babbitt run with higher compression heads, inserted bearings give me a better peace of mind for now and especially the future. Who knows how long the Babbitt pouring guys of today will be doing this 10-15 years from now? I bit the bullet and converted my engines to inserts so that I will never again be dependent on the quality of a Babbitt pouring job, an almost lost art these days. Also for the record I agree with posters, who maintain that a higher compression cylinder head (say, 7:1 or less) will not adversely affect Babbitt bearings if the Babbitt was poured properly in the first place and the driver uses common sense, such as not lugging the engine or over-revving. No type of bearing will be able to stand up to that kind of abuse.
Marshall

[duke36]

Originally Posted by Railcarmover

To maximize bearing life full flow oil filtration and avoiding spark knock is important.The effect of spark knock on bearings increases with higher compression.Folks who want the power but look original with the 5.5 or 6 to 1 head and use an A distributor risk accelerated bearing wear due to detonation.One thing I'm not convinced about is the value of a counter balanced crankshaft vs the dynamic balanced crankshaft in the Model A.Does anyone have hard evidence of increased life vs cost? my gut says it doesn't pencil out..

Some posters have mentioned timing issues with the FS auto ignition used with a high compression head. I had a similar issue because the prior owner's FS zip wouldn't allow enough retard on grades with resulting knocking. Pulled it in favor of the stock dizzy to allow for manual adjustments to suit conditions. I also have a counter balanced crank with lightened fly and V8 clutch which though not empirically tested has very smooth running.

[BRENT in 10-uh-C]

Originally Posted by duke36

Some posters have mentioned timing issues with the FS auto ignition used with a high compression head. I had a similar issue because the prior owner's FS zip wouldn't allow enough retard on grades with resulting knocking. Pulled it in favor of the stock dizzy to allow for manual adjustments to suit conditions. I also have a counter balanced crank with lightened fly and V8 clutch which though not empirically tested has very smooth running.

So is the root problem with the lack of longevity with the babbitted bearing because of the Babbitt, --or because of the Distributer? As Marshall stated, no bearing will withstand detonation.

[Bob Bidonde]

I thought that this topic would stimulate some interesting discussion. Marshall, you didn't disappoint us as your escapades are always interesting, and I appreciate your sharing experiences with us.

It would be a fantastic endeavor and valuable to all of us to have all of the reproduction heads tested on the same dynamometer. One of the unknowns regarding compression is the additive dynamic pressure head that occurs due to fluid mechanics.

As for those who have concerns about babbitt life with high-compression heads, I suspect that adding counterweights to the crankshaft may be more stressful to the bearings.