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When the question came up as to how well some of the various exhaust and header designs perform on the Ford Y-Block family of engines, the 312 dyno mule was again put to work in doing an extensive exhaust system test. Twenty-four different exhaust systems ranging from single exhaust to stepped headers were tested with each system being tried in a variety of configurations. Where possible, the different exhaust systems were also tested with and without mufflers and a variety of head-pipe lengths. When mufflers were used, they were sized according to the pipe size going into them which required having a variety of chambered mufflers on hand for this test. Except in the case of where the headers used for the 2010 EMC competition were used, mufflers were a deterrent for making additional power. While there are mufflers out there that are not a detriment for power production, those simply were not on hand for this test.
The engine used for the testing presented here is a +060 over 312, cast pistons 0.025” in the hole, the rotating assembly balanced, a Crower Monarch cam with 238° @ 0.050”, ground on 110° lobe centers, and 0.461” lift at the valve after valve lash while using Harland Sharp 1.6:1 roller rockers. A stock Mummert aluminum 4V intake manifold topped with a 2” dual oval carb spacer and 750 cfm Holley carb feeds air and fuel to the engine. A MSD distributor and wires along with Autolite #45 spark plugs gapped at 0.035” keeps the cylinders firing. An Innovators West harmonic damper is being used on this engine after finally abusing the original damper to the point that the rubber started coming apart. The damper was changed out long prior to doing the exhaust tests. The static compression ratio is 9.6:1 using a pair of heavily milled but mildly ported ‘posted’ ‘G’ heads. The porting and milling were worth an additional 18 HP over a stock set. The key here was to eliminate the cylinder heads as the bottle neck for power production so that any differences in exhaust systems could be more accurately evaluated. A considerable amount of thought went into how to present this data. While graphs give a good visual, they can get very busy quickly if trying to show several tests on a single graph. A chart format is ultimately decided upon as it gives a quick overview of all the different exhaust systems at a glance. To get a better feel for the overall performance of a given exhaust system, a scoring format is used as it rates the test over a rpm range rather than looking at individual peak hp or torque values. For this, the rpm band for the tests was maintained at 2500-5500 rpm. While the tests could have started at 2000 rpm, this is hard on the engine and especially the main bearings so 2500 rpm was the starting point. The scores are calculated by adding the average of the torque and hp values together, multiplying by 1000 and dividing by the cubic inch (322). In the case of a tie, the peak hp value is then used as the tie breaker. In the following chart, the exhaust systems are listed in the order they scored from lowest to highest. Where exhaust systems were tested with several configurations, the highest score from those tests is the one listed.
|Description.||Score||Peak HP||Peak TQ||Avg HP||Avg TQ||Mufflers||Testing configs|
|Single exhaust with crossover pipe||1484||239||303||202||276||NO||2|
|1955/56 Dual Exhaust manifolds||1629||274||327||223||301||NO||4|
|Reds two tube headers||1635||278||327||224||302||NO||3|
|1957 Dual Exhaust manifolds||1650||279||330||226||305||NO||4|
|Fenton cast iron manifolds||1663||282||332||228||308||NO||2|
|Tri-Y stepped shorty Tbird headers non-firing order specific – GB||1675||294||332||230||309||NO||4|
|Ram Horns w/2”into 2¼” head pipes||1683||283||337||230||312||NO||2|
|Shorty 1.625” w/box collectors – DC||1693||284||336||231||314||NO||1|
|JC 4 tube car chassis shorty headers||1739||296||347||238||322||NO||6|
|Tri-Y pickup headers firing order specific-CC||1739||297||347||238||322||NO||5|
|Sanderson 1½” T-Bird headers w/2½” head pipes||1751||297||350||240||324||NO||11|
|Sanderson 1½” Pickup headers w/2½” head pipes||1751||300||350||240||324||NO||5|
|Reds 1.625” 4 tube hdrs for 55/56 car||1753||295||347||240||325||NO||8|
|Fenderwell headers 1.75” tubes – MW||1768||306||344||242||327||NO||5|
|Fenderwell headers 1.625” tubes||1769||308||346||243||327||NO||5|
|KC 4 tube Maxton Mile 1 5/8” headers||1775||310||351||244||328||NO||4|
|Rdstr 4 tube 1.75” gattling collector hdr||1778||309||355||244||329||NO||2|
|FPA T-Bird hdrs 1.625”/1/75” stepped||1780||311||342||244||329||NO||13|
|Jardine 1½” Tri-Y for 55/56 car||1791||308||349||249||328||NO||3|
|Marino unequal length by design 1.75” race car specific & 2.5” merge collector||1794||309||346||250||328||NO||1|
|Kaase EMC headers – 2015 Champion||1796||307||348||250||328||NO||1|
|Jardine 1.75” Tri-Y for 55/56 car||1798||304||355||250||329||NO||3|
|EMC headers 1.75”/1.875” stepped w/3” merge collector||1798||309||343||250||329||YES||4|
|CDT ’63 Falcon unequal length by design 1.625/1.75” stepped||1809||311||344||251||331||NO||3|
|Description.||Score||Peak HP||Peak TQ||Avg HP||Avg TQ||Mufflers||Testing configs|
As can be observed, it’s not necessarily about the peak numbers. In some instances, the scores on some of the exhaust tests are found to be higher but with lower peak numbers than another set of exhaust tests with higher peak numbers. For drivability purposes, the scoring format gives a better indicator of overall performance rather than using a peak number.
The two sets of headers that were built with ‘unequal length tubes by design’ do show some promise as both sets are in the high range of values of all the exhaust systems tested. The idea behind those unequal length tubes is to more evenly distribute the pressure buildup at the collector that occurs when the two cylinders on each bank fire in a back to back fashion. On the Ford Y, it is cylinders 8 & 6 on the left bank and cylinders 2 & 1 on the right bank where those pressure build ups originate. To help equalize those pressure build ups that occur at the collector as a result of the Y firing order being what it is, the tubes for cylinders 2 & 8 are made intentionally shorter while the tubes for cylinders 1 & 6 are made longer by design. The remaining cylinders all remain at a standard and equal length. By doing the tube lengths in this fashion, the exhaust pulses of cylinders 2 & 8 are permitted more time to evacuate from the collectors before the pressure pulses from cylinders 1 & 6 come in behind them. The firing order nuance where there are two cylinders firing one after the other on each bank occurs on all V8 engine designs. This is sometimes compensated for by designing a 180° header where a pair of tubes cross over (or under) the engine so that each collector is truly alternating from side to side in conjunction with the exhaust pulses that enter them. Very few vehicles can benefit from a true 180° header design simply due to chassis limitations. For the Ford Y, the firing order is such that the cylinders requiring shorter tubes are already closer to rear of the engine and subsequently the collector thus making the headers somewhat easier to fabricate when going for this particular design.
Always keep in mind that this header test was performed on the same engine with no modifications being made to the engine itself to complement a particular header design. That’s all fine and good for this particular test but these same headers tested on engines modified differently will have different results. Cubic inches and the various modifications performed to a particular engine will dictate special header construction parameters for an engine. For a street engine running through a full exhaust system, then many of the headers will be close in performance to each other although there may be obvious differences in tube diameters, lengths, and collectors. For engines using full exhaust systems including mufflers, then the whole system must be taken into consideration. What follows are pictures of the various exhaust manifolds and headers tested. They are pictured in the order in which they scored from lowest to highest.
As Frank Rice so eloquently mentioned about this series of testing, it was indeed exhausting. All for now and happy Y motoring. Ted Eaton.
This article was previously published in The Y-Block Magazine, issue #161, Nov-Dec 2020.
The Rollmaster true roller timing sets have been available for a number of years now for the Ford Y-Block family of engines. These have been a big plus for those engine builders that go to the extra effort of degreeing in the camshafts as the lower crankshaft gear is keyed for nine different camshaft positions. Before these Rollmaster timing sets came to market, degreeing in the camshafts on the Y involved offset keys or broaching new keyway slots in the crankshaft or camshaft timing gears. The offset keys were always questionable strength wise regardless if the valve spring pressures were increased or not. The practice of broaching new keyway slots in the gears is not an exact science when it comes to getting the new keyway in the exact ‘right’ location. The Rollmaster timing sets eliminates those prior difficulties.
When David Church acquired a 1955 Ford Customline two door sedan, it was found that it was originally ordered as a law enforcement car with the P code 292 and a three speed standard transmission. A little back tracking finds that the car was purchased new in North Carolina and when found by David, still had the 1967 North Carolina license plates on it but was now sitting in a South Carolina field. It had been well over 40 years since the car had been last registered and state inspected. Although that car had been sitting in a field for a number of years, a bit of fuel poured into the ‘Teapot’ 4V carburetor and a battery boost gets it started. It drives itself up and onto a trailer for the trip back to Mississippi. The odometer is showing 60K miles but when looking at suspension, pedal wear, and general oil and grease build up at various parts of the car, the assumption is the car has 160K miles instead. More time elapses and now the car is undergoing a complete restoration including an engine rebuild. The engine rebuild is where I come into the picture.
This is the article recently published in The Y-Block Magazine issue #146 (May-June 2018) authored by Joe Craine.
Part of the blueprinting process during any engine buildup will include degreeing in the camshaft. This operation is performed to insure the camshaft is phased or installed at the desired position in relation to the piston sitting at TDC. While degreeing in the camshaft during its installation may seem to be an activity reserved just for the race engines, the fact remains that it’s just as important on the daily driver applications as it is for high performance engines.
Part I of this article went into detail as how to find exact TDC. With that now behind us, the actual process of checking the camshaft and how it is currently phased within the engine can begin. For this, a 1.000” travel dial indicator will be required that can measure the up and down motion of the lifters. While the number one cylinder is customarily the cylinder of choice in which to check the camshaft, any cylinder can be used to degree in the camshaft once TDC has been found for that cylinder. In fact, later in this operation another cylinder will be checked in which to both verify the results obtained off of the first cylinder check and also insure that the camshaft is at least consistent in values on two different cylinders. For now, the number one cylinder will be used as a reference.
Most camshaft timing sets for the Ford Y family of engines (239/256/272/292/312) requires that there be twelve pins between the timing marks on the sprockets and for those marks to be on the oil filter side of the engine when doing the initial chain installation. The exception here is that this only applies to Y engines that actually use a timing chain and does not apply to right hand or reverse rotation marine engines that use a gear to gear setup. While the Y is not the only engine to use the pin or link count between gear marks to time the camshaft, most V8 engine families simply align the timing marks on the cam gear and crank gear with the centerline of the engine. Due to the infrequency of engine manufacturers using the pin or link count for camshaft timing, it does leave the door open for mishaps by those not familiar with this.
Although there were a multitude of Ford 272 Y-Block engines used in both cars and trucks, they are pretty much disregarded as the basis for a high performance build and for that matter, as a replacement engine when a 292 or 312 is available instead. While building a high performance 272 Y has been on the ‘like to do’ list for awhile, it has been a hard sell when the larger Y engines simply make those higher power numbers much easier to come by. That all changed recently when a customer wanted to use the original 272 block from their 1956 Ford pickup as the basis for a new engine in that same truck. In this instance, they wanted modern performance upgrades applied to it including a pair of Mummert aluminum heads.
By using just the right combination of parts, exceeding that magic 1HP to cubic inch ratio is indeed possible while still doing it with a pair of unported iron Ford Y-Block heads. The key here is in using a modern piston ring design and maximizing the compression ratio while still being able to have an engine that will run on available pump gasoline. Not to be left out are the intake, carburetor, camshaft, and cylinder head choices which are also just as important.