why my gov surged and I couldnt win 1st place

DaveKamp wrote: Added bonus to the long rod, is that the G-forces subjected to the upper half of the reciprocating assembly are dramatically reduced.  If you're intent on spinning it fast, that's a prime way to keep it from coming unglued.

Back to the first photo- what we're looking at here is a rod failure, not questioning the ability to 'make power'.  Evidenced by the photo, it takes no forensic talent to determine that the load subjected to the rod, was greater than the rod could withstand.  The question, is what aspect of loading caused the rod's modulus to be exceeded.

The first and foremost condition which would cause a failure of a structural element, is when that element is subjected to load which does NOT evenly distribute upon the element's section modulus.

Take a 40' piece of I-beam, and lay it across sawhorses, first vertically then horizontally, and you'll see that in each plane, there is a certain amount of deflection that occurs due to the beam's own weight.  You'll also find that if you add a certain amount of weight to the center of that beam, it will deflect by a certain distance.  This is called ELASTIC MODULUS... and you can predict that if a given weight causes the beam to deflect an observed distance, that increasing the load by a proportion, will increase the deflection by a proportionate distance.  If you attempt this with the beam in both positions, you'll see that more deflection occurs on one plane, than on the other-  this is because the I-beam's material is distributed differently with respect to loading forces.  If you repeat same test, with a structural shape other than I beam... say... square tubing, or round tubing, you'll find that the same deflection occurs, BUT... since the shape is symmetrical, deflection is the same regardless of which side is up.

IF you continue to add load to the shape, eventually, you'll exceed the material's tensile strength, and some part of the shape will fatigue.  Logically, the area of section modulus that fails FIRST, is the part which is farthest from center of axis... because the geometry of deflection causes stress to occur there first.

Now, take that I-beam, place one end on a sawhorse and clamp it down.  Put the other end on the sawhorse, but twist it 90 degrees, and clamp it down flat.  Now put a load in the middle.  It will deflect, just like before, but it will fail much sooner, firstly because the deflection load is irregularly distributed about the shape, and secondly, because the material is under inital stress of torsion PRIOR to accepting the actual load.

Now where's this all going?  It goes right back to what Grumpy said about observation vs. analysis:  What you observe, and what you attempt to predict, are two different things, and what you Observe, can Quantify, and predictably Repeat is ALWAYS correct.

The conclusions here are clear:

1) The existence of stress caused rod failure.
2) Only one rod appeared to have failed...
3) SOMETHING about the crank and other rods appeared to be bound.

#1 is obvious... with added note that the rod did not separate.  #3 suggests that observation #2 is errant- either the crank, other rods, or block has stressed.

Next:
 
4) The stress which caused rod failure, is a composite stress of ANY AND ALL forces applied to rod.  This includes
A: Compressive, down the centerline of the rod
B: Torsional, twisting of the piston with respect to the rod (i.e. crank deflecting under load)
C: Lateral, a sideways load of the big end vs small end (i.e. crank moving forward in block)
D: Tractive: rod pulling against piston (i.e. high rate-of-change-of-velocity of piston)

When designing a mechanism, you can't design based solely on the forces you INTEND to have occur- you must design based on what occurs as a result of ALL FORCES.  This includes twisting of the block, crankshaft, cam, clutch... everything.  This also includes G forces from piston speed.

My reference to rod length, first and foremost, is to respect the fact that a short rod length results in a greater deviation from zero thrust angle, and a higher rate of change of velocity.  In many applications, this isn't a problem, particularly where a rod can be made large, and beefy enough to withstand all stresses, and still be slow enough in Dv/Dt to prevent the composite stresses from resulting in failure.

In the case of this scenario, my gut feeling is that, under load, you're generating enough deflection, so that the COMPOSITE stresses are causing the failure... meaning... WITHOUT any deflection, I'd bet that rod would hold up just fine, and probably to a bit more, than what you're subjecting.  Lowering the thrust angle, however, provides more 'compliance' in the reciprocating assembly to allow TOLERANCES to mitigate deflection.

All I'm going to say is interesting. Keep us thinking and posted.

Sheessse -- Who doesn't know this stuff ???? 

Couple of notes for 'ya here, Mitch:

The de-facto standard 'text' for any internal combustion engineering student is "The Internal Combustion Engi8ne in Theory and Practice, Volume 1 & 2, by Charles Fayette Taylor...    Surprisingly, it wasn't a required text in any engineering classes, but if I were the professor, I would certainly require a front-to-back read for every mechanical or thermodynamic engineering sophomore.   It's published through M.I.T. Press, ISBN 0-262-20051-1 (hardback) and 0-262-70026 (soft).

But my apologies for taking so long to come back with the details- I was on business in Houston and Phoenix, wanted to have the text in front of me so I'd give you pointers to the correct page.  In any event, this pair of books is absolutely golden, as the technical description of engineering factors steps far-and-above what an everyday hot-rodder will divulge in a competetive environment.

I think the best reference to the situation you've found, is in Volume II, pages 496 through 498, it describes the stresses and mathematics of crank deflection.  Page 503 has a few paragraphs on how crank deflection and cyclic balance affect alignment, and take into consideration tolerances for rod/stroke ratio.

I have little doubt that your filled block is maintaining dimensional integrity, save for whatever thermal expansion occurs.  I think what's happening, is that your crankshaft is acting like a 'rubber band', and is flexing far enough to cause the rods to get catty-whompus'd, hence, the bend starts, weakening the rod.  A stiffer crank would help solve this... geometrically a longer rod would help, and one other thing (which may seem bizzare) is running higher clearances at the big and small ends of the rod, so crank thrust or deflection are more 'tolerated'.

I know that 'billet' is a common term, but it's frequently, and for some reason popularly mis-used... 'billet', from a metallurgical and manufacturing definition, is a 'raw' state, not rolled, just poured into a slab and trimmed to rough dimension... basically a shaved ingot.  Those main caps are probably much more- they've likely been cut from rolled steel, which is akin to forging, but rather by compacting through a rolling mill, it has a much higher strength than just a slice of 'billet'.

And a couple of question-ish comments...

You refer to 'conservation of energy'... you're not dealing with a drag-race engine, so many of the concepts found in that type of competition don't apply, and some of them are actually totally counterproductive.  For example, in a drag-race application, you can have a lightweight car, perfect gears, and incredible torque numbers, but an engine with too much rotational inertia will not be competetive because the engine cannot move through it's RPM range fast enough to accellerate well.  Furthermore, you want a drag-race motor to have a wide powerband, that is 'peaky' enough to give a good hard push at 'both ends of a gear'.  In a pulling application, there is no benefit to having an engine that can change speed rapidly... instead, you WANT it to hold it's speed... so having high rotational inertia is a GOOD thing.  Next, you want a powerband that will be strong from governed speed all the way down to the point where you'd spin out or kill it.

I'm perplexed as to why you'd use an inertial chassis dyno.  I think it'd darned near an international law that every third tractor show has a guy who brings his old M&W hydraulic PTO/Belt dyno... I know our local group (Deer Valley) has one in tow just about everywhere, and guys put their iron horses on 'em to see how well they're doing.

An intertial chassis dyno, for all respective purposes, tells nothing other than how the engine and powertrain fare with respect to accellerating a given weight of vehicle to a given speed.  Horsepower numbers are CALCULATED, not measured... so following the chassis dyno's data as a method of checking your work is misleading at best, and counterproductive at worst.  Really, the horsepower and torque figures of your engine are irrelevant... I think a better way for you to do it, is to find a 100' stretch of dirt, and find something really big to tie your tractor to, and then rig up a makeshift sled... and just drag it back and forth, throw some more scrap metal on it, 'till you can't pull it... then find a way to make it pull. 

MY test-sled is an old hydraulic press... came from a railroad maintenance facility, they used it to press wheels, brake disks, and bull-gears on/off locomotive axles.  It consists of about 12,000lbs of steel, sitting on a 6' square steel plate, and I've thrown another 1000lbs of steel scraps on it.  While it doesn't give me a comparison against an actual manned sled, it gives me an excellent frame-of-reference as to how my WC, WD, D17 and B pull, and of course, when loaded to limits, what the tractor's reaction to load IS... then I make corrections, and try again.  The only thing to keep in mind, is to keep ALL the pulling conditions constant, while making measured changes in just ONE factor, that way, one can correlate factorial changes to measured results.  This also gives a certain amount of guarantee that if failures are gonna occur, they occur in your backyard, rather than on the track.

mlpankey wrote: We have a test sled we drug it around Thursday before going to the pull on friday. We drug it thursday at a lesser rpm than we drug the sled friday because we had gov weights together holding the rpms down thursday . they exploded friday night and our rpms went even higher than we had ever seen them do to the tires unloading allowing the engine to see no load on friday. heres a calculator for flywheels. As for the chasis dyno being unproductive I wouldnt say that .I have yet to see a wide band meter you could hook to the tractor supplied on a pulling sled or a lab top maping timing curves. two things increase torque flywheel diameter and the engines power output. Now just when does the 300 lbs a piece tires and wheels 53 inches tall tires wheel speed affect torque. http://www.botlanta.org/converters/dale-calc/flywheel.html

Also having less friction due to less weight rotating on a bearing cross section will make a engine more throttle resposive and yet make more hp and torque also . It can even be seen in the valve train also when weight is reduced there as well . Weight increases friction . Friction robs power.

Under governed-speed continuous-load conditions, the flywheel diameter has NO effect on engine torque.  None.

Take that 12hp Kohler... get 10 ft-lbs at 2200rpm.  Put a flywheel on it that's 20' in diameter, get 10 ft-lbs at 2200rpm. 

Only difference, is that the POLAR MOMENT of the flywheel will limit the rate-of-change of rotational speed of the engine.  You're not shifting gears, or cornering through a tight racecourse here.

Now, if you compare the small and large diameter flywheel on a BRAKE-type dyno, and measure for a VERY SHORT TIME, the large-diameter flywheel will require more torque-load to change rotational speed, but this is totally irrelevant in a governed application... the whole point, is steadily increasing load under constant engine speed.

Best torque isn't necessarily coincident with highest compression... best torque occurs when you completely fill the cylinders.

Stretching it out by 5/8" relaxes the geometry substantially... draw it out on a piece of paper, and compare the difference in thrust angle between the rod and piston.  Now turn the assembly to the side, and imagine the crankshaft being crooked... and the deflection of the crank being 'taken up' by the connecting rod FLEXING.  With a longer rod, the amount of flex required to take up that deflection is substantially lower, so the fatigue point of the rod is much harder to reach.

To compare this to something totally different...  imagine being a short, squatty dude on a bicycle... where the bicycle has a HUGE crank.  Now space that huge crank WAY wide, and pedal it.  Pretty uncomfortable, as your hips and knees will be splayed way out.  This is what I believe is happening in your engine.

Now, take that short squatty guy, and give him really long legs... that splayed motion is now a whole lot less splayed.

You could have that block sitting on a granite surface plate, with a dial indicator, measuring an absolutely true crank in the block, with perfect tolerances in main and rod bearings, correct end thrust ratings, etc., but when installed in the tractor, with a sled on the drawbar, throttle open, timing advanced, and scads of wet fuel going into the chambers, that crankshaft looks like a jump-rope on a hot saturday sidewalk in Chicago.  Allowing for that to happen is an absolute MUST... 'cause if you don't, SOMETHING is gonna give.

ML - Not knowing your exact build-up.  In order to get a higher deck height, and use longer rods are you using a .25 - .375 deck plate and setting the sleeves ontop of the block?  - AL

DaveKamp, cool to hear somebody else owns a set of those books. Well I say owns, mine got loaned out to someone who moved away so they are gone now some 25 years ago. I lost interest and never bothered to replace them. Never thought I'd meet someone else who had them.

Yeesh. 3 mains and rods that should have "Briggs & Stratton" on them somewhere? That's too funny.

Mitch-  there's no replacement for displacement, but the one thing that can replace cubic inches.... is cubic money.

Yes, filling the cylinders, and doing it with a perfectly metered, fully atomized mixture of fuel and air... and then touching it off, and having proper chamber geometry to rapidly propogate the flame through the chamber so that maximum chamber pressure exists from 45 degrees ATDC to 135 ATDC, you'll get the greatest amount of torque.

A more rigid crank will help.  Remember, this is only a 3-main-bearing engine, and while that #1 cylinder is firing, #2 is coming up on compression, #3 is exhausting and #4 is taking a deep breath.  That means the FRONT span is flexing down, while the back end is flexing up.

And the note about balance is valid- the ideal configuration for a 4-cylinder single-plane crankshaft, is in an opposed configuration... a boxer.  An inline four can have good secondary balance (pistons going up vs. pistons going down) but the rods swinging right-to-left have different geometry from those spinning left-to-right, hence a 'primary' imbalance.


MD, you're spot on regarding the hydraulic droplet situation... and that's why I posted the excerpt above illustrating differences in properties of fuels.  Carbohydrate fuels (which Methanol and Ethanol are) have totally different stoich, vapor pressures, and specific heat, and the carbon-bond energy and effective flame speeds.  What makes them substantially different from hydrocarbon fuels, is that they're VERY likely to experience state-change under a rapid pressure rise.  Add to the fact that the primary advantage of nitromethane, is that you can dump in over 8x the LIQUID quantity in each power stroke.   At high mechanical compression ratios, that's flirting with a hydraulic lockup event.  Gasses are compressible, liquids, however, are not.

It's easy to observe the result- if you watch a top-fuel dragster in slow motion, you'll see a flame jump out of each pipe, on each successful firing event.  When the engine is idling, it'll miss on about every third or fourth cylinder... eventually, incoming airflow will clear out the cylinder and it'll fire again... and residual fuel in the pipe will barf a fireball... good to stay out of the zoomie's blast.  It's not until you get the RPMs up a bit, that the air-fuel charge velocity gets high enough to suspend the droplets and generate an effective burn, and once you REALLY have it going, you get a nice little blue/yellow 'bunsen burner' cone going on at the end of the shorties.  Reason for the nice pretty blue/yellow cone... only about half the fuel actually burns IN the cylinder... the rest goes out the stack unburned, because available oxygen inside the chamber, is gone.  One of the advantages of nitromethane fuels, is that there's enough latent oxygen IN the fuel, to allow it to burn, and it does... but it doesn't burn fast enough.  The unburned portion,  however, is superheated above auto-ignition temperature, so the moment that mixture hits open air, it incinerates, leaving that pretty flame.

Now, if you compare that flame to a sample of methanol that you place in a cup and burn in free atmosphere, you'll see essentially no flame... the burn cycle emits essentially all heat, and no visible light energy.  This is pretty dangerous territory, especially when there's a fuel spill on track or in the pits... crews could run right through burning fuel and not know it... at least... not for a moment.  Some additives will make a brighter flame, which is good from a safety perspective.

DaveKamp wrote: Timing curve, on a governed engine, is totally irrelevant.  When you set your advance weights, they're either in, or out.  Engine speed is either above (advanced) or below (retarded)... if you're operating in the interim range, you're not 'into' the fat of your torque range, which means you're done with your pull. Yes, friction of a bearing is relevant to cross-section, but only if you have physical contact.  You're running bearings that are hydraulically supported in a non-contact state.  If you get friction, you'll know, because your bearing shells will be in pieces in the pan. You're dwelling on details that, from a net output standpoint, are totally insignificant.  If you were to actually measure, and sum up ALL the friction, including wind drag and oil windage you'd find that, compared to your draft load, the horsepower consumed by friction is a microcosm of dragging a 2' piece of door-chain in the dirt behind the sled. The inertial chassis dyno is an irrelevant reference, because it does not apply a load- it relies on inertia of a spinning drum or disk to 'estimate' power.  If you were to put a Dodge Viper on the inertial chassis dyno, you might see 400-500 indicated HP.  Put a Kenworth road-tractor on the same inertial chassis dyno, you'll see 100 or so.  This is because the road-tractor's powertrain is geared towards pulling an 80,000lb load up an 8% grade... not accelerating a 2800lb load to 160mph in the shortest possible time.  You referred to throttle response.  In a constant speed, governed engine, there is NO throttle-response.  You start your pull... perhaps a bit light on the throttle, and then bring it up to speed... and as load increases, throttle opens fully, and STAYS THERE.  Throttle response is necessary for rally racing, where speeding up and slowing down is necessary to compete.  It's also required for shifting gears in a manual-transmission.  Totally irrelevant for a tractor-pull consideration... almost as irrelevant as throttle-response in a diesel-electric locomotive.  Ask yourself:  Is the engine within it's powerband? Is the throttle at Wide Open?  If either of these are "no", then you're either not hooked to the sled with the very immediate intention of winning, or most of your engine is laying on the track, in a big oil slick. The #1 determining factor of how well you'll do in ANY tractor pull, is defined by the amount of weight on your driven wheels, the diameter of your driven wheels, and the amount of drag induced (including drag which occurs from your non-driven wheels).  Once you've reached the limit of your tractive effort, the additional drawbar pull can only be increased by increasing wheel horsepower by an incredible multiplier.  That's the Wismer-Luth calculation:  http://www3.abe.iastate.edu/ae342/AE342_2008/Lectures/Traction.pdf So what this means, is you can take a 20,000lb articulating 8-wheel tractor, rip out the V8 turbodiesel, add about 40x more gear reduction, and put a 12hp Kohler underhood, and still drag that sled to full-pull.  If it's too much load, gear it down some more.  Yes, you can even chain the tractor down and SPIN ALL EIGHT WHEELS with a 12hp Kohler.  The drawbar draft will be enormous (about 7500lbs!), and all you'll have underhood is a single-lung thumpin' along at 3600.  What WON"T you get?  Easy:  You won't get FAST.  It'll take a week to get down that track... you'll want to use the whole fuel tank, and take turns at the helm, but the nice thing is, you'll be able to sit in there and eat dinner, watch a movie, probably take a nap. Harold (Luth) is a personal friend of mine, he did this study many years ago, when he was early in his engineering career with John Deere Moline.  This study wasn't done by proving a theory with casual tests, it was done by extrapolating formulae from empirical data... thousands of combinations of tractors, tires, draft loadings.  They used a test-sled equipped with an electronic strain-gauge and a chart recorder to log each one.  This was long before 'personal computers, but if I were to repeat his study, I'd do exactly the same, and put a couple of PCs in there to record the strain-gauge data, as well as measure the linear drag on the sled shoe, position of the slug, etc., simply because that level of data density is now available. Matter of fact, I have a few used 50,000lb load-cells (electronic strain gauges) lying around, I could send you one.  You figure out how to integrate it into your drawbar, or your favorite test-sled, and wire it to a common weighing instrument, and then come up with some method by which to calibrate it, you could measure drawbar tension as well.  Simply for the sake of competition relativity, you could just use it uncalibrated, and use it as your meter to measure draft results.

Dave, isn't the 12hp Kohler in the articulated chassis going "Around Robin Hood's Barn" as Dad would have said to illustrate mechanical advantage? Once you overcome the tractive limits, I don't see how adding more engine power, or increasing mechanical advantage will help. Speed helps by adding inertia. Once you start reaching the limits of traction, that's why there are speed limits in many classes, to limit inertia. 

Another thing about nitomethanol is pour some on concrete and stick a lit match to it the match will go out. Take a claw hammer and hit the concrete  where liquid is puddled with sufficient shock and if you have a arm and life left be verry thankful. It doesnt like compressive shock.

Edited by mlpankey - 26 Oct 2010 at 7:16am

We've all got our own ideas on how to build an engine, we all have a set of rules to pull by that dictate a max RPM, ground speed or some other limitations. Some of you feel that there is no replacement for displacement.  Far from true.  Is cubic inches, stroke length, rod ratio or  intake flow the most important thing to consider?   A fair bit of it will depend on your RPM or breathing (carb, manifold) restrictions. 

Edited by wi50 - 26 Oct 2010 at 6:47pm

mlpankey wrote: wi50 wrote: We've all got our own ideas on how to build an engine, we all have a set of rules to pull by that dictate a max RPM, ground speed or some other limitations. Some of you feel that there is no replacement for displacement.  Far from true.  Is cubic inches, stroke length, rod ratio or  intake flow the most important thing to consider?   A fair bit of it will depend on your RPM or breathing (carb, manifold) restrictions.    I feel that one of the single most important factors in an engines potential is the exhaust.  If the exhaust can't exit, where's the room for the fresh air charge? Makeing total refinement of the intake port, manifold and carbuerator less important than the exhaust.  Some of you have to run with the "stock appearing" manifolds while other rules allow anything to run.  A well designed and properly sized header will make more power than any other modification. Is engine size or displacement important?  Yes, but it's not near is important as good breathing ability, build an engine large, and it will only slow down to make it's power when the load comes on.  Build one a little smaller and it may well have more peak power, and it may make it at a higher RPM, or have better ability to maintain it's speed when the load comes on.  If I can build a 226 Allis to over 400 CID, will it make more power than one that is less than 300 CID? What about one built to 200 CID?  Chances are that the 200 CID one is jut to small, but the 300 CID may be "just right".  It can have a higer rod ratio that keeps from side loading the pistons, we can have a little more dwell time on BDC and TDC.  Some of you feel that dwell time is wasted time, but what about the ability of the exhaust to scavange the cylinder?  What about less wasted energy in piston accleaation and deceleration?  A higher rod ratio will increase these factors, as well as maintain a better angle putting less stress on the crank and rods.   What is compression ratio?  15:1 is as useless of a number as 11:1.  How full can I fill the cylinder?  How large of a cylinder and at what speed can  I fill ito what percentage?  A high compression ratio may be impressive, but it's like boost pressure in a super stock tractor, it's only an indication to how poor our cylinder head is.  If I could fill the cylinders to 100% capacity, maybe a 4:1 comp ratio would be all the engine could withstand.    What good is a verry large engine if it can't breathe well enough?  Sure the peak torque numbers may be high, but if the RPM is to slow we loose to much ground speed.  What is the difference in gear ratios to shift down one or two gears?  What increase in engine RPM do I need to be able to keep the same ground speed as I have in that higher gear?  In a lower one, my engine RPM can drop and I have lesser chanve in ground speed, also less stress on my parts.   I'm not telling anyone how to build their engine, but I see many factors that people forget when building them.   I'd like to share a couple past experiences.  My old 201 Allis engine ( we had to use the old WC-WD blocks for the WC-WD tractors or a D-17 in the D-17, I couldn't use the better D-17 block and crank in the old WC.  We have no RPM limet and no carbueration limets other than a single barrel updraft carb at the time, now there is no rule.  It's built to 268 CID, verry small.  There's a few things that could be improved on, maybe a bit longer stroke and a little less rod length but the combination of parts is a 4" stroke Leroi crank offset ground to 4.125", the rods are customized from a Perkins diesel engine and are at 9.1" length.  The bore is 4.5625 because I got a good deal on a pile of forged pistons with a verry low compression height.  I won't waste time on the block or head modifications, cam specs, etc. Comp. ratio isn't that high but it breaths well enough to make up for it. We figured out and built a verry good intake manifold, carb, and the exhaust header is tuned and sized to the engine the best a couple dumb farm kids could do.  I made a steel flywheel and a double disc clutch assembly with as much weight on the outer mass of the flywheel as possiable.  The whole unit was about 125# when finished, my thoughts were that once it was up to speed it would make up for some of the short stroke when the load hits.    I rember going to Iowa one night to run and there was an Oliver 88 there with (going from memory a 540 CID engine).  Supposidly at the time $15,000 in the engine from some big name machine shop and was unstopable.  I was just hopeing not to look like a fool with half the engine.  The Ollie made a full pull and was impressive.  I ran in a gear where I figured I couldn't spin the tires, just snuff the engine but I figured it was my best chances, but the dang thing made it out the end also.  THe other Allis, M's and 460's didn't.  We came back and the Ollie spun out, my engine wound up good and carried it but snuffed, 18 feet ahead of the Ollie.  Another night I was at about 180 feet when the spark plug wire fell off ( I had hit it with the side panel and knocked it off the dist. cap), by some stroke of luck we made it past the 88's, M's and the other Allises.  Lucky that night.  Then I rember a fella that traveled a ways one night and had some big HP numbers and a big displacement Allis, it spun the tires pretty well but the little engine ended up 80 feet in front   Comparing the Allis engines to each other we ran against some friends quite a bit, built to the same set of rules with headers, large carbs, etc. 380 or so CID engines, one was over 400 and there were a few in the mid 300's.  Not all the time but more of the time than not the little 268 would get further on the track.  I didn't spin the tires that often, it would usually snuff out but it had the ability to get higher groundspeed and maintain it for longer than in a lower gear than the others would in a higher gear.    In a limeted RPM type pulling this engine wouldn't be worth $#@! but when you could let them run it was tough.  I'd usually try to have it at 4500 RPM or so on the line, ride the twin disc clutch for a bit and it would usually rev around 6000 RPM, sometimes on the right night it would go well over.  Lug it under 3000 though and the fire went out quick.   I need to get it out again and have some fun.  I'm working on a D17 engine to have a little fun with for a limeted RPM and 4mph class, it's not going to be huge but with "stock appearing" OEM type manifolds and carb it can't be, or it will just be a dog.  I keep weighing out my options and running numbers to see what I want to do, but I'm thingking in the 300 inch range give or take 20 it should be "just right" to have some fun with and not feel bad about useing it a bit on the farm now and then.    How in the world do you think a header will help a 226 engine on the exhaust . Just a little secret At .400 valve lift the intake valve flows 143 cfm the exhaust flows 177 cfm . this is why I said in stock form the turbo for a 201 or 226 making 7lbs of boost would be the single most power adder one could do . Allis engineers realized to get torque they had to restrict the exhaust from being such more  free flowing .  If you cant get it in it then why worry about getting more out . Best trorque occcurs when the exhaust valve flows out  only 85% percent of what the intake lvalve flows. the piston and natural draw from a header tube or stack will take care of the rest. the single best way to get more intake flow from a head on a naturally aspirated engine is to increase cylinder bore.  I ran a 310 engine for several years the 360 392 400 plus inch engines most of the time beat it . They had a low rpm torque engines that meant they didnt have to have everything perfect to make a good run as one with a smaller less forgiving engine does.

also a piston cannot dwell more at both tdc and bdc. if it dwells more at tdc it will dwell lessat bdc and vise versa. I dont believe you run a 4.125 stroke with a 9.1 long rod either cause if you had a flat top piston with a 1.2 comp. height you would have .360 thousandth in the hole and with a 4.5 bore that would  be a high compression  engine . So is the pin up in the oil ring?  unless you made a deck plate then you made pushrods also .

Edited by mlpankey - 26 Oct 2010 at 8:02pm