engine masters 2006 - more power from any engine

8/3/2019 Engine Masters 2006 - More Power From Any Engine

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15 DEASORSOUEEZINGMORE ORSESFROM OURMOTORTEXT AND PHOTOGR/qPHYBY JEFF HUNWCUTT

e've all heard about the three inevitabilitiesin life: death, ta:


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No mafterwhatengineyou're unning, hereare hingsyoucandoto up he powerante.AlthoughCtementsRacingEngines on'trevealatt the specsonits 800hp,400ci, ll -atuminummonster,manyof the ricksusedhere canbe usedto get morehorsesfromyourmi[[.

ENGTNE ASTERS.WINTER 2006


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we are freeing up horsepower by reducing friction, don'tforget roller rocker arms. These are common at mid-toupper levels of racing. If you're racing in a Super Stockclass,check to seewhat you're running. Goodroller rock-ers can add as much as 10hp at the upper rpm limits.

ans fake. But when it comes to motorU that can be made are real. You needmineral-basedoil in a new en$ne in order to get the ringsto set.After that, don't let anything except premium-blend synthetic oil get into your en$ne. Synthetic oilslubricate better at lower viscosities, hold up betteragainstheat, resist gummingup, and iust plain workbetter. Back-to-back ests on rnengine dynamometerwith an engine that has already been broken in showeda Shp gain in synthetic over mineral oil, at the sameweight.The superior lubricating properties of syntheticmotor oil will often allow you to move to a lower weight,but be careful here. Before changing weights of oil, besure to check with your engine builder first.BIG ORE,HORTTROKEMost classes imit maximum displacementbutsay little in the way of bore and stroke limits, sowhat do you do? Many enginebuilders are pushing thelimits of big-bore,short-stroke engines.A race engine sa big bundle of compromises;but, if handled correctly,utilizing a bigger bore can have several advantages.First, a bigger bore helps reduce one of the biggest

limitations in a two-valve engine: valve shrouding. Beforethe air/fuel mixture can move down into the bore, it hasto move out to get around the valve. If it hits the cylinderwall as soon as it moves past the valve, flow is limited.It's better to have more room between the valve seat andthe nearest obstruction.Another advantage comes from shortening thestroke. Because the piston travels a shorter distance,piston speed in a short-stroke motor is slower at thesamerpm. On the power stroke, this translates into thepiston spending more time in the top inch or two of thebore-where power is made. Shortening he piston travelalso reduces the area of cylinder wall that must bescrubbed by the ring package. Reducing the contactbetween the rings and cylinder wall means ess friction.Finally, given the same deck height, shortening thestroke means you can stuff in a larger rod. A higherrod/stroke ratio reduces the maximum angle betweenthe center of the rod journal and the center of the wrist-pin when the piston is centered between TDC and BDC.This reduces the tendency of the rod to try to push thepiston into the cylinder wall, also reducing friction.There is a limit, however. Generally, increasing therod/stroke ratio pushes the powerband higher in therpm range. f you push the ratio too high, the enginewilllose all responsivenesscoming out of the turns.

ENGTNE ASTERS.WINTER 2006

Rol]er cam/tiftercombinations equire ess energy o turn and canalso ake advantage f more aggressive am-tobeprofitesnot possi-bteon ftat-tappetcams.

A stock carburetor rom the major manufacturers s going o begood ight out of the box.Raretywitt it beperfectuntess t getsa lit-tte TLC rcm a goodcarb uner.

DIAL OURARBURETORFewareasof a race en$ne can limit potential morethan a poorly calibrated carburetor. It goesbeyondjust chan$ng the jets.An outof-thebox carb will workadequately,but to really makesure it feeds ust the rightamounts of air and fuel to the cylinders, it needs a lot ofTLC from a capable carb tuner.The first thing a good carb tuner will do is blueprint theentire assembly.No matter how high the factory's qualitystandards, a mass-produced product will have limits onhow tightly tolerances can be held. Becausea carb tunerdeals with each carburetor on a caseby


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signal without blocking flow too greatly. Finally,good gainscan also be found by working on the butterflies.They mustshut completely, et still allow the right idle rpm in order forthe engne to havegood torque from the low rpm.MINIMIZEOUR AINSYou can lower the friction between he rod mainson the crank and rod bearingsby reducing the sidediameter of the mains.The stock rod journals on a Chevy350are 2.100nches,but in Bow-Tieequipment, hey arereduced to 2.000.Aggressiveenginebuilders have beenpushing he limits in stock car racingengines o the l.gggHonda ournal size.Reducing he sizeof the journal reduces he amountofbearing surface, which reduces the associated riction.Cuttinga maindown from 2.100o 1.888may not sound ikemuch, but multiply that eight times for all the connectingrods, then multiply that number by your average racingrpm. Now you get the picture.

Smallerbearingsalso have other benefits.They requireless oil to lubricate properly. Everybody knows the oilpump is a big sourceof loss of power to the rear wheels,so any chanceyou get to dial down the oil pressureshouldbe welcomed.A third benefit from this tip is that rod mains also meanthe big end of the rod can be smaller.We are now talkinglessrotating weight and more clearance nside the block forstroker applications.The advantagehere won't necessarilybe big numberson the dyno, but you will feel t on the trackby how quickly the engine responds o the throttle. Thereduction in rotating weight and friction translates nto anengine hat will spin with greaterauthority.

r ffi:ff:i["ffi]*tfl:"of the fan pushing air around makes or a pretty goodworkout. Now,picture that fan on the front of your en$ne.The energy required to turn the fan is the same hing amechanical adiator fan is doing to your engine.Air mayseem thin when you're sitting in your LaZ-Boy watching

Monday Night Football,but at 2,000 pm, it's a viscous,power-robbingsyrup. Now imagne someoneoffered to puta second motor under your hood. you'd take it, right?That's exactly what an electric radiator fan is all about.Electric radiator fans completely remove the task ofpulling air through the radiator from your racing engine. fthe race is short and you can get away with using just thepower from your battery, the elbctric motors that powerthe fansare freeenergy. f you're competing n longer racesand must use an alternator to keepyour battery from goingdead,you're still doing better than using a mechanical an.A secondarybenefit of electric radiator fans s efficiency.The fans mount directly to the radiator, and their closeproximity to the unit means much more air is pulledthrough the radiator instead of around it. This also meansyou don't need o build a fan box-which makes t easier oget to the front of your engne while it's in the car. Hey,that's not a power tip, but who can't use a few tips on sav-ing time and energy?

g 'il#il:l?:,n"ffil?"nare perfect from the foundry, and unlessyou're buyngCNCpiecesof art, your cylinder headscould probably usea little work with a carbide bit to ensure he airlfuelchargemakes t to the combustion chamber as efficientlyas possible. t'snot just about getting the most flow possi-ble. A good port job takes the fuel,as well as the air, intoconsideration.The fuel has to stay in suspension f it'sgoing to burn properly once the spark is applied, so agood intake port is built to ensure he fuel doesn't sepa-rate from the air. The most common methods used are asfollows: shapingthe short turn so the air doesn't slow toomuch before entering the chamber,and designingbound-ary layer turbulence so there aren't .,dead"spots againstthe walls.When going to all this trouble to build the perfectcylinder-headports, don't forget the intake manifold.Tous, the manifold and heads are two completely differentparts. But racing fuel, once it's mixed with air inlhe carbu-retor, does not differentiate between an intake manifoldrunner and an intake port. There is, however,a rough tran_sition between he two. So when havingyour headsported,consider the entire path from the bottom of the carburetorall the way to the valve seat.

-f :,T"TH*"$mesofar that good engne builders are beginning o tailor theirseat designs o match the ma:


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HighJift en$nes, those reaching0.750and over,may ben-efit from steeper seat angles. This is because during themajority of the time the valve is open, it is an appreciabledistance off the seat. Because of the distance, the air/fuelmixture doesn't have to bend as much to get around thevalve. In this situation, a valve seat around 5f55 degreesmay improve flow into the chamber.The other angleswillalso be steeper,and you may simply want to subtly blend inthe transition between he port and seat by hand. Be awarethat a steep seat angle ike this causes he valve to poundthe seat.Even with hardened seat nserts, they aren't goingto last ong.Lowerlift engines (engines with less than 0.500 lift)may see a differencewith shallower seats.The oppositereasoning s true here. Low maximum lift means he valvespendsmost of its time near the seat, and the incomingair/fuel mixture must travel around the lip of the valve toget into the chamber.In this situation, a seat angle from40 to 45 degreesmay help flow. The trouble here is thatthe angle may direct air straight into the chamber wallsand actually increaseshrouding. t can work, iust not inevery case.

GET BSTANDPWe're on a roll with the valvetrain, so here'sanother idea that will make more power withalmost any enginecombination.Straightervalves improve air/fuelflow into the combustionchamber.The reason s,as the valves are angled ,straighter (parallel withthe direction of pistontravel), the pressuredcreated by the piston moving toBDCacts more equally all the wayaround the valve. For a primeexample,pleasesee Chewolet's23-degree eads versus its higherperformance l&degree heads.

On an angled valve (moving

sure drop pulls the air/fuel mix-ture mostly through the bottom of the valve (the areaclosest o the piston) because t is in a straight ine. Thepart of the valve that is angled away from the bottom ofthe cylinder does not flow as much of the air/fuel chargebecauseof the convoluted path the mixture must travelto enter the combustion chamber and move down intothe cylinder.The moral of this story is to keepa minimum angleonthe valves. For any given head, anglemilling, when donecorrectly, is almost always an improvement.This processnot only improves the valve angles but reduces chambervolume and raises he ports.E ENG,NEMASTERS.WINTER 2006

thelineofvalvemovementmore@torcoo1ingthentvesif i f f isBFWtowarderpendicuraro he ine ;ffit1,i:',I:It;,'il,',tlT:l:iH'i:ililltltiiillilJof piston movement), the pres- bodyofherocker.

Engine oatings re still beingdiscovered s retiableways oincrease nginepower.The bonus s that specialblendsare beingproducedoday hat can be retiabty pptiedby he builder n hisown shop.

YOUR OAT,IREnginecoatings are only recently becomingacceptedby the majority of enginebuilders,sothe scienceof coatings or raceengines s still on the steeppart of the learning curve. Coatingscan serve many pur-poses:Friction reduction, heat absorption, and heat deflec-tion are the most common usages,but there are also otheruses such as chemical resistanceand the all-important"looks pretty" factor.Since he first three are the ones thathave to do with making power, hose are the only oneswe'll deal with here.Friction-reductioncoatings can be used in a multitudeof places inside a race engine. Mostcommonly, friction reducers arefound on the pistonskirts and bearings.The best ones not only

reduce parasitic lossesbut also protect partsfor a short time in theevent of brief oil starvation. Heatabsorbers and deflectors can beused strategically hroughout theengine to keep hot things hotand cold things cold. A goodexample is coating the intakemanifold to insulate the incom-ing air/fuel charge from beingheated by the block or exhaustheaders. Headers, meanwhile,can be coated to retain the heat

so temperaturesdon't get so hot inside the engine com-partment that the carburetor, electrical system, and othersensitivepiecesdo not becomeheat soaked.I l|l GrvE'EMHEHAFrlz*::ffi ::1lff,Ti:"li-l#v,l"

systems and racespecific shaft systems.The sameholds truefor both systemson new heads.Shaft-mountedocker armsare nherently more stable than their stud-mountedbrethren.Whenyou factor in a combination of high rpm alongwith allthe variables hat comewith time and wear. a shaft-mounted


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systemwill definitelypreserveyour power longer.1 . ,I -t ofagood itf U justensureyour oil pump gets adequateoil flow by gatingoff thesump. They also makepower.A good racing pan isdesigned o get oil away from the crank and keep t away.Oil, Iike water, offers more resistanceas you try to moveit. Imagine umping off the high dive and hitting the waterflat on your back.Yeah, t hurts just thinking about it, butthat's the sameeffectwhen any part of your crank makescontact with oil splashingaround in the bottom of thepan.A point on the outside of the counterweight of acrank spinning in excessof 7,000 pm is moving at around170mph. Any oil it contacts will offer a significantamountof resistance.That's why good racing pans havewindagetrays designed o scrape oil off the crank and big hckoutsto keep t away once it's off. The kickouts, or wings, n apan serve a few important purposes: hey keepoil awayfrom the crank; they increasevolume while keeping hepan shallow so the en$ne can sit low in the car; and theyincrease he surfaceareaof the pan,which increases tscapability to cool the oil.Manyracersconfuse he purposeof the largevolume builtinto a racing oil pan. It isn't to hold extra oil so the oil tempstays ower.That only bringsthe oil levelbackto stock oil panlevels and introduces windage.The extra volume is to keepthe oil in the bottom of the pan and away from the crankWhen comparedto a stock pil, o good racing pan can makea dozenhorsepoweror more ust from reducingwindage.LET HE PARKSLYModern racing engnes are continually push-ing the maximum rpm envelope.More rpmmeanhigher gearratios, which meansbetter mechanicalleverageat the rear wheels. That's a good thing, but higherrpm also mean he electrical systemhas less ime torechargebetween spark-plug firings.Many stock classesrequire stock ignition systems. Formost racers, hat means unningsomeversion of an FIEI.AntlEI (Fligh-Energygnition) is a good,simple ignition for low-rpm street cars,but it runs out of power around 5,000 pm.Whenthat happens, t simply cannot provide enoughspark

to properly fire every cylinder at the right time. The resultis the same with any overmatched ignition system-theen$ne simply seems to "lie down" at the end of thestraights. If this is one of your problems, consider upgfad_ing your ignition system.COOLPRINGSWith racing engnes pushing the rpm limitever higher, the weakest link has becomethevalvesprings. They are required to be super strong to keepthe entire valvetrain under control at extreme rpm withoutbreaking or even losing pressureover time. you can helpthem do that by makingsure they stay cool. This is especially important in dry-sump en$nes where you are pulling

Oit quirtersn hentve coyers hoot steady tream fcooting ilonto hewtvespringsokeephemwithina reasonableperatiigtemperature.a lot of vacuum throughout the block and inside the valvecovers. Now,any cooling oil that reachesthe springs isquickly sucked off and pulled back into the oil reservoir.Useoil squirters to makesure a steady stream of coolingoil is showering your valvesprings. The conventional routeis to use squirters built into the valve covers. They are rela-tivelysimple but require an extra line to run from the pumpto the connection on the valve covers.A simpler route is touse special rocker arms with a built-in squirter. These arespecial shaft-mounted pieces that receive oil from thepushrod and use t to lubricate the shaft.Asmall hole drilledinto the body of the rocker allows oil that's pumped inaround the shaft to squirt out and onto thevalvespring. Thisdoesn't provide quite the coverage hat valvecover systemsdo, but it still works verywell.This tip doesn't translate directly into power,but you canuse its effects to makemore power. By helping your springsstay coolea they will last longer.Now you have lessconcernabout losing power due to a spring dropping its tension.This can evenallow for a more extremespring selection.Ell

ENGTNEMASTERS WTNTER2006

engine masters 2006 - more power from any engine

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