Show HIGH SPEED ENGINE SCORt t w. w REPRESENTS AN AC ACHIEVED HI EVE ME I r. r r of or 3 I yBy i IS AN AMERICAN OJ By Merle Shepard j 5 I 4 much has haa been said sHill lately latch on the I SO S subject of or high speed engines that I k it is Js interesting to noto nolo how the characteristics of or an engine e of or this typo type differ from Crom rain those of or other engines In the early lays days of or the automobile tho the engines In use were large in bore hort and j slow In speed with a no strong resemblance resemblance j blance to the iho type of oC power plant used I for stationary work In fact tho the do- do designs de do- 81 signs of the tho engines used d for tor motor cars Cir I worn were simply simp altered stationary power fIIlL plants liLli When hen an engineer of or tho the present lily day sets nets lB out to hn nn un crl ermine which will carry a 0 car of given wel weight ht over tho the road at r reasonable speeds anc and with economy the first thing that he ho settles upon upon- Is Js the tho amount of piston displace displace- ment lie Hi- knows from pi pst t experience that it will lake a a. certain amount of ot I displacement to secure a n certain I amount of or power and ho he also knows know that ho must have a 0 certain number of horsepower to meet the requirements of ot ofa ota a certain weight of ot car After Arter this is determined tho the bore and stroke aro arc fixed and it IB la becoming general practice tice on average a size engines to have ha the stroke somewhere n near Rr 17 Um times 8 the tho bore This of or course varies varle with different factories but hut tho the r relationship is Iii most often quite close to tho the figure given It was wan not many years ars ago when there were wro quite quit a few tew engines engine in American cars car In which tho bore and anti stroke were equal Tho The last of or these has passed awa away r. r and the Ion long stroke to bore ratio has become the accepted accepted ac no- practice GAS PASSAGE CLEAR In order to meet met the demands for tor the high speeds It Is necessary that tho the gas tas passage through which the Int intake ke keIs gas gasIs gasis Is drawn into the cylinder cUnder nn and the exhaust exhaust ex ex- cx- cx haust tas 18 expelled from it shall be as IlS I large as WI possible In fact tact on some Bome of or i tho the latest cars curs designers have haye even gone gono so 80 far tar as to use use- two Intakes an and two exhaust valves ahe per cylinder to secure the greatest possible openings opening The Tho majority however content themselves themselves them them- selves elves with one intake and one exhaust to toach etch ach cylinder cUnder On our present day high speed peed en engines englad en- en incA glad the intake Ja gases e pass through the intake manifold at speeds ds of about feet teel per second The manifolds an and the tho gas passages are as free from Crom sharp bends s as a possible and it has hRS b beets been n a point mint o of design that has been ben beneo very eo carefully studied in the tho past year or two to make mako these ports a. a as free from restriction and interference with tho the passage of ot g gas as possible It Jt has hR been figured that in order to have o the engine elop develop Jt its maximum I horse power at about r r. r p. p m m. It ItIs ItIs Is necessary to go as ns far tar as a. possible in valve sizes J. J For or instance if It an engine en engine n en- gine has bas a cylinder er with 3 4 33 34 in bore boreI and four our valves each ach 1 4 3 In diameter were used ed the tho engine would probably I be he ablo able to develop clop its maximum horse horsepower horsepower horsepower power at 1 about r. r p. p m m. if It all the ports portH and the combustion chamber were properly designed and the thenIe valves nI had hada a n. lift of ot about 16 5 In in- in that J is K ever every time Urno mo tho the valve aho was lifted from Its ts s seat at att It t would rise a distance of or 5 16 16 in Another very important consideration in tho hJ high h epe speed engine is the tho amount f l' compression flon When the tho piston is at atthe tho the top of or Its stroke tho the combustion chamber space is J generally ner t about 18 IS to 20 O p per r cent of ot the total volume of ot the cylinder Compression p pressures are arc generally given In turns of or pressure that is Is pressure above ahot zero and with a n combustion chamber of ot the size mentioned the compression pressure pressure pres pres- sure would b be be- from 75 to 95 pounds per Ier square Inch absolute The better tho the shape shapo of or tho the combustion chamber the better tho the characteristics of or the high speed cn engine ln It should be free from pockets where dead gas can gather and should closely I approach a hemisphere in shape The moro morn nearly th the tho combus- combus Uon tion chamber resembles a ht Bernie with the piston at the basis of r hemisphere the less the a amou heat that will be thrown away c the tho cooling water It ha has a i lJ been e er I l through columns column I that tho the lass Ins to the cw ee I water represents a as much as at 30 t f t IH per r cent of ot the power which Is pu rl pi the tho tank In th the form of or gasoline t MOVING PARTS IMPORTANT With Uh th the engine laid out as rl the stationary parts par are art concern concerns the above manner the first step wards securing a a. high sp speed e en ln has been ben accomplished Th The Tho mo me parts partH are th the next step and even the tho best of or design of or cylinder and ports the thc high speed will not be reaL unless s the parts aro also In with tho r requirements high speed KJ Probably the most Inn imI ant consideration of the these moving mo T I 1 is the tho piston Various materials material used for tor the manufacture of this C Cost Cast Iron steel el and aluminum a s aaro aaro sare aro are tho the most frequent Cast Iron Is the cheapest an am eaR easily 11 cast to shape but when made very cr lI light ht the walls wall are arc so that tho the pistons are f easily broken iron pistons therefore fore when j r strong are only medium weight an an- of or the lI lightest ht t weight possible pistons are very eo expensive because must bo be manufactured by mach processes which aro oro lon long lone and a e Aluminum alloy pistons aro light t also have a great eat many followers believe that the best results can b cured with them Others Other how equally equall Important favor the cast cat At any rate to secure the highest Bible sible speed from Crom an engine tho the pl pi aro are made madeS as S light as possible Conn Connecting rods rod also must prim bo be light but it is II every very bit as Im Imant imant ant that they should be stron strong A explosive e forces of or the t gasoline asoline be transmitted through tho the conn rod Very high grade alloy steel used for tor their manufacture an and material is generally refined PO so U In III possible to suspend awe ave Ight of ot pounds on a square Inch st H strod strod rod of oC this material without has in material suffer any permanent di dl tion CRANKSHAFT LIFE OF ENGIN The crankshaft is of course courBe tb tho of or tho the engine It Is the part T F transmits the t explosive force torce Into r Jn lag ing en energy rS' rS and therefore It must I 1 I good as it I is possible to make mak I I should be stiff and of or liberal dimes and should also be carefully bah bala because of unbalanced forces Corces at sos s Sj s o-s high as r r. r p. p m m. Is 15 to e II e vibration which is very to the driver er and also which sho the tho life lite of or the en engine ne In the tho valves the best possible must also be bo used Tun Tune steel is favored ored b by man many other using different alloys an and some iron The thickness of or the valve 31 will depend very much on the ma nu used These should also alCo be bo of or weight so that it docs does not take a a. amount of or effort erfort to open them a al that they close quickly enough h t plow t. t low 10 tho shape of ot the earn cam The Tho springs should be bo so laid out as aa to the work of or operating the valve e aas a a. aas as possible nn and at the same time them close quickly enough h so Uta tha true shape of ot the cam earn Is follow tho the valve alve me mechanism Ver Very oft happens ns that the tho cam will run from the follower when high speed spero LUBRICATION THE SAME The Tho question of or lubrication ant and Uon tion are aro tho the same with high sp spec e sines as 88 the they have been with the 1 speeds except that the they are arc Intents On account of ot the tho he- he high speed pt d pre feed teed oil has hIlS increased ns as it is more mort taint tain in the thc maintenance of ot the tho oil oU Continued d on page 7 1 HIGH SPEED ENGINE Continued from Crom page pae 6 6 The quality o of the oil is alt also highly highl Important Important Im Im- in hl high h speed work as the str sPy ps on the the- oil are arc much hl higher her What hat We wo have h learned on the racing tractor can an be applied vcr very well wen to stack Mock car design where high speed en enInes engines en- en glues gines Ines arc are u used d It Is necessary of oC course to make mak man many modifications so as to make male the engines durable and also to mal make them capable f t economical jauntily e manufacture Therefore on the stock engines we would expect to see tho the bearing surfaces lau laner el than on racing cars the moving mo parts E slightly heavier ler and the parts like conn connecting rods not machiner all over as they would hE be In a a- racing car It becomes i a t compromise between high output of power from Crom the engine and durability with economical manufacture an Important important im Im- consideration William J. J Cowan formerly with Skeen fe Skeen attorneys has has haa opened offices at Walker Bank build building In InA A |