Cam duration vs compression ratio


cam duration vs compression ratio Apr 12, 2003 · Posted April 12, 2003. 0:1 compression, dual plane intake, 600cfm carb, auto transmission 3400 pound weight 260°-268° advertised duration, 210°-220° duration at 0. Estimated Maximum Intake Duration Performance Note: We find that few street bikes actually need compression ratios higher than a nominal 9. also indicates dual valve springs. stock compression ratio engine, a camshaft with Crane Hi-Roller Cams are computer designed less duration is recommended. insyaallah Dec 07, 2007 · but sure can make a lazy off the line engine if mis-matched with low compression ratio or to big of a cam. Same motor but race prepped. 5:1 to 10. For example, no matter how much duration you have, a stock Model T motor is never going to turn 5,000 RPMs. It is very important to keep your combinations balanced; for example, you can not use a 270 degree camshaft with 8:1 compression. 2:1 static compression ratio, 300 degrees of advertised duration, and an intake closing of 58 degrees at 0. 8 so I can run a big duration cam. Re: Comp ratio vs cam duration. With "wild" (lumpy) cams, it is suggested that the CR be raised. The compression stroke begins when the intake valve closes. Each cc is about . 050" number when your cam is a brand like Comp Cams which typically only provides you with an IVC @ . com Compression Ratio: The true "measured" compression ratio is a very important fact in determining which camshaft is best for your combination. Adding that to the 10. 6 dynamic. The shorter the duration, the less air brought into the cylinder, which also affects Sep 29, 2020 · Longer duration cams cause the intake valve to close later reducing the dynamic stroke and as such the dynamic compression ratio. Improved ramp design results in low valve train noise. 472/. Oct 30, 2009 · November 2, 2009, 09:23 AM. ) is only one of several factors involved in determining how much pressure is developed in the combustion chamber. 00 geared, 4800 lb "lead May 06, 2016 · To a large extent, valve clearance determines the compression ratio because the piston’s valve notches account for much of the combustion volume. 3. Camshaft timing events must be directly tied to compression ratio. Widening their separation angle helps increase upper rpm power output. 040. Jan 28, 2006 · The more duration you add, the more compression you'll need and that combination will increase the upper mid-range and top-end power. This calculator is useful for finding out your IVC @ . 75:1 using the MG Metro cam (252 inlet/268 ex 108 LCA timed at 106) resulted in a Apr 22, 2021 · As an example, imagine a 350 small block with an 8. 25:1 voodoo 60203, 3:42 Posi GTA rims Dec 29, 2015 · If a street car has smaller lift and duration numbers, they might run 112 or 114. I would say that a 13:1 engine needs a cam in the 285-290 degree duration @ . Current carb type and size. 5-1 compression and a 350hp 327 GM -151 cam in it ([email protected], 114 lsa). Assuming your motor is somewhat "fixed" then this is the one area you can easily change. Oct 30, 2004 · That is why the cranking compression lowers when you install the bigger cam in an engine which doesn't have its cam timing and compression ratio properly matched. assalamualaikum dan salam sejahtera kepada pencinta ilmu pemotoran. 7:1 SCR. a mis-matched engine just never works out well. But we just learned on static compression ratio is directly related to stroke. 75 compression ratio advised. Meant for engines up to 96" and 10:1 compression ratio. With a good flowing set of heads, engines like this can easily make over 1HP/CID and 1+ft. Gross lift at the valve. I understand static compression ratio and that the dynamic compression is a result of the engine running and is higher, usually! Sep 06, 2021 · With stock 5. 450/. ratio should be Cam Timing vs. CID. 5:1 or higher, for 280* duration you gotta have 10:1 or higher, etc? Nov 05, 2010 · The static compression ratio can't be achieved in a high-revving engine with a long duration inlet cam. Nov 02, 2009 · Re: Comp ratio vs cam duration. 3000-5000 rpm. The V/P Index is 45. 050" duration needs to increase by 80 or 100 to obtain the same effective duration. I learned about the relationship between valve clearance and compression ratio back when we were building 287-cubic-inch Modified engines in the ’70s, and it’s a lesson that has stayed with me Nov 19, 2008 · keep in mind swapping heads gives you the option to increase or decrease the compression ratio of the combo, and once the compression ratios increased you can use a longer duration cam timing without sacrificing a great deal of low rpm torque, that you would loose with the lower compression ratio if the same cam were installed in the lower compression ratio combo For example A 10:1 compression ratio simply means that 10 units of air will be compressed into the space of just 1 unit. Mar 05, 2001 · Over and above the camshaft, I would like to take the opportunity to list the components that made this particular MGB a real pleasure to drive. A cam with a longer intake duration will reduce static compression pressure at low speed which in turn will tend to reduce low RPM torque. I do understand that when an engine It is most affected by the effective camshaft intake valve duration (usually measured at . 33:1 at sea level. 302 is bored . Nov 05, 2010 · The static compression ratio can't be achieved in a high-revving engine with a long duration inlet cam. Sep 06, 2021 · Compared to stock, hot rod cams have higher lift, more duration , steeper ramps to achieve this and overlap because of longer duration giving the great sound associated with a hot cam. If you put a mild cam in a 13:1 compression engine, the dynamic cylinder pressure might be equivalent to 15:1 with a larger cam. 25 compression ratio. Jul 11, 2016 · 350 S/B Chevy - 9. There are various DCR calculators on the web but there’s another factor at play which is much more difficult to pin down…. T-bucket might rattle it's brains out in an RV cammed, 3. compression ratio. Jun 11, 2008 · Thus a high performance cam with long duration should ideally be combined with a higher static compression ratio. 2 compression. The longer the duration, the lower cylinder pressure and working compression. Comp Cams has a good hydraulic cam for you, part number CCA-21-404-4. Effective CR is the term I use, others may call it something different. 050" lift Camshaft timing events must be directly tied to compression ratio. 050", LSA, and intake centerline. 5:1 would be a lot better. Bore size also plays a role. This means that a late closing intake point (with a long duration cam) reduces the engine’s dynamic compression ratio. 5 to 1 for cast Pistons) and yet compression is down due to cam duration. Once you have a cam duration figure in mind, attention must be paid to compression pressure. 5 to 1. 4 Camshaft Valve Timing Degrees Calculator Find out your camshaft's valve timing events @ . That cam has LOTS of duration for a 327 and a pretty wide LSA, it will rev to the moon with good flowing heads. (200cc ) the duration needs to be increased by 10 at 0. 500 doesnt flow more. Would I be better if my compression ratio is on the higher end of the suggested range (e. When we go back to the basics, the big increases seen with a combo of more compression and cam are easier to understand. It seems to be a border line ratio in between two cams in the line ups of most manufacturers. 006” as the value for calculating the advertised duration. 008 below the deck (flattop stock hyper pistons, stock valve reliefs) and heads are 60cc, gasket is about . 387 = 12. Aug 11, 2009 · Cams certainly have an effect on measured compression! It is the difference between Static Compression Ratio and Dynamic Compression Ratio. cam for up to 10:1) or the lower end (cams for 10:1 plus)? Apr 21, 2010 · Here is a real world example for you. 072/1. 050-inch lift and 110 degrees of lobe separation. Using a high lift cam with a stock or lower displacement engine may be an exercise in futility. 030 over 289, stock crank, flat top pistons with valve reliefs, not sure on thickness of head gasket, edelbrock e-street heads with 60 cc combustion chambers, 1. If a longer duration cam is selected you must raise compression. Of course the static compression ratio is a large determining facor in DCR too. For the record, most successful race engines run dynamic CRs of about 9:1, and a good street motor on service station fuel about 7. By removing 7cc that is increasing the CR by 1. 050 inch lift and a 110-degree centerline would be the maximum for your application. I do understand that when an engine Details: Long duration cams delay the closing of the intake valve and substantially reduce the running compression ratio of an engine compared to the SCR. Mar 27, 2017 · Proper camshaft selection is a combination of first and foremost, your experience coupled with the determined usage; engine displacement, compression ratio, fuel system carbureted or injected, RPM range power desired, transmission type/converter stall speed, vehicle weight, final gear ratio, tire height, cylinder head and valves, head flow Apr 01, 1997 · Many cam companies give a minimum and maximum compression ratio acceptable for a given cam in a noncomputerized engine. Too high a compression pressure will yield too high a peak combustion pressure and thus cause detonation. 14+ Other than that the tq/hp curves will look very similar against cams with less LSA. the 113. The bigger the bore the further the flame front has to travel from the spark plug and the higher the chance for detonation. of combustion pressure at peak torque. Dec 29, 2019 · "When modifying an engine, it is important to match the compression ratio with the duration of the cam. It's also affected by the amount of advance or retard of the camshaft. Nov 26, 2003 · AntiVenom brings the CR up to 12:1 on Z06s when doing head and cam packages by taking 7cc off of the surface of the heads. Both crank 150-160psi. 6 of the LS6 head it puts you right up to 12:1. Think about it this way: If you increase the cam’s duration so the valves are staying open longer, you are lowering the effective compression ratio of the engine. 216326 26H 11/35 102 226 262 . 1 dynamic compression ratio (DCR). 5:1, and you use a camshaft that is fairly large (increased overlap between lobes allowing both the intake and exhaust valves to be open at the same time) then you will bleed off cylinder pressure As a rough rule of thumb, you can look at this combination from the standpoint that as duration on the camshaft increases, you can also squeeze the static compression ratio a little tighter. A conservative camshaft needs a conservative compression ratio as well. Vehicle weight and transaxle gears Generally speaking, the lighter a car’s curb weight is, the hotter the cam’s specs can be. There are detailed explanations of this out there, and there are even software applications to show you how a certain cam might affect measured compression. Oct 11, 2021 · Second, as cams get more aggressive (bigger), they usually need a higher static compression ratio to support them. 150" deck height and a 2180) your compression ratio would acutally be about 10. Let's take another motor. If you have a lower compression motor, say 9. Where a 106 or 8 would fall to the floor, the wider lobes 110+ will hang on longer, but only with big compression ratios. Cams with greater duration will tolerate higher static CR; likewise, retarding the cam closes the intake valve later during the compression stroke, bleeding off volume (especially at low RPM where detonation has more time to outpace the expanding flame-front). but if u r at or over . The bigger the cam, the later, past bottom dead center, the valve closes and the compression stroke starts. This is determined by the interactions of the static compression ratio, the rod ratio, and cam timing for closing the intake valve. 4. 5-1 compression 350 with a 260 duration comp cams high energy cam ([email protected], 110 lsa), the other has about 9. It also offered a healthy at the time camshaft with a . If the compression ratio isn’t in line with the cam duration, the closure point of the intake valve, the dynamic CR, and cranking pres- sure, will consequently be low. Duration 212/218 lift 477/484 . 50:1 rearend gear ratio. Of course at higher rpms there is less time for the pressure to escape so it does regain some of its efficiency but remember that Mar 05, 2001 · Over and above the camshaft, I would like to take the opportunity to list the components that made this particular MGB a real pleasure to drive. The static compression never changed, but the effective compression surer did. Detonation can be cured by running the correct high octane fuel, reducing the compression ratio, adjusting for richer carburation, using cooler plugs, increasing the cam duration, adjusting timing, or a combination of these methods. 5:1. Compression Ratio. Of the variables, the most important is cam timing which has a dramatic effect on your "dynamic" as opposed to your static compression ratio. 050" to have the same effective duration. For every 10 CI. Rochester 2g with the number that you indicated above. 006" number . Specifically, the intake valve closing point is intimately related to an engine's dynamic, or "effective" compression ratio. When modifying an engine, it is important to match the compression ratio with the duration of the cam. 10:1 is about the upper limit to run on 92 octane and still maintain decent bottom end torque and vacuum pull. Now switch to a longer duration cam. The problem is created when too much duration results in lower cylinder compression pressures at low RPM which reduce the low RPM torque Fit a longer duration cam eg FK10 and you now find Static CR needs to be up around 9. They recommended going with relatively mild street cam like a Comp 260H grind, which has a . 050 to run on 93, and Jan 18, 2015 · Where I fall down is when static compression ratio is quoted as a maximum ( usually 10. 060 over 10. Quench area is important too. The increase in cubic inches demands an increase of May 06, 2016 · To a large extent, valve clearance determines the compression ratio because the piston’s valve notches account for much of the combustion volume. 460 Lift and 222 degrees of duration. Going from the stock 9:1 Compression Ratio to 10:2 is good for about 3% increase. See full list on crankshaftcoalition. A compression ratio that might work fine on the street in a radiclly cammed, 4. As there has to be some point in which you begin to measure the lift of a cam there are usually two It's important to be aware of a few ways camshaft lift is talked about. Feb 08, 2016 · A camshaft duration of 214 to 218 degrees (intake) at . It measured 232° on the intake lobe with the lobe positioned at 104° (the 041 intake is 231° at 112°) and 239° with the exhaust lobe at 116° (the 041 is 240° at 115°). Compression Ratio 9:1 * Roller Rockers 1. kali ni sy kongsi pengalaman berkaitan camshaft dan die punye charateristic. Now let's say the intake cam on this motor closes when the piston is half way up the cylinder. 5:1 or higher, for 280* duration you gotta have 10:1 or higher, etc? When modifying an engine, it is important to match the compression ratio with the duration of the cam. Compression to some extent is the smallest piece. Jun 08, 2021 · The ’32 Ford weighed in at around 2800lbs with a 350 cubic-inch engine at 9:1 compression, a TH350 transmission with a 2200rpm stall and 3. Duration - The time in which the valve is off the seat during tappet lift, measured in CRANKSHAFT degrees. Sep 29, 2020 · Longer duration cams cause the intake valve to close later reducing the dynamic stroke and as such the dynamic compression ratio. A number like 7:1 is common. The compression ratio (CR) plays a big part in how well an engine performs. Im looking for the most power on pump gas and no valve clearance issues, but Im not worried about road performance. It’s a How does compression ratio affect camshaft selection? The key fact to watch here is cylinder pressure. It featured a 9. Run on the Dyno in the stock configuration with long tube headers it produced 313 HP @ 5,400 RPM and 355 Lb-Ft of torque @ 3,800 RPM. Cam duration at 50. lobe seperation 110 compression height vs Oct 05, 2018 · You can actually raise compression if you’re running a mild camshaft profile or using a higher octane fuel. 6 More duration in a camshaft, both for the intake and the exhaust lobes, is usually useful for racing. 442/. The compression ratio is 10. Aug 31, 2018 · BTW COmp cams recommended 31-234-3 they said it was better to under cam than over cam. lb. 3-10. Originally posted by SpiderGearsMan. Jan 10, 2010 · This is because compression cannot begin until the intake valve closes. Camshaft Valve Timing Degrees Calculator Find out your camshaft's valve timing events @ . The problem is created when too much duration results in lower cylinder compression pressures at low RPM which reduce the low RPM torque If a hydraulic cam is being replaced with a solid cam, the 0. The resultant longer effective compression stroke always delivers a higher gauge reading. you need the duration to prevent detonation. 1981 Chevy monte carlo 396 BBC . With an engle 120 (anyone have an actual 120 cam card?) which I believe closes around 75 degrees abdc you are with in the range for 91 octane. Just like retarding a cam, a longer duration will delay the valve closing, which can lower cranking compression but will allow for greater cylinder filling at high rpm levels. Sep 11, 2013 · they brought into my shop its was very obvious (at least to me) that it was the combo of low compression, too little displacement, with too much cam duration , a restrictive exhaust or some guy who was trying to save money and continuing to use a stock stall speed torque converter, or retain a badly mis-matched 2. 508 CAM - 'The Grim Reaper' Aggressive pulling power with a "nasty" sound. Mar 09, 2011 · Cam timing plays into it as well. Compression Ratio . CR Compression Ratio 12. Filter types and location in fuel system. Advertised duration cam families vs static compression ratio's here. I don't have the exact figures to hand, but the gist for example is that for a static compression ratio of 9. 5:1 compression, dual plane intake, 550cfm carb, 4 speed transmission, 3400 pound weight 260°-268° advertised duration, 210°-220° duration at 0. 55:1 Part # 1. 050 lift, and . Since your pistons and heads are stock your static compression ratio is 10. The REAPER 508 grind will shine in 114" and larger cubic inch engines with added compression ratio. 050-inch plus 15 degrees equals a 73-degree ABDC closing point. lobe seperation 110 compression height vs At this RPM your motors effective compression is the same as the static compression ratio and the dynamic compression ratio is completely irreievant. Nov 27, 2014 · For a street cam ive always liked the mid 240's duration intake closing in the low to mid 40'slsa in the 107-110 range and overlap in the high 30's to low 40's lift well although as stated if the head is stock going over . 490 . Using the pistons advertised compression ratio can be very misleading too. The shorter the duration, the less air brought into the cylinder, which also affects compression. RFOR-234/450-8 2000- Compression must match cam duration. Feb 18, 2008 · Octane vs. I was wondering how a reground cam with the stock duration but extra lift would affect the performance of a motor, specifically if this would negatively affect the idle quality and low RPM power of a motor. 7 inch rods that would make a dynamic compression ratio(DCR) of 7. The more "overlap" your cams have, the lower your "actual" as opposed to your static compression ratio will be. A 1. and 14. 5:1 compression ratio, and a 280* duration camshaft, and an aggressive naturally aspirated-esque timing curve and decide to supercharge it for more power. Conversely, you can not have 10:1 compression and use Jan 16, 2015 · I have seen a 100-plus-hp increase from a 355-ci small-block Chevy with 25 degrees more cam duration, 0. so,, in his (Vizard's) example,, 10. That way the engine can benefit at high RPM from the maximized amount of intake charge afforded by the late intake valve closing, and still achieve sufficient compression of the mixture as a by-product of the dynamic compression ratio. 520: A replacement part for S&S emissions certified engines, this is a short duration emissions cam with very little overlap to reduce emissions of unburned hydrocarbons. cam duration and timing. 030 over, pistons are . More duration will drive DCR and cranking compression down, earlier ICL will drive it up, and later ICL will drive it down You absolutely cannot go by a shop manual for cranking compression on a modified engine. Apr 05, 2013 · On the other hand, if the long-duration cam does a better job of filling the cylinder at high rpm than the short-duration cam, more air and fuel will be trapped in the cylinder and the resulting dynamic compression ratio will be higher. [180], it was reported that the Miller cycle engine required the use of a supercharger. Optimum compression pressure is 160 - 170 psi, at least with old Pontiacs. 2 similar weight pickups, both nearly identical in all aspects except 1 is a 8. 5:1, so, using "stock" is a good way to make a bad mistake. As you see, the size and compression ratio increases still don't bring the motor back up to the stock figure when the cam is this hot - the V/P is down more than 6%. As there has to be some point in which you begin to measure the lift of a cam there are usually two Mar 16, 2010 · The first special cam (cam #1) was specified with a duration similar to the Pontiac 041, but with a tighter lobe separation of 110°, vs. 56 geared, 1800 lb. When Bigger Is Better Larger cubic inch engines work better with cams with increased duration and lift. 006 lift on hydraulic cams). Jan 10, 2004 · Doesn't Your compression ratio also have a lot to do with your Cam's duration? For instance: I have an edelbrock performer plus in my 302. Alternatively, if you are running a bigger camshaft to gain maximum top-end power, cam makers often suggest reducing the lobe separation angle to recover power lost in the lower rev range. AC 45 sparkplugs also # on distributer should be1110996. 0:1 would be 1400lbs of combustion pressure How does compression ratio affect camshaft selection? The key fact to watch here is cylinder pressure. ” Mar 27, 2018 · 3600 cruise RPM, 9. While additional cam duration can produce more useable power, to much duration can hurt the performance. / 1969-90 366 C. 0:1 compression ratio, cast iron 882 heads, and a Quadrajet induction system. 08:1 rear gear ratio, Jan 26, 2013 · Okay based on information you posted else where (33cc heads . The cranking pressure is 111 psi absolute (96 psi gauge pressure). giving it more compression minimises these losses. Using your values I do get the same 9. but the force created with the high compression is the means to burn more fuel and move more air=more power. The problem of knock, (where the air fuel mix prematurely ignites) is controlled to a large degree by the compression ratio. /CID with little worry about overheating, detonation and longevity. Later closing means a shorter effective compression stroke. To achieve higher engine speeds you must have a head and manifold that will flow freely and a high enough compression ratio. At this point, I could get the compression ratio higher to 11. 482 inches of lift with a 110 degree lobe center. 5° of the 041. 5:1 with proper engine components and good tuning. For example A 10:1 compression ratio simply means that 10 units of air will be compressed into the space of just 1 unit. I learned about the relationship between valve clearance and compression ratio back when we were building 287-cubic-inch Modified engines in the ’70s, and it’s a lesson that has stayed with me Dec 28, 2013 · I really don't understand the relationship between cam size and compression ratio. Hydraulic camshafts will typically use 0. 5:1 compression ratio, with my rod combo and cam choice gives me a dynamic of 8. I. 7:1 static compression ratio (SCR) and an 8. But with a longer duration cam and a higher compression ratio, power at middle and high speeds will be increased which is what you wanted all along. 1:1. Head Type and valve size. May 05, 2007 · A word of warning here though: short duration cams and increased compression ratios don’t agree as well. Depending on your compression ratio, either the XE274H (above 10:1) or the 275DEH/EX264H (below 10:1) should work well in a street application. 472 lift. 625-inch valves, and heavy-duty valve springs and 1. Apr 17, 2019 · The pressure is greatly affected by the timing of your valve events - i. Fuel Pump Brand and Size. Mar 11, 2017 · The 15H indicates the particular engine combination which is 389 CID with 10. comment: performance street cam, 9. duration means nothing on the compression stroke when both valves are closed. "Stock" compression in a Mopar can run from 7. 138 Stock Bolt-in cam 96–103 inches and stock compression ratio. 440-inch lift, 212-degrees duration at . Tags compression octane ratio. Apr 29, 2013 · As long as your static compression ratio doesn't go over 9. IMO not a very good choice of a cam for a street cruiser with a 2600rpm converter,relatively low compression and a dual plane intake. It is important for engine builders to seek out as much information from the customer on the build as they can. However the longer the cam duration is, and the higher the lift, actually lowers the dynamic compression ratio. Trans type (OD?) Max Shift RPM. Compression ratio is decreased from 10:1 to slightly less than 8:1 [181]. 100 more lift, and 2 points more compression. 41/09 106 230 266 . Inside the refined F-casting (H-1971 and Ga-1972) cylinder heads are 2. The cam spec we are interested in to determine the DCR is the intake closing time (or angle) in degrees. Camshaft: Actually camshaft size, which is based on duration, when the valves open and close, not lift. Conversely, if the duration is only slightly above stock, it’s going to be dangerous to squeeze much more than a typical 9:1 compression ratio without Nov 21, 2014 · The camshaft determines the engine’s horsepower and torque curves, so the cam has to match not only the application but all of the other components that go into the valvetrain, the cylinder heads, compression ratio and induction system. COMPUTING COMPRESSION RATIO Compression ratio is defined as the ratio Sep 15, 2018 · A genuine 10. Gear Ratio. according to the comp ratio calc my comp. 0:1, which gives about 8. 55:1/KIT * LCB Exhaust Header Part # EXL18 Free-Flow 2 inch exhaust system (Glasspack F18 front. e. 87:1-3. ratio should be The effective compression ratio is 5. Apr 21, 2010 · Here is a real world example for you. The #400165 cam was for the automatic-equipped W-30 and has 285/287-degrees duration with . High compression will increase horsepower regardless of the camshaft profile. Apr 08, 2009 · a longer duration, high overlap cam and richer and cooler overal fuel/air mixture will tolerate more compression than the opposite, for a given fuel octane. camshaft profile #0 not sure exactly duration , lift , lobe separation on that is but can find out. g. A cam with monster duration will bleed off some of the compression and allow you to run a higher compression ratio. Fuel Line sizes from the cell to the Apr 29, 2013 · As long as your static compression ratio doesn't go over 9. As an example, a stock Model T has a 4:1 compression ratio, poor air flow and a poor head design. a split-duration cam with 222 degrees intake duration and 236 degrees Sep 09, 2019 · I was thinking of running a compression ratio around 10. Apr 09, 2009 · How do I determine the compression ratio needed for the camshaft and piston/head configuration I have? Is there a magic constant that is used, say, for 260* duration, 9:1 is ok, for 270* duration, you need 9. Feb 20, 2013 · I used to use this with a grain of salt. 050" lift by inputting intake & exhaust duration @ . 464 106 114 Idle-4500 SMOOTH 817 B Oct 30, 2014 · Cam duration and timing will affect how high you can go, too. 9. Requires high lift springs and normal clearance Apr 03, 2009 · I think the cam has a lot to do with your engines compression ratio because a bigger cam will bleed off more dynamic compression. If advancing the camshaft 4°, here’s what the DCR looks like using the same combination that targets a 9. Jan 26, 2013 · Okay based on information you posted else where (33cc heads . 439 . As long as dynamic CR is between 9 and 11:1 the cam is appropriate for the application. In Ref. Nov 25, 2004 · I guess its the 10:1 ratio that confuses me a little. I have no idea what kind of compression ratio I have but I know its not very high. It’s a Thus, a high performance cam with long duration should ideally be combined with a higher static compression ratio. As far as I know, a big cam hurts low RPM power because the extra duration reduces the effective compression ratio It featured a 9. (CHAIN DRIVE) Hydraulic Flat Tappet Cams MC22127 HYD 2 192 202 261 272 . Because a rocker arm multiplies the movement of the tappet, valve lift is not the same as cam lobe lift. 60:1 shaft-mounted rocker arms were used. Cam Walk Valve Lift - The distance that the lobe of the cam lifts the tappet multiplied by the rocker arm ratio determines the valve lift. Your objective needs to be the highest compression possible without detonation, which harms the engine. 500 quicker or for longer due to ramp rate and total liftthen u will push out a broader power band vs a cam with only . Cam lobe lift, also called Gross Lift, is the distance a cam moves a lifter/tappet. 050" lift stock compression ratio engine, a camshaft with Crane Hi-Roller Cams are computer designed less duration is recommended. 0:1 static compression ratio would be approximately 1000 lbs. The increase in cubic inches demands an increase of Oct 11, 2021 · Second, as cams get more aggressive (bigger), they usually need a higher static compression ratio to support them. . 248/250/252 = 8 to 1; 258/260/262 = 9 to 1; (The 266 can go either way). Head flow if possible. Do you know the compression ratio ? Mac_49 Jan 18, 2015 · Where I fall down is when static compression ratio is quoted as a maximum ( usually 10. Conversely, if the duration is only slightly above stock, it’s going to be dangerous to squeeze much more than a typical 9:1 compression ratio without With a given static compression ratio, you will always have a higher reading on your compression tester gauge with a stock or low duration cam, because you will be closing the intake valve earlier on the compression stroke. 5 to 1, you will be ok on pump gas. This camshaft revs up faster than the 521 grind, sounds nastier and pulls harder but is more difficult to tune. Therefore, the real effective capacity of the engine is only 80% of the volume of the combustion chamber. This is why hard core race cams have explosive power bands. 5 to 10. This is a single-bolt cam. The wiseco pistons I got say that the valve reliefs are extra deep or what ever for the valves to clear. Dec 03, 2007 · I notice the wider lobe separation high compression engine holds on ALOT better to tq/hp past peaks. Sep 06, 2021 · With stock 5. 06:1. Feb 05, 2008 · Duration & overlap will affect the Dynamic Compression Ratio. Jun 26, 2019 · Sometimes people take a car that starts off with a 9000 rpm redline, has an 11. While additional cam duration can produce more usable power, to much duration can hurt the performance. Sep 29, 2013 · - I don't know your advertised duration and couldn't find a matching cam, so I estimated 274 duration and put it on 106. As far as I know, a big cam hurts low RPM power because the extra duration reduces the effective compression ratio Real compression is activated during the remaining 80% of the stroke. This will give you a DCR of half the SCR. 120 Great for two-up touring, this cam will add torque and HP at lower and middle RPM ranges. Convertor stall. However, at high rpm the incoming fuel/air mix attains such a velocity that it is able to rush into the cylinder unhindered despite the ascending piston forcing gas already in the cylinder upwards, and maximum possible compression is attained. 050" lift 302 Ford- 8. The proper method of selecting a camshaft is complicated and involves many factors including cam lift, duration, compression, and engine breathing. 0 V + Vcl Vcl NOTE: 1) Math reduction; /4 x 16. 5:1 rocker arm ratio takes . NOTE: Also modify the intake manifold to maintain port alignment. On that very same cam, if you narrow the lobe separation, the power band will come-on a little higher in the RPM range, but when it comes-on, the power curve is steep and brutal. More about compression ratios later. The second is the effective compression ratio, which the engine sees when the intake valve closes against the valve seat. Modifying the intake valve closure after bottom dead centre is a favourite trick of tuners and engine builders to sneak a bit more dynamic compression. My motor is a . 2:1 which is in the ball park for the cam and should run nicely on pump fuel with carbs etc. Apr 22, 2021 · As an example, imagine a 350 small block with an 8. Rocker arm ratio. This combo degrades the dynamic compression to a pathetic 6. It features 214/229 degrees duration at . 87 The precise amount is limited by block deck height, casting thickness, valve-to-piston clearance, etc. 5:1 compression, 2000+ stall convertor CHEVROLET Big Block V8 1967-95 396, 402, 427, 454 C. 5 to 10:1 to achieve a dynamic CR close to 8:1. Compression Analysis; The experienced engine builder (Harley-Davidson, Mopar, or Ferrari) knows that the “advertised” compression ratio (suggested by the owner’s manual, piston manufacturer, etc. Car weight. cam duration vs compression ratio

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