Dynamic compression ratio octane chart. Came up with a static compression of 8.
Dynamic compression ratio octane chart. 5:1 compression on 93 octane.
Dynamic compression ratio octane chart For any given compression ratio, there exists a minimum gasoline octane requirement, as shown in the chart shown at the right: (ref: Advanced Engine Technology by H. e. _____ Apr 3, 2010 · Pulled out my cam card while in the shop today. 61:1 . Therefore with the mild cam it will have a high dynamic compression ratio, probably 9. 95 PSI. Octane levels of gasoline have dovetailed with these increases. I did it back to back, same day. Nov 10, 2020 · We’ll assume you are running a 4. 75:1 for a twin cam to about tops. 0 to 1 supercherger compression ratio I could run 91 octane or pump gas. Feb 18, 2009 · Your compression ratio won't change, but your compression pressure will. 052 without any shims. After that time, the average compression ratio continued to increase due to advanced engine design and controls, diverging from the octane trend. The formula for calculating your exact Final Compression Ratio is as follows: Final Compression Ratio (FCR) = [(Boost/ 14. , cam timing, altitude, and boost of 0 PSI is 7. Your effective boost compression ratio, reflecting static c. My current build is at 8. Union 76 site has a chart of how many gallons of 100 to mix with x gallons of 93 to get x octane May 8, 2009 · Like cam intake valve closing point and Dynamic Compression Ratio stuff for starters. 31:1 . Your dynamic cranking pressure is 167. If you can't find some of the numbers, just leave them as is. Your dynamic compression ratio is 8. 15:1 C116 oct. 5 degrees ABDC, yielding a 2. 8 cc These combustion or clearance volumes are required with each cam profile to reach the appropriate dynamic compression ratio. 1:1 on 87 octane with slightly less duration and I have 70,000 miles on my DD 1776/67 Bug. 75 inches. 2:1 Your dynamic compression ratio is 8. That's why, when we talk about the best compression ratio, we should focus on the DCR and not on the static CR. Which I believe mine is around 14. Here’s an example of a 350 with a 10. 05 inches. Should this be safe on 91 octane at sea level? Thanks for any insight! Nov 14, 2011 · I run the 525sc blowers with 3. 9mm & 14mm Pulleys; Final Compression Ratio Chart This chart shows the final compression ratio combining the static compression ratio of an engine and the maximum blower boost from the blower system. Your chart above says I should be able to run 87-89 octane. setting up proper dynamic compression ratio) will usually run just fine on 87/89 octane at 9. vs. Static compression ratio is affected by multiple variables including crankshaft stroke, piston-to-head clearance, head gasket thickness, and piston valve reliefs (if present) or the presence of a dish or dome in the piston. 0 12. 5:1 compression on 93 octane. Oct 14, 2015 · Thant being said I was using the Wallace Dynamic compression calculator. if compression ratio is more than 12, I need 96 octane, but this is for cars. Re: 427 BB: Maximum Compression Ratio on 92 octane 09-16-02 01:17 PM - Post# 124884 In response to toro455 here is the KB Spec page with your piston (176). 37 PSI. To see what the effect of bore, stroke, rod length, cam timing, compression ratio, boost pressure and altitude is on your dynamic compression ratio, simply enter the seven variables and the calculator will display the results in a new pop-up window. . 5:1 to 8. 0 13:0 The higher the final compression ratio, the higher the octane rating of the fuel must be in order to help prevent detonation and serious engine damage. Again, this is because the amount of air/fuel compressed by the piston in the dynamic situation is now equal to the amount compressed if you simply calculate the compression statically -- this is the May 16, 2006 · Compression Comprehension. Dynamic Compression Ratio. While intended mostly for Jeep engines, it'll work just as well for any other engine too as long as you can provide all the necessary specifications. 895:1. Calculating Dynamic Compression Ratio: Practical Examples Example 1: Standard Passenger Car Engine. 6:1 static compression ratio yields almost 7. May 15, 2012 · Compression ratio came in right at 11:1 (just a touch over), and I ran it on 91 octane gas here at 3300 feet where I live. Dynamic Compression Calculator Bore diameter (inches): Stroke length (inches): Combustion chamber volume (cc): Head gasket thickness (inches): Piston dome volume (+) / dish (-) or valve relief volume (cc): Deck Jul 22, 2024 · Dynamic Compression Ratio (DCR) is a more accurate representation of an engine’s actual compression ratio during operation compared to the static compression ratio. 700" connecting rod and 87 octane unleaded gasoline in a naturally aspirated engine. To help determine compression if you have 6 days ago · Retrieved from "https://www. r. 5:1 or 10:1, you will only be able to run a small amount of boost. 31 :1. 045". 5:1 compression for unleaded BUT you need stainless valve seats to prevent wear. 7 cc 7. 9/1. Jul 24, 2000 · Using Pat Kelly's calculator your dynamic compression ratio is a little over 7. Of the variables, the most important is cam timing which has a dramatic effect on your "dynamic" as opposed to your static compression ratio. Obviously, those compression numbers will drop if I'm in the hole at all. I have 10. Nov 20, 2020 · C3 Tech/Performance - Max pump gas compression - I know we have some savvy engine builders on the forum and I am requesting your opinion on max static compression for a 91 octane, (California),pump gas, aluminum head, carbureted, small block Chevy. 25:1. A static compression ratio by itself will not tell you whether or not you will have detonation or whether the engine will actually have too low of a static compression ratio. V/P (Volume to Pressure Index) is 48 Static Vs. To help determine compression if you have This is why some engines require 100+ octane with an 11:1 compression ratio while others are perfectly fine on 91 octane with a 13:1 compression ratio. 5 Dynamic Compression Ratio CHART C6 Tech/Performance LS2, LS3, LS7, LS9 Corvette Technical Info, Internal Engine, External Engine, Tech Topics, Basic Tech, Maintenance, How to Remove & Replace Sponsored by: Jan 10, 2010 · from what Ive seen working on and tuning engines ,those charts are depicting about the ideal maximum compression ratio to run,in your basically stock engine, giving you a bit of a hedge for detonation resistance, and they pretty much assume a 14. 5:1 dynamic compression ratio for 91 octane pump gas. Download the dynamic compression ratio calculator spreadsheet here: https://kyushaspeed. I use this to get worse case scenarios. 5:1 or even 10:1, whereas an open chamber head will have trouble running 87/89 if you venture anywhere over 9:1 CR. Nov 3, 2009 · I was told up to 10. While static compression ratio assumes the intake valve closes at Bottom Dead Center (BDC), the dynamic compression ratio takes into account the actual closing point of the intake Spark timing must then be retarded, far back from the maximum brake torque (MBT) value, resulting in a loss of torque. 8 11. 5 May 13, 2012 · At this point, because the engine is reaching 100% volumetric efficiency, the dynamic compression ratio IS EQUAL TO the static compression ratio. Came up with a static compression of 8. Edelbrock rpm performer heads. Grumpyvette. I don't understand this lousy octane situation people seem to mention either. The compression ratio of your engine has a direct relationship to how much boost you can run. 21, Cranking Pressure 169. V/P (Volume to Pressure Index) is 141 Jul 19, 2011 · 87 octane compression ratio cut-off point. 61:1. Will this work for towing using 87 octane gas? 91? Jun 27, 2019 · Static compression ratio of 9. 95:1 & dynamic compression of 8. 25:1 78cc chamber. Use a positive 17 for the cc's and check the "Dome" radio button. octane; The compression ratio of your vehicle is from 10:1 to 11:1, you can use 92. 5 / 104 / 6. My goal was 11:1 compression N/A, but it looks like it will be higher given my chamber fotw 1043 august 20 2018 engine compression ratio and, compression versus octane chart good read vintage ski, compression versus octane chart good read vintage ski, boost compression ratio chart, understanding compression on a pump gas street motor, put 87 octane in my nismo page 4 nissan 370z forum, fact 940 august 29 2016 diverging trends of engine, explained octane rating cetane rating Jul 28, 2010 · a 8. Engine temperature is also a factor. 1:1 dynamic comp ratio in an aluminum headed SBC engine on 93 octane pump gas alone. 86:1 . Oct 14, 2016 · youll generally be fine with 93 octane fuel and using aluminum cylinder heads if you keep the engine coolant temps under about 215F and the DYNAMIC compression under about 8. 46. 5:1 cr engine with a "little cam" can have more cranking pressure than a 10:1 cr engine with a "big cam". result: Static compression ratio of 9. 35:1 . 5:1 drag motor can run 91 octane without pinging. Your dynamic cranking pressure is 163. Or even a 318. Sep 7, 2015 · Calculate your engine's dynamic compression ratio to determine octane needs:if you've ever been curious about your turbo/supercharged or high compression N/A engine's "max" compression ratio, look In order to determine the octane booster that you need, either discuss with your tuner, and know your compression and/or boost pressure. May 6, 2005 · What is a good baseline dynamic compression ratio to run in an everyday driver engine with an intake valve closing at 33 to 38 degrees cam timing, 5. Apr 13, 2020 · DYNAMIC Compression Ratio: 8. 5:1, totally acceptable to run Many are saying these Dynamic compression calculators have been found useless. 25" pulleys and make 6. Compression ratio is Dec 4, 2017 · Posted: Sun Dec 03, 2017 11:16 am Post subject: Dynamic compression ratio on engle W100 & W110? Fuel octane; Fuel Octane Calculation. 75 stroke 6. 5 * ((180 - 30) / 180 Aug 26, 2016 · Engines do not pay much attention to compression ratio, either static or dynamic. Other shapes of combustion chambers might have detonation. Nov 29, 2010 · It is not static compression ratio that guides what octane to use but dynamic compression ratio. Calculates minimum fuel octane requirement for gasoline; Works with naturally aspirated, supercharged, or turbocharged engines; Calculate the minimum gasoline fuel octane required based on your engine's compression ratio, maximum boost pressure, spark advance, and air fuel ratio. 2 10:5 / 97 / 1. - download Drive Chart for 1/2" Pitch Pulleys - download Drive Ratio Chart for 8mm Pulleys - download Drive Ratio Chart for 13. 10. Again, this is because the amount of air/fuel compressed by the piston in the dynamic situation is now equal to the amount compressed if you simply calculate the compression statically -- this is the In order to determine the octane booster that you need, either discuss with your tuner, and know your compression and/or boost pressure. They do respond to the temperature produced by dynamic compression. Compression in the 7s are for stock cams. 37:1 . Most conventional Mar 22, 2021 · Here is the short list of some basic things that can be done to lower the dynamic compression ratio (DCR). Effective stroke is 2. If I zero deck the block then I get 10. 44 PSI. 53:1. 3 to 1 dynamic compression ratio. May 25, 2019 · 2) Static vs. I'm looking for comments, questions, answers from experienced engine builders on this one please. Increase the lobe centerline of the camshaft (more distance between intake and exhaust lobes) Retard the camshaft Use this dynamic compression calculator to quickly determine the compression ratio of your engine based on entered parameters. Your dynamic cranking pressure is 155. Consider 9. The dynamic compression is always lower than the static compression if the intake valve closes after bottom dead center (ABDC). Results. 81 PSI. Jul 30, 2024 · The higher the octane, the more compression the fuel is able to resist and the higher the potential compression ratio. 5 is the max DCR to target for regular pump gas compatibility, I think, for 93 octane, but that's generally as much info as I can find. 4:1 to 16. Mar 21, 2007 · I’m into Touring 3. Determining what the compression ratio is after the intake valve closes provides valuable information about how the engine will perform with a particular cam and octane. 5 / 1. Jul 21, 2010 · COMPRESSION RATIO CHART (Precise est for 10:0 & above comp ratios) Engine Octane Required Compression / Minimum Octane Required (Some cases need Higher Octane) / # oz per gal Kemco Required With 93 Base Fuel. a min of 3000rpm tickover is not good in traffic. To calculate the dynamic compression ratio (DCR) for a typical passenger car engine, which might have a static compression ratio (SCR) of 10:1, and an intake valve closing point of 30 degrees ABDC (after bottom dead center), use the following formula: DCR = SCR / (1 + 0. Nov 20, 2015 · The first is a calculated number called Research octane and the second is Motor octane generated by actually testing the fuel in a variable compression ratio single cylinder engine. The generally accepted conservative estimate is 8. 5:1 compression? On pump 93? And what cam or dynamic compression ratio are you at? My high compression N/A build just turned into a centri build, and I'm trying to determine the limits of high compression with boost. Mar 14, 2006 · Now then, what would be a safe dynamic compression ratio for 105 octane, in a quench headed FE? The chart from that Vizard article I have been quoting seems to indicate 10. In engines with lower compression ratios, detonation is still possible when the engine is running hot and under a heavy load, so there is a slight advantage to using higher octane fuels in any engine. It is derived from the sweep volume of the cylinder using the full crank stroke (BDC to TDC). Feb 20, 2013 · on a low compression ratio engine (7. Aug 20, 2018 · The engine compression ratio of new cars and light trucks (black markers below) increased along a similar course as octane rating from the 1920s to the 1970s. Safe deck but good squish. 2psi. You Can Also Read: How to Read Fuel Tank Pressure Sensor Voltage Chart Apr 22, 2021 · This equals 62 degrees. ” Dec 19, 2011 · Static compression ratio of 11:8:1. 55 inches. But you better have a cooling system that's up to the task. There is no universal transfer function of compression ratio to octane requirement, for cars or for bikes. I start to worrying about 87 octane with pressures get over 170. Cammed, Screwed and LOUD Whipple 2. Fuel octane requirements for gasoline engines vary with the compression ratio of the engine; diesel cetane requirements also vary with the compression ratio. Dec 29, 2013 · does anyone have a good chart or enough experience for quench, static compression,and dynamic compression related to octane at sea level :huh: i know there are lots of rules of thumb but im looking for someone with real experience with the stroker an. 18:1. 8:1. 0 dynamic compression for a street car. I am running aluminum heads and I know they can handle a little more dynamic compression. Be careful when comparing octane numbers in the USA with the rest of the world, we use (RON+MON)/2 whereas most of the rest of the world uses RON. Camshaft is another, and combustion chamber design is a big one. 0:1 with the . 5:1. You can run . It won't run on pump gas. 5 more dynamic compression if you have aluminum heads. Your dynamic boost compression ratio, reflecting static c. Hunt up Pat Kelley's great DCR site and read it at least three times and I have!! Next, a close quench dimension of like anywhere from just kissing the piston flats to to the head flats up to about . 01 Recommended compression per octane 12:1 93 Pump 14:1 110 oct. Oct 14, 2014 · I've done a few different searches and went through a few posts (there are lots of them depending on search criteria) that discuss dynamic compression ratio and pump gas. Here is a displacement and static/dynamic compression ratio calculator. Lower the static compression ratio (SCR) Install longer connecting rods; Increase the advertised intake duration of the camshaft. "In a four cylinder, 2-liter engine, each cylinder would have a 500 cc capacity," says John Nielsen, director of approved auto repair with the American Automobile Association (AAA). Nov 27, 2023 · Super mild cam so I shot for a lower DCR. 4:1 with the . 030-inch Air/Fuel Ratio. 5 / 100 / 2. 198 or 8. Jul 26, 2022 · First the terminology. Compression Ratio and Boost Pressure Relationship. 1:1 compression ratio: 4. Pontiac sites included. Much care is put into my engines though to ensure the setup is right (quench, a/f, timing, valves, mls, ect. I aim for a conservative 7. Your dynamic cranking pressure is 174. 6:1 static compression but I can run 92 octane just fine because I run aluminum heads and my dynamic compression ratio is 8. 9 10:4 / 96. 2:1, dynamic compression is based on where in the crank rotation the valves both close as the piston can,t compress anything until the valves seal. 5:1 compression ratio can run on higher-octane pump gas (91-93 octane) but may benefit from fuel additives or octane boosters for added safety. 5 dynamic is a safe spot for pump gas compression, so with the calculator i now have figured for the chart below, I changed the pistons to dual valve relief flat tops to drop the compression just slightly. What would be very useful is a calculator that would indicate compression temperature at any ratio. 8 cc 7. Web calculate compression + boost for octane. php?title=Dynamic_compression_ratio&oldid=3488306" A cylinder with 10 units of volume (called the sweep volume) and a chamber with a volume of 1 has a 10:1 compression ratio. Your dynamic compression ratio is 7. im going for between 10:1 and 10. octane Oct 3, 2024 · The Dynamic Compression Ratio (DCR) is a vital metric in engine design and tuning, offering a more accurate representation of an engine's compression behavior under dynamic conditions, unlike the static compression ratio which doesn't account for the valve timing. Mar 4, 2014 · I'm running 8. Feb 24, 2023 · I've put in all the calculations and if it comes out to be a zero deck my static compression will be 9. What is the highest compression ratio engine ever? Some specialized race engines have compression ratios exceeding 15:1, but they require racing fuels with extremely high octane ratings. Compression temperature, combined with inlet air temperature will determine which fuel can be used. Compression Ratio And Octane Chart - Web in order to determine the octane booster that you need, either discuss with your tuner, and know your compression and/or boost. 26# From Brian's chart, I can get by with 91 octane (175-185 psi) Mar 16, 2019 · That is why all of the race fuel mfgs have charts which tell you which fuel to use based on static compression. 5:1cr) this cam makes a real good street strip supercharger cam in a 340 360. 8:1 and with the CB cheater cam it works out to a dynamic compression ratio of 6. 1. crankshaftcoalition. 5 or 11 to 1. 16 dynamic coming up on my 496 build. That motor was also running a HR cam that was 242/248 @ . (A compression ratio in an engine is the ratio of the cylinder's combustion chamber divided by the total volume of the cylinder). The 291 is a hemispherical head if I recall, so you should be OK with 87 octane, but you're probably right on the edge. 7:1 f/a mix ratio to minimize emissions. 08 gears behind a BBC built strong enough to handle 7 Grand but for those into Hi-Ratio Gears and Week End Drags, a Fuel Octane Vs Dynamic Compression Balance means Performance and in either case Camshaft selection is critical. 039 gaskets and a little over 7. 5 11:0 / 98 / 1. The compression ratio that is built into your engine is called “static compression. 5:1 dynamic compression. calculating your dynamic Jul 8, 2012 · Anyways, I was looking into static vs dynamic compression ratio and theoretical boost limits on 93 octane. 35 bore 3. Your dynamic cranking pressure is 165. It seems our engines have been running the same compression ratios on the same fuel for the last 30 years. Be Coll radiator in place. This is why some engines require 100+ octane with an 11:1 compression ratio while others are perfectly fine on 91 octane with a 13:1 compression ratio. 7) +1] x CR Feb 26, 2021 · Here's mine: Using that same calculator as you are, I ran a 9. What you are asking for is static compression corrected for intake close not dynamic compression. Jump to Latest Keep in mind the chart is for dynamic c. Keep following these technological advances, and that’s why a modern, bone-stock Miata can run 93-octane fuel along with a 13:1 compression ratio–and why, on the track, today’s GT3 and GT4 race cars only need 100-octane unleaded, today’s other race fuel commodity. My 383 has 10. The dynamic compression ratio of a Pro Stock engine is probably less than 9:1 but who cares. X2 with BigDog, 9. The values in the chart are conservative. Web calculate your engine's dynamic compression ratio to determine octane needs:if you've ever been curious. Better to buy 100 octane and mix with 93 "if" you ever needed higher octane for a build. Putting the TA 284-88H with 110* lobe separation and 4* advance through the dynamic compression ratio calculator with a 9. Feb 3, 2018 · Page 1 of 2 - Compression Ratio And Fuel Octane - posted in Problems, Questions and Technical: Hi all, Ill be taking in my car for rolling road tuning shortly (engine spec below), and did have some doubts about whether I should be taking it with standard 95 RON. Nov 5, 2020 · Camshaft, Rod Length, Boost and Altitude Correction to Compression Static compression ratio of 11. No problems. You want to shoot for around 8. Dynamic Compression Ratio, on the other hand, uses the Sep 28, 2023 · A 10. And the so-called compression ratio -- and each engine has its own ratio -- refers to just how much of that fuel and air combination the piston compresses. Nov 6, 2024 · I have 11:1 383 on 91 octane. Compression ratio is the ratio between the swept volume of the cylinder with the piston at bottom dead center and the swept volume of the cylinder with the piston at top dead center. 0 to 1 since my static compression ratio is so high, so I dialed back the timing to 28, 2 years now and the thing runs strong as ever. Want to know what your static and dynamic compression are? The static and dynamic compression ratio calculator can do it for you. It actually MPH's faster in the quarter mile with regular Chevron 91 octane than it did with VP C12 race gas. 52:1. 76 rod 9. Use low-octane rating gas for engines with a low-compression ratio. Calculate. Can easily maintain 180F water temps. This gives a static compression ratio of 7. Oct 16, 2021 · It was closer to 9. The simulation is using 87 octane. Oct 31, 2011 · Who is running boost with upwards of 10. You can run 11:1 or even 12:1 compression on your pump-gas street motor, but you'll need this simple advie to make it happen. My 12. the cam is ground with a 110 intake centerline and 277 advertised duration. so that may be a little much for you. May 13, 2012 · At this point, because the engine is reaching 100% volumetric efficiency, the dynamic compression ratio IS EQUAL TO the static compression ratio. 9/1 and a dynamic ratio of 7. 5:1? Also are namura pistons reliable/good quality? Jan 21, 2011 · The cylinders deck out at . Here are the exact compression ratio and octane numbers: The compression ratio of your vehicle is from 9:1 to 10:1, you can use 90. 5 usually on 91 octane. 9. 46 static with 8. Use this calculator to see what the effect of bore, stroke, rod length, cam timing, compression ratio, boost pressure and altitude is on your dynamic compression ratio. In the case of Rockett Brand’s E85, the Research number is 116 and the Motor number is 108. My proposed set up was 4. To determine octane to your compression, follow our easy to use chart below. with that said, I would say that 160psi of cranking pressure indicates it should run easily on low octane pump gas. com. Previous owner said this 425 ran great on 91-93 octane. Dynamic Compression plays a big factor for any rebuilt engine. au/shop/dynamic-compression-ratio-calculator/Blog post here: http Dynamic Cranking Pressure: (at 150 rpm starter rpm) Note=> after 7 to 10 needle pulses on a hi-quality Compression Tester The slower the cranking RPM, the lower the cranking psi The faster the cranking RPM, the higher the cranking psi The poorer the Piston Ring seal, the lower the cranking psi The poorer the Valve Seat (and guide) seal, the lower the cranking psi In addition, aluminum Blocks Nov 17, 2008 · fuel octane, air coolant and oil temps, spark advance and plug heat range all effect the results, when you see a chart like these below, they provide a good guide to keep you out of potential trouble, but each combos unique and has a different potential to cause detonation, simply slowing the ignition advance , and changing to a different plug Because, if the vehicle requires a high octane but the fuel used has a low octane, the vehicle engine will sound ticklish. thats why you read plugs after a full throttle run and need a higher octane fuel then the dynamic compression would suggest Feb 6, 2024 · I did some lurking around old posts it seems like around 8. 87, DCR = 8. Your dynamic cranking pressure is 172. Static Compression Ratio (SCR) is the ratio most commonly referred to. need to run on pump 96 octane gasoline and no more than 8. 0 to perhaps 8. They don't care about dynamic compression ratio. 9, Comp 106360's, BBRC return system, ID1000's Aug 29, 2016 · The engine compression ratio of new cars and light trucks (black markers below) improved along a similar course as octane rating from the 1920s to the 1970s. 37 inches. May 21, 2010 · Static compression ratio of 10. As with other calculators, equations are provided as well. 62 PSI. static. Jun 21, 2009 · In a nutshell, closed chambers with the right cam (i. 018 gaskets, which is basically saying your cam is too big for your combo, or your compression is too low for that cam. Heisler, pp. 00 PSI. Most of them seem to agree that 8. Obviously Ill be taking it to the RR with the same octane fuel that I intend to use long-term, and Id pretty much decided on 95 RON Dec 10, 2014 · My understanding was anything under 12. Many are saying these Dynamic compression calculators have been found useless. 3 568 = 77. Nov 4, 2024 · Less ignition advance also reduces the need for octane. CAM PROFILE 270 280 290 Volume at valve closure Compression ratio -1 7. 5 is safe, maybe 10:1 max with It stands to reason that higher compression RATIOS will yield higher cylinder pressures (given that nothing else has changed before the compression ratio was raised) Well. Oct 16, 2014 · Things like camshaft choice and where they are set up will change your dynamic compression and you may have some room but that's you and your tuners call. Then follow our mixing charts provide our Calculator App, above. 3 539 = 73. With 93 octane, I would not have to Octane booster is not in itself much. If you have a high compression ratio, such 9. 2:1 dynamic compression. I felt like I was living on the edge going this high on compression, and kept the timing back around 32 degrees, but never saw any signs of detonation. , cam timing, altitude, and boost of PSI is 8. 35 :1. Jun 11, 2020 · They’re all over the chart from 5. Dynamic compression happens in a running motor and includes volumetric efficiency in the calculation among other things, different topic. No biggie. 594 static and 8. 04 head gasket 1000 ft alt. A big YMMV. 653 dynamic. Just need to back timing down 1-2 degrees. Using a calculator program I got intake closes 68. 5:1+ which would be way too high to run safely on 91 octane gas. This tends to be true for older, traditional engines with less effective combustion chambers. 25:1 . Nov 13, 2018 · High compression ratios strongly favor detonation, so engines with high compression ratios must use higher-octane fuel. Oct 21, 2007 · Compression ratio is only one factor. Compression ratio and power • When gasoline-powered motor vehicles first came into widespread use, the compression ratio of their engines averaged 4-to-1. For engines with a high-compression ratio, use a premium or super-rated fuel. 030-inch bore. 6 10:25 / 96 / . we just determined that the higher pressures are a major player in causing the fuel to auto ignite (not good) hence, the need for higher octane with higher compression RATIOS. 5 11:8 / 101 / 3. 0 / 95 / . V/P (Volume to Pressure Index) is 133 RICK'S Calculator says: SCR = 9. E-85 has an equivalent octane rating of 105, and with an expected operating temperature of around 180°F, the maximum dynamic CR is slightly above 10. 6:1, but varied some due to assembly tolerances with the deck and compression height. 050, on a 106 ICL. 00 inches. 86 :1. Obviously, the static compression ratio will be above that. As we mentioned before, the dynamic compression ratio is the one that happens inside the engine. With these inputs, the UEM calculator offered 8. After that time, the average compression ratio continued to improve due to advanced engine design and controls, diverging from the octane trend. Do a web search for dynamic compression ratio. com/wiki/index. 87:1. Think I will be able to run 87 octane if I assemble the top end as-is? Dec 20, 2023 · If, for example, the relationship of the BDC volume is 13 times larger than the volume at TDC, then the compression ratio is 13:1. 3 589 = 80. 711" dynamic stroke for a dynamic compression ratio of 8. also the higher the comp ratio generally the higher the tickover. This seems like a good place to be to me. A good match to a Weiand 142 blower on a low cr 340. Nov 20, 2022 · Use the standard compression ratio fuel octane chart to know the fuel suitable for your engine. Cam will be very mild with 218/220 duration, 495/512 lift and 112 lobe Jul 21, 2009 · After reading the recent threads here about dynamic compression ratios I ran my #s on the silvolite calculator. However, that same 11:1 static compression ratio engine with the radical 259/269 duration camshaft would have a dynamic compression ratio in the neighborhood of 7. Combined CR: 13. Dynamic Compression Ratio (DCR) is an important concept in high performance engines. 177). , cam timing, altitude, and boost of 0 PSI is 8. According to the calculator my Static compression ratio is 10. Effective stroke is 3. Engine compression ratio is the relative volume of a cylinder from the bottom most position of the piston's stroke to the top most position of the piston's stroke. Jan 16, 2010 · what is the maximum compression ratio i could run if i am running av gas in my xr 400? 11:1, 12:1, 12. khsiwmlkmibafierthcjantfzsolzejvlmrofqllwngnzszzhuzbh