Ideal rod ratio Reher-Morrison Racing Engines 1120 Enterprise Place Arlington Texas 76001 817-467-7171 FAX-468-3147 Mar 27, 2017 · Some engine builders say a “good” rod ratio is anything 1. The most common ratios are in the range of 2. 25mm rod (1. Jan 7, 2021 · With the 331-inch combination and its 3. Sep 29, 2009 · Ideal Rod Ratio. Generally, a higher rod ratio (closer to 1. and add . As for V8s, they typically range from 1. The maximum lsa is about 130 degrees, the minimun rod ratio is about 1. 26:24: So really it comes down to the quality of the Sep 12, 2010 · All I am trying to do is get you guys to help me figure out if there is an ideal lsa for a given rod ratio. 750 stroke in a 9. Naturally Aspirated. Divide rod length by the crank stroke and you get the rod ratio. How is it calculated? Use the following formula to calculate rod ratio: Rod Length ÷ Stroke Length = Rod Ratio. 72 RR Mar 1, 2008 · Rod Ratios. 75 is considered “ideal” by some respected engine builders, if the breathing is optimized for the design. A 454 BBC has 4. ÒgoodÓ rod ratio is anything 1. 66:1, while the 347’s 3. Oct 28, 2004 · I don't think anyone can say that's a short rod engine. 0 to 2. 66 ratio or even lower ratio if he could physically do it. Dividing rod length by stroke equals 1. 55 or higher. I thought 1. A quick internet search told me 1. 6mm rod lenght we have stroke/bore:1. . 75" crank owner is using +. 000" stroke equals a 1. Example: a 5. 9 allowing the piston to “dwell” at TDC for a longer period. You simply put the longest rod you can physically fit in the motor. This ratio (normally represented by “n”) can be calculated as follows: Ratio “n” = Rod Length ÷ Stroke Apr 27, 2022 · Ever hear the term “rod ratio”? It’s the number you get when you divide a connecting rod’s eye-to-eye length by the engine’s stroke. How to determine the Engine Volumetric Efficiency (VE) of the G16B and what role it Jan 30, 2021 · If we had the worst rod ratio (1. A Rod ratio of 2. 48 inch stroke. 8/81. For example, say you’re building a stock small block 350 Chevy with 5. 4mm and put it in a b18/b20 block. I have never said that there are not both high and low limits one must avoid. 7:1, with some race engines up to a 2. 025 rod/stroke:1. = 1. Intake Efficiency; An “n” value of 1. one of the problems with these longer strokes is that the builders must use a 133mm to 134. Apr 10, 2004 · one of the novel approaches using a stock crank is to find a b17 81. 8" rods the ideal would be 107. 5 and 1. 8 deck block with a 1. 59 lsa (almost a full 120 degrees, one What rod ratio is ideal for a high-revving engine? High-revving engines typically benefit from a higher rod ratio, around 1. 44 rod ratio) results in a change of peak acceleration at TDC of what, ballpark it at 5%? And as you point out a lot of very successful high winding engines have pretty “low” rod ratios – not mentioned but the K24 has a rod ratio of 1. It influences factors like piston speed and dwell time at top dead center. 75 range, and Ferri prefers the 1. At the same Here we have two engines. 7-inch rods and a 3. 56 achieve peak piston speeds of over 7000 feet-per-minute (FPM). 5 to 1. Sep 4, 2002 · Ideal rod to stroke ratio is probably about #49 on the 50 things to worry about. 2 compression height piston. 15471 Views 107 Replies 44 Participants Last post by Ben Mens, Sep 21, 2010 Jump to Latest O. With the Spicer Rod Ratio Calculator, you can easily calculate the ratio between the length of the piston rod and the stroke length of the engine crankshaft. 90 crankshaft in it. The Honda B18C1 inline-4, for example, has 138mm rods and an 87. 7 in. 5:1 was a general guideline? The other reason I wanted to do this may sound silly, but here goes. 78 with 1. 45 rod = 1. 4 = 1. As you can see the only difference Feb 26, 2002 · As far as I'm concerned 1. For many years the ideal rod/stroke ratio was thought to be a 1. It was designed as a Carolina rig rod, though that’s not one of my usual techniques. With a big stroker motor you can forget all that. 46 of an inch. 5 V12 Honda 88x48 rr=2. 4 rr=2. 75 stroke and 5. For a good illustration of what increasing the rod length does for an engine, we'll use a 350 Chevy. Darin Morgan R&D-Cylinder Head Dept. Sep 30, 2009 · Naturally Aspirated. They could go well together all up the line then like that then. 53 rod ratio. Mar 28, 2005 · When I discuss Rod Ratio I always dismiss people who think there is an " ideal" rod ratio and are willing to compromise the overall engine design in order to achieve this " ideal" Rod ratio. With the Rod Ratio Calculator, you can easily calculate the ratio between the length of the piston rod and the stroke length of the engine crankshaft. 66 rod ratio) to a theoretical 125mm rod (1. I am thinking about it, could use all the help I can get. The F1 numbers are due mainly to the engines’ short strokes. Feb 5, 2005 · When I discuss Rod Ratio I always dismiss people who think there is an " ideal" rod ratio and are willing to compromise the overall engine design in order to achieve this " ideal" Rod ratio. For example, a stock small block Chevy 350 has 5. It was my go to 1/2 oz chatterbait or big spinnerbait rod last season and I still use it for that sometimes. What are the implications of a high or low Rod Ratio? A higher Rod Ratio typically leads to improved engine Nov 30, 2022 · That rod is a great moving bait rod. 4 mm. 00 stroke and 6. 65-1. 62 but in the 3rd option 80mm bore 89mm stroke 137. stroke: 5. 2mm stroke for a ratio In the first option that I said with 80mm bore and 82mm stroke and 133. Rod length ratios are calculated by dividing the rod length by the stroke. 48 inch stroke which is equal to 88. 250 long Oliver rod, so I'd need a new set of rods. Rod ratio is a crucial factor in engine design and tuning, as it affects several key engine dynamics, including: Piston Speed: Rod ratio directly influences piston speed, which can impact engine efficiency, power output, and mechanical stress on components. 6 to 1. If you want to know an engine's rod-to-stroke ratio, you should divide connecting rod length by the stroke (which is the distance the piston travels within the cylinder). 77:1. 73/1 Jun 13, 2005 · with 4. 7 range) while many V6s have somewhat higher rod ratios of 1. 15462 Views 107 Replies 44 Participants Last post by Ben Mens, Sep 21, 2010 Jump to Latest O Jul 2, 2023 · The Importance of Rod Ratio. Ideal Rod Ratio. 58:1. 68 Jan 16, 2024 · The rod ratio is also known as the rod-to-stroke ratio, and that name describes it all. 2. 45 rod ratio. 75 being "ideal"). A 400 SBC has 3. If 'x' amount of power is required to turn the blower to get 'y' boost and 'z' HP. 11 rod/stroke:1. 5 and 2. 637 for the rod ratio. You need to take into account the rev range you expect your engine to be operating in. 7 Rod ratio is the relationship between the Connecting Rod Length and the Stroke Length of the crankshaft. Ideal Rod Ratio Jun 22, 2020 · Q: What is rod ratio? … A: Rod ratio is the relationship between the Connecting Rod Length and the Stroke Length of the crankshaft. Then I read where Stock Chebby engines had less. While the rod/stroke ratio of the 347 is acceptable, it affects the pistons’ compression height, reducing it to what some builders feel is unacceptable, at least for a street engine. 1x Rod constructor gets split into two belts of rods, one into assembler with screws making rotors. 4) / 2 = 3. Measure the ratio between the length of the piston rod and the stroke length of the engine crankshaft, which moves the piston from the bottom of the cylinder wall to the top. Generally, ratios between 1. A higher rod to stroke ratio is better suited for high RPM. 75mm rod lenght we have stroke/bore:1. Sep 16, 2015 · Let's talk about rod ratio. If you're running a Mopar then look carefully into using a 400 block with a 3. A stock 5. Jump to Latest Oct 8, 2014 · At the same time, there's a point where rod lengths can get too long for a particular stroke and we're leaning on that line also. 55 and higher was considered safe. 6:1. 0 to 1) How much further down in the bore is the piston worst case verses best case ratio, at peak cylinder psi? Now figure highest piston speed verses height in bore. Inactive User : Join Date: May 2002 . It works as a big crankbait rod for things like dt16/20 baits. 1:1 rod ratio. 0-rod ratio optimum for best power. Engine Package Summary rod ratio is calculated by taking the connecting rod length and dividing it by the crankshaft's stroke. Stroke; The ratio between the connecting rod length and the stroke length of a motor greatly affects the way it performs, and how long it lasts. 78 mm. Sep 30, 2023 · Why is the Rod Ratio important in engine design? The Rod Ratio plays a critical role in determining engine efficiency, power delivery, and overall performance. this wont be totally accurate as the distance you are measuring actually is the hypotenuse of a triangle and with the long side being the rod length Measure the ratio between the length of the piston rod and the stroke length of the engine crankshaft, which moves the piston from the bottom of the cylinder wall to the top. May 4, 2002 · Maybe I'm missing something but isn't rod ratio determined by dividing the rod length by the crank stroke? If so a 350 chevy is 3. 91. Oct 18, 2018 · If you look at that BMW S14 graph, going from the 144. This is also known as top dead center, a term used when timing the engine. Aug 8, 2016 · Rod ratio is the mathematical relationship between the overall length of the connecting rods and the stroke of the crankshaft. 4 to over 2. 4 to 1) And the best rod ratio ( 2. The one point I am trying to make is that trying to HIT some "ideal" rod ratio at the expense of other more important design criteria is a big mistake. 7 rod that is equal to 144. Newest [ December 12, 2024 ] The Key to Making Your Car Fast: The Torque Converter Technical Info As you can see the only difference is the length of their connecting rods. Oct 8, 2023 · Formula: Rod Ratio = Connecting Rod Length / Crankshaft Stroke Length. I did a search here but didn't find what I was looking for so I started a new thread. What would the maximum RPM be on the G16 for an ideal street, track & drag setups? 11. 75 to 1 was figured out by i think enzo ferrari but it does vary some with engine use higher ratio for higher rpm, lower ratio for lower rpm just another dual quad 545 Sep 18, 2010 · Naturally Aspirated. 8 range. This would put you Rod/Stroke ratio to 140. A NASCAR Cup engine piston speed reaches 8800 FPM at 10000 RPM with an RSR of 1. A good rod ratio is considered to be 1. 4:1. 67 rod ratio. Mar 13, 2003 · There's a constant chatter about small block builds and needing 6"+ rods to get the right rod to stroke ratio because you JUST MUST HAVE a rod:stroke ratio that is around 1. 9, which reduces piston stress at high speeds. 100 big end diameter, so the easiest way to measure would probably to remove the oil pan and measure from the exposed part of the pin, to the parting line between the rod and rod cap. Rod Ratios. Sep 4, 2002 · Can anyone tell me what the IDEAL bore/stroke rod ratio is? #2 09-01-2002, 06:49 PM dirty dan. 4 lsa, would be the same r/r as a 350 so if you had 1. A 350 with a 6 inch rod would be 1. 2:1 or a 1. 15462 Views 107 Replies 44 Participants Last post by Ben Mens, Sep 21, 2010 Jump to Latest O Nov 16, 2005 · A good rod ratio for high revving is considered to be from 1. 54mm what its the pro and cons of this two for example if u can please explain it I'm really trying to learn. 7 Sep 4, 2002 · Can anyone tell me what the IDEAL bore/stroke rod ratio is? #2 09-01-2002, 06:49 PM dirty dan. 75:1 and the CTR b16b is 1. b18a rods are 137mm long, so (89-81. connecting rods and a 3. Dec 31, 2011 · An interesting fact is that the rod/stroke ratio is in 1. May 25, 2022 · I believe the “ideal” rod ratio is dependent on the application? Should it be a big concern for the 5000 rpm engine that’s pushing you’re ‘77 LTD down the road, probably not. Rod Ratio vs. There’s been a lot written over the years about rod length-to-stroke ratios, and some experts consider a 2. 45:1 –1. 40-inch stroke takes the ratio down to 1. 7 to 1. 8 you would need 140. A higher rod ratio will improve engine efficiency and reduce piston loading. Some people say the ideal rod ratio is 1. Before you blast me with obscure engine combinations I must say, NO I am not condoning sticking a 4. 1 rod ratio you would need 117. If you lengthen the rod relative to the crank and the ratio grows larger, the wear goes down as does the piston speed, but this will contribute to an engine having a very narrow useful torque range. 44 rod ratio) results in a change of peak acceleration at TDC of what, ballpark it at 5%? Feb 5, 2005 · When I discuss Rod Ratio I always dismiss people who think there is an " ideal" rod ratio and are willing to compromise the overall engine design in order to achieve this " ideal" Rod ratio. Well, this thinking is backwards because it's the lightweight pistons that put you at that ratio, not the need for that ratio in the first place. Oct 18, 2018 · So, controversial opinion ahead – I honestly think that rod ratio is lately really overstated as something to shoot for. Where is the piston at peak speed in bore from top? Sep 5, 2020 · NASCAR and FORMULA 1 ROD STROKE RATIO & PISTON SPEED At 18000 RPM Formula One engines with an RSR of 2. How does rod ratio affect engine performance? Rod ratio can influence engine smoothness, efficiency, and the rate of wear on engine components Mar 31, 2023 · The ideal rod ratio is between 1. 0 are common in production engines. 400 rods, which is a 1. 5 mm rod length so that the rods and pistons fit inside the deck height of the B18 blocks. thank you Dec 1, 2005 · The rod is dictated by the piston design, stroke and deck height not a preconceived "ideal " rod ratio. 25-inch stroke, the rod/stroke ratio is a solid 1. Co-incidence? I don't think so. Connecting Rod vs. 32, 2000 Ferrari V10 96x41. As you can see, there is no perfect answer when it comes to selecting a rod to stroke ratio. 927 small end, and 2. 0, with many falling in the 1. Four cylinders tend to have lower rod ratios (1. Feb 7, 2002 · VI. 66 – 1. 135 rods = 1. While Oct 3, 2024 · What is an ideal rod ratio? There is no one-size-fits-all answer, as it depends on the specific engine design and its intended use. 9. Inactive User : Join Date: May 2002 Sep 4, 2002 · Can anyone tell me what the IDEAL bore/stroke rod ratio is? #2 09-01-2002, 06:49 PM dirty dan. That is usually 77 to 79 degrees after TDC. 64 Rod Ratio May 26, 2023 · The Rod Ratio Calculator is a tool that calculates the rod ratio of a crankshaft based on the piston rod length and crankshaft stroke length. 26:13: And that particular engine, we ran it to 10500 RPM and it was still very very reliable. There are a couple schools of thought with rod ratio. then you would need aftermarket rods. Jump to Latest May 7, 2005 · Technical Section. Dec 26, 2007 · I currently run a +. Inactive User : Join Date: May 2002 Sep 6, 2007 · 9. 48 in. 8mm rods to compensate. Feb 16, 2011 · Engine / Turbo. 44, 92 3. It is pointless to address the length of the connecting rod in any engine, racing For example, I'm using: 1 iron miner into 3 smelters, into 3 constructors (1x plate, 2x rod). This calculator is for anyone who is takes interest in engine building or automotive performance. 2. 75 to 1 is the ideal rod length to stroke ratio, regardless of application, and any number going down numerically is not favorable. 5:1) may be suitable for engines focused on torque and Sep 29, 2009 · Ideal Rod Ratio. 12. ÷ 3. What is a good rod ratio? A good rod ratio depends on the engine’s design and intended use. orasengines Feb 21, 2009 · ideal rod/stroke ratio is 1. Jump to Latest Nov 16, 2005 · A good rod ratio for high revving is considered to be from 1. 77. A lower rod to stroke ratio is better suited to low RPM. If you look at that BMW S14 graph, going from the 144. 54, and I know drag guys stroke them even Feb 17, 2012 · we find that recent N/A F1 engines had an unusually large rod ratio (and some unusual reasons for this are apparent) unusually high bore:stroke ratios seem to be accompanied by unusually high rod ratios eg Coventry-Climax FPF 94x90 rr=1. 375:1 ratio. Production engines may have rod ratios that range from 1. This will give you about 470 inches with very good ratios. 1x Rod constructor goes into another constructor making screws, screws are then split into 2 belts. It uses a 5. 000" rod length divided by a 3. The current 4. 66 to 1. You can only alter the rod ratio so far with the parts that are currently available, if you stick to typical combos. Guess what? the Civic b16a 's rod ratio is 1. So on paper that doesn't give us an ideal rod to stroke ratio, a little bit better than the 100 millimetre stroke crankshaft but still not ideal. 7:1 or higher) is preferred for high-revving engines, while a lower ratio (around 1. Jun 7, 2024 · Divide rod length by the crank stroke and you get the rod ratio. Conversely, a lower rod number can increase engine torque or horsepower. Both have the same bore and the same stroke. 75-1. Jan 22, 2004 · a stock sbc has . How does rod ratio affect engine power produced in terms of low end revs and high end revs? What would be the ideal rod ratio to have a engine rev upto 7000-7500 rpm? 10. 8. 4:1 is not going to help matters any. Sep 11, 2015 · Generally speaking, the rod ratio for gasoline-based, automotive engines operating in typical rpm ranges will be about 1. 26:21: Again it was purely for a drag application. uvhwx psk eeja lneeshr cslqn fkvln oczmc nxy tnppvd tldzvh