How to convert compression ratio to psi? First, determine the compression ratio. Calculate or measure the compression ratio. Next, determine the pressure. Calculate or measure the atmospheric pressure. This is 14.696 PSI at sea level. Finally, calculate the PSI. Calculate the PSI using the equation above **To** **calculate** the pounds per square inch (**psi**) **from** the **compression** **ratio**, one needs the **compression** **ratio** and the atmospheric pressure measurement. Then, the first number in the **compression** **ratio** is multiplied by the atmospheric pressure, then divided by the second number in the **ratio** Hit the SAMPLE button to see how it works. The formula that is used is: Effective Compression = ((Boost PSI / 14.7) + 1) * Current Static Compression Ratio 1 Bar = 14.5 PSI Compression Ratio is based on the Ideal Gas Law and is the ratio between Discharge Pressure Absolute and Suction Pressure Absolute. CR = pd / ps (1 How to convert an engine's compression ratio to PSI (pounds per square inch): (X*14.696)/1 (14.696 is standard atmospheric pressure at sea level.

Compression Ratio The compression ratio is the ratio of the absolute discharge pressure (psia) to absolute suction pressure (psia), found using the formula Discharge Pressure Absolute ÷ Suction Pressure Absolute. In that chart that accompanies part one of this series, the left side (Y-axis) represents compression ratios Compression Ratio = (Swept Volume + Clearance Volume) / Clearance Volume Compression Ratio = (626.8cc + 63.5cc) / 63.5cc Compression Ratio = 10.9:1 Run your numbers twice or three times to make.. To find the compression ratio (CR) you divide the total swept volume with the total compressed volume. This is how you find out what these totals are: Swept volume = chamber volume + piston volume + gasket volume + clearance volume + cylinder volume Compressed volume = chamber volume + piston volume + gasket volume + clearance volum

Personally I do believe that cylinder pressure can be converted to compression ratio. If your compression ratio is 12:1 theoretically that means the compression is 12 times atmospheric pressure. (atmospheric pressure compressed to 1/12th its uncompressed volume) At sea level there is 14.7psi of atmospheric pressure. 14.7 x 12 = 178psi Calculate basic compression pressure from the two low- and high-speed effective compression ratios of 7.32:1 and 8.55:1, respectively, assuming standard sea-level atmospheric pressure of 14.7 pounds per square inch absolute (psi) If you already have your swept volume calculated, you can plug the clearance volume value and the swept volume value into the formula CR = (Vsw + Vcl) / Vcl to find your engine's compression ratio. Add the swept volume and cylinder volume together first. Then, divide the result by the cylinder volume to find the compression ratio * The compression ratio is the ratio between the volume of the cylinder and combustion chamber in an internal combustion engine at their maximum and minimum values*.. A fundamental specification for such engines, it is measured two ways: the static compression ratio, calculated based on the relative volumes of the combustion chamber and the cylinder when the piston is at the bottom of its stroke. A change in head pressure does not influence the compression ratio as much as suction pressure. If the head pressure in both our examples were 185 Lbs. instead of 160 Lbs., the first example would have a compression ratio of 20:1 and the second example 8:1. High compression ratios are a major reason systems run hot

Multiply atmospheric ambient pressure (14.7 psi) X the first number (s) of the ratio divided by the second ratio number. This is a rough guide. If you subtract %20 from your answer should bring your final answer nearer to a measurable figure. 204 view Here are some data on the relationship between compression ratio and compression. The Bosch Automotive Handbook gives the following formula: Compression = (Compression Ratio minus one) to the 1.1 to 1.2 power multiplied by Atmospheric Pressure. Given Atmospheric Pressure at sea level = 14.7 psi, we have the following The compression ratio is just the ratio of cylinder volume plus head volume to head volume alone. The actual psi readings on a compression test are related not only to the compression ratio but to the ability of the piston and rings and head gasket to seal Calculate the PSI to compression ratio. For example, if you have a manometer reading of about 15 and your compression ratio is supposed to be 10:1, then your PSI should be 150, or 15×10/1. This..

Plus, according to the math problem, if you had a compression ratio of 1:1, you would be pushing 14.7 psi. So there isn't any REAL way of telling an engines compression ratio without getting the. The more overlap your cams have, the lower your actual as opposed to your static compression ratio will be. To give you an idea of this, an 11.5:1 compression motor may have cranking presures of 165 psi whereas another 10:1 motor may show 190 psi. If the barn door is open the horses are going to get out 1101 W. Rialto Ave. Rialto, CA 92376, USA +1 (310) 361-0020. 23 Mount Erin Rd, Blair Athol NSW 2560, Australia +61 2 9607 229

- This is everything you need to do to calculate your compression ratio. No foolin'. Every equation and process demonstrated. Find all your variables. Know..
- The calculator will spit out the compression ratio in an instant. It is especially handy in quickly comparing how various changes will affect the ratio, without all the longhand-math and slide.
- Enter the measurement designation in either inches, 1, or millimeters, 2. Enter the cylinder bore diameter. Enter the piston stroke length. Click on Calculate Displacement. The value will be returned in CR, Compression Ratio from ALL input values excluding Total Volume. You can also calculate Total Volume from bore, stroke, and CR
- g, compression ratio, boost pressure and altitude is on your dynamic compression ratio. Of the variables, the most important is cam ti
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- Once you've found the compression ratio, then you multiply it by the intake manifold pressure your vehicle's engine is producing at idle. For example if a 2009 4.6L Ford F150 has a compression ratio of 9.8:1 and its intake pressure is at 17 in.Hg, then you can expect a cylinder pressure in the 170 PSI range (17 x 9.8 = 166.6, which I then round.
- The next step is to figure out the compression ratio, using absolute pressures. Using our example, we had 17 psi boost in the intake manifold. Let's suppose the pressure drop from the turbo outlet to the manifold is 3 psi; so the actual compressor outlet pressure is 3+17=20 psig. The air pressure is 0 psig, but since the turbo is sucking air to.
- Basic Valve Sizing: Air valves are sized for flow capacity (Cv) based upon a given cylinder piston size, stroke and travel time requirements. Cv us actually a flow coefficient that measures the amount of air a device can pass. The following formula can be used for air valve sizing
- 14.7 = Atmosheric Pressure @ Sea Level (psi) CR = Engine Compression Ratio To compensate for altitude when computing desired effective compression ratio use the following equation: Corrected compression ratio = ECR ‐ ((altitude / 1000) * 0.2) Where: ECR = Derived from the above equation or table.
- The calculator will spit out the
**compression****ratio**in an instant. It is especially handy in quickly comparing**how**various changes will affect the**ratio**, without all the longhand-math and slide. - g overlap
- How to calculate Compression Ratio . Forumla-Head cc = Deck cc = 1 cylinder volume. Head cc + Deck cc. Example - 69mm X 90.5mm engine size = 1775 ÷ 4 = 443.75cc .060 Deck = 9.80cc : Head = _____50.00cc : 503.55cc. Compression Ratio Chart. 1300, 1500, 1600cc Type I, II & III Single & Dual Port Heads CC in Head - Depth of Flycut. Bore X Stroke.

- My question is. If I know my cranking pressure and I know all the internals. Can I use cranking pressure to verify compression ratio. I ask cuz I'm pretty sure I'm at 9.5 cr and the shop told me that 165 psi cranking pressure isn't 9.5. That I'm more like 8:1. Here is what I'm using to get my compression ratio from the calculators on line
- The compression ratio is fixed, a variance in altitude will not affect the actual ratio. The air density is less at higher altitudes, as a result power will be lost and cranking psi will be lost. 09-14-2012, 12:15 PM #
- e the no
- The storage volume for a compressed gas can be calculated by using Boyle's Law. p a V a = p c V c = constant (1). where. p a = atmospheric pressure (14.7 psia, 101.325 kPa). V a = volume of the gas at atmospheric pressure (cubic feet, m 3). p c = pressure after compression (psi, kPa). V c = volume of gas after compression (cubic feet, m 3
- CR=Compression Ratio; VE=Volumetric Efficiency (constant, always a factor 1.15) CP=Compression Pressure; Cranking Compression Formula: AP x CR x VE = CP Example (my bike, 2001 Aprilia Futura, 998cc v-twin) 14.7 x 11.75 x 1.15 = 198.62 psi Another Example (2005 Suzuki DRZ400SM, 398cc single) 14.7 x 11.3 x 1.15 = 191.02 psi
- e your actual octane needs. Compression Factors. Boost. Engine Compression Ratio. Air/Fuel Ratio. Calculate. Results. Combined CR: 13.01 Recommended.

Trapped compression ratio 8.36:1 Static compression ratio 14.27:1 Actual cranking psi on my compression gauge 194 (checked both cylinder before i measured head volume so residual oil didnt boost cranking psi) final point: calculation is good but make sure you take actual measurements as you assemble * For an approximation take your compression ratio and multiply by atmospheric pressure ( 14*.7 PSI at sea level, lower the higher you go). If you had 10:1 compression and lived at the beach this would give 10X14.7= 147 PSI. Naturally there are other factors involved besides altitude Compression Calculator Simply fill in the form below to calculate your compression ratio Bore: (diameter) in. mm Stroke: in. mm Cylinder Head Volume: cc in. Effective D. Welcome Guest My Account Order Status Wishlist (866)762-7527. Products. Air & Fuel Delivery; Apparel, Decals, Books, Gift Cards. Static Compression Ratio: Take Out Window (Hold the Mayo between your....) If you want to take the formulas with you and put them in your tool box, here they are. 16.387 is a number than converts cubic inches to cc's

but sure can make a lazy off the line engine if mis-matched with low compression ratio or to big of a cam. a mis-matched engine just never works out well. so in his (Vizard's) example 10.0:1 static compression ratio would be approximately 1000 lbs. of combustion pressure at peak torque. and 14.0:1 would be 1400lbs of combustion pressure. Compression ratio determines the type of fuel, how much boost, and has a significant influence on an engine's power and torque potential. Calculating compression ratio is pretty straightforward.

#5. R-502 High side @ 290 psi / Low side @ .2 psi Compression Ratio @_____ #6. R- 410A High side @ 417psi / Low side @ 132psi Compression Ratio @_____ Take a look at the gauges to the left and calculate the compression ratio from the readings shown. Is it a good ratio or one that will cause trouble? Good ** Effect and typical ratios**. A high compression ratio is desirable because it allows an engine to extract more mechanical energy from a given mass of air-fuel mixture due to its higher thermal efficiency.This occurs because internal combustion engines are heat engines, and higher compression ratios permit the same combustion temperature to be reached with less fuel, while giving a longer. bar, or, roughly estimated in pounds per square inch (psi) as between 15 and 20 times the compression ratio, or in this case between 150 psi and 200 psi, depending on cam timing. Purpose-built racing engines, stationary engines etc. will return figures outside this range. Factors including late intake valve closure (relatively speaking for camshaf 254.7 PSIA Discharge ÷ 89.7 PSIA Suction = 2.84:1 Compression Ratio. The compression ratio will change as the evaporator load and the condensing temperature change but in general, under near design conditions, you will see the following compression ratios on properly functioning equipment depending on the efficiency and conditions of the exact. Calculate basic compression pressure from the two low- and high-speed effective compression ratios of 7.32:1 and 8.55:1, respectively, assuming standard sea-level atmospheric pressure of 6.67 Kilogram per square inch absolute (psi)

Calculate the compression ratio. Enter the information from steps 1-3 into the equation above to calculate the compression ratio. FAQ. What is a compression ratio? A compression ratio is a fundamental specification in combustion engine design that measure the ratio of the total working volume of a piston and it's compression volume The better the intake filling is, the higher the pressure achieved on the compression stroke. This, along with as high a compression ratio as the fuel permits, means significantly higher pressures on the power stroke. On to the compression stroke. The higher the compression ratio, the higher the resultant combustion pressure (a) Calculate the ultimate (nominal) compression and tensile force capacity of the RC section shown below. (b) Also calculate the stresses in concrete and steel when the section is subjected to (i) one-tenth its ultimate load, (ii) one-half its ultimate load [Given: f c = 3 ksi, f y = 60 ksi]. 2.5 ct 2.5 s10 (a) Eq. (2.3) P n = 0.85f c A c + Compression Ratio and Displacement Calculator This simple tool allows you to calculate the STATIC compression ratio of an engine. It will also allow you to calculate the engine displacement in Liters and Cubic Inches. See Below for explanations of the fields required Compression Ratio and PSI Compression Test I agree no, not really 9.6 = 135 PSI 10.1 = 145 10.5 = 158 11.0 = 175 180 is very high - this motor will need liquid dynamite to run without pinging. So many other factors. This is a rough estimate +/- 10% on the way you do your compression test

The factors that influence compression force for a given application, and a method of finding its approximate magnitude are explained in the section called O-Ring Applications. Compression load tables included in the eHandbook are limited to 70 and 90 durometer materials I don't think the compression ratio is as telling or easy to calculate as the compression or PSI. I had a pump dome that would get up to 175 PSI and for the most part it ran fine on 93 octane, but when it got hot it seemed like it was on the edge of detonation Im aiming for a decent amount of boost, not some silly 20psi or anything, but id be happy with 8-12 psi intercooled. Talked to forcedinductions.com and they were thinking that would be more than possible on about 9.5:1 compression. So, not totally sure but seems doable. hence the questioning of the forums Compression set is a measure of this decay, expressed as a percentage. When compression set reaches 80 percent, most O-rings are in danger of losing their ability to seal. O-rings at higher squeeze levels generally take longer to reach that 80 percent compression set level

* There is really no 100% accurate way to calculate your compression ratio from psi, but there is a formula that will get you fairly close*. First take your psi reading and divide it by 14.7 (for example, psi reading is 170 divided by 14.7 = 11.56). Then take your engine size and multiply by .01 (for example 250cc x .01 = 2.5) Calculate basic compression pressure from the two low- and high-speed effective compression ratios of 7.32:1 and 8.55:1, respectively, assuming standard sea-level atmospheric pressure of 14.7 pounds per square inch absolute (psi). A compression process typically following this pressure volume relation is known as polytropic process For calculating compression ratio you should know the swept volume and clearance volume of the engine cylinder. Then you can use the relation, r= 1+(Vs/Vc) 120-150 psi is normal for most automotive purposes. The higher compression ratio the higher the compression test readings. 100 psi would be about right for an engine with a 8 to 1 compression ratio. your engine should run fine with that reading

Compression Ratio In Engines 15.03.2013 · Eingebettetes Video · how to calculator compression ratio and head gasket thickness bodgit and leggit garage - Duration: 37:45. bodgit and leggit garage How to calculate static engine compression ratios. Includes basic compression ratio calculator A gasoline piston engine that can dynamically change its compression ratio —that is, the amount. For carbureted engines with compression ratios of 9:1 or less and boost levels in the 8-14 psi range, pump gasoline works very well. Compression ratios of 10:1 and higher require lower boost levels, higher octane fuel, intercooling, or some combination of the above ** You can try different combinations by changing the head chamber volume ccs, engine block deck height, cylinder bore size, etc**. and see how they affect compression ratio. This static compression ratio calculator is an accurate tool and can assist you with selecting the best combination of parts for your engine

- Calculate Boost Compression Ratio: Wallace Racing BACK to Calculators Todays date is 4/30/2021. Boost Compression Ratio Calculator: Boost Pressure in PSI
- 110-130 PSI . How do you convert compression ratio to PSI? To calculate the pounds per square inch (psi) from the compression ratio, one needs the compression ratio and the atmospheric pressure measurement. Then, the first number in the compression ratio is multiplied by the atmospheric pressure, then divided by the second number in the ratio
- That is, 800 psi (55 bar) pack-and-hold pressure on one machine with an intensification of 10:1 develops 8000 psi (551.7 bar) plastic pressure in the nozzle, but on another machine with an intensification ratio of 12.75:1, 800 psi hydraulic pressure develops 10,200-psi (703 bar) plastic packing pressure in the nozzle
- Calculate Boost Compression Ratio: Wallace Racing BACK to Calculators Todays date is 2/9/2021. Application: All vehicles that reference MAP To allow you to view actual boost pressures above atmospheric pressure you can simply make a custom PID. 17 psi is the gauge pressure, the absolute pressure at sea level is 14.7 + 19 = 33.7
- crankshaftcoalition.co
- ed 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
- Consider the fact that, to produce 880 HP at 9000 RPM, requires 513 lb-ft of torque, for a peak-power BMEP of nearly 216 PSI (14.92 bar, torque ratio of 1.43). Peak torque for that same engine was typically about 535 lb-ft at 7800 RPM, for a peak BMEP of over 226 psi (15.6 bar, torque ratio of 1.50). THAT is truly astonishing

- The formula for calculating your exact Final Compression Ratio is as follows: Final Compression Ratio (FCR) = [ (Boost/ 14.7) +1] x CR Boost = Maximum blower boost 14.7 = PSI at sea level CR = Engine Compression Ratio
- Compression ratio is based on volume, and psi is a measure of pressure. Although they're related, they are not based on each other. You could fill bicycle tires and car tires to 35 psi, but they both have much different volumes
- Compression Calculator Simply fill in the form below to calculate your compression ratio Bore: (diameter) in. 1 COMPUTING COMPRESSION RATIO Compression ratio is defined as the ratio between the Total Volume (Cylinder Volume plus Clearance Volume) above the piston at BDC and the Clearance Volume above it at TDC. 190 PSI is 9:1 200 psi is 9. 75cc.
- And if you're trying to get new numbers for a compression check: P1 = reference pressure (like the 133psi service limit stock) V1 = reference volume of compressed air (58.74cc stock) P2 = pressure you nee

** 1 psi**. 36 psia to 250 psia. 3%. 1% Operating pressures at each stage are expressed in the term Compression Ratio. Depending upon the use of this term, it may be defined at the cylinder flange pressures or the internal pressures. Compression ratio is the discharge pressure divided by the suction pressure (in absolute pressure units).. Definition. Data compression ratio is defined as the ratio between the uncompressed size and compressed size: = Thus, a representation that compresses a file's storage size from 10 MB to 2 MB has a compression ratio of 10/2 = 5, often notated as an explicit ratio, 5:1 (read five to one), or as an implicit ratio, 5/1 Is there a formula or even a ball-park way to determine compression ratio based on the psi rating from a compression test. I got around 140 psi on my 351w with afr 185s (i think the 58cc comb. chambers) and im not sure if the pistons are slightly dished but they are relieved

But with this simple formula, all you need to know is your engine's compression ratio, and you can very quickly calculate how much cranking compression pressure your engine should produce, no matter if it's an old carbureted trail thumper or a modern EFI repli-racer. AP = Atmospheric Pressure (about 14.7 @ sea level) CR = Compression Ratio Actually you can just do a compression test and get the max psi and then from that calculate the actual compression of the motor. To me this is much more important than the theoretical max compression that a motor can make if the valves opened and closed at tdc and bd

- How to Calculate Compression Ratio from Scratch As an example, let's calculate the CR for a popular big-block Chevy application. Starting with a .060-inch overbore (4.310-inch) and 4.250-inch.
- Now the piston starts it's upwards stroke, compressing the air/fuel mixture to pressures of 100 to 200 psi or more. The actual pressure depends on when the intake valve closes, the pressure in the intake manifold (MAP or Manifold Absolute Pressure), Compression Ratio, and other details
- For four-stroke engines it is standard practice to calculate compression ratio based on the full swept volume of the engine. This is often referred to as geometric compression ratio but is also known as the static compression ratio. The compression ratio can also be calculated based on the swept volume after the closure of the intake port
- Trying to calculate changes in psi and temperature with a known change of volume. One cubic foot of air (14.7 psi) compressed to one tenth its original volume. 10:1 compression ratio. Starting temp=70° F or 294°
- Since no compression builds until after the intake valve closes, it's the corrected compression ratio that gives the best indication of how pump gas friendly your motor will be. Premium pump gas in the U.S. will generally tolerate corrected compression ratios of somewhere between 8.8:1 and 9.3:1
- um heads on pump gas, and 15psi is about as much boost as you can safely run before you at least start losing a.
- This calculator will calculate both Static and Dynamic compression ratio Compression Ratio is the ratio of an engine's cylinder volume vs. its combustion chamber size. Static Compression Ratio numbers are the ones you hear thrown around the most (10:1 compression), and it takes into consideration the full sweep volume of the cylinder in.

As Don says, at a first approximation, you multiply 15 psi x the compression ratio, but there are problems: The cylinder pulls a vacuum, and never reaches 15 psi unless you wait with the piston all the way down (BDC - bottom dead center) For example, if there are 140 cubic inches of space in the cylinder when the piston is at the bottom and there are 20 cubic inches of space when the piston is at the top of the stroke, the compression ratio would be 140 to 20. If this ratio is expressed in fraction form, it would be 140/20 or 7 to 1, usually represented as 7:1. Figure 1 For example in a compression ratio of 14:1 the sum result is 14+1, so 15 should be the pressure value as indicated on the manometer. 8 If there is a problem with your car's engine compression, it is best to take it for a service check to determine the source of the leak and allow professional to fix it I have purchased a reman. crate engine that crank-tests to 150 psi, but I have no other way of determining where I am on compression ratio before I tear into it. I'd hate to mill another .020 off the head and deck the block if it's already at 9.5 or 10.0:1 Engine Compression Ratio (CR) Calculator Enter Cylinder Bore Size 3.551 Enter Piston Stroke Length 3.54 Enter Head Gasket Bore Diameter 3.62 Enter Compressed Head Gasket Thickness .0036 Enter Combustion Chamber Volume In CCs 42 add 6 psi @ 15.5 hp per psi and you get roughly 90 hp gain...of course this is all based on what I consider low.

- Daily Slideshow: This famous custom F-100 is headed to Barrett-Jackson's Scottsdale auction
- That calculator seems pretty close. It predicts 185 psi for my combo, and I've recently measured 180 psi, cold engine, throttle body closed. Note: removing the carburetor made no difference whatsoever. You can't estimate cylinder pressure by multiplying atmospheric pressure (14.7 psi at sea level) by the mechanical compression ratio
- g. Purpose-built racing engines, stationary engines etc. will return figures outside.
- ute So, the consumption rate of a 2 bore, 4 stroke cylinder operating at 30 complete cycles per

An engine's compression ratio is a big deal. You never see a low-compression racing engine unless it is arbitrarily limited by some class restriction. Higher compression ratios yield more power in racing engines and street engines. Everyone remembers the anemic low-compression 1970s and nobody wants to repeat them. Once the OEMs gained greater control over [ Compression Ratio Calculations - posted in Problems, Questions and Technical: The topic of Compression Ratios keeps cropping up, so here is a guid to how to measure and calculate the various aspects of CR Calculations; 1. Measure the average distance from piston top to block deck level with the pistons at TDC. Take the average for all 4 pistons.2 Dynamic **compression** **ratio** calculators. Dynamic **compression** calculator by Kelly Dynamic **compression** calculator by KB Wallace Racing DCR calculator; Note: Some dynamic **compression** **ratio** calculators (like KBs) ask for an additional 15 degrees of duration be added to the IVC @ 0.050 lift point nnbfigure. This works OK on older, slower ramped cam.

of excessive compression ratios. Compression ratio is a term describing the compression cycle in a compressor cylinder, and while suction and discharge pressures are used to calculate it, the ratio itself is independent of pressures. By definition, compression ratio is the ratio of the absolute discharge pressure (psia) to th Compression ratio, efficiency of the pipes, timing, squish clearance and head design, are some of the more important factors to use. Perfect example, my Husky 346xp chainsaw has 185 cranking psi and runs fine with 91 octane As the ratio of L1/d1 is equal to L2/d2, the compression ratio then consequently returns. In this way, the pellet quality is guaranteed and the lifespan of a die is extended. I have to repeat it again that the compression ratio is a dynamic parameter during pellet production for a pellet mill

Compression Ratio is a design feature that will only change when physical dimensions of cylinder/head/piston changes. There is a relationship between the two: To calculate the pounds per square inch (psi) from the compression ratio, one needs the compression ratio and the atmospheric pressure measurement COMPRESSION RATIOS & MEASUREMENT - by the technicians of Group K. THE TWO MEASUREMENTS OF COMPRESSION - Compression ratios are referred to and measured in two generally accepted ways. They are, mechanical compression (also called calculated compression), and the more popular indicated compression that is derived from a common compression gauge - You can calculate λc for the column, the read the value of φcFcr/Fy - The column strength will be equal to φcFcr/Fy x (Ag x Fy) EXAMPLE 3.2 Calculate the design strength of W14 x 74 with length of 20 ft. and pinned ends. A36 steel is used. Solution • Step I. Calculate the effective length and slenderness ratio for the problem • Kx = Ky. The difference in the readings was only like 5 psi. on both the cold and hot readings. According to the TW manual, the normal psi. should be 128 give or take. Using your calculation table above our readings at my altitude should be around 119 psi. The best I got on my TW was 90 psi. and on Mrs. Admiral's between 90-95 psi

Then, for the June '01 issue, we tested another small-block with an XE268 camshaft, this time with a 9.75:1 static compression ratio that produced a cranking compression of 175 psi I calculated you compression ratio using the following: 4.030 bore 3.75 stroke 62cc chamber-6cc(estimated) for the .100 dome pistons.039 gasket thickness pistons .020 below the deck This calculates to 12.47:1! It's going to be very hard to get this motor to pull way down in sixth gear on pump gas without detonation