The forged pistons that used to be listed as TRW, are now the Speed Pro Power Forged branded piston sets. 67drake, Mar 20, 2020. w/ auto. Any power gained by the increased compression very likely would be lost by poorer combustion efficiency due to the misshapen piston. I would suggest to compare with other milling charts. Starting with 60F air at atmospheric pressure of 14.7 psia. HO and Super Duty engines were the most desirable. If you have any that you would like to see on this site My goal is to have smoother running motor after adding headers and s bit better performance daily driver, don’t want hot rod it. Pontiac definitely operated under a different mind set than Chevrolet division. Sometimes it's difficult trying to explain to fellows who are new to hot rodding that you have to match the characteristics of the camshaft to the static compression ratio of the motor along with the operating range where the cam makes power. The ending pressure would be 375 psig. The top-performing 421 Super Duty featured streamlined, aluminum exhaust manifolds. Unlike Static Compression Ratio, Dynamic Compression Ratio takes into account camshaft timing by considering the intake valve closing point in relation to the piston position. It is to be used as a guideline in determining the proper maximum boost level for a specific application. if (document.layers) The 455 powered the Pontiac GTO and Firebird. if (e.which==2||e.which==3) {(message);return false;}}} Compression ratio: 10.1:1: Horsepower (hp / kw @ rpm) 350 / 261 @ 5200: Torque (lb-ft / Nm @ rpm) 365 / 495 @ 4000: Recommended fuel: 92 octane: Maximum engine speed (rpm) 6200 : Emissions controls: catalytic converter/EGR: Estimated fuel economy (mpg city / hwy / combined) TBD: … Complementing the four-barrel was the functioning scoop, and a dual exhaust system with a single crossflow-type muffler helped the engine breathe. I have felt that heavily loaded vehicles running almost continuously, such as trucks and tractors, could have a problem. HO and Super Duty engines were the most desirable. A stock 1969 350HO was rated at 325hp. A small block GM is a chevrolet. Complementing the four-barrel was the functioning scoop, and a dual exhaust system with a single crossflow-type muffler helped the engine breathe. goes up. Click on Calculate Displacement. One cc will be deleted for each .005″ removed from the head. This chart shows the final compression ratio combining the static compression ratio of an engine and the maximum blower boost from the blower system. Static compression, (C.R.) Most of the 1960's standard Pontiac engines were high compression by todays standards. yours to be this size. The Dallas Area Pontiac Association is not responsible for the content of websites linked to from within this website. Performance suffered and the 455 was emasculated to just 200 hp. //Disable right click script III- By Renigade (renigade@mediaone.net) Bore: (diameter) Stroke: Cylinder Head Volume: Effective Dome Volume: Use (-) for Dome and (+) for Dish. (Note: If you click the buttons more than once, it will continue to add to the bore's value.) In these applications, the engine is mounted longitudinally. Feel free to drop me a note. Pressed. A small block GM is a chevrolet. Reply. Dome type pistons were not used by Pontiac. In 1962, Pontiac engineers were able to wring an incredible 405hp from the 421 with an 11:1 compression ratio and two four-barrel carbs. If you have aftermarket cylinder heads, the manufacturer's website should have a flow chart for your heads somewhere. High-ratio rear axle gearing was used to keep engine speed relatively low, which lessened emissions and improved fuel economy. Pontiac responded by … Larger or smaller cubic inches, different lobe separation angles and other variables will alter these figures, but at least it's a starting point in the explanation of using a certain range of cam with a certain range of static compression ratio. Final compression ratios in excess of 12.4:1 are not recommended for use with "pump gas." Consider this….to build a set of Stock Pontiac 6X heads that will flow 240 cfm and net you a pump gas friendly compression ratio you will need to spend about $1,500.00! The Pontiac Catalina is an automobile which was part of Pontiac's full-sized line from 1950 to 1981. The volume of the chamber can be changed by milling the head surface. Enter the piston stroke length. The first important change came under the hood, where a 287 cid overhead-valve V8 was nestled. The 1970 to 1971 Pontiac 455 generated 325 and 455 foot-pounds of torque. To ensure suitable engine operation on unleaded fuel while reducing emissions, GM mandated a maximum compression ratio of 8.5:1 for the 1971 model year. of torque at 2,800 RPM. The first important change came under the hood, where a 287 cid overhead-valve V8 was nestled. Most of the 1960's standard Pontiac engines were high compression by todays standards. Pontiac engines were available in many different displacements, ranging from 265 CID to 455 CID. Compression Ratio Calculator. Just complete your engine setup, click calculate, and you’re on your way to maximum performance. function clickIE() {if (document.all) {(message);return false;}} 1996 Pontiac Trans Am LT1 ; 1992 Ford Mustang 5.0L Coupe ; Boost Compression Ratio Chart From RPM Outlet. Compression Calculator Simply fill in the form below to calculate your compression ratio Bore: (diameter) in. Example: Chamfer on piston outer edge. Get your engine's optimal compression ratio and total displacement in no time flat! goes down; if the displacement is increased, the C.R. This chart is nowhere near scientific or definitive in its scope. SD engines have 4-bolt main blocks. When linked to a manual transmission this motor had … That's how they made good power. Calculated Engine Compression Ratio:1: Total Displacement Volume: cc: Updated 6.01.11 Leave us a question or comment on Facebook . If the chamber volume is increased, the C.R. If you have aftermarket cylinder heads, the manufacturer's website should have a flow chart for your heads somewhere. Ring land volume. It is not recommended to go The author claims no responsibility for the info contained in these recommended Prior to assembling any engine. on a Pontiac is a function of the chamber volume and the engine displacement. This lowering of the compression ratio, due to the late closing of the intake valve, is the primary reason cam manufactures specify a higher static compression ratio for their larger cams: to get the running or dynamic CR into the proper range. 1971 LS6 with 4 Barrel Carb Max Brake Horsepower: 425 @ 5600 rpm Max Torque: 475 @ 4000 rpm Stroke: 4.00 Bore: 4.251 Compression: 11.25 Firing Order: 18436572. var message=""; 400 / 546 @ 4400 (est. trans.) They will increase compression, but they also disturb the operation of the machined combustion chamber. Note that a normal valve job sinks the valves about .025″ which adds 2 to 3 cc to the combustion chamber. STATIC COMPRESSION RATIO CHART FOR PONTIAC ENGINES AND HEADS Cylinder Head Chamber Volume, cc's #400 bored.060" %428 bored.060" ~455 bored.060" *Actual displacement of 350. Troubleshooting Diagnostic Trouble Codes: P0301, P0302, P303, P0304, P0305, P0306. Also, the 455 power range is much lower than the 400 and the 1.66″ exhaust valve may work as well as the 1.77″ on the 455 street cars. determine how much). // -->. On a Pontiac engine the compression ratio's were change by Welcome Guest My Account Order Status Wishlist (866)762-7527. * I am looking for some good articles for the third Compress the gas with absolutely no cooling by cylinder walls, piston, and cylinder head. Compression Calculator. For the 455, Pontiac expanded the cylinder bore to 4.152 inches and the stroke to 4.21 inches. Cometics are a little pricey, but it’s another option. The indicated CR’s are for planning only, and complete calculations using all variables are. The Pontiac 455 V-8 was actually a bored out 428-cubic-inch V-8 with a bore and stroke of 4 inches by 4 inches. When linked to a manual transmission this motor had … The theoretical ending temperature for compression ratio of 10.4 is 867F. When Chevy's of that era had a 10.25 compression ratio in an engine it had at least one 4 barrel on it and generally two a a rump and thump camshaft, and definitely dual exhaust. goes up. Pontiac engines were available in many different displacements, ranging from 265 CID to 455 CID. 1971 LS6 with 4 Barrel Carb Max Brake Horsepower: 425 @ 5600 rpm Max Torque: 475 @ 4000 rpm Stroke: 4.00 Bore: 4.251 Compression: 11.25 Firing Order: 18436572. document.oncontextmenu=new Function("return false") Get your engine's optimal compression ratio and total displacement in no time flat! 1972 LS5 with 4 Barrel … 1972 LS5 with 4 Barrel … (this is assuming 6cc for valve relief, 9.7cc for head There were also numerous head castings. If .030″ or more is removed, the intake side of the head should be cut equally to maintain port/bolt alignment. TRW Automotive / Speed Pro Quality . *Pontiac 400 Compression area=25.45 + head cc (this is assuming 6cc for valve relief, 9.7cc for head gasket, 2cc ring area, and 7.75cc deck height volume.) COMBUSTION CHAMBER VOLUME.