Guest polarity Posted October 10, 2002 Share Posted October 10, 2002 How do I know which cam I would want to run, I'm sitting here going through Summits catalog and can not figure out which cam I would want to use. Any suggestions? Quote Link to comment Share on other sites More sharing options...
Tim240z Posted October 10, 2002 Share Posted October 10, 2002 More info needed: What compression ratio What heads What inlet what carb (or FI) What rear ratio what gearbox (trans) what size tires how will you use the vehicle etc etc Tim Quote Link to comment Share on other sites More sharing options...
Guest greimann Posted October 10, 2002 Share Posted October 10, 2002 You have touched on one of the more complex issues in engine component selection. Before anyone can help with a recommendation, come back with some answers to these questions: What is the main purpose of the car (street only, 50% street / 50% track, race only?) Is low rpm drivability desirable? What power level are you shooting for? What pistons are you using (Dish, flat top, dome)? What is the CC of the heads? Is fuel economy important? What is the rear gear ratio? Stick or automatic? There are probably other considerations, but these are the majors. Quote Link to comment Share on other sites More sharing options...
Guest polarity Posted October 10, 2002 Share Posted October 10, 2002 maybe I've asked my question too early. Because I dont have the answer to most of those questions. I plan on using it for street driving (sometimes hitting the track just for a day out) and occasionally running over a few ricers. I'm not looking to pull 11's my any means maybe a low 13 would be good. I dont know what gear ratio. It will be a stick (trying to get a t5) and I'm looking for a very wide powerband. I want it to be quick off the line and keep going from there (maybe to 6500 rpm?) I was looking in summit at the vortec heads, but dont really have a set choice on anything yet, its all just trying to find out what I need. Billy Quote Link to comment Share on other sites More sharing options...
Tim240z Posted October 10, 2002 Share Posted October 10, 2002 Billy, If you haven't decided on heads yet, do a search on Vortec heads. GrumpyVette had some very good suggestions on alternatives. I am using the Vortec heads on my 71 truck and am very happy with them. I bought the upgraded heads (stronger springs) from Scoggin Dickey an am running a L98 cam grind, but I think that the Iron Eagles are a better choice, but search away.... Tim Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted October 10, 2002 Share Posted October 10, 2002 read this first heres some GENERAL TIPS on engine planing things to keep in mind! READ THIS http://www.carcraft.com/editorial/article.jsp?id=868 HERES A BUNCH OF SBC COMBOS http://www.ryanscarpage.50megs.com/combos1.html (1) your normally limited to makeing about 1.25hp per cubic inch of displacement unless expensive high rpm parts are used or power adders like nitrous are used the larger the engines displacement ,the easier it will be to make any power level, starting with a 283 or a 307 puts your at a distinct DISADVANTAGE compared to a 350 or 383, 400 size engine (2)hp= torque x rpm/5252 so..... 400 ft lbs at 3000rpm=228hp 400 ft lbs at 5000rpm=380hp get the IDEA, the higher in the rpm range you make max torque the higher your hp will average! (3)looking at cylinder head flow numbers ((.257 x cfm at max cam lift x number of cylinders = hp POTENTIAL)) so...you can normally make ABOUT a MAX POTENTIAL HP of 411hp with heads that flow 200cfm 514hp with heads that flow 250cfm 617hp with heads that flow 300 cfm (4)all parts in an engine MUST be matched as to the ONE rpm range that your trying to make max hp in..... if you mis-match the rpm range of the parts the results will be far lower than the lowest rpm level of the least effective parts! (5) by far the most comon mistake is buying DEALS on parts that don,t match the rest of the parts in yout engines rpm range or not matching all the parts in the engine to a planned rpm range (6) the cross over point between useing a dual plane intake and a single plane intake is approximately reached at 3500 rpm and 230 deg@.050 cam durration or put another way if your engine spends almost all its time below 3500rpm and your cam has less than 230@.050 durration a dual plane intake will work best, if you spend almost all your time with the engine spinning OVER 3500rpm and your cam has more than 230@.050 durration a single plane intake will be best. this of course assumes your smart enough to know that the cam durration must also MATCH the ENGINES intended RPM RANGE and youve matched all the parts to the cams rpm range(the cam is the brains of the engine and determines what rpm range all the other parts should match, so FIRST PICK the rpm range/hp goal, pick heads that flow enough air to meet that goal, pick a cam that matches that goal and pick all the other parts to match the heads and cam here this will give you new guys some basic info cams http://www.newcovenant.com/speedcrafter/tech/camshaft/1.htm (theres 10 lessons ., read them all) http://www.howstuffworks.com/camshaft1.htm intakes http://victorylibrary.com/mopar/intake-tech-c.htm compression, http://victorylibrary.com/mopar/cam-tech.htm oil http://www.micapeak.com/info/oiled.html pistons/rods http://www.babcox.com/editorial/us/us20114.htm http://victorylibrary.com/mopar/rod-tech-c.htm http://www.engr.rutgers.edu/~llongo/8K.html headers http://www.geocities.com/MotorCity/Track/6992/vizard.html http://www.ssheaders.com/header.htm hp/torque http://www.carcraft.com/editorial/article.jsp?id=868 basics An internal combustion engine burns a mixture of fuel and air in an enclosed space. This space is formed by a cylinder that's sealed at one end and a piston that slides in and out of that cylinder. Two or more valves allow the fuel and air to enter the cylinder and for the gases that form when the fuel and air burn to leave the cylinder. As the piston slides in and out of the cylinder, the enclosed space within the cylinder changes its volume. The engine uses this changing volume to extract energy from the burning mixture. The process begins when the engine pulls the piston out of the cylinder, expanding the enclosed space and allowing fuel and air to flow into that space through a valve. This motion is called the intake stroke. Next, the engine squeezes the fuel and air mixture tightly together by pushing the piston into the cylinder in what is called the compression stroke. At the end of the compression stroke, with the fuel and air mixture squeezed as tightly as possible, the spark plug at the sealed end of the cylinder fires and ignites the mixture. The hot burning fuel has an enormous pressure and it pushes the piston strongly out of the cylinder. This power stroke is what provides power to the car that's attached to the engine. Finally, the engine squeezes the burned gas out of the cylinder through another valve in the exhaust stroke. These four strokes repeat over and over again to power the car. To provide more steady power, and to make sure that there is enough energy to carry the piston through the intake, compression, and exhaust strokes, most internal combustion engines have at least four cylinders (and pistons). That way, there is always at least one cylinder going through the power stroke and it can carry the other cylinders through the non-power strokes. http://www.howstuffworks.com/engine.htm short answer is pick a cam that gives you between 8:1-8.5:1 Dynamic compression and is designed to work in the rpm range the heads and intake you pick matches if you want a list of parts that will work well together Ill give you one but please understand if you sub even one part with something else it may not work as well, think of it this way, say youve never made cookies and I give you a recipe/formula that says use 2 1/3 cup flour 1/2 cups white sugar 16 oz c-chips 3 eggs 1/2 cup shortning 1 1/4 cup brown sugar 1 tsp baking soda 1/2 cup butter 1 tsp vannilla 3/4 cup walnuts 1/2 cup raisins (good cookies btw) and you follow directions except that your out of white sugar so you use 1/2 cup of salt, to you the salt looks the same,mixes the same,costs about the same, and the cookies look the same when your done, want to bet the RESULTS ARE FAR FROM THE SAME!!!!! well its the same deal with engines , I don,t care how close it looks or costs, if its not a perfectly matched part the RESULTS WILL DIFFER Quote Link to comment Share on other sites More sharing options...
Guest polarity Posted October 10, 2002 Share Posted October 10, 2002 quick question about intakes. I see in Summits catalog an intake by Weiand its a Stealth intake says it produces power from idle to 7000rpm. How do I know which of these intakes are telling the truth (or is this really a good intake) and which ones are just marketing hype? Billy Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted October 10, 2002 Share Posted October 10, 2002 intakes are fairly simple to pick if you spend most of the time your useing the engine at or below 3500rpm and the cam in that engine has less than 230 intake degs @.050 lift your better off 90% of the time with a dual plane intake, if your engine spends most of its time spinning 3500-7500rpm and the cam in your engine has 230 intake degs. @.050 durration the single plane intake will work better most of the time! the further from the cut point you get the better that intake style will work. Quote Link to comment Share on other sites More sharing options...
Guest polarity Posted October 10, 2002 Share Posted October 10, 2002 well first let me say thanks grumpy for all the help. I hope by time I get done with this swap I'll know 1/100 of what you do, and I'm glad you take your time to share all your knowlege with us. But now on to MORE questions (YAY) Why would an engine spend more time at such high rpms? I can picture drag racing and such but at that point its from 800rpms up to 6500 then shift same amount through the whole range. I guess if I dont know why I would keep my engine at that high of a rev I probably wont be doing it, but maybe you guys could shed some light on it? Thanks again to grumpy and all who help me with every one of these problems Billy Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted October 10, 2002 Share Posted October 10, 2002 ok lets look at an example,use this dyno info and figure what intake and gearing will be best, the tools are below.(hint)if the engine ever sees below 4500rpm after first gear or above 7500rpm your doing something wrong http://www.chevymania.com/dyno/dyno.cfm?num=10 http://www.bracketracer.net/carmath/dynochart.asp http://users.erols.com/srweiss/calcrgr.htm http://users.erols.com/srweiss/calcmph.htm http://users.erols.com/srweiss/calcrpm.htm Quote Link to comment Share on other sites More sharing options...
utvolman99 Posted October 11, 2002 Share Posted October 11, 2002 The stealth intake is a good intake. I had it on a 351W in a mustang. With that said it is still a dual plane intake. Dual plane intakes are more for lower RPM torque and single plane intakes are more for higher RPM. A lot of people on this board recomend either the Victor Jr. (Single plane) or the Performer RPM (Dual plane). IMO with such a light car the Vic Jr is a good choice. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.