camshafts????

how do you choose aftermarket camshafts. I've heard of 264 degrees duration, 272, 28...so on and so forth. What do those numbers mean and how would you decide what's best for you? Thanks

You read and you ask around what is the best solution for your car and for what you want to achieve.

The duration is measured in crankshaft degrees and are the time the valves are open. Typically there are ratings for the intake cam and the exhaust cam. There are usually also ratings for the valve lift.

It entirely depends on what the purpose of the engine will be. You can usually choose a cam that is slightly greater duration than your stock cam and get a noticable power increase, but the main thing is this; A larger cam shifts the power band up the RPM range. Right now you're getting usable street power probably from idle to 5000 rpms (depending on the vehicle/engine) Switching up a few degrees duration will move your powerband to maybe 1500-5500 rpms. A high performance street cam will move that up to 2200-6500. An engine like that will SUCK on the street due to the fact that you have to rev it before you get decent power. It also will require hundreds or maybe thousands of dollars in other parts to match the characteristics that the cam creates; airflow, transmission, rear gears, vehicle weight, etc.

If you want the long answer I can give it to you, but its a lot of theory and abstract stuff. Give us your current engine/car and we'll maybe be able to help you with a decision for now.

the big question is all engine or boosted?

Racer, To answer your questions...How to choose? Well, and please don't be offended, if you have to ask how, then you shouldn't choose your next camshaft. Call a reputable cam manufacturer and they will provide a cam that fits your needs. I would call a few actually. Take advantage of their dyno time and experience. Nothing else can make or break your engine (not in literal terms, but performance wise) like the wrong cam for your combination. Saab answered the duration question.

the car that I got is a 1986 toyota corolla GTS. I want to go all engine on it. I know the block can take somewhat of a beating but I wanted more power than what it has.

Benchtest-It's not that I don't know what I want, it's that I have no idea what those #'s mean (how they are determined, what they affect, etc...) so I don't have something to make my decesion off of. I know what I want as far as my goal but I don't know how to go about choosing what way to go. Anyways, thanks for the help so far. Anymore help?

Racer, I strongly recommend that you call some cam manufacturers and tell them your desires. That is what they do and the well-known brands do it very well. The duration numbers are as Saab said. They are determined by measuring the cam itself (actually they are designed-in, but you can measure if you want). When comparing the durations of different cams, be sure to use the .050" lift specs. Curtis' post covers the change in rpm band with larger duration cams. You could check the web sites of some manuafacturers and they will tell you the requirements for the cams as well as the results expected. I haven't tried it, but a search on cam duration should yield some information for you also.

Racer, Listen to bench test. If you talk to a company and discuus want you want out of your engine they will be able to give you a part number on the spot. Getting in over your head and choosing the wrong cam can make for a seriously unenjoyable ride. I would also suggest giving the boys at toysport a call. I'm pretty sure they have a wealth of knowledge for your specific application and can get you the parts you need.