Thread: 385 fast burn crate engine 350ci

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Henry is right,a motor that runs well is built for a purpose and all of the parts go together for that purpose.A massive carb on a stock engine ....performance goes down,high rpm manifold{single plane} on a stock motor...performance goes down.Huge cam ,stock motor performance goes down.......now take those parts and use the proper heads and short block ,with the proper gearing,etc..and you have a good motor.

High rpm and big cam durations are for the track or some one who likes to fiddle with the engine ALL the time,if you want the car to pull hard and be fun to drive on the street and idle,leave the big cams and the high rpm intakes on the shelf.Compression ratio and head flow make horsepower,the rest of the parts have to match those 2 figures.

Take what you have now ,find the compression ratio and head flow numbers and let that tell you what cam you need,then you take the cam spec,which tells you the operating range or rpm range and dynamic compression and then select a intake that matches those specs.Then use max rpm and cubic inches to figure size of carb,since you are building a street ride,you should use a vac secondary carb.

If that seems like alot to figure, then do exactly what henry said and get the hot cam ,any larger of a cam and the rpm that the motor starts to pull at goes up.{example} From a dead stop the smaller cam pulls harder and sooner in the rpm range of 1000 rpm to 6000 rpm,the smaller cam will pull hard from about 1500-2000 rpm up,the large cam will not start to pull until well above 3800-4200 rpm.That gives you 4500 rpm of pull before you have to shift with the small cam and about 2000 rpm of pull before you have to shift with the big cam.
Soo what does this all mean...?
It means the motor with the small cam will pull away from the same motor with the big cam off the line and the big cam motor will have to play catch up when it hits about 3800 and starts to pull,meanwhile the motor with the small cam is starting to lose some power to the big cam as the rpm approches 6000 .Keep in mind the small cam motor will achieve this rpm faster since it starts pulling sooner in the rpm range and therefore reaches max rpm faster than a big cam motor,Repeat for second gear and by this time you are well above any posted speed limit and will have to or need to shut it down.
The track only deal is alot different story,this is where you can use high rpms and a big cam by taking advantage of a large stall speed or manual tranny and big gears 4.88 or larger to keep the motor in its rpm band of 4000 to 6000 and now with the matching parts the big cam starts to show its stuff and get with it,while the motor with the small gears 3.73 and smaller cam,will show its weakness of small rear gear and lower rpm range in this high rpm enviroment,but will be way way better on the street than the big gear big cam motor.

This is not the only way to look at it and there are definatly exceptions to any rule ,but this should help you better understand the technical advice you are recieving and how motors and parts are working in unison to accomplish the same goal by being built for the same purpose.You just cant bolt on a nascar intake and be the fastest ......the rest of the parts have to match or...... you have done the opposite of what you bought the intake for ,which was more power.Same thing with the rest of the parts they need to match existing parts or they will do you no good at all ,infact they will actually lower current performance.