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I think it extends the engine rpm band. Different cylinders come into prime conditions at different times.....Quote:
Originally posted by Dave Severson
Ok, so now let's throw in a set of 4 into 2 into 1 merge collectors.....I know they help low end torque and top end horsepower, just don't have a clue WHY!!!!!!
The bigger and shorter the collector, the higher the rpm the engine must turn to come to optimum wave lengths for scavenging effect. Wouldn't that mean you could tune the collector to give the same affect as backpressure?? Maybe a 21/2" instead of 3" would benefit as well without the top end problems of backpressure.
A couple hours of dyno time with a few sets of headers would give you the answer. Considering the cost of dyno time, I doubt you could find significant gain to justify the expense. Without a check on the dyno, most of this is just opinion and guesswork anyhow......
Performance wise, you could probably buy a set of ready made headers and make the car 100 pounds lighter. I've got to build the headers for the Ranchero, might as well try to maximize the performance if you have to custom build, otherwise, I doubt the gain is worth the expense........