theMax

I was watching one of the many hotrod shows on lately and they mentioned that headers (where you match all the runner lengths) only benifit NA cars.

For boosted cars it is only important to get the right size to get rid of the gasses because the system is pressurized.

Sounds reasonable, so in this case there could be a differend set of headers for boosted maxs'

???

formz

I know exactly what show you watched. He only said that because he didn't want to make equal length headers... not because it makes more power.

Nealoc187

iTrader: (23)

Whoever said that is not giving out good information. Headers will give more of a gain on an FI car than an N/A car. The only thing is that with most turbo applications you can't use "headers" because you have to bolt a turbo to them, however on the maxima since our headers are so short you could still use aftermarket headers and then reroute the exhaust to where you need it and have the benefits of the headers over the stock manifolds, in addition to having a turbo.

DAVE Sz

iTrader: (2)

You mean that dope on American hot rod?

formz

You obviously didn't see the show... He wasn't using a turbo. He was using a supercharger on a 4.8L v8. Equal length manifolds are great for turbos because they route exhaust pulses at relatively the same speed to decrease spool time.

However, with a supercharger, since its not attatched to the exhaust in any way shape or form, equal length headers don't mean a damn thing. He was RIGHT when he said it on the show.

And now, it wasn't from American Hotrods, it was from Rides.

Dave B

A well designed set of tubular headers work great for turbos, BUT if the header is made out of anything other than cast iron, it will eventually crack due to the extreme heat a turbo developes. Most people don't want to deal with cracking headers or the expense of making a cast header.


Dave

MAXimumHP

iTrader: (7)

The advantage to equal length headers is efficient scavenging. The exhaust leaves the exhaust runner in pulses and ideally you want those pulses to line up correctly so that the just as the runners come together one pulse creates an area of low pressure behind it effectively sucking out another pulse from an adjacent cylinder and so on. It's always best to have this design, but in the case of superchargers, the air is forced out by the compressed air which has a much greater effect than sucking. (did you ever see anyone suck their birthday candles out?) So the scavenging principle is not quite as important (but still there because all efficiencies still exist). Bottom line for supercharged engines is to minimize backpressure, then worry about equal length if you have room.

Nealoc187

iTrader: (23)

I never claimed to have seen any show. I was responding to the the idea that headers only give gains on N/A applications which is rediculous, not a TV show. Whoever said that headers are useless in anything but an N/A application is completely wrong. Exhaust scavenging efficiency gives gains on any application, FI or NA.