headers

[RobE30]

Are long tube headers worth it? DD 325is w/ cam and soon to be upgraded software (miller maf w/ either 17 or 19# injectors)

[!kid]

a nice set of exhaust headers will complement a larger cam nicely.

[xLibelle]

m20 has pretty good low end torque. long tube headers are pretty much the best thing you can do for it, regarding exhaust.

the level of torque is another reason superchargers are a viable option over turbos. generally speaking turbos are better, so's not to start a sc/turbo war, but the sc on the m20 is way more fun!

[digger]

[RobE30]

I should've added that I'm currently using IE's shorty headers w/ no cat. I'm just worried about shifting my torque curve too far up the rpm band and killing my low end

[nando]

long tube headers don't shift the torque curve up, they bring it down.

shorty headers would actually do that, but since the stock manifolds are pretty short you don't really have anything to lose.

[xLibelle]

longer the primary, the higher peak is shifted

[T Verdier]

long tube headers don't shift the torque curve up, they bring it down.

shorty headers would actually do that, but since the stock manifolds are pretty short you don't really have anything to lose.

longer the primary, the higher peak is shifted

so which is right and which is wrong? You both say something different.

[kamotors]

I always thought that longer primary was more low end power. I know in the dirtbike world, shorter exhaust setup is more top end, longer the exhaust more bottom end.

[jmr302]

I always thought that longer primary was more low end power. I know in the dirtbike world, shorter exhaust setup is more top end, longer the exhaust more bottom end.

I'm just guessing that you're talking about 2-strokes. They're a bit different since the exhaust scavenging helps draw in the air/fuel mixture. That's the purpose of those big reversion chamber volumes.

[nando]

4 strokes use exhaust scavenging as well

[RobE30]

My knowledge of exhaust "scavenging" is limited to air-cooled vw's. I can tell you whats gonna work better on what engine etc, but haven't really looked into the best setup for an m20. I know that equal length tubing is best, but does anyone have any tube length measurements from their own past experience? Also what dia tubing works best (NOT a racecar) just looking for the optimum setup for a DD. I'd kinda like to build my own, modeled after "Stahl" headers but am open to suggestions. Or are ebay headers (affordable) the same thing? I know it's been covered but I was weighing things out before I use up some favors @ the local machine/fab shop. If you think I'm nuts for not just swapping in an m/s-50 is b/c I want to see how much I can get out of the M20 while still retaining reliability and the basic original design of the engine.