Exhaust Manifold
 

Hey all, I was wondering. will getting after market headers improve the gas mileage? After adding an intake, i was just wondering if i add the headers, will it give it a tad more mpg. Thanks

i'll bite...lol.ussually headers add power..a few rpm's...generally adding rpm's will decrease your gas mileage in some sort of way.if the loss is minimul it could be worth the gains in rpm...and all this would depend on how you choose to drive after said mods.you might waste gas just listening to those headers rev.


poor stagnent thread....made me feel bad for it.

You have one header btw.

A header will help gain you MAYBE 1-3 hp on a stock car, with stock tuning. Add an intake for 1-2 hp, and a cat-back exhaust for another 3-5 hp MAX (again... on a stock car with stock tuning/ECU).

Add those (I/H/E) mods, and get the ECU chipped and tuned, you would be looking at about an additional 10-15 whp, depending on the worthiness of the tuner you go to.

In any case, for the money you would spend for that 20 hp, it is not worth it at all.

thanks for the info. i decided against it, i mean id like to have a faster d15 but after 17 years, ill just baby it till i drop a swap in it.

I would think you might get a bit more fuel mileage, especially if you swap out the catalytic converter for a high-flow one. You're basically allowing the engine to breathe better.

I've always been on the fence as far as an intake goes. On one hand, it allows the engine to ingest in more air. But I would think that with the extra air comes more fuel because the ECU is trying to keep a nice, healthy air/fuel ratio.

When I was experimenting with fuel mileage results a few years ago on my old Corolla, I netted almost a 1 mpg increase from changing to a high-flow intake. So I did actually gain something on that particular car, but I'd have loved to have seen what the fuel injectors were doing to compensate.

Two facts to bear in mind that people seldom consider:
1. headers are significantly lighter than a stock exhaust manifold! a lighter car = increased acceleration, safety (braking, steering), efficiency (to a point).
2. if you remove your stock manifold, you're also removing the catalytic converter to make room for the headers. more flow yes, but some states/countries have emission testing that will detect the rise in pollution (if you don't install an aftermarket cat further down the pipe).

^^ #2 is not true 100% of the time. All 92-95 Civics had a cat separate from the manifold that was under the car with exception to the VX hatch back. (96-00 EXs and SIs do not have the cat in the manifold either)

Simple answer....yes but not much. Worth it? Up to you.