Civic VX: Headers vs stock exhaust

[PaleMelanesian]

I wouldn't dismiss the OEM setup for getting high mpg.

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(and it's not even a VX)

[Ryland]

Originally Posted by Joe1234

I'd be happy if it got the 40+ mpg it is supposed to get. Right now I'm prepping it for paint.

With everything working correctly, you should see 50+ mpg with normal driving.

[ShadeTreeMech]

Originally Posted by Ryland

With everything working correctly, you should see 50+ mpg with normal driving.

Is that ecomodder-normal driving, or normal people driving? There is a bit of a difference

Part of the point of smaller exhaust is to get rid of the stuff before it cools off and starts to weigh a bit more and slow down from lost momentum. (Some sports cars insulate the exhaust system.....I wonder why....my Maxima in good tune gets close to 30 mpg while being a quick 4 door sedan and it has insulated exhaust.) Kinda like how a river speeds up at a narrow bend, a narrow exhaust pipe will let the gasses exit quickly and preserve the momentum they got from the engine shoving them out.

[mcrews]

bottom line.
The car is an FE model. Specificly designed for high mileage. This model has it's own exhaust header, different fornm the others (as some one has already clearly stated).

oh well what do those stupid honda engineers know anyway. we should kick this to the unicorn corral........

[Ryland]

Originally Posted by ShadeTreeMech

Is that ecomodder-normal driving, or normal people driving? There is a bit of a difference

EPA rating is 52mpg highway, My last tank of gas on my civic VX was 55mpg, normal driving, part of it with 3 people in the car, part of it with letting my dad drive, part of it with a friend of mine who needed to barrow a car using it however they drive and the rest of it was with me hauling stuff around, I thought that with letting others drive it that my mileage my drop, but it stayed the same.

If you folks think that installing larger exhaust will help, why doesn't the math and science behind exhaust design and sizing agree? bottom line is that exhaust flow is in pulses so "free flowing" and "back pressure" doesn't hold true like it does if you were a plumber.
The only advantage if larger exhaust that I've seen is that it's louder so you can feel and hear better when you are giving it to much gas, allowing you to fine tune your driving style, beyond that there is no math to back up claims that it will help mileage.

[mcrews]

This has happen now, twice in the last month, were some new owner of a honda civic has a rice'ed out ride and wants some advice.

Add (for lack of a better description) the 'bolt-on boys' pop up and tell us their anedotal stories about how 'bubba' got better mileage bolting on 4inch headers.

NOW, I say that tungue-in-cheeck but am somewhat amazed. It's like suddenly 'we aren't in Kansas anymore Toto'!

What i really am amazed at is the the op has YET to measure the od of his exhaust pipe.

[Bow]

My hole point is, how much are you going to spend up front to save some fuel.

If the OP has a car with a header and a large exhaust, but doesn't have the stiock parts to put back on, he has a couple choices:

Drive it as is and see how well he can do with no investment

Try to barter his aftermarket parts for stock replacements, and deal with his car being non-drivable during the removal/shipping/install times (if he can find them local, remove the shipping time from the equation)

Cough up some cash for OEM Honda parts and put them on... then he can figure out how much fuel he needs to start saving before he actually breaks even and starts actually saving money...

I run a header on my truck ($180 for an aftermarket Pacesetter 4-1 header, or $380 for an OEM replacement cast iron manifold (the original unit cracked between cylinders 2/3)..

The header alone is a 50% weight savings over the stock unit...

I'll bet he can get close to stock mileage by adjusting his right foot

[Ryland]

The other way to look at it is, say you spend $250 on a brand new manifold, figure out what kind of mileage the car gets in it's current state and figure out how much your mileage improves, save the difference and once you have enough to buy your next section of exhaust get it, mileage improves again and the amount going in to your savings account increases, at some point you run out of parts that need to be fixed and you start saving for your next car, or house or retirement or whatever it is you want.

[mcrews]

gee, hate to rain on your post........but here is what you said

"Your best bet is to leave the header... it will flow better than the stock manifold, as stated above.

Which is really kinda wrong.
The model is the VX. that's the FE model. as has now been said several times, it has it's own manifold from ther factory that, (gee i don't know....) is designed SPECIFICALLY for FE.

So imho, don't think your right.

AND that is not he same as what you then posted........

Originally Posted by Bow

My hole point is, how much are you going to spend up front to save some fuel.

If the OP has a car with a header and a large exhaust, but doesn't have the stiock parts to put back on, he has a couple choices:

Drive it as is and see how well he can do with no investment

Try to barter his aftermarket parts for stock replacements, and deal with his car being non-drivable during the removal/shipping/install times (if he can find them local, remove the shipping time from the equation)

Cough up some cash for OEM Honda parts and put them on... then he can figure out how much fuel he needs to start saving before he actually breaks even and starts actually saving money...

I run a header on my truck ($180 for an aftermarket Pacesetter 4-1 header, or $380 for an OEM replacement cast iron manifold (the original unit cracked between cylinders 2/3)..

The header alone is a 50% weight savings over the stock unit...

I'll bet he can get close to stock mileage by adjusting his right foot

Again, hate to make a big deal about this.....BUT,
1. throw out the spare...it weighs more.
2. while he can't buy the new parts he might be able to trade for the used ones.
3. and I really doubt, that just because you might have gotten results w/ your header, the fact that his car is designed for fe and is now not designed for optimal fe.......

[mcrews]

Originally Posted by niky

You never want backpressure.




A well-designed set of breathing modifications will often increase fuel economy, unless it interferes with MAP function on your Civic (and they usually don't... not as with MAFs) or O2 sensor function. I had a full set-up on my car that didn't affect fuel economy one bit. And it got even better after we tuned the ECU.

**********and ur car was the same VX US spec'ed model........right???*********
That car being a Honda, instead of chasing theoretical lost MPG that you're not sure is lost, it might be better to add something that can gain you MPG, for sure. Lots of cheap tuning solutions for Hondas, from ECU-swaps to chips to Hondata (pricey though) systems... just check for legality in your particular state...

again, I'm trying to understand how this post, while well intentioned, really pertains to the ops. How is he chasing 'theoretical lost mpg?"
Remembering he has the VX model.

And I have yet to see, ANYBODY telling me that they ABA tested their mods.....
come on......at least AB?????