im planning on building a header for my new bone stock 95 ls, but i want to build this car for gas mileage and dont really care about the power it gains as long as its not loosing power.

iv'e looked around a little but pretty much everything i find is focused more on power or gimicks. so my questions are; 4-1 or 4-2-1, long or short runners/where to place collector(s), tube diameter, if 4-2-1 should the diameter step up or stay the same?

also if anyone knows of a good article or resource on tried and true mpg mods (no hydrogen generaters or fuel magnets) post em up

 

Stock??? j/k i'm interested to see what people think on this.

 

if your looking for mileage then I would say build the header with low rpm power in mind.. so long , small diameter primaries and a good 4-2-1 collector..

 

keep it stock and spend the money re-tuning the fuel map?

 

For highway mpg:
-Block 1/2 of the grille at least
-Cut up the rear bumper to catch less air
-Remove mud flaps
-Tighten gaps around hood
-Narrower tires
-Make sure all splash shields are in place and even consider some new ones

For city mpg:
-Lighter rims
-Low rolling resistance tires
-Stop carrying around unnecessary stuff

Generally, at higher speeds aerodynamics is what matters. At lower speeds, anything that makes the car harder to accelerate matters. I actually feel the motor is a small part of the equation (as long as it's in good running shape) and the car surrounding it is where the largest gains are to be made.

 

yeah i plan on doing all the aero stuff latter, mainly lining the bottom with aluminum sheet with a small rear diffuser.

as far as tuning the fuel map, i could take the AEM EMS out of my gsr to test with but for a more permanent solution what whould the cheapest way/system to have a tunable fuel map (not that im cheap, but kinda dumb to spend a ton of money just to save a little at the pump).

but the main reason im asking about the header is because i want to make one for the car anyway, i just want it to go with the big picture of more mpg.

 

Agreed. Estimate where your your hwy cruising rpm is and use a header designed for that range.

 

I have been up to 70+ mpg on a bone stock (engine wise) civic with 200,000 miles on it.

Njn63 has some good ideas to increase your mileage a few percentage points but i have learned through my experiences...

The biggest and best change you can make is adjusting the NUT behind the wheel.

IMO I wouldn't start to worry about header design untill you have doubled your cars EPA staimates with it being stock.

Example - My mom owns a Prius. She averages in between 50-55 mpg in the city. The same car, same day, i can easily average between 70-100 mpg.



nut behind the wheel dude, nut nehind the wheel

 

Id hate to have my nuts behind your wheel.
nut
wheel

wheel
nuts...etc

 

i do agree with the whole nut behind the wheel theory as i am pretty heavy footed but this car is mainly driven by my gf and she drives slower than my grandma!

were gettin about 27 mpg now, i'd like to at least see 40

 

i don't have much to add here, other than my ls/vtec with a RMF narrow header got 29 mpg consistantly. no real tuning other than a vtec controller and spoon ecu.

 

ive done some more reading and what ive come up with and decided to do agrees with this^.

i'll make a 4-2-1 pair sequentially, im gonna try and see what sizes in tubing are available and see if i can step it a few times from probably 1.5-2" then up to 2.5 at the collectors end, see how long i can get the primaries and even put some length into the secondaries. i have a high flow cat and 2.5" exhaust from my gsr laying around that i will probably shorten to accommodate the slightly longer header.

if anyone see's any problems with any part of this, as far as mpg goes, let me know. thanks

oh and where can i get the 15* bends in stainless to cut up to make the merge collectors? iv'e cut strait tubes to merge before but i really like the look of the bent ones.

 

I would go no bigger then 2" exhaust for better mpg.

 

Why??? I diasgree

A engine tuned for MPG is a funny beast. IMO go as big as you want on the exhaust (after header), make sure to pair it with a WARM air intake and you have a good start.

hmmmm, maybe we should start a discussion on pumping losses always a fun topic

 

im always down for a good read/discussion!

im using the 2.5" cuz i already had it, but i was also on the same page, thinking that the less back pressure from the bigger exhaust would decrease pumping loss. i'll give the header a 2" collector with a 2-2.5" cone at the end into the cat.

as for the warm air intake, im assuming your talking about a short ram? iv'e been toying around with the idea of taking a cold air (again since i have one laying around) and adding a ram air scoop in the bumper opening with a remote cutout so that i can shut it and get air from somewhere else in shitty weather. now since i will be able to close this ram air tube i'm probably gonna put it on this car anyway, but as far as mpg goes will ram air increase the mileage due to the engine not having to pump as hard at speed to get air in the cylinder or will it lower the mpg by having to add extra fuel with the extra air? iv'e read that on certain domestics with factory ram air that there scoops become inefficient over certain speeds because they fill with air faster than the engine can use it so the air kinda backs up and gets pushed around the scoop instead. so is there a formula that i can use to determine what size i need to make the scoop so that it takes in enough air to reduce the pumping loss of the engine without adding too much air which would require extra fuel?

 

Figure out how much money you'd spend trying to save gas and just buy the 500 gallons

 

The exhaust is rarely the issue. Depending on the cam (overlap), you may need some added resitriction. For MPG I think the best combo would be a D13 or D14 [crank] with a HX head, and an EMS like Hondata, Neptune, or eCtune. Less reciprocating mass, decent swirl-enducing head, and a wideband-augmented ecu with the miriad of hidden fuel & timing trims that will help out. Since it's a B-series, I'd almost guess a b16 with a cam profile similar to a HX and an LS manifold modified to fit would be best. If you can, a B20 intake would probably help. One is the long-runner "tunnel ram" manifold (b20b), one has a plenum-chaimber said to help midrange (b20z). A light flywheel will help, although the overall reduction in power might make city driving harder, or burn clutches out fast.


One thing about leaning your fuel maps out, your will peak NOx production around 15.5-16.5:1 afr's. Most cars that have this sort of lean burn mode will flicker rich every now and then to help burn those emssions that accumulate on the catalyst. The old Insight can go as lean as 26:1 if you can keep the throttle constant for long enough. Tap it or let off and it can hit 13:1 momentarily.


lol, I'll usually say that to people who want to make huge changes. However he seems to be able to built it himself, and plans on doing it more for enjoyment and a challenge than for saving the earth.

 

Not only the old insight can do that

Great ideas though, right on the money. but i would add a modified GSR intake to bump the mid and upper range a bit.

I have always wanted to build a destroked d series

 

ding ding ding, we have a winner! this isnt my one man war against global warming or an insane plan to spend a dollar to save a penny, i think my gsr MIGHT get 5mpg of 93 octane or higher when its spoolin up the gt40! but this car is a dd and i like making my own stuff, so as the oem parts need replaced why not replace them with a better performing part? in this case better performance as in mpg.

i'm planning on making an IM for the gsr, if all goes well (which it should) i might consider making one for this car as well but idk yet.

what is the cheapest fuel management available that will let me remap the fuel?

oh, and why do you say i would want restriction in the exhaust??

 

You don't necessarily want restriction, but you need to keep the exhaust velocity high.

 

Prob thinking out side the box but put the LS motor into a CRX and sell the teg shell lol INSTANT increase in MPG

 

Not sure if this is necessarily true. I never got much better than 30mpg with a stock LS in my CRX a year or two ago. But then again, I usually beat the **** out of it.

 

anyone know where to get 90* mandrels in ss between 1.5 and 2" that dont have legs? i'm looking at burns but i figured if anyone has them without legs it will be cheaper.

what are the benefits or differences in performance/flow of a parallel merge collector compared to a splayed merge collector?
so far what iv'e found its gonna be around $50 for the bends to make each collector if i make parallels compared to the price of foot of straight tube if i splay them. so unless theres a noticeable difference it seams kinda dumb to make the parallels other than they look nicer.