I get 180 max miles a tank

Standard '94 8v vitara/kick/tracker with calmini back half exhaust, no cat

Driving at (wait for it) UNDER 35mph 'cos thats my islands speed limit! And about half of that driving is offroad most of the time.

Would love to get more outta it, as i'm just about to stick on 6" and 32" mayb 33"s

Would the calmini manifold/header and a safani snorkal improve it at all?

Two things to bear in mind when making comparisons:
1. A 4dr has a bigger fuel tank and therefore generally does more miles per tank.
2. A US gallon is rather small.

let's put some metric numbers in here.....  i get 400km per 50L tank everytime, very mixed driving but have noticed that since it's been cold the mileage is dropping a bit.  also notice that if i run over 90 octane fuel my tracker runs much better, it's the 2.0L 4cyl with less than 40000km on it to date.  running 31x9.5 swampers with 30psi on the street.  if i drive over 100km\h the mileage drops on the highway for sure, especially with more weight loaded into it.  at 60mph(100km\h) i'm sitting around 2700rpm i think.

30 psi isn't metric niether is 31 x 9.5    joking... I went down to 23 psi and that tank bore about 25 mpg.. down 2-3 MPG. I'll try 30 psi on this tank. I have tiny 215 tires right now.

bzzr2 are you running stock gears, 5 speed, 2 door, 5th gear?  I'm stock 4dr probably runing at 3200 rpm at 60 in 5th gear. I was wondering what my rpm would be with 30's or 31's.

true enough, i somehow trailed off the metric numbers there.....  yes, stock 4.62 gears, 5spd, 2dr, 2003, running 5th on the highway.  i double checked the rpm's and they are actually just a shade over 2500 |removethispart|@ 60mph/100kph. it runs fine but i do use 4th on hills quite often.

Thanks for that, bzzr2, that's about what I expected/hoped for stock gears. I drive lots of flat freeway at 65-80 mph in the deadly Phoenix quagmire. Hoping the rpms will help with mpgs a little to compensate.

Thanks for that, bzzr2, that's about what I expected/hoped for stock gears. I drive lots of flat freeway at 65-80 mph in the deadly Phoenix quagmire. Hoping the rpms will help with mpgs a little to compensate.

Upping your tire pressure will help by reducing rolling resistance, but the larger tires won't (certainly didn't with me, anyway, and I only went to 29s).  In 5th, your revs don't really make it up to the powerband before your speed reaches a point where the aerodynamics start killing you.  Unlike a car that's making more than enough power at a certain RPM to handle the air resistance (in which case dropping the rpm's, will help), your truck is fighting a losing battle.

As an example, I'd wager (of course, I often lose bets..) that, with the larger tires and no tail wind, your wide-open top speed is higher in 4th than 5th.

I do most of my driving at 60-75 mph on dead flat freeway in not very windy Phoenix. You think dropping my average rpms in 5th gear from 3200 down into the high 2000s won't help my gas mileage? I get that moving bigger tires takes power so I'll lose some on hills and stop and go driving. But you think the wind sheer will kill huh? I was hoping for more of a break even than saving big bucks or anything like that.  How much did you lose with 29's?

Thanks

I do most of my driving at 60-75 mph on dead flat freeway in not very windy Phoenix. You think dropping my average rpms in 5th gear from 3200 down into the high 2000s won't help my gas mileage? I get that moving bigger tires takes power so I'll lose some on hills and stop and go driving. But you think the wind sheer will kill huh? I was hoping for more of a break even than saving big bucks or anything like that.  How much did you lose with 29's?

Thanks

Yep, dropping your rpms at a given speed also drops your power output.  If our motors had a nice, fat, flat torque curve, dropping rpms wouldn't hurt as badly (power vs. wind) and you'd most likely get a gain.  But that's just not the case with those 4-cyls.  As I recall, I lost about two mpg, corrected for the odo/speedo change, in both my 96 and my 03.  At slower speeds (50 or under) where it doesn't have to work so hard to push the air, the bigger tires probably would improve mileage like you'd think (although, to really max it, you'd have to downshift for all hill or acceleration events).

Now, if you want to REALLY destroy your mileage, flip open the "sunroof" on the convertible and drive across Kansas at 70+ mph with your upsize tires.  I think I got 17-18 that day...highway...