Suzuki Grand Vitara XL7 - FC improvements

[Larco]

Hi there!
Been a silent member since 2010. Located in outskirts of Stockholm Sweden.

A few years ago I have had a 2001 Grand Vitara with the 2.5l V6 which i modifyed a bit. change the engine to a 2,7 liter and fabricated diy long tube headers about 1 meter long and som other smaller stuff. Loved the platform in many ways but my needs changed, the economy did not do it any favors at the time and it wasnt the extended 5-seat (XL7) variant so it was to small for my liking. Sold it 2018 i think.

Recently I found my self in need/"want" of buying a car. I found a grand vitara XL7 5-seater pre facelift, which fits many practical "wants" of my but the fuel economy of the V6 isnt the best. Which leads me to this post.

What can be improved FC-wise?
And how much could be gained.
What are the biggest efficiency pits that i perhaps can correct?
Some low hanging fruit?

I'm guessing the worst FE enemies is
*The V6 has alot of internal friction (each cylinder ads up).
*auto transmission.
*HD-drivetrain
*235/60-16 tires (205 would probably be enough)

Aero is probably horrible.
- underside is very dirty with the ladderframe etc. Would putting a full flat aero underbody on it account for something? Max driving speeds is probably 110km/h or lower.
- Minimising rear wake should be doable with some kind och box extension on the boot lid?
- minimising och variable cooling intake and changing to electrical fan.
- Taking of the roof rails
- Side mirrors will probably stay as original to not loose the practicality when reversing but mayby the can be replaced with som 360 camera system if one exists.
- Lowering 1-2 inches might be in place because im mostly using it as a wagon for transportation and not offroading so gound clearence is not of an imidiet concern. This will make the wheel gap to arch smaller also.
- Wide body arces will probably stay but perhaps i can reshape with aero in mind.

Engine and drivetrain
- Engine probobably cant get much more efficient without replacing the V6 with a 2l 3-4 cylinder which will not happen in the near future.
- Might a swichable warm air intake do anything for me?
- Manual front hubs to disengage front 4WD axle some say can help FC but i do not know how much but i would allow me to use the low range without 4wd which i always wantet to be able to when low speed maneuwering woth a trailer. but i would like to keep 4wd for the snow months.
- Changing the tires from 235 with to 215 might be worth sometning. I did get 215 winter tires on my last car seemed to balance the incresed winter FC somewat.
- Gaspowered engine heater for the winter month. i do not have an electrical outlet most of the time.


I know it is not the best ecomodder platform but THIS thread is more of a what can be done to THIS model to lower the FC losses to enjoy it more. I'd rather spend Money improving the car than paying for gasoline.
I know the gains is hard to come by but perhaps 10-20 % gain would be possible at least.
I've read all guides on the site.

Please see the attached Pictures of the car in question.

Thanks for your input.

[freebeard]

What is the stock tire size? Usually taller tires are used to lower RPMs at cruise. This interacts with gearing.

An airdam/partial bellypan/skid plate optimized for snow would be an interesting design challenge.

Front air curtains and Moon disks?

[Larco]

Originally Posted by freebeard

What is the stock tire size? Usually taller tires are used to lower RPMs at cruise. This interacts with gearing.

An airdam/partial bellypan/skid plate optimized for snow would be an interesting design challenge.

Front air curtains and Moon disks?

Stock tire size is 235/60-16
On my prevous GV i put on 215/70-16 for the studded winter tires. The larger circumference made my speedo show the actual GPS-speed. And the handling was still as expected but a little softer with the more sidewall.
I belive FC was better because of the skinnier tires. About the same as summertime apart from the cold starts which sipped alot of extra fuel.
215mm or skinnier tires like 185-205mm width would be good i think.

In my old car I put 4 extra driving lights on the roof rack above the B-pillar for fun. Thought it would feel as a deployed parachute but i actually did not notice as large drag/resistance as I would have thought. But mostly drove below 100km/h also...
This made me come to the conclusion that the mechanical side was the big culprint to FC and aero did less below 100km/h (60mph)

A bellypan and skid plate would help save the car from rust also. Only positives as i see it. so that would probably be among the first mods. The ladder frame is easy to cover with aluminum or plywood sheats.

If one really streamline the whole car and added a rear box cavity on the boot for a smaller wake, like the attached A2 picture?
Would the proposed aeromods actually be that notisable, you think?

[Larco]

Hypothetically
If i were to remove the front driveshaft and shift the trans into low range in areas were speed is lower. Autotrans would still shift normaly but effectivly like a close range box. Could that account for some savings with some good planing in Urban areas?

[cRiPpLe_rOoStEr]

Originally Posted by Larco

215mm or skinnier tires like 185-205mm width would be good i think.

Skinnier tires, as long as they're also not much smaller in diameter than stock ones, also tend to be advantageous for efficiency, because of the lower rolling resistence. Once in a while, even a slightly smaller diameter won't really harm fuel economy, once the rolling resistence is lower, yet for SUVs it's hard to find a skinnier tire suitable to the load and speed.

A bellypan and skid plate would help save the car from rust also.

I wouldn't really hold my breath for a belly pan and a skidplate to be much of a rustproofing. If it eventually gets more debris and even some chemicals trapped between the belly pan and the frame rails, it may be troublesome. But, just like I usually see in nearby construction sites, as long as you clean it after going off-road, in order to avoid accumulating corrosive materials around the frame (even the soil and some amendments used in agriculture may have some corrosive compounds to a certain extent), it won't be bad.

Would the proposed aeromods actually be that notisable, you think?

Usually aeromods are quite easily noticeable. If unwanted attention from police or traffic enforcement could lead you into trouble, be careful about how extreme you would be willing to try aeromods...

[Larco]

Originally Posted by cRiPpLe_rOoStEr

Usually aeromods are quite easily noticeable. If unwanted attention from police or traffic enforcement could lead you into trouble, be careful about how extreme you would be willing to try aeromods...

I was not specific enough.
I meant to say if the suggested aeromods would give a large enough FC improvement be noticeable at the pump?

Is I understand all the aero accounts for only about 3-11% of the total consumption in normal urban-highway situation. Then the improvements made would be fractions of 11% at most?

I found this on the web for the XL7 2002 model:
Drag coefficient (Cd, Cx, Cw) 0.5
Frontal area (A) 2.66 m2 (est.)
Aerodynamic coefficient (Cd×A) 1.33 m2 (est.)
Aerodynamic resistance at 100 km/h (62 mph) 33.1 kW (est.)

Cd is quite bad at 0.5.... tough...

[freebeard]

Cd is quite bad at 0.5.... tough...

That just means the changes you make can have a greater impact.

[y2kbug]

Originally Posted by Larco

Hypothetically
If i were to remove the front driveshaft and shift the trans into low range in areas were speed is lower. Autotrans would still shift normaly but effectivly like a close range box. Could that account for some savings with some good planing in Urban areas?

Has anyone here ever tested this? Im interested but i currently don't have a 4wd vehicle to test it with. If One doesnt need 4wd, it sounds like a good way to take advantage of extra features.

[Ecky]

I know you've said you want to keep it, but I figured I'd pose the question anyway - some mods are in opposition to a vehicle's utility. What do you get if you lower an SUV, put narrow LLR tires on it, remove the cargo attachment points (roof rails), and downsize the engine?

Google tells me the petrol GV has a fuel consumption of 10.5 L/100. A Honda Jazz Shuttle ends up having similar cargo space and seating capacity (and here, a lower price, even) with a fuel consumption of around 3L/100. What it lacks compared with the GV is that it's lower, has narrow tires, a downsized engine, and no rooftop cargo attachment points.

~

That said, if it's a vehicle you love (which is the best reason to buy and keep something), to me the biggest fuel eater appears to be the automatic transmission. I'm uncertain how many gears are in yours, but a search seems to suggest the autos available for that generation are not very economical gearboxes.

My experience has been that a V6, if geared correctly, isn't much of a penalty over a smaller i4 when cruising on the highway. The biggest increases in fuel consumption for the larger engine are around town, and on cold starts. With like-for-like gearing the v6 will consume more fuel in all scenarios, of course.

[Larco]

Originally Posted by Ecky

I know you've said you want to keep it, but I figured I'd pose the question anyway - some mods are in opposition to a vehicle's utility. What do you get if you lower an SUV, put narrow LLR tires on it, remove the cargo attachment points (roof rails), and downsize the engine?

What can i say. I keep coming back to these old 4x4 suzuki. They are great, good value except fore the fuelconsumption. Good ride, 4x4 with low range.
I am not going extreme with the mods.
I’ve seldom used the roof rails anyways. The old one i fitted 215 tires which did performed well. 235 wide is just overkill. One can have another tire set if needed for some reason. SUV stuff or winter…
I just want to optimize things so i perhaps can enjoy the car a little more.
The underbody is just aero-dirty, the fendergap is huge, the rear is probably a dissaster. That should be free gains. But how much?