New (to me) truck and sanity check

Hey all, just traded my 2017 Tundra for this 2018 that I happened to find locally. It was pretty well set up with KO2s, Airlift bags, TRD Pro exhaust, Viper remote start & security, topper, and the real reason I made the trade, a Magnuson supercharger. I don't love that it has a spacer lift and 20" wheels, so will probably swap those out sometime in the future. The tires on it are 295/55R20, which are only .7" taller than stock. Would love to find some 18" wheels and get some 295/70R18 KO2s on it soon. I just like the look of that a lot more.

I need help wrapping my mind around this though: My old truck was getting about 16 mpg and was pretty much stock, just with a topper and Duratrac tires in the stock size. The computer on this 2018 so far is telling me I'm averaging almost 18 mpg. I don't believe the speedometer has been adjusted for the tire size, but even taking that into account, it seems crazy to me that I would be getting better mileage with a supercharger than I was with my (mostly) stock truck. I don't know if the previous owner re-geared or anything like that, which could possibly help right? Am I missing something here?

Pics for attention:

 

Could have been re-geared and or Tuned?

 

Yeah I know it was tuned because of the supercharger, just wasn't expecting that much of a difference. Don't get me wrong, I'm loving it

 

If you dont calculate the mileage yourself and rely on the computer you do not know what it is really getting.

Sanity measuring is outside of my skill set. Way outside.

 

The computer doesn't recalculate to account for the supercharger. Mine is usually around 17.5mpg on the truck, but hand calculated it's about 12.5mpg. I've found that if you take what the truck shows and subtract 5mpg from that you'll be very close to the actual mpg. Welcome to the Magnuson club.

 

Ah good to know. So should I just take the mileage from the truck and calculate when I fill up? I know it won't be exact because of the change in tire size, but it's such a small difference, it won't be far off.

 

Also, any tips on maintenance or things to know for the supercharger? I had a supercharged Tacoma for a few years but this thing is a different beast.

 

Yup, take your miles driven (make sure to reset the trip odo) and divide that by the number of gallons it takes to refill. If your truck is showing 18 your probably ~13mpg which makes sense with the additional lift and tires on the truck.

 

No real maintenance for the supercharger itself. The oil in the unit is good for 100K, but I'll probably do mine sooner. I'd keep up on your spark plugs and that should be it. There have been a few cases of coolant leaking from the reservoir hose where it connects on the plastic tank - I swapped mine out to the Figs Engineering reservoir to avoid any potential problem with that. May want to look into a PCV catch can as well. Otherwise you should be good to go!

 

Its possible but I wouldn't trust what the computer displays; recommend hand calculating your fill ups OP.

 

Let me know if you find the KO2s in that size. I checked around March and they weren't supposed to be available until September at the earliest. I went with them in 305

 

Ah, good to know. I'm torn, because these still have a lot of tread left and I don't really want to spend close to $3k on tires & wheels right now. But not loving the size and offset of these. I'll probably run them through the winter and see what I think next spring.

 

From my research back then, Discount Tire, 4wheelparts and Costco would be the first places to be able to get them. Costco was cheapest and my local store had no problem installing non standard sizes. I ended up at Discount, they called BFG directly and spoke with a couple of people for me. That's when I found out it would be a yearish before I could expect the first run. We test fit some sizes of KO2 and the 305s fit with just a little passenger side bar rub. My tires were from the previous owner and they were trashed so I didn't want to wait. My next set will be that size though.

 

Nice …….would love to install the super charger. With Priemium fuel at $1.70 litre here ( that’s just of $8.00 a gallon if considered us exchange rate)

I waited for a long time to get the ko2’s that size but last fall I had to pull the trigger and new tires for winter.
Install Falcon wild peaks at3/w’s because that’s all I could get…..not sure if I will ever go back to ko2’s really liking the ride of these wild peaks… great in snow and seams the be wearing better than ko2.
May be a option for you.

 

I saw the same benefits when I had my MSC on my 2017. I had the speedo calibrated too. I had a 6” lift with 37” tires. I had the lift and tires before the SC, so my comparison is before SC and after SC since the truck was exactly the same set up. That said, I did see significant loss of MPG when I was heavier on the throttle BUT I did see significant SPG (smiles per gallon) gains!

 

Oh that’s good to know, I’ve been looking at the Falkens too. They seem to have a lot of hype, I was just going on my experience with the KO2s.

 

those SPGs are going to cost me a lot of money