The Tundra’s 5.7 VVT-i System Explained
Jason Lancaster | May 26, 2008 | Comments 12
By now, you have probably heard a mechanic or automotive enthusiast tell you that an engine is basically one large air pump. Basically, the more air an engine can suck in to combine with fuel, the more power it can create through combustion. It also follows that the more efficiently an engine can remove exhaust gases from the cylinders, the better it can manage that power. Air flow from one end to the other is key to a healthy, strong engine.
The powerful 5.7L V8 features dual VVT-i technology.
Air flow is affected by many different components in the motor, but the valves in the cylinder head are what directly control the amount of air entering a cylinder and the volume of exhaust gases leaving it. The intake valves open up just prior to combustion in order to allow air to flow in and mix with fuel, and the exhaust valves open after the ignition of this mixture in order to suck out the resulting gases. The timing of the valves is controlled by a rotating shaft called the camshaft. The camshaft has lobes which push up on the valves in order to open them and drop them back closed again. How long these valves remain open, and at what point in the combustion cycle, can have a big impact on the drivability and power generated by an engine.
Unfortunately, street vehicles are a compromise between reliability, fuel efficiency and power. While race vehicles have engines with camshaft designs that generate large amounts of power while being used only at specific, high revolutions, your daily driver sees a wide range of rpm
Filed Under: TundraHeadquarters.com
20 mpg 5.7 i-force? What are you dreaming try 12 at the most
Joe – 12mpg is a little low, but 20mpg is probably a little high. Most people get closer to 18. Sorry – our enthusiasm got the best of us.
I have a 2008 4wheel drive with 8000km’s on it and I get 20miles to the imperial gallon, while jigging around the country, and town. Is this likely to improve as I get a few more miles on the engine?
Dwayne – Your mileage is excellent – if it gets any better I’d be very surprised.
I want some of what you guys are smokoing! I have a 2008 5.7 2wd crewmax and the BEST I have ever got out of the beast is 17 on the highway and that was driving like your mother….Most of the time I hover around 15gpm. If you are buying this truck for gas miles you are high. Buy it becase it kicks the crap out of everything out there, red light to red light.
Joe and Mark I get 22.5mpg at 55mph. I get over 20 going 60mph. I do have add ons AFE and Borla Pro XS. I got 17.3 on a trip to New Orleans from Jax doing 85mph. This is mostly flatland also. My commute to work is 28 miles one way. Out of that 28 miles, 18 miles are Interstate 95 and 9miles are 4 lane 60 mph and the last mile is 4 lane 40mph with 2 redlights. I’ve been avg 20 mpg per tank. So it can happened, even with my 5.7 big block.
Mark – Your numbers are pretty close to normal, but some people just get better mileage than everyone else.
Just sittin here surfin and came across this site. I have an 02 Tundra and I’m buying an 08 next week if Gustav don’t ruin my plans in Louisiana. About the gas mileage. I have seen over the years that driving habits make a real difference in mileage.
My wife has a Pathfinder with trip computer, as sure many of you have and it shows that the car gets peak mileage at 61 MPGs. On level ground, it shows 26-28 MPG. Faster speed or slower speed, and it starts dropping a little.
And, I get better mileage than she does with it. She has a heavy foot and I like finess. I get all the fasty driving I can handle at work. 30 years in law enforcement.
I do worry about Micky, driving 85MPG to New Orleans. What could possibly make you want to “hurry” to New Orleans? : )
Mom passed away 90 minutes before I got there. She was in the hospital with pnuemonia and it got worse giving her a 20 – 40 % chance making the through the night. No I don’t care for New Orleans one bit that’s why I won’t live there. I left in 82 never to return to stay. Being one person who tries different gas grades and companies I tried ethanol on the way back at the same speed. I used ethanol at 55/60/65/70 and I got worse mpgs at slower speeds. At 85 I got the same mpgs as non ethanol gas. I’m avg per month just over 20mpg. David I do alot of traveling hence the mileage on my 07. I’m at 37,500 miles now. I use the different grades at the speeds of 55/60/70 on my trips to see what I get and I posted before my results. I finally replicated my trip to Orlando at 55mph and had 24.7mpg. This is not to mention the horn blows and suggestions you get doing 55 in a 70.
I Have a 2008 SR5 Crewmax 4*2 when I’m going down a hill my rpms goes up over 2 when im not touching the pedal. Does this suppose to happen???? Anyone?
Well I haven’t had the experience of driving a Tundra or riding inside one. But what i have heard is that they kick ass. The thing I don’t understand is that they say it produces 381hp at 5600rpm and 401lb of torque at 3200low so if makes 381 hp at such high rpm what about at 2000 3000 4000 rpm what does it how many horses does it produce there.
Jose – HP is a function of RPM – to calculate HP you have to multiply by RPM. Tiny little 2.4L Formula racing engines that redline at 18,000 RPM produce 700-800 HP, but they couldn’t possibly tow or haul anything because they don’t have enough torque. The moral of the story? HP isn’t really that important – it’s all about torque and gearing. Toyota’s setup is best because they combine a very powerful engine with a 6-speed automatic transmission.