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Low pressure turbo

Why aren’t more manufacturers using 4 cylinder engines with low pressure turbo? The Volvo V40 wagon gets better mileage than most small hatchbacks, 28 CTY, 34 HWY.

The '04 V40 (latest year I could find on is rated 19 cty, 27 hwy. It calls for premium gas. The turbo adds cost and complexity. You’ll rarely find a turbo on an economy car.

Turbo’s do not do well when abused and maintenance gets skipped, and eventually they need to be replaced which usually costs a good amount of money. If I was designing a car for the masses I don’t think I’d have a turbo in mind very often. Just ask VW which often sees ruined 1.8 turbos that didn’t receive regular oil changes. In the end, you build a repuation for the car as being expensive to repair and high maintenance. This is Saab’s rep.


See Dave, I’m learning!

Saab tried it in their 93 Linear and it got very good mileage but not a lot of sales. It was rated at 20/30 but in reality got close to 30 around town and mid thirties on the highway. The engine is great as it makes full torque below 2000 rpm so it feels quite good in normal driving and uses regular fuel.

The 1.8t failed mainly in Audi A4/Passat due to a design flaw. They rearranged the oil sump to fit a longitutinal install and made it slightly smaller and flow not as well so stretched oil changes beat the oil up.

The failure is not common in the 1.8T with larger oil sump(original design) used in the Beetle, Jetta, Audi TT, and Golf/GTI.

To be reliable an engine with a turbo has to be made much stouter than a regular engine other wise the internal pressure created by the turbo will be more than the heads, pistons, rods, and bearings can take. This raises the weight of the engine and requires a heavier front end on the car to handle the extra weight.

If you are trying to build a small cheap car adding extra metal to the project is contrary to the idea.


Same with my '02 V40, 1.9t. EPA estimates were way off. I get 28 average. On trips, 35 mpg. So far, 85000 miles and with regular oil changes (every 6000) no problems. It is not like the other turbo chargers. Low pressure vacuum means no lag and good torque at regular RPM. Uses regular fuel.
Circuitsmith found bad data.

I think you guys are missing the point. LOW PRESSURE TURBO. Not the extra strain on an engine as the regular turbo chargers. The engines are no stouter than without the turbo.
Fuel economy is improved and no need for premium fuel.

I don’t think we’re missing the point. You say there’s benefits, and there are. We’re arguing that it’s a cost and maintenance issue. A turbo and the plumbing necessary costs money and brings with other possible problems that have to be dealt with. You do know that engineers and bean counters at car companies get into arguements over spending an extra 25 cents on a gauge or a switch right?