I dont see much supercharging going on anymore and have never seen one on a diesel engine. I think I know they use turbos since the air is so dense from being heavily compressed, and a turbo is kind of free.
Superchargers not for diesels?
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Cummins had 275hp engine with a blower in the 50's called the iron lung. All 2 stroke Detroit's had a blower.
GMC 671 blower is one of the most well known and common blowers used, they also had a 471 and 871.
They take a lot of power to run them, they can produce and enormous amount of boost but also a lot of parasitic drag.
They take a lot of power to run them, they can produce and enormous amount of boost but also a lot of parasitic drag.
2 strokes have to have a blower, it's for scavenging, not boosting. I remember the Cummins with the supercharger, but the truck was late '60's, early '70's....but NZ was always running late. Mazda used a comprex supercharger in diesel cars in the '90's, it was a weird thing, half supercharger and half turbo.
Supercharged engines consume too much of their own output huffing themselves!
Originally Posted By: Silk
2 strokes have to have a blower, it's for scavenging, not boosting. I remember the Cummins with the supercharger, but the truck was late '60's, early '70's....but NZ was always running late. Mazda used a comprex supercharger in diesel cars in the '90's, it was a weird thing, half supercharger and half turbo.
Yeah, I've seen couple of the Comprex Camrys around here (grey import), one running 100 WVO.
The COmprex is an amazing bit of kit, the shaft power only being to keep the cell plate rotating, rather than compressing
2 strokes have to have a blower, it's for scavenging, not boosting. I remember the Cummins with the supercharger, but the truck was late '60's, early '70's....but NZ was always running late. Mazda used a comprex supercharger in diesel cars in the '90's, it was a weird thing, half supercharger and half turbo.
Yeah, I've seen couple of the Comprex Camrys around here (grey import), one running 100 WVO.
The COmprex is an amazing bit of kit, the shaft power only being to keep the cell plate rotating, rather than compressing
Their marine diesels here in the US also have this feature.
I have seen them on Volvo's in marine applications. They want low end grunt when you fire wall the throttles and super chargers do that.
Although more recently they just use different size turbo's and lots of computers to do the same thing.
Although more recently they just use different size turbo's and lots of computers to do the same thing.
Turbo charging is far more efficient.
If I had to take a guess Id say the low rpm of the diesel is far from ideal for a super charger.
All the two stroke detroits were super charged but as mentioned it was to keep the air flowing in the right direction. They had no intake valves. Only ports in the lower cylinder wall too allow air in. They did use exhaust valves in the head though.
Some of the higher output models had both a super charger and turbo charger.
If I had to take a guess Id say the low rpm of the diesel is far from ideal for a super charger.
All the two stroke detroits were super charged but as mentioned it was to keep the air flowing in the right direction. They had no intake valves. Only ports in the lower cylinder wall too allow air in. They did use exhaust valves in the head though.
Some of the higher output models had both a super charger and turbo charger.
Originally Posted By: CDX825
If I had to take a guess Id say the low rpm of the diesel is far from ideal for a super charger.
Traditionally, superchargers have been better at low rpms and turbos at high rpms. In the 90s I drove a supercharged Lancia and a turbocharged Lancia with almost the same peak power, and the supercharged car just felt like it had a bigger engine, whereas you had to rev the nuts off the turbo car to get any power at all.
If I had to take a guess Id say the low rpm of the diesel is far from ideal for a super charger.
Traditionally, superchargers have been better at low rpms and turbos at high rpms. In the 90s I drove a supercharged Lancia and a turbocharged Lancia with almost the same peak power, and the supercharged car just felt like it had a bigger engine, whereas you had to rev the nuts off the turbo car to get any power at all.
I worked on an EMD 567 (2 stroke diesel) engine in school that had a turbocharger driven by gears with an over running clutch. The gear drive allowed that giant turbo to spool up quicker. In that application the engine was run at a constant 720 rpm.
Turbo's are cheaper and easier than a supercharger in most cases. packaging is more flexible as you can place them any place after the exhaust manifold within a reasonable distance from the engine. Superchargers require maintenance, either belt changes or oil changes or both and require the accessory drive to be engineered to handle the additional lateral load.
Diesels also lend themselves to turbos in that they move much more air than a gas engine, they have no throttle plates to limit the air flow through them so you have a much higher volume of exhaust gases under low load conditions to keep the turbo spinning.
Diesels also lend themselves to turbos in that they move much more air than a gas engine, they have no throttle plates to limit the air flow through them so you have a much higher volume of exhaust gases under low load conditions to keep the turbo spinning.
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