Turbo vs blower
11-25-2007, 01:00 PM
#1
Gold Member
Gold MemberThread Starter
Turbo vs blower
Why dont we see more turbos in hp engines in powerboating would think the lag would not be a issue with motors always loaded
you would think they would be easer on parts vs blowers
you would think they would be easer on parts vs blowers
11-25-2007, 01:10 PM
#4
Registered User
The constant on/off isn't really well suited for turbos. Plus, to be Coast Guard approved, the application has to be completely water-cooled. To do so interferes with turbo efficiency. If the turbine housing is cooled, that draws heat away from the unit. The turbine uses that heat to drive the compressor.
Mercury did quite a bit with turbos in the late 80's and early 90's. The APBA was less than friendly and accommodating on the topic. Tom Gentry did well with his turbo engines but nobody was really interested in the concept.
As far as reliability, they've been putting superchargers on production automobiles for some time now- the reliability issue is pretty much licked. turbos are substantially more complex that superchargers. The plumbing alone can be very complex- with pressurized oil for the bearings, wastegates, cooling, etc. Blowers are cheap, easy and reliable. And, a way more linear power curve in the process.
Mercury did quite a bit with turbos in the late 80's and early 90's. The APBA was less than friendly and accommodating on the topic. Tom Gentry did well with his turbo engines but nobody was really interested in the concept.
As far as reliability, they've been putting superchargers on production automobiles for some time now- the reliability issue is pretty much licked. turbos are substantially more complex that superchargers. The plumbing alone can be very complex- with pressurized oil for the bearings, wastegates, cooling, etc. Blowers are cheap, easy and reliable. And, a way more linear power curve in the process.
11-25-2007, 01:32 PM
#5
Registered
turbos are better in every single way, even the lag is better then not having it, it is like a cushion for when you mess up getting on and off the throttle. the only problem is engine builders not knowing how a turbo works.
11-25-2007, 01:59 PM
#6
Registered User
11-25-2007, 02:03 PM
#7
Registered
While a supercharger's boost curve is linear, the power curve is not.
When a turbo spools up, it makes max boost then. At whatever RPM range, and holds that to red line. A supercharger has a linear increase in boost (centrifugal), or volume (roots/screw), that maxes at max rpm. So while WOT will be similar in power, the power under the curve of a turbo will be much higher.
There are many downsides to properly applying turbos in boats. Look at drag racing, turbos are increasing in numbers almost every month.
Also, the parasitic draw of a supercharger is huge. I haven't been able to find it again, but there was a test done with a turbo/supercharged ford engine. They ran the engine N/A, and put a 20 lb boost regulator on the output of the supercharger and turbo. They found that the turbo took about 20hp to run, and the supercharger around 300. These were moving the same amount of air at the same pressue, with the engine running the same N/A induction. So, you get an extra 300 hp that the engine is making already.. so in theory if you make the same Hp turbo vs blower, there is far less strain on the engine.
When a turbo spools up, it makes max boost then. At whatever RPM range, and holds that to red line. A supercharger has a linear increase in boost (centrifugal), or volume (roots/screw), that maxes at max rpm. So while WOT will be similar in power, the power under the curve of a turbo will be much higher.
There are many downsides to properly applying turbos in boats. Look at drag racing, turbos are increasing in numbers almost every month.
Also, the parasitic draw of a supercharger is huge. I haven't been able to find it again, but there was a test done with a turbo/supercharged ford engine. They ran the engine N/A, and put a 20 lb boost regulator on the output of the supercharger and turbo. They found that the turbo took about 20hp to run, and the supercharger around 300. These were moving the same amount of air at the same pressue, with the engine running the same N/A induction. So, you get an extra 300 hp that the engine is making already.. so in theory if you make the same Hp turbo vs blower, there is far less strain on the engine.
Last edited by Joe92GT; 11-25-2007 at 02:06 PM.
11-25-2007, 02:30 PM
#8
Charter Member # 55
Charter Member
While a supercharger's boost curve is linear, the power curve is not.
When a turbo spools up, it makes max boost then. At whatever RPM range, and holds that to red line. A supercharger has a linear increase in boost (centrifugal), or volume (roots/screw), that maxes at max rpm. So while WOT will be similar in power, the power under the curve of a turbo will be much higher.
When a turbo spools up, it makes max boost then. At whatever RPM range, and holds that to red line. A supercharger has a linear increase in boost (centrifugal), or volume (roots/screw), that maxes at max rpm. So while WOT will be similar in power, the power under the curve of a turbo will be much higher.
A roots blower will make max boost depending on load and not necessarily based on rpm. If youre cruising at 2000rpms and mash the throttle, it will go to max boost almost instantly and stay there all the way to max rpm.
11-25-2007, 02:51 PM
#9
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Turbos run best on cold and thin air. The higher the alitiude the better the performance. To be effective they must be installed before water is introduced into the exhaust system. Turbos also work best on quick-high rev engines. Wastegates would be another issue.
Performance boats usually run two exhaust pipes. Therefore todays typical exhaust configuration in a twin engine boat would require four turbos. The Turbo Inlet Temperature (TIT) could get as high as 1850 degrees if leaned to much. Turbos require a cool down before shutting down. No cool down results to a melt down of the turbo's bearings. A turbo on a boat would require constant monitoring of temperatures and adjustment of richness to keep the temperature in line. This operation can be achieved with computers as in todays cars or be done manually ( a lot of monitoring).
Prochargers are the way to go. Wesco (Jenison, Mi) is building a line of performace boat motors with single and dual prochargers. These units are equipped with chill boxes to conidtion and densify the air before induction. Some cool stuff.
A set of these will be running in the Fort Myers area around the beginning of next year. No blower belts, chillers or big blowers to haul around. A couple hundred pounds off each engine. That is large.
Performance boats usually run two exhaust pipes. Therefore todays typical exhaust configuration in a twin engine boat would require four turbos. The Turbo Inlet Temperature (TIT) could get as high as 1850 degrees if leaned to much. Turbos require a cool down before shutting down. No cool down results to a melt down of the turbo's bearings. A turbo on a boat would require constant monitoring of temperatures and adjustment of richness to keep the temperature in line. This operation can be achieved with computers as in todays cars or be done manually ( a lot of monitoring).
Prochargers are the way to go. Wesco (Jenison, Mi) is building a line of performace boat motors with single and dual prochargers. These units are equipped with chill boxes to conidtion and densify the air before induction. Some cool stuff.
A set of these will be running in the Fort Myers area around the beginning of next year. No blower belts, chillers or big blowers to haul around. A couple hundred pounds off each engine. That is large.
Last edited by The Menace; 11-25-2007 at 02:53 PM.
11-25-2007, 03:25 PM
#10
Registered
how often have you ran you boat hard and then instantly shut the engine off, never unless you were broke, you always have a cool down period to get to the dock, trailer, party spot, ect.
