Go Back   EcoModder Forum > EcoModding > EcoModding Central
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 02-06-2016, 06:39 AM   #1 (permalink)
PizzaRimBoy
 
Join Date: Dec 2015
Location: SoCal
Posts: 72
Thanks: 2
Thanked 15 Times in 7 Posts
Turbo With an Alternator

Thinking about putting a turbo in my car to overcome pumping losses and power an alternator so i can unbelt the regular alt.

The car has a carb. I'd maybe try to up to 6psi of boost on the engine for performance. I wonder if this could be done? Would the turbo spin at too high of rpms for the alternator?

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 02-06-2016, 09:39 AM   #2 (permalink)
EcoModding Apprentice
 
Join Date: Feb 2010
Location: Howells Ne
Posts: 126

Supra - '88 Toyota Supra

superhawk - '98 Honda superhawk
Last 3: 27.62 mpg (US)

Lesabre - '96 buick lesabre
3800
90 day: 25.85 mpg (US)

Saturn - '97 Saturn Sc2
Team Saturn
Sports Cars
90 day: 39.12 mpg (US)

Truk - '99 Ford F150
Team Ford
Pickups
90 day: 24.43 mpg (US)

Golf - '03 Vw Golf
90 day: 38.57 mpg (US)
Thanks: 17
Thanked 7 Times in 6 Posts
Given the design of a turbo this doesn't seen feasible. It might be possible to remove the intake side of the turbo and somehow rig the shaft up to a alternator but the drag created by the alternator would probably require the engine to be running at a high rpm in order to spool up the alternator there would be much more loss than gain. That doesn't mean that a turbo by its self is a bad idea for fuel economy if set up properly. I remember reading an article a couple years ago about a guy turboing his motorcycle for improved fuel economy I believe he called it improved volumetric efficiency
  Reply With Quote
Old 02-06-2016, 10:17 AM   #3 (permalink)
Master EcoModder
 
oldtamiyaphile's Avatar
 
Join Date: May 2009
Location: Australia
Posts: 1,508

UFI - '12 Fiat 500 Twinair
Team Turbocharged!
90 day: 40.3 mpg (US)

Jeep - '05 Jeep Wrangler Renegade
90 day: 18.09 mpg (US)

R32 - '89 Nissan Skyline

STiG - '16 Renault Trafic 140dCi Energy
90 day: 30.12 mpg (US)

Prius - '05 Toyota Prius
Team Toyota
90 day: 50.25 mpg (US)

Premodded - '49 Ford Freighter
90 day: 13.48 mpg (US)

F-117 - '10 Proton Arena GLSi
Pickups
Mitsubishi
90 day: 37.82 mpg (US)

Ralica - '85 Toyota Celica ST
90 day: 25.23 mpg (US)

Sx4 - '07 Suzuki Sx4
90 day: 32.21 mpg (US)

F-117 (2) - '03 Citroen Xsara VTS
90 day: 30.06 mpg (US)
Thanks: 324
Thanked 444 Times in 313 Posts
Turbos spin at 50,000 - 100,000 rpm. Alternators spin at 1600-12,000.
__________________






  Reply With Quote
The Following 2 Users Say Thank You to oldtamiyaphile For This Useful Post:
aerohead (02-06-2016), Xist (02-06-2016)
Old 02-06-2016, 11:43 AM   #4 (permalink)
Master EcoModder
 
Join Date: Aug 2010
Location: Philippines
Posts: 2,173
Thanks: 1,739
Thanked 588 Times in 401 Posts
Formula One cars use a device called the MGU-H (uh... Google says Motor Generator Unit - Heat) to harvest energy from the turbo and to enable quicker spool up at transitional rpm. So yes, the possibility is there.

But these units are pretty high-tech stuff... there's a big electric motor splitting the intake and exhaust sides of the turbo, spinning at 100,000 rpm.

I doubt you'll be able to make enough electricity off a regular turbo to replace your alternator... unless you're driving at full boost, all the time.

Turbo boost is "free" power only in the sense that the boost the turbo provides counteracts the extra backpressure created by the turbo. If you disconnect the intake side, you're just making the engine work harder to spin those exhaust turbines. Probably won't be as efficient as an actual alternator.
  Reply With Quote
The Following User Says Thank You to niky For This Useful Post:
Xist (02-06-2016)
Old 02-06-2016, 04:22 PM   #5 (permalink)
In the fasting lane
 
RedDevil's Avatar
 
Join Date: Dec 2012
Location: Nieuwegein, the Netherlands
Posts: 3,954

Red Devil - '11 Honda Insight Elegance
Team Honda
90 day: 51.64 mpg (US)
Thanks: 1,681
Thanked 2,197 Times in 1,422 Posts
Wait a minute - you mean a turbo on the air intake, powering an alternator by the difference between atmospheric pressure before and the part vacuum behind the throttle valve, right?

That may work in theory, but you will have a hard time finding a fitting turbine.
Also it would only work on part load; if you idle not enough air is flowing through the turbine to keep it spinning despite the large difference in pressure, and at WOT there is no pressure difference to spool up a turbo.

I confess having thought along these lines myself.
At 2000 RPM at 50% load my 1339 cc engine pumps 22 liters of 50% vacuumized air per second, that dissipates about 1.1 kW of power over the throttle plate.
If you can get 25% of that in electricity, it may just be enough to sing it out for the day without an alternator, but you'd need to charge the battery at home. A bigger battery, preferably a lithium iron one, would be advisable in this setup.

Anyway, subscribed...!
__________________
2011 Honda Insight + HID, LEDs, tiny PV panel, extra brake pad return springs, neutral wheel alignment, 44/42 PSI (air), PHEV light (inop), tightened wheel nut.
lifetime FE over 0.17 Gmeter or 0.1 Mmile.



Investors woes:
"In hindsight, I should have placed a bet on the horse that won the race"
"In hindsight, I should have bet more on that horse"

Last edited by RedDevil; 02-06-2016 at 04:38 PM..
  Reply With Quote
The Following User Says Thank You to RedDevil For This Useful Post:
JRMichler (02-06-2016)
Old 02-06-2016, 05:10 PM   #6 (permalink)
BeginnerModder
 
Join Date: Oct 2015
Location: Wylie, TX, USA
Posts: 102
Thanks: 30
Thanked 48 Times in 29 Posts
Quote:
Originally Posted by RedDevil View Post
Wait a minute - you mean a turbo on the air intake, powering an alternator by the difference between atmospheric pressure before and the part vacuum behind the throttle valve, right?

That may work in theory,
I don't think that would work in theory either. You are restricting the air intake, making the air do "work" and "work" is never free. The engine would be doing the same or more work to make the same electrical power as a belted alternator.

Same theory as putting a windmill on top of your car. It's not free to push the blades through the air.

Putting half of a turbo on the exhaust side and running it through a planetary gear reduction seems pretty plausible.

Take a look at the centrifugal superchargers. They use a belt off of the accessory pulley to spool a compressor wheel... just use the same gearing and use an exhaust turbine to spool your alternator.

A broken centrifugal supercharger on eBay could yield some fantastic parts... I really like the idea.
  Reply With Quote
Old 02-06-2016, 06:32 PM   #7 (permalink)
EcoModding Lurker
 
Join Date: Dec 2009
Location: Sunny Arizona
Posts: 53
Thanks: 0
Thanked 8 Times in 6 Posts
Turbo with an Alternator is feasible

The turbo with an alternator is feasible and has been done. I don't know if they sell them now, but Garrett designed and built some turbos with a three phase motor/alternator between the turbine and compressor. Their objective was lag reduction, but with the appropriate controls, one of those would do what you want. That said, the design and development of such equipment is well beyond the capability of the vast majority of even professional engineers, it requires a team of engineering specialists. Like you might find at Garrett. As far as possible alternator speeds go, I have worked on the design, development, and test of alternators that operated WAY over 100,000 rpm. Windage, bearing, and magnetic hysteresis losses do add up, but I think you could go 1,000,000 rpm, if you could get the rest of the system to support that speed. That may have also have been done, on some space based cryo-coolers. There is a lot of stuff that never makes it to consumer media.

The comments about nothing being free are largely true, the only free energy I associate with a turbo, comes from the reduction of normal shock losses in the exhaust port due to the back pressure of the turbo. That shows up as about a 0.5% decrease in BSFC if you compare turbo, and non-turbo versions of the same engine from Yanmar, Kubota, etc.
  Reply With Quote
Old 02-06-2016, 07:58 PM   #8 (permalink)
Master EcoModder
 
JRMichler's Avatar
 
Join Date: Feb 2011
Location: Phillips, WI
Posts: 983

Nameless - '06 GMC Canyon
90 day: 37.45 mpg (US)
Thanks: 188
Thanked 415 Times in 266 Posts
Quote:
Originally Posted by RedDevil View Post
Wait a minute - you mean a turbo on the air intake, powering an alternator by the difference between atmospheric pressure before and the part vacuum behind the throttle valve, right?

That may work in theory, but you will have a hard time finding a fitting turbine.
Also it would only work on part load; if you idle not enough air is flowing through the turbine to keep it spinning despite the large difference in pressure, and at WOT there is no pressure difference to spool up a turbo.

I confess having thought along these lines myself.
At 2000 RPM at 50% load my 1339 cc engine pumps 22 liters of 50% vacuumized air per second, that dissipates about 1.1 kW of power over the throttle plate.

If you can get 25% of that in electricity, it may just be enough to sing it out for the day without an alternator, but you'd need to charge the battery at home. A bigger battery, preferably a lithium iron one, would be advisable in this setup.
Convert pumping losses into usable energy. If you could figure out a way to control such a power recovery gadget, it could replace the throttle plate. Maybe a supercharger connected to an alternator, with the alternator field controlled by the gas pedal?
__________________
The vacuum gauge plus wheel covers helped increase summer 2015 mileage to 38.5 MPG, while summer 2016 mileage was 38.6 MPG without the wheel covers. Drove 33,021 miles 2016-2018 at 35.00 MPG.
  Reply With Quote
Old 02-06-2016, 08:56 PM   #9 (permalink)
EV convert
 
oil pan 4's Avatar
 
Join Date: Jul 2011
Location: NewMexico (USA)
Posts: 9,557

Sub - '84 Chevy Diesel Suburban C10
SUV
90 day: 19.5 mpg (US)

camaro - '85 Chevy Camaro Z28

Riot - '03 Kia Rio POS
Team Hyundai
90 day: 30.21 mpg (US)

Bug - '01 VW Beetle GLSturbo
90 day: 26.43 mpg (US)

Sub2500 - '86 GMC Suburban C2500
90 day: 11.95 mpg (US)

Snow flake - '11 Nissan Leaf SL
SUV
90 day: 141.63 mpg (US)
Thanks: 228
Thanked 3,124 Times in 2,444 Posts
You still have pumping losses if its a gas engine.

Why not just get a turbodiesel (no isobaric losses), pull the belt off the alt and replace the alt output with solar panels and put the belt back on the alt for long night trips?
__________________
1984 chevy suburban, custom made 6.5L diesel turbocharged with a Garrett T76 and Holset HE351VE, 22:1 compression 13psi of intercooled boost.
1989 firebird mostly stock. Aside from the 6-speed manual trans, corvette gen 5 front brakes, 1LE drive shaft, 4th Gen disc brake fbody rear end.
2011 leaf SL, white, portable 240v CHAdeMO, trailer hitch, new batt as of 2014.
  Reply With Quote
Old 02-06-2016, 09:39 PM   #10 (permalink)
Master EcoModder
 
Join Date: Aug 2010
Location: Philippines
Posts: 2,173
Thanks: 1,739
Thanked 588 Times in 401 Posts
Oh, intake?

To make 6 psi on an average-sized four-banger takes about 10-15 horsepower worth of power, going off of what Thomas Knight did with their electric superchargers back in the day.

Normal operating vacuum wouldn't even be able to turn such a thing, let alone produce meaningful power from it. If you've ever dismantled an air intake and put your hand over the intake hose or carb ("burping" the carb to clean it used to be such fun!), you'll know how little vacuum it produces at idle or low rpm... much less than a shop vacuum. Now those vacuum motors have the equivalent of about 2-4 horsepower... So say you have about 1 hp of suck available at cruise... then consider some of that suck has to go to intake air to power the engine... you're getting much less than that going to the intake alternator.

Consider it takes at least 2 hp to turn a regular alternator, and 10-20 hp at full electrical load, there isn't much of a comparison there.

More effective to run a generator off the exhaust side. Cap the turbine speed by braking it down with a generator when at full load... also eliminates the need for a wastegate, as you can control maximum boost pressure, as well.

  Reply With Quote
The Following User Says Thank You to niky For This Useful Post:
Xist (02-07-2016)
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com