Switchable Turbo?
Discussion
A friend of mine has just bought a Nissan 200SX S13 and asked me an interesting question earlier on today. He asked if it was possible to disable the turbo with a switch. He doesn't always need the boost and the subsequence decrease in fuel economy.
I haven't got a clue, thus this post
Could this be done with some sort of electrically actuated clutch between the impellor and compressor? I don't understand how turbos work very well, so I may need this explaining as well!
thanks.
I haven't got a clue, thus this post
Could this be done with some sort of electrically actuated clutch between the impellor and compressor? I don't understand how turbos work very well, so I may need this explaining as well!
thanks.
Fitting some sort of clutch between turbine and compressor would be complicated and expensive, and would probably add to the inertia of the assembly giving you massive turbo lag.
The most cost-effective way of keeping the turbo off boost is to keep the revs down and use high gears.
Begs the question, why buy a turbocharged sports coupe in the first place?
The most cost-effective way of keeping the turbo off boost is to keep the revs down and use high gears.
Begs the question, why buy a turbocharged sports coupe in the first place?
Andrew Noakes said:
Fitting some sort of clutch between turbine and compressor would be complicated and expensive, and would probably add to the inertia of the assembly giving you massive turbo lag.
The most cost-effective way of keeping the turbo off boost is to keep the revs down and use high gears.
Thanks.
Andrew Noakes said:
Begs the question, why buy a turbocharged sports coupe in the first place?
He loves the power, but just not all the time as it is a little hard on the wallet! Apparently the turbo comes in at 3,000rpm; which makes accelerating without using the turbo an arduous task as the engine's way off it's peak torque and efficiency. Engines are designed as a whole package.
If a turbo is fitted - the compression ratio would be lowered in relation to the max amount of boost expected.
Having an engine capable of high boost and bhp / litre would be desirable but the trade off is fuel economy.
If for example the 2 litre 16 valve turbo pumps out 350 bhp then you have the power of a 5 litre V8 .. so you will get the same fuel economy as the larger engined cars when using all the power.
When not using all the power - you have the trade off : which is :
1) the compression ratio is lower than is ideal
2) the turbo uses some power - think of it like a restriction in the exhaust and the engine (pistons etc) have to push it .. a little bit.
So - in reality : the 2 litre probably has the fuel economy of a 2.5 litre car and the pull on boost power of a much larger car..
In short - you cannot turn off the turbo.
Hope that helps.
If a turbo is fitted - the compression ratio would be lowered in relation to the max amount of boost expected.
Having an engine capable of high boost and bhp / litre would be desirable but the trade off is fuel economy.
If for example the 2 litre 16 valve turbo pumps out 350 bhp then you have the power of a 5 litre V8 .. so you will get the same fuel economy as the larger engined cars when using all the power.
When not using all the power - you have the trade off : which is :
1) the compression ratio is lower than is ideal
2) the turbo uses some power - think of it like a restriction in the exhaust and the engine (pistons etc) have to push it .. a little bit.
So - in reality : the 2 litre probably has the fuel economy of a 2.5 litre car and the pull on boost power of a much larger car..
In short - you cannot turn off the turbo.
Hope that helps.
My 5.7 running 7psi boost is effectivley like driving 8.5L engine, And I can confirm that it has the fuel economy of one!
Yes, Keeping of the throttle would help, but then again - its just tooo much fun not to!
To answer the original question, fit a boost controller. And perhaps a wastegate that opens at a low pressure.
>> Edited by eliot on Sunday 5th March 08:50
Yes, Keeping of the throttle would help, but then again - its just tooo much fun not to!
To answer the original question, fit a boost controller. And perhaps a wastegate that opens at a low pressure.
>> Edited by eliot on Sunday 5th March 08:50
My supercharged 5.7 can manage about 25mpg on a run, less through towns etc.
It isnt really much worse on fuel than my old 4.6 twin turbo RV8.
Proper mapping makes a huge difference to economy. Standard cars are good for emissions and various other things, but there is much room for improvement as far as economy goes.
It isnt really much worse on fuel than my old 4.6 twin turbo RV8.
Proper mapping makes a huge difference to economy. Standard cars are good for emissions and various other things, but there is much room for improvement as far as economy goes.
stevieturbo said:
My supercharged 5.7 can manage about 25mpg on a run, less through towns etc.
It isnt really much worse on fuel than my old 4.6 twin turbo RV8.
Proper mapping makes a huge difference to economy. Standard cars are good for emissions and various other things, but there is much room for improvement as far as economy goes.
35" mud tyres, 4wd, auto box , nearly 2 tonnes weight, brick-like aerodynamics tend to affect fuel consumption on mine. mid-range I'm just lean of stoic, but quickly ramp to about 12:1 under load. Could be improved if I could get it on a rolling road I guess, but haven't really bothered about it. 70mph cruise with a locked torque convertor turns about 1800rpm, 14.7 afr - so should be quite efficient, but I rarely drive it like that.
Toyota Superchargers as fitted to the 4AGZE an 1GGZE were clutch activated electronically, they only engaged at high throttle settings on the road car to try and solve the fuel consumption problems that occur with an 'always on' supercharger as Mercedes found.
You could sell the turbo and fit a supercharger, modify it to be activated by a switch and with some tuning it should work. Otherwise the easy way is to just bleed off all the unneeded boost as mentioned above. I guess you could run it on crap fuel with that setting as well as the compression ratio will be low with no boost to cause the engine to ping (just remember to fill up with premium when your planning on running boost!).
You could sell the turbo and fit a supercharger, modify it to be activated by a switch and with some tuning it should work. Otherwise the easy way is to just bleed off all the unneeded boost as mentioned above. I guess you could run it on crap fuel with that setting as well as the compression ratio will be low with no boost to cause the engine to ping (just remember to fill up with premium when your planning on running boost!).
Some crazy ideas popping up here..
How much money do some people intend to spend to TRY and save a few pennys worth of fuel ??
Turbo cars are generally very efficient, and more so that n/a car for what they give power wise. The most sensible option would be a proper mappable ecu. At least that way you can have more power, and better efficiency. But even that will cost hundreds of pounds, if not over a thousand.
Unlesss you do high miles, you will be a while saving that back.
If its turbocharged, just enjoy it. Isnt that why you bought it ?
How much money do some people intend to spend to TRY and save a few pennys worth of fuel ??
Turbo cars are generally very efficient, and more so that n/a car for what they give power wise. The most sensible option would be a proper mappable ecu. At least that way you can have more power, and better efficiency. But even that will cost hundreds of pounds, if not over a thousand.
Unlesss you do high miles, you will be a while saving that back.
If its turbocharged, just enjoy it. Isnt that why you bought it ?
stevieturbo said:
Some crazy ideas popping up here..
How much money do some people intend to spend to TRY and save a few pennys worth of fuel ??
Turbo cars are generally very efficient, and more so that n/a car for what they give power wise. The most sensible option would be a proper mappable ecu. At least that way you can have more power, and better efficiency. But even that will cost hundreds of pounds, if not over a thousand.
Unlesss you do high miles, you will be a while saving that back.
If its turbocharged, just enjoy it. Isnt that why you bought it ?
To be honest, that is a fair comment. Doing 10,000 miles a year, even going from 20 to 30mpg only saves £500 a year. I expect that we're talking more about going from 20 to 25mpg to be honest, so £250 a year saving. It was an interesting theoretical question though
I think some driver adjustment of the turbo sounds like an interesting idea - worth pursueing bearing the costs and savings in mind. I've given my friend a link to this thread, and he says "thanks for all the comments"!
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