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Rear Mounted Turbos
- Thread starter Jat_172cup
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- turbo
If we consider elements of 'boost' as a constant (effective density), then effective conversion of boost to work done is the result of the thermal efficiency of the engine, not of the turbo system itself.
If we are talking about the efficiency of the turbo system itself, simply due to the nature of a turbo as a heat engine.....the farther away from the exhaust valve you get, the cooler and denser the exhaust gas gets. That is a lot of lost potential energy right there, and because of this turbo choice for rear mounted applications is considerably different, relying more so on pressure differential than converting the energy in still burning and expanding gasses.
If we are talking about the efficiency of the turbo system itself, simply due to the nature of a turbo as a heat engine.....the farther away from the exhaust valve you get, the cooler and denser the exhaust gas gets. That is a lot of lost potential energy right there, and because of this turbo choice for rear mounted applications is considerably different, relying more so on pressure differential than converting the energy in still burning and expanding gasses.
1.2 Clio
Drop the attitude, if you were to put your hand across the exhaust manifold there would be a lot more pressure there, than at the back of the exhaust. Temperature drop across the pipe alone would cause a fair decrease in pressure. (as said above by Ben)
As for having the throttle fully down. Ok, you'l loose low end rev efficiency then?
"You want to use this naff all airflow to spin up a turbo? You're mad!"
no one said i wanted to and after all your started it... little bit of sarcasm and you think i have a bad attitude. clearly there is not naff all air flow other wise these systems wouldn't work. Also i have not been sectioned so on both accounts you are wrong. hence my tonque in cheek reply. however i am sorry i upset you.
no one said i wanted to and after all your started it... little bit of sarcasm and you think i have a bad attitude. clearly there is not naff all air flow other wise these systems wouldn't work. Also i have not been sectioned so on both accounts you are wrong. hence my tonque in cheek reply. however i am sorry i upset you.
you seem to feel very strongly about this rear turbo idea, do you work for balancemotorsport or something
Colder air is denser than hot air might I add. :rasp:
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since i read about the rear mount thing in PPC i have read a lot of posts on a lot of forums it generates a lot of haters and comments where people don't think - i have to admit to becoming a bit of rear mount advocate
wot do you reckon about them ?
A
ashy_gtt
How would the oil return work if the turbo were mounted lower than the sump?
I'm not sure what all the arguing is for because it looks like a pretty crap idea.
Without getting into thermodynamics surely common sense must prevail when considering a modification like this?
I'm not sure what all the arguing is for because it looks like a pretty crap idea.
Without getting into thermodynamics surely common sense must prevail when considering a modification like this?
ITB'd MK1
turbos are run by heat energy though
I thought it was just the movement of air?
Nice idea I remember reading about an M5 which had a twin rear mounted turbocharger
, but as ben has said its more efficient/easier and probably cheaper to mount in the traditional method. So 9 times out of 10 this is what people will go for.I'm also interested in the oil drain/return query that was posted up can you shed any light?
Ph1 Clio V6, Ph2 172
Not being funny but unless anyone trys this, whats the point in slating it??? You could throw thousands at a typical turbo set up but unless a bit of thought goes into it, it will no doubt give crap result too.
I remember seeing one of these setups and it did require a fair ammount of thinking to get it working propperly. For a start most would assume a big bore exhaust would be a good start but no. A smaller diameter one increases the exhaust pressure and speed entering the turbo. It won't spool up so quickly as a turbo sitting on the cylinder head but its not at all that bad. An intercooler isnt really required with these as 1, the main idea is to run pretty low/moderate ammounts of boost with them and 2, the turbo's run a hell of alot cooler. That means the actual volume of the inlet isnt that much greater than a typical intercooled car.
As with anything in the tuning/performance world there's pro's and con's with everything. No doubt you'll be better of placing a turbo as near to the exhaust valves as possible but for an easy way to a fair few more ponnies with a factory feel, this is quite a nifty idea.
I remember seeing one of these setups and it did require a fair ammount of thinking to get it working propperly. For a start most would assume a big bore exhaust would be a good start but no. A smaller diameter one increases the exhaust pressure and speed entering the turbo. It won't spool up so quickly as a turbo sitting on the cylinder head but its not at all that bad. An intercooler isnt really required with these as 1, the main idea is to run pretty low/moderate ammounts of boost with them and 2, the turbo's run a hell of alot cooler. That means the actual volume of the inlet isnt that much greater than a typical intercooled car.
As with anything in the tuning/performance world there's pro's and con's with everything. No doubt you'll be better of placing a turbo as near to the exhaust valves as possible but for an easy way to a fair few more ponnies with a factory feel, this is quite a nifty idea.
Focus RS Mk1
agreed ^ you can see the logic and for a low boost cheap setup then its an alternative to the conventional method. But anyone who is serious about wanting more power (eg worthwhile boost) would have to go the conventional way.
both methods have pro's and con's and both have thier place. The kit shown on that 205 looks rough as houses in all fairness so id imagine with a bit of clever and neat engineering it could work quite well.
nice to see people think outside the box though. certainly gives us something to ponder over each day!
both methods have pro's and con's and both have thier place. The kit shown on that 205 looks rough as houses in all fairness so id imagine with a bit of clever and neat engineering it could work quite well.
nice to see people think outside the box though. certainly gives us something to ponder over each day!
Ph1 Clio V6, Ph2 172
Well seeing that we are talking about turbos here, no doubt that won't be a problem. The turbo will just make negative pressure positive up stream of the compressor.
not just for low boost on sts website they have a customer who has run a 8.87 second quarter !
http://www.ststurbo.com/fast_customers
good point and also most cars don't generate downforce they generate lift so the air under the car isn't negative pressure or is it?
Exactly that. Anti-lag meant they had turbo speed for much more 'time' than they required to produce steady state peak inducted air mass requirement (for want of a better term). As such they wouldn't waste the energy but use it to compress air mass into a storage tank which was then released under conditions where either the anti-lag wasn't able to acheive compressor speed quickly enough or they required even greater levels of airmass to produce torque for short periods of time.
Essentialy it got around the air restrictor rule as all inducted air mass had passed through the spec restrictor....... just that it wasn't all used for combustion at once ;-)
Oh and guess who did the control systems for it
Cheers
M
My hero:hail:Exactly that. Anti-lag meant they had turbo speed for much more 'time' than they required to produce steady state peak inducted air mass requirement (for want of a better term). As such they wouldn't waste the energy but use it to compress air mass into a storage tank which was then released under conditions where either the anti-lag wasn't able to acheive compressor speed quickly enough or they required even greater levels of airmass to produce torque for short periods of time.
Essentialy it got around the air restrictor rule as all inducted air mass had passed through the spec restrictor....... just that it wasn't all used for combustion at once ;-)
Oh and guess who did the control systems for it
Cheers
M
It was 'my lot' who designed, developed and engineered it rather than me - I'm not that old LOL .Fred will get the pun ;-)
That system is pretty basic compared to what we do these days. Boost control on the F2 cars for example is way more advanced, as is our closed loop gear control stuff oh and our per cylinder knock control stuff is pretty cool as well. Some current WRC stuff run combusters as well which are hugely cool in that they can maintain 120,000RPM of compressor speed at idle!
Problem these days is that you aren't allowed to do trick stuff like the reserce air mass tank anymore. It's massively annoying. Part of having regs is to find a legal way to engineer an advantage IMHO.
Cheers
M
That system is pretty basic compared to what we do these days. Boost control on the F2 cars for example is way more advanced, as is our closed loop gear control stuff oh and our per cylinder knock control stuff is pretty cool as well. Some current WRC stuff run combusters as well which are hugely cool in that they can maintain 120,000RPM of compressor speed at idle!
Problem these days is that you aren't allowed to do trick stuff like the reserce air mass tank anymore. It's massively annoying. Part of having regs is to find a legal way to engineer an advantage IMHO.
Cheers
M
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