Dumb Q #1: Benefits of Larger Turbo
- Thread starter sdutton007
- Start date
Adam_Glanza
Member +
exactly, both turbos are hardly straining but the td05 will always make more power.
it may take longer to achieve that power but obviously when in affect it will supply alot more air
it may take longer to achieve that power but obviously when in affect it will supply alot more air
Dave@TM-developments.com
Trader
Adam_Glanza
Member +
sorry not you dave, that was aimed at gtti
Dru_Dragon
Fresh Recruit
Hmm, makes for an interesting read. So from what i can gather the pressure of the air would be the same with the different turbos, any excess being controlled via the wastegate. But the density of the air inside the engine would be effected by temperature.
GTti
Member +
Adam first you need to understand what volume is.
http://en.wikipedia.org/wiki/Volume
http://en.wikipedia.org/wiki/Cubic_metre
^^ Volume
If that block is filled with concrete, rice, sand, paper, air, water the volume is the same whatever occupies the space.
The mass filling the volume can be different, as I've said about ten times now!
http://en.wikipedia.org/wiki/Volume
http://en.wikipedia.org/wiki/Cubic_metre
^^ Volume
If that block is filled with concrete, rice, sand, paper, air, water the volume is the same whatever occupies the space.
The mass filling the volume can be different, as I've said about ten times now!
Adam_Glanza
Member +
ok i never admitted to be a genuis, but i know wat im saying in my own head 
i just dont see the arguement against? your only comparing when a smaller turbo is out of its efficiency?
i just dont see the arguement against? your only comparing when a smaller turbo is out of its efficiency?
GTti
Member +
The only reason why I think there is a torque reduction on hybrids is the fact that power is shifted up in the rev range.
It's harder to exert a force on a flywheel that is already roating at x000RPM.
After all thats all that torque is - the rotational force at the leading edge of the flywheel.
Just as you suposidly drop torque when fitting a lighter flywheel, there is less mass rotating so a slightly lesser force is experienced.
Derek
Lifer
TurboDave
Member +
Air pressure is measure in PSI in this case whereas the actual air mass is measured in CFM (Cubic foot per minute), the TD05 will be able to create more CFM than the TD04 both at 1 bar, its like having a voltage of 12v and 100amps (TD05) where you can still have 12v but only 50amps (TD04), therefore the mass of air is greater at the same pressure.
Plus the temperature of the TD05's air will be cooler than the TD04 which does make a difference, the TD05 can have 15psi's worth of air at a cooler temperature which wil contain a greater mass of air than the TD04's warmer charge at 15psi.
Plus the temperature of the TD05's air will be cooler than the TD04 which does make a difference, the TD05 can have 15psi's worth of air at a cooler temperature which wil contain a greater mass of air than the TD04's warmer charge at 15psi.
GTti
Member +
This is exactly what I'm saying. And this is where the link above starts to apply.
But at 9psi on a TD05 and TD04 the difference will be not be significant enough to create any noticeable amount of power. All you will do is change driveability.
The extra mass of air will only significantly change once the temperatures start changing and a more dense mass can be achieved!
For a stock engine the CT9 is perfectly suited to give the best results for power, torque and driveability - which happens to run at 8/9psi on full boost.
So back to the topic, I'm still insisting that 9psi will not give you anymore power regardless of the turbo you are using (Unless it's stupidly small and working its nuts off).
TurboDave
Member +
It will give some increase in power but only a small amount, 9psi on a CT9 at 1300cc would probably produce more power than a GT35 on the 1300cc engine at 9psi because it takes so much energy to drive the exhaust turbine.
I do agree though that although the TD05 has a greater CFM rating until the temperatures increase (boost) the differences will only be minor.
I am not saying anyone is incorrect and I havent read the entire thread but I am just saying it as it is.
GTti
Member +
Probably, a greater resistance against exhaust flow? Less velocity?
Adam_Glanza
Member +
i do understand temperature does play a factor, but yet again thats a more advanced question.
i thought the question was a basic "does a bigger turbo produce more air @ same pressure as a smaller turbo". and i believe the answer to that is yes?
i thought the question was a basic "does a bigger turbo produce more air @ same pressure as a smaller turbo". and i believe the answer to that is yes?
TurboDave
Member +
There isnt a yes or no answer.
It depends on what size turbo and on what application as well as loads of other variables.
Gtti, yes the GT35 being so large would take so much energy from the 1300cc engine to spin the exhaust turbine and turn the shaft in turn spinning the comp wheel and compressing the air that it may not even spool to 9psi until near the limiter.
A TD05 will create more horsepower at 15psi than a TD04 at 15psi but the TD04 should create more low end torque which will equal the power created by the TD05's horsepower at higher up the rev range. If all variables were equal (almost impossible) each turbo compressing the same amount of air 15psi but the larger one having a higher CFM, the amount of power overall including torque and bhp through the entire rev range should be equal due to E=mc2 because most of the exhaust gasses will be fully used by the turbos at low boost to try to spool the turbine. The TD05 should create a higher bhp at the top end but the amount of power should be equal to the TD04 because "energy cannot be created nor can it be destroyed". Obviously how efficently the turbos transform the energy from the exhaust manifold is also a factor.
I think this pretty much answers it.
Dave
It depends on what size turbo and on what application as well as loads of other variables.
Gtti, yes the GT35 being so large would take so much energy from the 1300cc engine to spin the exhaust turbine and turn the shaft in turn spinning the comp wheel and compressing the air that it may not even spool to 9psi until near the limiter.
A TD05 will create more horsepower at 15psi than a TD04 at 15psi but the TD04 should create more low end torque which will equal the power created by the TD05's horsepower at higher up the rev range. If all variables were equal (almost impossible) each turbo compressing the same amount of air 15psi but the larger one having a higher CFM, the amount of power overall including torque and bhp through the entire rev range should be equal due to E=mc2 because most of the exhaust gasses will be fully used by the turbos at low boost to try to spool the turbine. The TD05 should create a higher bhp at the top end but the amount of power should be equal to the TD04 because "energy cannot be created nor can it be destroyed". Obviously how efficently the turbos transform the energy from the exhaust manifold is also a factor.
I think this pretty much answers it.
Dave
Last edited:
sdutton007
Member +
Actually, I asked "what difference does a bigger turbo actually make?" i.e. why the bigger turbo makes more horsepower at the same psi
TurboDave
Member +
Not taking into account every vairable which, we have seemed to be drawn into, the larger turbo can flow more air (higher CFM) at the same psi as a smaller turbo of a lesser CFM & "the larger turbo will be more efficent at the same psi", although the last point it isnt strictly true because where as turbo housing sizes are important the trim of the compressor & turbine wheel are the most important factors and not strictly the larger housings.
probably because of all the stuff you have to add/change to make that diffence in power
Adam_Glanza
Member +
to be honest sdutton it kinda moved on from that now lol
but yeah i understand..
its a very intresting thread neway, should be more of these!
but yeah i understand..
its a very intresting thread neway, should be more of these!
Guye
Lifer
I truely find theads like this enjoyable to read. I always feel somewhat smarter afterwards. I can now see there is no wrong or right answer presented in this thread but all the points do compliment each other. I see the point GTti is making. Although it is true that a larger turbine will have a higher cfm rating the induction temp will have an effect on engine output as well. Most of us have proven this by simply adding a FMIC to a stock ct9 setup. Pressure drop aside, the engine produces more power simply by lowering intake temps (no additional fueling). When the intake pressure is raised to reflect the original boost levels, the difference is even more noticible because of the lower intake charge temp. Same psi, but I can see how charge temp would effect the cfm of the turbine. If this is the case, it is theoretically possible to achieve an even higher cfm rating with a ct9 by further cooling the intake charge, making the air even denser. This is the priciple used by intercooler sprayer kits.