does having a larger TB than turbo outlet give more power?

GeX

GeX

GeX

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Been pondering this one; I'm going to pick figures out of the air for this.

You have a 1.4 turbo charged engine. You are using a small turbo. The engine has a 32mm throttle butterfly. The turbo has a 32mm compressor outlet.

Beyond the throttle plate, the throttle body tapers out to 45mm and into the plenum.

Would fitting a throttle body with a larger throttle plate give more power. If you fitted a 45mm throttle plated body so that it matched the inlet, would that give more power? If so, why. The inlet tract already opens up to 45mm just beyond the throttle plate.

Assuming the pipework from turbo to throttle is 32mm, why would having a bigger throttle plate than the compressor outlet give more power. Would (and if so why) increasing the diameter of the compressor > tb pipework increase power.

From my understanding, increasing the size of the pipework will allow the turbo to spool up quicker (less restriction as it has a larger volume inlet tract to fill), but it will cause more lag (it will take longer to compress this larger volume of air).

Do my ponderings make sense, anyone got anything to add?
 
why more peak power, it allows the larger volume of compressed charge through quicker?

i like to understand why
 
"Inlet boost pressure is only one half of the deal. Pressure differential is the real value.
A bigger Turbo will produce more power on the same engine at the same boost level, because the Exhaust turbine will be less restrictive. This means exhaust manifold pressure will be less, and consequently the cylinder chamber pressure will be less too, allowing more fuel air mixture into the engine, thus more engine power."
 
i'm not on about increasing the size of the turbo tho, nothing will change in the exhaust side.
 
Couple of the peeps over on the owners club I'm on have fitted larger TB's to their cars. The inlet is the same size diamter, but the TB is now not tappered inside, it's more straight all the way down inside and add's about 5mm to the overall ID. RR graphs have shown a few bhp increase but a good mid range torque increase! These are N/A cars. (Fiesta ST's).

So assuming the same can be said about fitment to a turbo application, then yes, you will get a power increase. :)
 
I thought (rightly or worngly) a larger throttle body/plate just makes the car feel more responsive due to having a larger opening at the same amount of movement in pedal input. If you changed the plenum at the same time for a more optimum one then power gains could be had.
 
Firegod said:
Couple of the peeps over on the owners club I'm on have fitted larger TB's to their cars. The inlet is the same size diamter, but the TB is now not tappered inside, it's more straight all the way down inside and add's about 5mm to the overall ID. RR graphs have shown a few bhp increase but a good mid range torque increase! These are N/A cars. (Fiesta ST's).

So assuming the same can be said about fitment to a turbo application, then yes, you will get a power increase. :)
Click to expand...

no, different with na. With a nasp engine, after the TB you've got the air filter, which typically will be much larger than the entrance to the plenum. So by oversizing the TB, the engine has a massive volume of air (ie the world) to suck on. With a turbo application it is different because it is coming out of a say, 32mm hole.

I oversized the TB from 30mm to 40mm on my old nasp engine and it was a marked improvement!
 
GeX said:
no, different with na. With a nasp engine, after the TB you've got the air filter, which typically will be much larger than the entrance to the plenum. So by oversizing the TB, the engine has a massive volume of air (ie the world) to suck on. With a turbo application it is different because it is coming out of a say, 32mm hole.

I oversized the TB from 30mm to 40mm on my old nasp engine and it was a marked improvement!
Click to expand...

Ah ok, I wasn't too sure you see like, I say. :)
 
Its good practice to taper up the size from the narrow turbo comp. exit (narrow to maintain the A/R of the housing) so with the throttle being likely to be a distance from the turbo AND after the intercooler a 32mm throttle is pretty damn small, and of course the throttle even at full opening has a smaller cross sectional area than a pipe of the same diameter.

Include bends etc and its deffo worth getting the diameter up. What power output is the engine?

Good point on the throttle, especially on a turbo, its easy to get full boost at low rpm at less than half throttle on some engines which makes balancing power a very delicate affair.
 
GeX said:
no, different with na. With a nasp engine, after the TB you've got the air filter, which typically will be much larger than the entrance to the plenum. So by oversizing the TB, the engine has a massive volume of air (ie the world) to suck on. With a turbo application it is different because it is coming out of a say, 32mm hole.

I oversized the TB from 30mm to 40mm on my old nasp engine and it was a marked improvement!
Click to expand...
Every car I have owned has had the TB after the air filter. Otherwise your TB could get clogged with leaves and such.
 
Every car I have owned has had the TB after the air filter. Otherwise your TB could get clogged with leaves and such.
Click to expand...

Just what I was thinking.......
 
Tesla said:
Every car I have owned has had the TB after the air filter. Otherwise your TB could get clogged with leaves and such.
Click to expand...

i was working backwards from the engine in my head - not the airflow, i'm not stupid, i know where an airfilter goes. If you read the rest of the post, it is seems pretty obvious to me..
 
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