Outline · [ Standard ] · Linear+ Turbo A/r's, About The Air

[1JZ_Cressida]

been checking out some decent sized turbos out there and noticed that some A/R's and inlets are bigger than some.....Was wonder why does a car running at 14psi on the stock small turbo run slow and when that same car has a turbo with a bigger inlet and A/R(HKS GT28), it runs even faster with the same 14psi set on the controller?

forgive me but im not up to mark on the turbo thingies lol

[WhoDriving?]

The psi/horsepower concept is different for each turbo and each engine. 8 psi on a decently sized supercharger on a Mustang is about 375 hp. 12 psi is about 450 hp. 5 psi from a good sized turbo on a Mustang is about 425 hp.

25 psi of boost on a single turbo Supra is about 700 rwhp. 25 psi on a 16G Eclipse is about 400 hp (I believe). It's different from setup to setup.

Picture a garden hose vs a large water pipe. 14 psi is just a measure of pressure in each tube. The garden hose, however, will flow less water at 14 psi than a large pipe at 14 psi. The pressure is the same, but the volume of water is much different.

It should be noted, however, that generating 14 psi in a large tube requires more energy than creating 14 psi in a garden hose. This is why bigger turbos set to make more boost generally lag more than smaller turbos that don't generate as much boost.

[1JZ_Cressida]

ohhhhhhhhh i seeeee

[DarkStealth]

Thats why my tiny a** stock turbos spool at around 1800ish RPMs and hit full boost by 2400ish.
-Dan

[Touge MR2 Turbo]

MAN that would be great if like a T78 spooled like that... lol

[69Cougar]

Chris need turbos =(

[Uncle ben]

Trey from cobb tuning-Boost is basically the restriction of air flow into the cylinder. If Turbo A and B are both making 7psi at 5000 RPM on the same motor, they are flowing the same volume of air. The engine can only ingest a certain VOLUME of air at a given RPM, and boost is just the restriction created from the turbo trying to cram the air down the engine's throat (in layman's terms of course.) Sure, the turbos might be rated at different air flow rates, but the same engine and the same boost will ingest the same CFM (Volume of Air) at a given boost. All you can effect would be the MASS of air, as a result of the turbo's effeciency at said boost level...and therein lies your answer to power. If you can bring a higher MASS of air into the engine, in theory (given the right MASS of fuel and timing) you'll make more power.

There's also other issues like exhaust backpressures, pressure drops, yada yada yada.... just depends on how deep into the subject you want to get.

[WhoDriving?]

Yeah...and bigger turbos generally have greater efficiency allowing a greater volume of air into the engine.

Of course if you have a twin turbo setup on your Mustang then you shouldn't have had to Google that info.

[Uncle ben]

IT WASNT GOOGLED! i used aol web search! i guess im just lazy.........copy &paste!

[Uncle ben]

oh and another thing, incon built that turbo setup-not me. if its a bolt on affair and someone else installed it, why should i know anything about turbo's?(not saying im turbo illiterate or anything but) You seem a little tense.......maybe you should calm down a bit. Just because youve been on a street racing site longer than me, doesnt give you any right to slander every post i make, or act like you know more than me. Maybe you do, maybe you dont.........honestly i wont indulge in such childish antics with you anymore if its at all possible.