Do you get more power from different turbochargers with the same boost? for example will a b18 with a t3 with 7 pounds of boost make the same power as the same engine and boost with a t4.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mugentype-r &raquo;</TD></TR><TR><TD CLASS="quote">Do you get more power from different turbochargers with the same boost? for example will a b18 with a t3 with 7 pounds of boost make the same power as the same engine and boost with a t4. </TD></TR></TABLE>

Yeah, a bigger more efficient turbo will flow more at the same boost level. For Example: An SC61 will make more power @ 10 Psi than an SC50.

 

heck yes it makes a difference. i made more power with a t3/t4 @ 7psi than a 14b @ 12psi.

 

pressure doesnt make power.....air flow does

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by D@nnY &raquo;</TD></TR><TR><TD CLASS="quote">pressure doesnt make power.....air flow does</TD></TR></TABLE>

but pressure makes more air flow

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ham &raquo;</TD></TR><TR><TD CLASS="quote">

but pressure makes more air flow </TD></TR></TABLE>


acutally air flow creates the pressure...pressure is a restriction to air flow ...nice try tho

 

Just to recap what has been covered in this forum eleventy billion times already, yes it matters and here's why: keep these three things in mind; 1) flow rate, 2) boost pressure, and 3) efficiency. They will create the 3d map (or 2d map with isoclines) that you will use to determine how well a turbo fits your needs.

At every flow rate, and at every boost pressure (or rather every pressure ratio) for THAT flow rate, a particular turbo will have a certain efficiency. 75% efficiency or more is fantastic and is only found at the center of the efficiency peak if at all, 70% is pretty good and most turbos will be at least this efficient somewhere in their flow chart, 60% or less is getting pretty poor and should only be found at the upper or lower limits of the flow rate you are using.

What you WANT is a turbo that has good efficiency AT THE FLOW RATE AND BOOST PRESSURE THAT YOU WILL BE USING! There is a bandwagon here at H-T that thinks bigger is always better, and while that is often true it isn't always true! Despite what some here may claim, if two turbos have the same efficiency at the same pressure and flow rate, they will make *exactly* the same power AT THAT PRESSURE AND FLOW. The engine won't be able to tell the difference between the two AT THAT POINT because all it sees is X pressure and Y flow at T temperature. Sooo, decide where you want your powerband - midrange for daily driving, upper midrange to near top end for auto-x/road race, all top end for drag racing, etc. - and look for a turbo that has good efficiency at the boost pressure and flow rate for the powerband you want.

If your turbo is too small it will be inefficient at high flow and die out up top. If your turbo is too big it will be inefficient at low flow and won't spool until nearly redline if at all. If your turbo is designed to work best at high pressure ratios then it will probably suck for a low boost setup, and likewise a turbo designed to be efficient at low pressure ratios will blow donkeys at high boost. Think of these as the four sides for a rectangle of the BOOST RANGE x FLOW RATES that will work well for you. Now go find a turbo that has good efficiency within your rectangle.

Also keep in mind that your hot side (turbine) has to match your cold side (compressor), meaning --&gt; your turbine should be fairly efficient at the EXHAUST flow rates and shaft speeds where the compressor needs the most power. Too small and it chokes your engine with too much back pressure, which robs power. Too big and it won't spool the cold side early enough. Unfortunately it is more difficult to find efficiency tables for most turbines than it is for most compressors. Good luck with that.

Lastly, there are three things that are important for a reliable setup:
1) tuning
2) Tuning
3) TUNING!!!
Don't say you haven't been warned. Heed these words or your engine go BOOM!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by D@nnY &raquo;</TD></TR><TR><TD CLASS="quote">acutally air flow creates the pressure...pressure is a restriction to air flow ...nice try tho </TD></TR></TABLE>Actually it is the kinetic energy of the high velocity air stream flowing outward from the edge of the compressor wheel that is transformed into pressure (potential energy) when it slows down in the compressor outlet and intake plumbing. Nice try though!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tjbizzo &raquo;</TD></TR><TR><TD CLASS="quote">Actually it is the kinetic energy of the high velocity air stream flowing outward from the edge of the compressor wheel that is transformed into pressure (potential energy) when it slows down in the compressor outlet and intake plumbing. Nice try though!

</TD></TR></TABLE>

you should seriously think about killing yourself

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by D@nnY &raquo;</TD></TR><TR><TD CLASS="quote">

you should seriously think about killing yourself </TD></TR></TABLE>

Are you saying he is wrong? he's just saying where the extra airflow is coming from which is the compressor wheel. Larger compressor wheels are able to take in more air and expel air into the compressor outlet with greater force. Compressor wheel tip speed, exducer diameter, inducer diameter, trim as well as a few other things determine how much air is taken in and how much it is compressed. Do a search on the web for compressor tip speed and you'll come up with a few hits on how compressor design and tip speed affect airflow.

http://www.turbobygarrett.com/....html

http://www.rx7club.com/printthread.php?t=345518

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tjbizzo &raquo;</TD></TR><TR><TD CLASS="quote">Actually it is the kinetic energy of the high velocity air stream flowing outward from the edge of the compressor wheel that is transformed into pressure (potential energy) when it slows down in the compressor outlet and intake plumbing. Nice try though! </TD></TR></TABLE>

You're gonna confuse the poor chap, Danny said it well enough.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BlueShadow &raquo;</TD></TR><TR><TD CLASS="quote">

Are you saying he is wrong?
</TD></TR></TABLE>

no im saying what I just said.....