Importance of proper turbine and housing size selection.

[FunkyPhil]

Incase some are confused, A/R is the port just before the turbine wheel. Some manufacturers use other terms to describe this area. Holset and MHI refer to it as cm^2. This ports purpose is to vary the way the incoming exhaust attacks the turbine wheel causing a desired reaction.

A loose description of its purpose would be a garden hose and those little plastic yard flowers that spun in the wind.

If you took that open hose without a nozzle (your A/R) and let the water hit the flower (turbine wheel), it would make it spin. Just not vary fast. During this period the pressure within the hose (back pressure) will be very low. This also will allow the largest amount of water to leave the hose.

Take the same situation, but place your thumb over most of the opening, and you will see the water leave the hose at a higher velocity and the flower accelerate (spool) much faster than previous.

You have just changed the a/r or cm^2 to a lower value.

BUT, what you will also notice, is a substantial increase in the hose line pressure (backpressure)
Over time (RPM), this restriction hurts / chokes your engine and kills its efficiency (HP).

Enjoy!

[FunkyPhil]

(info from the turbine wheel thread- http://www.sqperformance.com/forum/index.php?topic=27.0)

thanks to SQR for the fine work!!!

testing was conducted with a STOCK SQ TURBINE HOUSING and an 18G comp wheel and 25psi. A/R (cm^2) remained unchanged. This shows how choked the G54 is with any TD05 turbine in place.



turbine wheel measurements (mm)
TD05 / inducer - 55.8 / exducer - 47.5
TD06 / inducer - 65 / exducer - 55

[FunkyPhil]

As you can see in the graph above, the largest gains are seen by using a better flowing turbine wheel. That is the important choice. You want to land in the middle of your target powerband. Turbine housing A/R can then be used to fine tune how you wish for the turbo to respond.

Without sufficient turbine & turbine housing (hotside) size, a compressor wheel is limited to available flow just like ANY pump. So until the exhaust bottleneck is rectified, you will not realize full compressor wheel capability (flow/hp)


So in conclusion,
    Stop running tiny ass hotsides on your starion / conquest turbo's.

[TainterRacing]

Is there a way to figure how much air is flowing threw the hot side??? The reason I am asking is I have wonder what % flows threw the wastegate when open.

[FunkyPhil]

Soooooo many variables come into play with that scenario. But I think your getting at the use of a larger wastegate to cover for an inadequate turbine.

If it wont flow well through this hole, add another? hahaha.

[TainterRacing]

mmmm all this has giving me a idea I will work on this winter. a way to test turbo and header flow that any dyi guy might be able to do.

[non-intercooled flatty]

More interesting stuff.

[wrngwae]

nice perspective and visual display.

[FunkyPhil]

From my turbine housing upgrade last year.

http://www.sqperformance.com/forum/index.php?topic=88.0

[TainterRacing]

So A/R is the same no matter if it is a t3 or a t4 right??

Brother went from a .63 ar with a 57mm wheel to a 64mm wheel Thats seen to be a great combo for his motor all tho I think a even larger ar might help.

[FunkyPhil]

So A/R is the same no matter if it is a t3 or a t4 right??

Brother went from a .63 ar with a 57mm wheel to a 64mm wheel Thats seen to be a great combo for his motor all tho I think a even larger ar might help.

according to what Ive seen on the dyno as well as speaking with PTE, they are not. More like boys sizes vs mens sizes.
Regardless, people need to focus less on AR and more on the turbine wheel itself.

An 80/62mm turbine wheel in a .6 ar housing will grossly outflow a 76/58mm wheel in an .8 housing.
then you have things like blade count and design that further alter things.  And then you add single vs twinscroll into the scenario...... TURBINE WHEEL FIRST!

[C89ZX7R]

(info from the turbine wheel thread- http://www.sqperformance.com/forum/index.php?topic=27.0)

thanks to SQR for the fine work!!!

testing was conducted with a STOCK SQ TURBINE HOUSING and an 18G comp wheel and 25psi. A/R (cm^2) remained unchanged. This shows how choked the G54 is with any TD05 turbine in place.



turbine wheel measurements (mm)
TD05 / inducer - 55.8 / exducer - 47.5
TD06 / inducer - 65 / exducer - 55

I run a TD05H-18G - 14b Chopped, Smoothed and Polished Housing

[TainterRacing]

Turbine wheel Both are .63 ar t3 60-1Hi-fi Head is a Heavy ported 2nd gen magna with stock cam
 roller cam. OS ss valves 3 angle valves Ti valve retainers. All other parts same on motor. Have switch cam now tho to race cam need to tune it when the trannys not blown....

old combo was a 2.229   2.559 inch 56.6mm 64.9mm This worked Crazy good mid to upper 300hp range 6400rpms 12psi-15psi NA Feel to it. With built head was able to get Full boost (14psi) on revving motor.

new combo is a  2.544   2.922 inch 64.6mm 74.2mm Still working on tuning and getting the tranny to hold up. But it has a MUCH better top end and with  out it tuned well gets full boost 3200-3400rpms

I cant say for sure as we have not had much time on the new turbine but I will guess its power band 15-to 20psi good for mid 11's with very little lag 7000rpm range 350hp-500hp Great for a street strip car. Will post more info when I know more solid ## on what all we get.

[mstieg]

new combo is a  2.544   2.922 inch 64.6mm 74.2mm Still working on tuning and getting the tranny to hold up. But it has a MUCH better top end and with  out it tuned well gets full boost 3200-3400rpms

I cant say for sure as we have not had much time on the new turbine but I will guess its power band 15-to 20psi good for mid 11's with very little lag 7000rpm range 350hp-500hp Great for a street strip car. Will post more info when I know more solid ## on what all we get.

Update on this Matt?

Based on the #s turned on mine with your help, that sounds about right.  Since updating several other things, the 74/64 turbine on the S256 hits full boost very early.  Should be sooner yet after porting.