meanteg

?

int3gra

cyan1de quote (i think he was referring to A/R)

The larger the number, the more lag will be incurred, but more high end
The smaller the number, the quicker the spool, but quicker it will fall off on top end

rtype11

aspect ratio, basically the largest diameter of a turbine or comp wheel divided by diameter of the same wheels smallest/narrowest part in percentage

BlueShadow

**SOUNDS BUZZER** your definition is correct but A/R stands for <U>A</U>rea / <U>R</U>adius ratio. (Area divided by Radius ratio)




[Modified by BlueShadow, 5:10 PM 4/26/2002]

BlueShadow

and to add to this too large of an A/R and you may need even reach your desired boost.

example: your desired boost is 18 PSI, you have an A/R or .82 or 1.xx something, the highest you might see at redline might be 12 PSI.

BTW those numbers aren't precise, I was just exaggerating them so you would see what I was trying to say.

rtype11

yeah that works too, aspect ratio is old skool i guess, I concede

degradated

I don't understand how the formula works...

Can someone give a hypothetical?

Say we are dealing with a turbine...

So you would take the area of the fin's largest part:

A = pi x R^2
A = 3.14159 x 1.125^2
A = 3.534

And the radius of the smallest parts let's say is 0.5, so 3.534/0.5 = 7.068. How the hell does that turn into an A/R of something like .64?

BlueShadow

well in maximum boost it explains the turbine and it even shows a graph, but I have a hard time trying to visualize the fans and the graph.

I do know that the <U>R</u> in radius, is the distance from the center of the section <u>A</u>rea in the cone to the center of the turbine shaft. but I cant exactly pinpoint what the area is...


[Modified by BlueShadow, 7:44 PM 4/26/2002]


[Modified by BlueShadow, 8:03 PM 4/26/2002]

CovertFI

a t66 means it has an A/R of .66 or both compressor and turbine???

BlueShadow

No, when you go into T66s, T78's and T88's you're talking about straight T4's. (I think)

The T4 turbines use the same A/R numbers we do. to the Supra and RX7 guys, to them a T4 1.1x A/R, is like a .63 to us Honda guys.

Also I think those designations are used by mitsubishi, and maybe turbonetics too.

Garrett has their GT3525-blah-blah to designate straight T4's and turbonetics also uses T04Rs, T04S, T04X (XS eng.), and even T04E to designate straight T4's.

EDIT: I visit http://www.rx7club.com and http://www.supraforums.com from time to time but my info might be a little off.


[Modified by BlueShadow, 8:10 PM 4/26/2002]

BlueShadow

here is a pic of the Area and the Radius I was talking about, the one in "the book" was a little confusing.




[Modified by BlueShadow, 8:24 PM 4/26/2002]

degradated

Ahh, that's totally different from what the other guy said.
Now I'm totally confused.

That makes more sense to me, though...I always thought that the A/R had to do with the housing and the trim had to do more with the wheel.

dbman96

Degradated wins the prize... but it gets REALLY confusing - when it comes to Turbines, that pic is correct - the A/R is area over radius.

But when it comes to compressors, there is another factor called "AR" that is "Area Ratio" which is the Area at the volute at the final exit(pi*d^2/4) divided by the flow Area at the exit of the DIFFUSER (pi*d*h) and this ratio determines whether the volute is accelerating or decelerating the flow of air after it leaves the diffuser. This stuff has more to do with stall / surge performance than anything else.

B20LS-T

Come again? HAHA im totally confused now..and I read the book too , I guess Ill have to read that section again.

dbman96

Maximum boost only covers A/R from the turbine point of view, which is all we should care about. I'm getting the other info from a turbomachinery textbook I have sitting on my desk.