How bad could it be? GT3071R 1.06ar
 

So some of you might recall my recent purchase of a new GT3071R for $650 just before Christmas. See thread My first turbo...

I was bound and determined to get a real GT hotside at a similarly ridiculous price point and I really wanted V-band too. Well, I practically stole one on E-bay for $53! ATP gets $380 for this housing new. The housing is *barely* used; except for some light soot inside it looks brand spanking new. (The auction picture doesn't do it justice) However, the ar is 1.06. I bought it to barter for the same housing in 0.63 ar. See thread Other turbo car forums: Where can I swap/sell this housing?

But I got to thinking... How bad could the spool be if I run this housing on the Miata while I wait for the right housing to come along? I mean even super laggy boost is better than no boost, right?

What do you guys think, will I see any boost with this housing?

i'm thinking it will suck pretty bad, but try it out and let us know, if you don't like it then swap it

ctpsloni on .net runs a 3071 i think he is happy with it.

I am 100% SURE that the 1,06 hotside a/r cannot work in your application.

0,63 is the best for miata engines

i doubt a 1.06 will ever make boost.

a .63 wont make boost on a 1.6 till 4.5K and make 12psi at 5K


http://forum.miata.net/vb/attachment...chmentid=38520

I think you will see boost, I think it will roll in around 5000 RPM or so. That's my guess. When it does it will be making more power per PSI than anything else we have yet seen on the Miata because of the large A/R.


Mark

build the motor to spin 10k rpms...and you've got yourself a turbo that'll scream up top...

thinking...Honda turbo. :)

My turbo has a .63 a/r, makes 10 psi at 3250 rpm.

yeah but you don't have a 3071 you have a t3. while the turbines are similar in size the compressor is 17mm larger in diameter that will adversely effect spool.

the .63 a/r is efficient at 20 lb/min, the 1.06 a/r is efficient at 27 lb/min...IIRC a 1.6L pumps out a mere 14 lb/min @ 7K.

I'm just basing that off the dyno results some other member saw himself, with is pretty good data to go by.

For means of personal education.. Does lb/min air in == lb/min air out? Can you figure out the air consumption with a simple mathematical formula accurate or do you have to know the cylinder head flow also?

Mark, are you saying you would expect the engine to be in vacuum until 5K?

...then .0002 seconds, 50 RPM, and 200 ft-lbs later I will Braineack my ass into a pole :)

hahahhahahahahahahahaha

The head (and intake manifold, etc) is a variable, but it's adequate to throw a guess at it. For a four-valve engine, I'd throw maybe a 0.9 at VE.

The general rule is that base airflow (CFM) at atmospheric is:
(cc * RPM * .5 * VE) / 28317

At STP, one cubic foot of air is 0.0807 lbs, so multiply that against the answer to get lbs/min at atmospheric.

Under boost, multiply that result against the pressure ratio to get true lbs/min.



edit: Here is an awesome calculator to do all the math for you and produce tables both in CFM and lb/min: http://www.lovehorsepower.com/CFM1.htm

air out through the turbine.

i use (CI x rpm) / 3456 / 14.47

When it does spool... It will spool pretty violently would be my guess.

Mark

I'll post this up since no one seems to be following the link. 1.6L 3071 at 12psi.

looks like a VTAK dyno

That unfortunately stops at 7k.

Frank