flexer

Oh sweet another guy with enlightening comments about buying a turbo based on performance not sound.


You got to wonder if these guys that post this stuff actually read the thread or just do a post based on what they think the thread is about.

J. R.

Spec_Ops2087

I guessed you missed the part where I gave you videos to let you hear how a GT35R sounds on a s2k because thats what your intial question was.


However, blow it out your ass if you want to be a dick.


FWIW, my last sentence in my previous post wasn't mean to come across as dick (more or less something obviously that you already acknowledged), however this post is mean't to come across as dick.

jei_s2k

We built this 600hp RSX a few years back. It uses a GT35R .82AR. Toward the end you can hear the speaker distort from the high pitch turbo whine Good stuff.

http://youtube.com/watch?v=pI37smpWxeo

flexer

Thank you for the video's and adding some good real hard data for the thread. I appreciate that.

As for your other contribution and me being a dick.....well fine, instead of saying what I did I should have responded with another clueless comment.

The topic of the title is: Do cops pull over cars that are brighter colors more?

Here is your clueless answer to the topic....ready?

Spec_Ops2087: I think people should buy the color of car they LIKE, not which gets pulled over more by cops.


So if this were poker. I saw your comment, and raised you a comment.

Boy I am being a dick. But hopefully like me Spec_Ops2087 your getting a little bit of a laugh out of it.
Lighten up some and this will seem a lot funnier.

J. R.

flexer

Slim,

Since one guy wanted us to have this conversation in the thread for others to read and maybe learn stuff we will just discuss it out loud.

so you said:

"As compressors reach their operating limits (the surge line and the choke line), they become very innefficient and they either spin so fast that the blades stop pushing air or the back pressure (boost) becomes so great that the flow actually reverses and goes the wrong way through the turbo (BAD). Under transient situations turbos operate at points all over their compressor/turbine maps. I'm sure this has something to do with varying turbo sounds, too."

The only time I know that a compressor can surge itself is when the throttle plate closes. Air under pressure will perform like a liquid and flow from highest pressure to lowest pressure. Before the throttle plate closed the lower pressure could be found in the motor and flow moved in that direction for this reason and also because the turbo moves are in that direction helping it to choose that direction as the direction of flow. Once you get off the gas and the butterfly closes making the intake track now a pressurized tube, lowest pressure is found before the turbo in the intake, so it will start to flow backward causeing compressor surge.

I have never heard of getting pressure surge from just running to much boost. I was always under the impression that you moved outside of the efficiency area by increasing the boost to the point that you are making more heat then you are moving more air, so as you heat the air up you are essentially flowing less. Or you are flowing the same but with the added heat you make no more power. Also you can step out of the efficiency range on the turbine side by running more air then then the wheel and housing can flow.

There is a lot of talk about people injecting water/meth into the turbo intake to pull the compressor map up and keep it in the efficiency range longer and allow you to run higher boost without just creating heat.

On the turbine side like we talked about. When running low boost the wastegate is letting a lot of the gas go by so the actual wheel size and A/R housing is not chocking out the system. But once you start going to higher boost levels, you will see that more gases must pass through the turbine wheel then bypass it and that wheels efficiency will now come into play also.

What do you think?

J. R.

Spec_Ops2087

flexer:Which exhaust sounds best?!
me:don't buy on sound alone!





not that an exhaust really does anything for a stock car anyway...

slimjim8201

[QUOTE=flexer,Dec 6 2007, 11:32 AM] The only time I know that a compressor can surge itself is when the throttle plate closes.

slimjim8201

I think this video is interesting. Don't know the exact turbo specs, but I imagine the turbo is large. Note the long spool up times (and also spool down). This sounds more like a centrifugal supercharger compressor. My guess is that the rotational speed of this turbo is quite a bit lower than mine. I can only hear my turbo spinning while it's beginning to spool. After that, I think the frequency is too high to hear and the other noises drown it out anyways.

STS Turbo on a Yukon

flexer

NOW THATS THE SPIRIT SPEC!!!

I laughed so hard at that my wife had to wonder what I was looking at on the computer.

J. R.

flexer

STS is just down the hill from me, so there are many STS cars/trucks/whatever running around. The turbo sound is so pronounced because the turbo spools very slow and is outside and RIGHT THERE.

J. R.