KeyserSoze

I just found a great deal on a garrett ta3405 (the comp wheel was upgraded to a V-trim wheel). The turbo is a .60 a/r with a v-trim wheel on the compressor side and a .58 a/r with an o-trim wheel on the hot side. Here is the compressor map: http://64.225.76.178/catalog/compmaps/fig7.html

I am looking to run this on my gsr (freshly rebuilt block). I want between 350-400whp. Is this a good turbo for my setup? I have done the math and it looks like it would work with some boost control from 12psi on up. Any opinions?? I am new to turbos and have just begun to understand to read compressor maps. I have done teh math and it seems to be a decent turbo, but I have very little experience with these things and it seems that the wisdom gained through experience is more important than book smarts only. TIA.

Oh, btw the boost control is not an issue as I have a decent ems.

KeyserSoze

bump

TheShodan

iTrader: (14)

In the upperband you will definately be out of the efficiency range of that turbo as well as not reach the power goal that you need with this turbo. The P Trim exhaust wheel works to a good point, but honestly, that compressor efficiency is not very good. You're out of the efficency range in 3 areas of the compressor island.

You're right, your math is really off.

KeyserSoze

So, what your saying is that even with boost control that this turbo is (compressor wise) will not get me to 350whp efficiently. And btw I know that the turbo will be reaching the surge line at 50% engine flow with a PR of 1.82 (12psi) or higher that is why I intended to use boost control on the system. The turbo hits 70% and ~67% efficiency at PR's of 1.82 (12psi) and 2.02 (15psi) respectively. I figured these efficiencies since the engine will be flowing no more than ~36lb/min at highest boost. I didn't realize that these numbers where incredibly inefficient. I guess my numbers ARE way off. I must be looking at this the wrong way. Maybe you know of a good source that will expand my understanding so I don't ask anymore questions based on my inadequate mathematical skills. Maybe a book more up to date than Corky Bell's maximum boost (since this is where I learned how to calculate engine flow and the other figures)? The math seems pretty simple to me, however I have just began to fiddle with f/i engines. Maybe my noobness is blindin' me from seeing that this turbo sux. Help me out here. Thanks.

KeyserSoze

The generic 3pt plotting system is just to generate a curve for your specific application right? So though your plotting only 3 pts what you are doing is defining a curve for your engine given the physical characteristics and the pressure you will be working at, correct? Doesn't the far left point (the usual 20% rpm flow calc, although I even used a LOWER Ev for this point assuming that the engine will not be as efficient at low rpm as it will at redline) allow for the determination of how your application will traverse the compressor map from basically low boost to peak boost? Isn't the 3 pt curve actually a curve with infinite points, but only 3-4 are used to get a general description of that curve? When using boost control the only points that will be stationary will be the first and the last, right? So (20% flow, PR = 1) and (100% flow, PR = max). Using boost control can't you define the path of the curve (your individual application) except for the the afore mentioned points? I ask these questions because these are some of the ideas (know looking to be completely unfounded and retarded) that I had about compressor maps in general.

I apologize for the pluthora of questions, but I am now even more confused than I was before. I know that this is a virtual paragraph of questions, however if anyone would like to answer any of these please do as I am now feeling quite inept at this stuff.

If that were an english paper it would have earned me a big fat F-.


Modified by KeyserSoze at 9:08 PM 8/13/2005

KeyserSoze

bumpity, bump, bump.

SHystrdyGSRtdy

if anyone knows anything about turbos, listen to "TheShodan".... he'll steer you in the right direction, i'm sure he can get you the turbo you need also.

KeyserSoze

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SHystrdyGSRtdy &raquo;</TD></TR><TR><TD CLASS="quote">if anyone knows anything about turbos, listen to "TheShodan".... he'll steer you in the right direction, i'm sure he can get you the turbo you need also. </TD></TR></TABLE>

Thanks for the suggestion. I don't doubt what he has said, but it seem would seem to me that the dynamics of the evaluation of a compressor map for a given app would have some flexibility because of the boost control option. But hey what do I know, I'm a retard at this stuff. Thanks. Back to the drawing board I guess.

Anyone else who can point me in the direction of some good literature, so I can study this stuff better and not ask retarded n00b questions like this??

Oh, and Shodan (if you happen to c this) what (turbo that is) would you suggest to suit my needs with a t4 exhaust housing. Thanks.

KeyserSoze

This isn't for instant gratification here, I am trying to learn. Can someone at least point me in the gen direction for literature where I can learn what misconceptions I have and straighten them out? I should have just made this one of those "which turbo is best for me" threads. I would have gotten like 50 responses.

PeakBoost

i hate to say it, but real world testing is the best place to soak up information.
the best i can suggest is to always think logically and mechanically.

as for your setup, theshodan is correct as the to4b vtrim is very inefficient above 35lbs/min.
ballparking 10hp per lb/min, 350hp efficiently. this setup using a large turbine section will lower the pressure ratio, bringing the efficiency way down (~60%-65%@1.8pr).

beyond this, the turbine section (.58a/r), even with an o-trim wheel will make for a very lazy powerband on the street.

all said, this turbo will work, but then again, so does jb weld...

there are many better choices for you.

pm me with any questions

ken

KeyserSoze

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PhoenixTurbo.com &raquo;</TD></TR><TR><TD CLASS="quote">
as for your setup, theshodan is correct as the to4b vtrim is very inefficient above 35lbs/min.
ballparking 10hp per lb/min, 350hp efficiently. this setup using a large turbine section will lower the pressure ratio, bringing the efficiency way down (~60%-65%@1.8pr).

beyond this, the turbine section (.58a/r), even with an o-trim wheel will make for a very lazy powerband on the street.

all said, this turbo will work, but then again, so does jb weld...
</TD></TR></TABLE>

Point well taken. Thanks for including some numbers with your answer, that always helps.

TheShodan

iTrader: (14)

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

You're right in some areas, but I can't get into ALL of my secrets... That's how I make a living.... Let's just say I use more than 3 points. I use 15-35.

Thanks for talking in MATH Ken.. Sometimes I don't relay it very well.