93LSivic

Did anyone here ver have a smaller turbo on their motor? I have an LS motor. The turbo I plan on putting on it is real small. Its a T3, the A/R is .48 but the compressor is .42. How is this going to do on my motor. I know everyone is going to reccomend a way bigger turbo, so please dont--just give me some feedback on what kind of performance i will see from this turbo. Obviously in the future i will be upgrading.
Really, just tell me what I am looking at here. Is it gonna run out of steam at 5K or will it be ok til 6.5K and just not flow too much air?
It is off of a late 80's Saab, but has been rebuilt, so its pretty fresh. Whats your guys ideas on it?
Also I am sure many others would like to see this question answered since there has been a lot of interest in junk-yard turbos and this is a very popular unit for the used turbo units.
Thanks, any response is accepted. No **** like "thats way too small" i already know this.

89civic1.8T

I have a TD04H-15C on my B18B. I am not sure how this turbo compares to your but mine is pretty small. I want more top end so I have a T3/T04E .68 AR/50 trim compressor. We'll see how this new setup works. I think your turbo is larger than my current one so it should have some topend but alot of midrang.

93LSivic

I think that the TD04 is a bigger turbo than this one.
Anyone else have an other info for my question?

Rob03Pro5

You mean a .63 A/R with a 50 trim right? That should supply plenty of top-end.. you'll just have more lag.

93LSivic

Ok, any help on this topic. PLEASE!!!!!

BlueShadow

no I think he meant what he meant, a T3 .63 A/R turbine and a T04E 50 trim compressor.


[Modified by BlueShadow, 2:58 PM 12/5/2001]

Rob03Pro5

I know.. that's what I asked.. cuz he originally said .68 A/R which is something I've never heard of. I'm well aware that the .63 A/R belongs to the T3 family.

93LSivic

Ok great why dont you guys solve his problem in another thread. Could someone please answer my question, since this is my thread and all.......

dbman96

Ahh... once again someone stumbles on the absolute best way to prevent anyone from answering his question.

BlueShadow

Sheesh its always me, me, me!

Nah I'm just messin with you, sorry to get OT but I re-read your original question and you pretty much answered your own question, yes it will run out of steam early, but how early? thats a process of guesstimation, unless you can find someone thats run a similar setup you best guess will do.

you said it was a T3 compressor w/ .48 trim? you might wanna reference it with similar trim compressors on http://www.turbocharged.com check the compressor maps and see what the max flow rate is for the most identical compressors. also what boost pressure do you plan to run?

and ROB92SC
since we cant argue in this thread.... what do you say we take this outside??

hehehe actually that was my bad, I didn't see that HE had typed a .68 instead of a .63 I think its time for me to get new glasses

TypeC

and just to add, the TD04 family has a WIDE variety of compressors, so you can't really say X is smaller/bigger than a TD04. The TD04 on the WRX is a TD04-13G which is one of the smaller ones (but flows enough for a 2L at 15psi), and they can go as big as a TD04-18T (both seen below). Soooo, you just need to use a turbo calculator ( http://www.bsmotor.com/turbo/kalkuler.html http://velocity.websitegalaxy.com/cfm.html ) and plot your PR vs CFM on each map and find what turbo is right for you. TD04's can be seen here (http://www.3si.org/member-home/jluci...turboguide.htm)




Good luck, -C

BlueShadow

hey 93LSivic,

I just looked at the compressor map for a T3 40 trim.

using 6 PSI as an example, the Compressor efficiency drops down to 65% at about 4000 rpms at this point the compressor efficiency goes way down, I don't know if you know this but when the compressor eff. gets low it starts to heat the charge air more and more which means the HP wont go up as much. 3800 RPMs is probably where this compressor will be at its peak performance.

check out the T3 40" compressor map on http://www.turbocharged.com

mark these points on the map(right side and bottom):

pressure ratio = 1.4 AND 8.9 lb/min
this is the flow rate of the compressor at 3000 RPMS

at PR = 1.4 AND flowrate = 12 lb/min
this is at 4000 RPMS

at PR = 1.4 AND flowrate = 20.7 lb/min
this is your engine at 7000 RPMS!!

of course on the last point (7000) compressor efficiency is about 30-50% and the air entering the intake manifold is probably scorching hot!


[Modified by BlueShadow, 2:45 PM 12/6/2001]


[Modified by BlueShadow, 2:51 PM 12/6/2001]

93LSivic

****!!! Figures I get a response that I have no idea what it means. For the longest time I have been trying to figure out compressor maps, but could never get it. Does anyone know where i can read up on these, basically get spoon fed on how to understand them? I dont get it.
Basically I should throw this turbo on ebay and save for a T3/T04e shouldnt I?

BlueShadow

Sorry didn't mean to confuse you but basically your compressor (T3 .42) will probably run out of "steam" at about 4000 RPMs and if you want to learn how to read compressor maps and calculate compressor sizes I'll be more than happy to show you.

What you need to do is find you airflow rate based on : your desired boost (PSI) engine size and engine redline. you need to find your Airflow rate at two points first point is at redline second point is usually at 75% of redline or where ever the compressor hits full boost, whichever is at a lower RPM. All you need to know is basic math, add, subtract, multiply and divide. you'll deal with different units of measurement (lb,cfm,psi) lets start:

Basics you will use these numbers later on
PRESSURE RATIO = (14.7 + your desired PSI) / 14.7 = PR
convert CFM to LB per MIN = CFM x 0.070318 = LB/MIN (@ sea level and 112 degrees*)
LITERS TO CUBIC INCHES DISPLACEMENT = # of L's x 61
CFM = Cubic Feet per Minute

now using my car as an example:
2.2L (134.2 cid), 7400 Redline, desired boost is 10 PSI

#1 CALCULATING AIRFLOW RATE AT REDLINE and 10 PSI
cid = Cubic Inches Disp.
VE = Volumetric efficiency in percent
.5 = (given) 4-stroke engine fills cylinder only on one-half the revolutions
1728 = converts cubic inches to cubic feet

Airflow in CFM = (cid x rpm x .5 x VE%) / 1728 = CFM no boost
CFM x PR = CFM under boost


so for my Lude:
PR = (14.7 + 10 ) / 14.7 = 1.69
Airflow = (134.2 x 7400 x.5 x .95) / 1728 = 272.99 CFM (no boost)
272.99 x 1.69 = 461.21 CFM under 10 PSI

now since most compressor maps have their flow rates in LB/MIN we need to convert CFM to LB/MIN. A cubic feet of air (length+width+height) weighs different at diff. Altitudes and different temperatures. to simplify it well just assume we are at sea level and the air temp is 112 *. the conversion number is 0.070318.

so for CFM TO LB/MIN = CFM x 0.070318 = LB/MIN
461.21 x 0.070318 = 32.44 LB/MIN

so here we have:
BASIC ENGINE FLOW RATE = 272.99 CFM
ENGINE FLOWRATE with 10 PSI = 461.21 CFM (32.44 LB/MIN)
PRESSURE RATIO (PR) = 1.69

so now we know our flow rate in LB/MIN
a 2.2L with 10 PSI of boost at 7400 RPM (redline)
flow rate = 32.33 pounds of air per minute (LB/MIN)
PR = 1.69
with me still? this is POINT NUMBER ONE. now we do the same for 75% of redline and 50% of redline.

#2 CALCULATING AIRFLOW RATE AT 75% RPM RANGE

now we will find the airflow rate at 75% redline = 5550 RPM (0.75 x 7400 = 5550)

(134.2 x 5550 x .5 x .95) / 1728 = 204.74 CFM no boost
204.74 x 1.69 = 346.02 CFM under 10 PSI

346.02 x 0.70318 = 24.34 LB/MIN

BASIC ENGINE FLOW RATE = 204.74 CFM
ENGINE FLOWRATE with 10 PSI = 346.02 CFM (24.34 LB/MIN)
PRESSURE RATIO (PR) = 1.69

#3 CALCULATING AIRFLOW RATE AT 50% RPM RANGE

As you may already know the point at which the compressor reaches full boost is largely determined by the Turbine side. but I usually calculate a third point just incase. I plot this third point on the compressor map this way if boost comes way early (50% redline) I know where I lie on the map.

50% of redline = 3700 RPM (0.50 x 7400 = 3700)
(134.2 x 3700 x .5 x .95) / 1728 = 136.50 CFM no boost
136.5 x 1.69 = 230.69 CFM under 10 PSI
239.69 x 0.070318 = 16.23 LB/MIN

BASIC ENGINE FLOW RATE = 136.5 CFM
ENGINE FLOWRATE with 10 PSI = 230.69 CFM (16.23 LB/MIN)
PRESSURE RATIO (PR) = 1.69

GATHER YOUR DATA

we have just figured out our engine's airflow rate at 3 RPM points (redline, 75% and 50%) you only need 2 at the minimum but you can use as many points as you want.

<U>POINT 1 (7400 RPM)</U>

FLOWRATE with 10 PSI = 461.21 CFM (32.44 LB/MIN)
PRESSURE RATIO (PR) = 1.69

<U>POINT 2 (5550 RPM)</U>

FLOWRATE with 10 PSI = 346.02 CFM (24.34 LB/MIN)
PRESSURE RATIO (PR) = 1.69

<U>POINT 3 (3700 RPM)</U>

FLOWRATE with 10 PSI = 230.69 CFM (16.23 LB/MIN)
PRESSURE RATIO (PR) = 1.69

these are the three points you will start referencing onto the different compressor maps, ideally you want all three to be within the highest percentile in the compressor map.

using this map of a T04E 60 trim first let me explain all the numbers on the map
1-left side, pressure ratio (how much boost you're running)
2-bottom side, airflow rate (LB/MIN on this map)
3-dotted line on far left side of "ovals", surge limit (if any of your points are to the left of this line you'll get compressor surge)
4-numbers on far right, 46020, 69640, 83972 etc, compressor fan RPM (yikes)
5-78%,75%, 74%, compressor efficiency, this is related to the temp of the air in the compressor, a low number (60%) means that the compressor is heating the air more a high number, (78%) means the air is not heated as much when it is compressed.


NOW all you have to do is take the each RPM point and put them on the compressor map, use the airflow rate and PR, wherever they intersect is where the point will go. ideally you want all points to be in the highest Comp. Eff. %, especially the redline and the 75% redline points.

go ahead and give it a try, but thats pretty much how you select compressors if any of the points lie:
-in a low Comp Eff %
-in the surge limit
-too high a Comp. RPM
you need to look at a different Compressor map cause the one your looking at is the wrong size, each Compressor trim has its own compressor map.

let me know if you need anything explained, its no problem




[Modified by BlueShadow, 8:32 AM 12/25/2001]


[Modified by BlueShadow, 8:38 AM 12/25/2001]

BlueShadow

Crap! I almost forgot!

you also need to draw /find the surge limit line.

its easy all you do is go to the bottom of the compressor map and draw a line from
PR = 1 and airflow rate = 20% of maximum, and draw a line from that to the RPM point at which full boost starts 3700 and 5550, as long as this line stays to the right of the surge limit you're ok. this line represents your rpm line from zero PSI to full boost (10 PSI)

so from PR = 1
and flow rate at idle:
max flowrate x .20 = idle flowrate
461.21 x .20 = 92.25 CFM
92.25 x .070318 = 6.5 LB/MIN

PR = 1
airflow @ idle = 6.5 LB/MIN

draw a line from that to the points at 50% (3700 RPM) and 75% (5550 RPM)

falcongsr

i love learning. thanks BlueShadow.

BlueShadow

HXMan

I don't quite understand....why would you calculate idle flow rate using the max flowrate with boost? Wouldn't you use the max flow rate at redline without boost figured in? Cuz, it isn't like you are boosting at idle.....

IM ALL BOB

*attempting to read post* ADD kicks in... forget it.. I'll just get my CLIFF NOTES
but thanks for explaining how to read and evaluate compressor maps

BlueShadow

The reason you have to find idle flow rate is so you can plot a surge limit line.
you draw a line from the idle flow rate to the 1st RPM point at which the engine reaches full boost (desired boost). This line needs to stay entirely to the right of the surge limit on the compressor map.

If you visualize it, you're making sure the turbo stays out of surge limit from a standstill (idle flow no boost) to full boost usually 3000-4500 for most VTEC's, this also varies based on turbo size.


[Modified by BlueShadow, 8:27 AM 12/25/2001]

BlueShadow

Its not that hard! I might have given a lot of useless info, or not worded it in the best way. I keep going over and over this stuff trying to find the best setup for my car. Eventually I got tired of writing it by hand, so I made up an excel spreadsheet that does all the stuff I went over here. All I have to do is type in my:

-desired boost
-redline RPM
-engine size in Liters

I'm trying to figure out a way to also figure in intercooler efficiency and PSI loss and other stuff. I was also trying to get the Excel to plot the lines on the compressor maps, but its gonna be real hard. It's gonna involve a lot of re-sizing of maps and a whole lot of other stuff.


[Modified by BlueShadow, 6:37 AM 12/18/2001]

TypeC

I did the same thing in JavaScript here: http://velocity.websitegalaxy.com/cfm.html
you also need to know (in addition to your 3 numbers) at what rpm you reach full boost.

-C

chri5

Very nice.

BlueShadow

[QUOTE
I did the same thing in JavaScript here: http://velocity.websitegalaxy.com/cfm.html
you also need to know (in addition to your 3 numbers) at what rpm you reach full boost.

-C[/QUOTE]

well the way mine works is, you type the three number I was talking about:

-redline RPM
-desired boost
-engine size (Liters)

and it will calculate multiple points, right now I only have it set to calculate airflow at redline, 65% of redline ond 50% of redline. Typically a turbo wont hit full boost until about 40-50% of redline so I don't think it's necessary to plot anything below 3000 RPM (unless you have a low redline). I can edit the excel spreadsheet to show as many points as I want, I also have mine set to change CFM to LB/min cause thats what most compressor maps have for airflow rate.

One thing I noticed though, when I used your Java and my Excel my flow rate at 7000 RPM @ 10 PSI came out to 30.5 LB/MIN and yours was 27.25 LB/MIN. What number did you use for Volumetric efficiency (VE%)? I used 90-95% and it looks like you used a lower number.

HXMan

That would be nice!