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Discussion Starter · #1 ·
Compressor Map

Ive tried searching on how to read these maps, but the thread was too old and the pics were hosted by imagestation (sucks). I have no idea on how to read this, its for a t3 turbo, with a 60/63 trim from a thunderbird. I want to know if this turbo would be sufficiant enough to run on the set up i want, I'm looking to make 250whp on a 97 gsr at 8-10psi on stock internals, ive been scowering all forums the past few days on all the turbo info that I can find, but i still cant figure these damn things out.

what my ideal setup would be (I know there is already plenty of these posts, but Im just throwing this out there to give more info to help me out.)

T3 turbo (Looking at 60 trim turbos)
Turbo manifold (brand unknown, still researching)
tial 35mm WG.*
2.5in down pipe
2.5/3in in/out high flow cat
custom 3in cat back exhaust
2.25 or 2.5in charge piping
FMIC
HKS BOV
aftermarket clutch
obd2-obd1 harness and ecu
Hondata s200
lots and lots of tuning

would I benefit from the use of bigger injectors, ignition, adj cam gears, anything else?


*I would really prefer to go with an external wastegate, because I've read that the internal WG would fail as the exhaust gases increase, thus causing "boostcreep" big NO-NO i know, the only turbos I can find in my price range all have internal WG,so it looks as if I'm going to have someone weld it and use an external WG, Id rather be safe than sorry.

LINK to external vs internal wastegates.


I think thats most of it, I'm still searching, man theres a lot of info and I'm still sifting through it and soaking it in. If Im missing something, please let me know.


Thanks for your time and your help.
 

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1. reading the compressor maps
I'd recommend getting the book 'maximum boost' by corky bell, or another book that deals with custom turbos if you can find one they'll have tons of info including how to read compressor maps and a lot more.
But i'll give you the quick version.
The scale on the left, pressure ratio is just the ratio between atmospheric press and the boost pressure you want to run. (14.7 + boost)/14.7 Note:(atmospheric press = 14.7psi)
The x axis corrected airflow is how much air you will be pumping through the setup, which of course varies with rpms.
airflow in CFM ( in cubic feet/min) = (displacement in cubic inches * rpm * 0.5)/1728
our gsr have a 110.16cc engine.
airflow in lbs/min = airflow in CFM * 0.0756
Now *adjusted* airflow = airflow * pressure ratio

What you do is first decide how much psi you want to boost and use that to work out both the pressure ratio and airflow numbers (airflow is rpm dependent too). The dot where they intersect is the predicted efficiency of that turbo for your car at that boost level and rpm.
You need a point on the graph for every RPM you're interested in, so the corrected airflow, or x scale, can also be interpreted as an RPM scale for your car.
Here are some examples and an excel sheet both for a gsr at 10psi:

Examples

2. other stuff
Yes bigger injectors. 450-550cc range.
I wouldn't recommend you touch ignition/cams/clutch etc until you have a problem and need to. But what do I know I'm still waiting on the parts for my first turbo project :>
 

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There are plenty of Boosted GS-Rs that use a similar turbo to get the hp you need. Just make sure that the Exhaust housing is a .63A/R so you can get a bit more top end. Be weary of getting used turbos from junkyards and the like because you don't know how it was treated, if it needs rebuilding, Foreign object debris, etc.

I get this turbo on a regular basis from Garrett, Precision, and Innovative. Give me a shout..
 

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Discussion Starter · #5 ·
Do you sell turbos or rebuild them? This is the exact turbo I want, but I dont want to rely on ebay as my only source for finding them. I've also looked at other places like cheapturbos.com and turbocalculator.com, but these places want anywhere from $400-800, a little out of my price range right now.

Would an internal wastgate be ok to run on 8-9psi? Id like to go with an external, but if an internal would hold up, Id go that route, just to save money and be SMOG legal if that ever came up. Which in my area I dont think it matters.

I went out earlier and bought "Maximum Boost", lots of good info in there. Ive started to dive into it, a lot of info that I was unaware of, and I can already tell Im going to need to be patient with this project and hopefully it will go smoothly.

2 problems I see here, 1) Im not a patient man. and 2) This book is going to pull me away from TI for a while, I dont know if I can deal with that, Im here all the time. Oh well, time to go force feed the brain some more.
 

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well, I got news for you >:)
1. it's good quality, powerful, fast, reliable
2. you don't pay exorbitant amount of money
3. you don't have to invest an obscene of time.
pick two.

examples:
greddy/drag
or
Walk into a shop and drop 15 grand and say "make it fast"
or
study your arse off.

If you're new to this game like I am, you're screwed on how much you have to learn too. You won't have time for any other sections on TI. No time for 'how does this colour rim look?' or 'my seat has popcorn kernels stuck in it and my arse itches' bullsh*t posts anymore. You'll find the TI FI forum is too slow and you'll monitor many other FI forums everyday while reading books and examining other people's setups.
If you wanna get boosted and you're not wealty, you're gonna think about nothing else or you'll never get it done.
 

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how do you convert cfm to lb again?

how come some say the 14b (~.42 a/r) is a great size for the ls but on a gsr it may die out at 8k, but then everyone recommends 60's for gsrs? from 40's to 60's seem like a big jump. i have both a 14b and .63 t3 for my stock ls and want to run 8-10psi and shoot for 250-300whp max before building the block up.
 

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How To Read Compressor Maps ;)

First you have to find out the size of your engine. As stated, the B18C1 is 1797cc's

But we want it in Cubic Inches, to find that out you multiply the CC by 0.0610237441

So the B18C1 engine is 1797cc
which is 109.6ci

Now we have to figure out how much the engine flows at redline

109.6 x 8000 (redline) / 3456 = 253.7 cfm

So at redline, assuming 100% volumetric effeciency the engine flows 253.7cfm. However what engine has 100% volumetric effeciency?

The B18C1 has about 90% VE, so lets figure that out

now w/ volumetric effeciencey
253.7 * .9 = 228.33 cfm @ 90% VE @ 8000rpm

Now we have to find out what that is in lbs of airflow

(CFM * .069 = lbs. of airflow at that rpm)
228.33 * .069 = 15.75 lbs. of airflow at 8000rpm.

now to find out how much airflow there is on a B18C1 with 8-10psi of boost at 8000rpm

(R x D x 0.5 x V x B) / 1728
R = max RPM
D = displacement in CI
V = Natural volumetric efficiency of the motor
B = absolute atmosphere pressure + boost

In order to find B, we have to use the follow equation
((boost in psi + lbs of airflow @ redline) / lbs of airflow @ redline)


8 psi = 8 + 15.75 = 23.75 / 15.75 = 1.50 pressure ratio

(8,000 x 109.6 x .5 x .9 x 1.5) / 1728 = 342.5cfm @ 8000rpm @ 8psi of boost

Now to convert that into lbs per min

342.5 / 14.285 = 23.9lbs/per min @ 8psi

Now on the compressor map, we use

X 23.9 (lbs/per min)
Y = 1.5 (pressure ratio)

Now on 8psi for this compressor map you are in the 65% range.

Now lets try this for 10psi

10 psi = 10 + 15.75 = 25.75 / 15.75 = 1.63 pressure ratio

(8,000 x 109.6 x .5 x .9 x 1.63) / 1728 = 372.18cfm @ 8000rpm @ 10psi of boost

Now to convert that into lbs per min

372.18 / 14.285 = 26.05lbs/per min @ 8psi

Now on the compressor map, we use

X 26.05 (lbs/per min)
Y = 1.63 (pressure ratio)

And that puts you way out of the islands. As you can see, this turbo is pretty small for a GSR engine, even running low boost.
 
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