elrandeeto

hey guys , i plan on starting to piece together a turbo system for my ls crx in a couple months . ive done alot of reading and im having trouble figuring out how the trim and ar affect how the turbo performs and if its top end or will spool up sooner .

what i want : to start i want to run with stock internals eventually upgrade ,
i would like to have around 225 to 250 whp , but not have to wait forever for it to spool up like around 5-6 k rpm , i would like it to start to spool up around 3500 probably 4 tops . i think that's about what i would like i just don't want a real high power band and only have the short power band in high rpms .

i plan on using crower 402 t 's or 403's not sure yet please give advice .

this summer the car is driven daily just to work and back and around town probably 15 maybe 20 miles on some days , and will be stored for the winter , next summer i plan on driving it less not as a daily

i was given a evo 3 mitsu turbo but its in pretty bad shape , and i would rather have a new one even if it takes longer to get . So i was wondering what turbo and specs would fit what i want most . thanks in advance , oh and i have a ls trans for now

elrandeeto

anyone?
someone recomended gt28 r seemed a little big but what do i know that why im asking

wantboost

iTrader: (2)

a gt28r would spool really wuickly on your motor, if you can afford it, run the gt28rs, it will make your desired power and spool quickly, but still leave room if you wanted to up the boost later down the road

elrandeeto

great thanks for the info . with the gt28r , is what i want pretty much the limit for that . Is that why u said the rs or i would just be able to upgrade alot further with the rs , theres only about a 300 dollars difference between the two , oh and as long as im under 300 hp i should be ok on stock internals correct it would only be for probably about 1 summer . If you dont mind can i have a few other options possibly that will fit what im looking for and how the performance will differ from each other . thanks again

elrandeeto

i saw the trim and ar numbers were higher so i thought it might be to big then i saw it only flowed 31lbs/ min compared to other turbos with lower trim and ar but flowed more. I think im starting to catch on

wantboost

iTrader: (2)

thats not the limit of the gt28r, but its clost to it. the gt28rs would just give you more power later on down the orad if you decided to up the boost a little

elrandeeto

ok great , thanks. any other turbos you can think of , from what ive read ball bearing turbos are better right? and spool quicker . i shouldnt have a problem having the 1150 for the rs within 2-3 months , but you never know **** happens . Thats why i was asking about other turbos that would perform about the same my goal is to have it all and on the car by next summer

wantboost

iTrader: (2)

well, another turbo is a 50 trim t3/t04e. it will spool slower but will still support your power goals

a1320addict

iTrader: (1)

you have pm! gt28r for sale!

95GSRT

I have a gt3255e, I make full boost by about 3800-4000 rpm. I'm making 250 whp on 7.5psi. And there is lot's of room for more power on this turbo. And you wont have to spend the big buck on it. Highly recommended.

a1320addict

iTrader: (1)

hows the midrange?
im makin 246 at 8 pounds with a gt28r...and its almost like driving an na car

elrandeeto

bump keep the options coming please

evosol

I think the t3/t4e 50 trim would rip on a LS. Thats what i run on my z6 and i'm really loving it! The gt28rs would be great too but its too much $$ for me.

elrandeeto

i was just reading up on my more turbo info and i read that you should be in boost for more than 15 sec at a time on stock sleeves bc of the heat . Well will this cause a problem with a turbo that spools up so early bc youll be in boost alot more / longer

thanks

.joseph

bump for some mo' comments...lookin to turbo my gsr, and i im almost set the gt28rs...any know how much power it will support? Im lookin for 350-400 whp...I dunno if the gt28rs can handle it? Sorry didnt mean to thread jack...get the gt28rs...i think its worth it

95GSRT

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Josef83 &raquo;</TD></TR><TR><TD CLASS="quote">bump for some mo' comments...lookin to turbo my gsr, and i im almost set the gt28rs...any know how much power it will support? Im lookin for 350-400 whp...I dunno if the gt28rs can handle it? Sorry didnt mean to thread jack...get the gt28rs...i think its worth it </TD></TR></TABLE>

I think it's rated for ~450hp

.joseph

awesome, good info...seems like the gt28rs is the right turbo...quick spool time, great response, but costs a buttload !

elrandeeto

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by elrandeeto &raquo;</TD></TR><TR><TD CLASS="quote">i was just reading up on my more turbo info and i read that you shouldnt be in boost for more than 15 sec at a time on stock sleeves bc of the heat . Well will this cause a problem with a turbo that spools up so early bc youll be in boost alot more / longer

thanks</TD></TR></TABLE>


Modified by elrandeeto at 5:32 PM 7/15/2005

a1320addict

iTrader: (1)

its all in the tuning....
and the gt28rs can do like mid 300 numbers...with the .8x housing form atp..above 350 from waht ive seen it starts running out of breath

elrandeeto

bump anymore info ?? so it should be ok to boost for longer peroids of time with proper tuning and stock sleeves??

KeyserSoze

Wow, do you realize how fast you would be going if you boosted constantly for ~15secs???? Probably in the range of like 105-115. It would be like a quarter mile dig. You should determine what type of airflow you will be pushing out of your engine, the pressure ratio that you will have at the boost level you will be running and determine if these two values correlate to a high (60% or higher) efficiency value on the compressor map for the turbo(s) that you are considering (I am still new to this so dont take this as fact, but I have done a little research and can understand most of the math behind it due to my schooling). The a/r is also important the higher the a/r the more power the turbo will be capable of and the lower the a/r the better low speed response (lower boost threshold, often incorrectly called lag). Here are some simple equations that you can use to find the airflow through your engine:

Airflow (cfm) = [(cid) x (rpm) x (0.5) x (Ev)]/1728

cid = cubic inch displacement

rpm = redline rpm

0.5 = this is cause the cylinders only fire every other revolution in a four stroke engine

Ev = Volumetric efficiency (I dont really understand this completely, but for inline fours it is about 85% from what I have read)

1728 = converts in^3 to ft^3

This number is the airflow of your N/A engine. To determine the airflow of your turbocharged engine you just need to multiply it by the pressure ratio.

PR (pressure ratio) = [14.7psi + boost (what you are going to boost)]/14.7

As an example my car (gsr, with .020" bore) has 218.47 cfm. If I want to boost 12psi the pressure ratio is 1.82, so I multiply the two numbers and find out that I will flow 397.62 cfm. Convert that into Lb/min (I dont remember the conversion right now, but it can be found easy) and get 27.96 Lb/min, because most compressor maps use Lb/min for the flow.

To check where the turbo will be efficient for your engine (airflow) and PR
1) Then take the compressor map of the turbo that you are considering and trace out (in my case) a PR of 1.82 and Airflow of 397.62 cfm (or 27.96 Lb/min) and see what the efficiency is on the map.
2) Now halve the max airflow number and plot it with the 1.82 (still my PR) on the same compressor map.
3) Now plot another point at Pr = 1 and at 20% maximum airflow (in my case it turns out to be 5.59 Lb/min) and connect the dots.

Note: x-axis is the flow rate and y-axis is the PR

The line you plot should always remain to the right of the leftmost line, cause for all intents and purposes that is the surge point of the turbo (surge = BAD). You are plotting this to see if the turbo will be in its efficiency range (where the turbo produces close to the amount of heat that it theoretically should while compressing the air, this means that it is efficiently compressing the air) with the boost it is generating and the airflow given to it. And then you can tell if the turbo you are considering is effiecient for your airflow and desired PR.

Sorry 4 the novel, but I figured that it might be easier to understand if I was a little wordy. Like I said b-4 this is only from my limited xp with F/I theory. I learned a little somethin and thought it might help you out. Remember always do the math yourself to make sure you are getting what you want.

ps - A good book to read to better understand f/i setups is Corky Bell's "Maximum Boost." Even a dumbass like me can mostly understand the book. I didnt know **** about this stuff b-4 I read that and now I can try to help spread a little (in my case VERY little) knowledge.

elrandeeto

wow great post thanks for all the info

elrandeeto

oh and what i meant about boost for 15 or so seconds is that say your inboost at 2800 rpm its hard to drive around without the turbo spooling up if you have to stay below 2800 maybe i misunderstood something?

elrandeeto

bump

elrandeeto

bump , just seeing if there is anyone else out there that would like to add some info thanks