F-Body Europe
http://forum.fbodyeurope.org/phpBB3/

Trying to choose turbo
http://forum.fbodyeurope.org/phpBB3/viewtopic.php?f=11&t=7748		 Page 1 of 1
Author:  Roy [ Sat Oct 27, 2007 7:08 pm ]
Post subject:  Trying to choose turbo
I am a little befuddled when it comes to this.
I have been looking at thisoneGarrett GT 2860RS
JeeJee , How do I read that Compressor map?
Author:  bahndrvr [ Sat Oct 27, 2007 10:00 pm ]
Post subject:  Hmm
Knew I liked you Roy, Disco Potato, that' what I was looking to run on my TT, would have given me around 450 with decent low end spools rather quickly. Look in the VW/Audi circles if you want a better price on it. I've seen them go alot f around 760 bucks, most I've seen paid was around 1700 though so you have to shop around Roy.

FYI, the T28's come on the Silva's over here, you could get one out the yard, and change the "Hot side, and build one for pretty cheap, but your probably better off going that route.
Author:  jeejee [ Mon Oct 29, 2007 11:12 pm ]
Post subject: 
Hey Roy,

this one looks a little on the small side but not too bad..

crash course for reading map :

a pressure ratio of 2 (on the left axis) means 1 bar (14.7psi) boost
1= atmospheric so 2.5 is 1,5 bar boost


corrected aitflow on the other axis in lb/min is about the same in horsepower so 30 lb/min is about +/- 300HP

the next thing you need to know is what horsepower your car makes at what boost pressure....
a typical standard 4x4 cossie makes 220HP at 0.65bar boost.
thats means without boost the engine would make aprox 130-135HP
(engine output doubles with 1 bar boost / 14.7psi)

That means that a cossie with a proper setup system at 1,5bar boost (pressure ratio =2,5) would make about 135HP x2,5 = 337HP

that is right on the edge of the map (2,5 on the left axis and 340lb/min on the other axis) the one you picked is not really capable supporting that kind of airflow and boost...
best would be to find a map where a pressure ratio of 2.5 (assuming that 1.5bar would be the max boost you want to run) with about 330lb/min would be in the area where the efficiency would be highest..

Image

this one is better suited for your purpose i think.

if you use the 2.5 ratio and 330lb/min you see you end up at aprox 76% efficiency and there is still some room left for more boost / airflow as opposed to the otherone that is maxed out..

running higher boost with the prober turbo should still keep you in the highest efficiency zone, BUT increasing the base (NA) horsepower with a head flow and cams etc etc, would need a different turbo
because with the same pressure ratio on the left axis you would need more airflow

i hoped this helps ?
Author:  Roy [ Tue Oct 30, 2007 2:57 pm ]
Post subject: 
Man that helped like a mud pie in the eye.
Let me go out an select another .
Author:  bahndrvr [ Tue Oct 30, 2007 4:17 pm ]
Post subject:  Alright Roy
Your making me break out old links now. I forget your car is alot more efficent than my old 20v Audi was, the Big boys were running 570hp on built cars with the GT30's, but spool time was an issue, don't know much about cossie's so not sure if that's a concern for you.

Here's ATP, like I said before, it can be exspensive, I just looked at these guys for ideas and then went from there to shop for particular part number etc...

http://www.atpturbo.com/Merchant2/merch ... y_Code=TBO

Also what trim are you considering, meaning .63 is a faster spool but stands to loose a little up top, and .7X is more mid and good top, then the .8X's are crazy up to 8000 rpm's and more. Just curious?
Author:  Roy [ Tue Oct 30, 2007 7:53 pm ]
Post subject: 
OKay
Here goes , with this one I want between 1.5 to 2 bar max. I believe this shouldnt have compressor surge or choke problems. Just concerned it might have some lag problems. I calculated max rpms for 6200 with an air flow of 40 lbs per min.
Image
Author:  jeejee [ Tue Oct 30, 2007 8:44 pm ]
Post subject: 
looking at the map you should be spot on with that boostpressures and airflow for a cossie :D very nice turbo ....

not cheap propably but one of the better turbo's for that engine i think
Author:  Roy [ Tue Oct 30, 2007 8:53 pm ]
Post subject: 
I am in the market search for one .
Author:  bahndrvr [ Wed Oct 31, 2007 1:16 pm ]
Post subject:  Sweet
Glad I could help, are you sure you're going to be happy with that .53 trim?

Not to ask a dickhead questions but have you had a good running car when you got into boost? The 30 is capable of ALOT of power, but that trim is kinda small, looks to work out perfect for what you want, but boost power is the most addictive type of power I've come across, and that turbo is pretty big so it's gong to sound good as "He said POOP" when you get above about 6 psi, just saying, you may want a little more up top, and on the Autocross, you'll be in the 3500 - 6500 rpm range right in the sweet spot of the boost:)

Mmm, sounds like so much fun.

And Roy, not trying to push buttons, just giving some constructive critisim, and I'll look and see if I still have link to better prices. Also, what flange design are you so I can give you more options?

4 bolt dual inlet, or the 5 bolt "wierd" inlet, 4 bolt one opening and what exhaust manifold/header are you running, can make a HUGE difference on spool time and boost cleanliness you know.

If your running stock, be sure to take the time to grind the insides down to as flat as you can, get rid of all the spare stuff, seems like your taking your time on this one, wouldn't mind seeing it soon actually:)

Trevor
Author:  jinstall [ Fri Nov 09, 2007 2:21 am ]
Post subject: 
Roy I am in the US(Alabama near Barber MSP) till the 17th. I can bring it on the plane with me.
Author:  jeejee [ Fri Nov 09, 2007 9:54 am ]
Post subject: 
well it doesn't get any better then that :P

Hey James , can you stuff an ls2 engine in you handluggage for me too ? :P
Author:  Garry [ Fri Nov 09, 2007 10:19 am ]
Post subject: 
Why not go LS7 right away? Not much bigger or heavier ... :lol:
Author:  Lancer033 [ Fri Nov 09, 2007 6:51 pm ]
Post subject: 
jeejee wrote:
well it doesn't get any better then that :P

Hey James , can you stuff an ls2 engine in you handluggage for me too ? :P


Don't forget the LS3 is out now. 6,2L > 6,0L :wink:
Page 1 of 1 All times are UTC + 1 hour
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
http://www.phpbb.com/