I am currently building a twin turbo 383ci for my 87 and am completly stumped as to what size turbos I should run and have been steered all over the place and I'm wondering if you guys could provide me any insight?!

The Engine is a 383ci with a 4 bold block, Milodan main caps, Lunati forged Crank, H-Beam rods, Forged pistons with 8.4:1 compression, Edelbrock victor JR. heads with mild porting, ICS Titan copper head gaskets, ARP studs throughout Wilson CNC ported victor jr intake with billet elbow and Wilson 90mm throttle body, Wilson High flow fuel rails with 90lbs/hr injectors and a fast xfi controlling it all. The cam is a solid roller with 236* intake and 242* exhuast and 580" and 600" lift ground on a 115 LSA. I think I will use 42mm Tial Wastegates and the headers are 1 3/4" custom Stainless.

I've built many motors but this is my first turbo build. From the research I've done I have been led to the Garret GT42's. Attached is a link giving the specs:

http://www.turbobygarrett.com/turbob...4_731376_1.htm

I will be running about 16psi of boost on the street with pump gas and water meth, and 22psi on the track. Let me know your recomendations and maybe some HP predictions. I will post some pics of the progress as we start getting the headers built but we can't do that untill we have the turbos so I can figure out where to put them.

 

Do I have to say anything else!

 

sorry i have no insight for you on this subject besides get big ones, that's gonna be bad *** man nice job!

 

those turbo's will make big power, 1 gt42will work just fine

 

I would prefer to have a twin turbo setup over the single as you can get away with two smaller turbos that spool quicker and still have the airflow to make big power numbers. A single setup can move a ton of air but you typically have to run a larger turbo which doesn't spool as quick. I'm not totally sure if this is true, this is just based on some of the researching I've been doing. Do you think two GT42's would be to big? Do you have any recomendations? I just don't want it to be a dog on the street when your not always in the upper rpm's like at the track, but my goal is 800rwhp! I know this is a lofty one but from some of the turbo builds I've seen I know it's possible!

On a side note I am going to start posting pics and descriptions of how we are building the headers in the next couple of weeks, if anybody is interested in the process we are taking to insure they are high quality and fit perfect?!

 

The small block sounds nice. You should have No problem seeing 800ish
A single or twin can spool on the street fine. It helps if the tune is spot on.

but if you want twins those GTs are nice.
smaller ones would get ya to your goal too

http://www.theturboforums.com/smf/in...?topic=61219.0

 

Just to let ya know, I'm in the middle of a very similar project, and if you are set on running twins, I would recommend something like twin 62-1's, or even 60-1s. They typically have a smaller turbine a/r, like .63 or so, which will help with your spool time. Either one of these could support 1000-1200rwhp on a 383 if you wanted to boost it that far.

Another turbo to look at with a twin setup on a 383 is the T61. Another great, quick spooling turbo that'll support alot of power.

Here is a great site that you can play with and it'll really help you figure out what turbo would work best for your goals

http://www.squirrelpf.com/turbocalc/index.php

Good luck! Hope you have a tranny and rear end figured out that'll live behind it!

 

t62-1's would be a perfect choice and they are a little cheaper and will make 1000 hp easily

 

That is a great calculator wp4! I think I found that twin GT40's would work best according to there efficiency map. We started drawing up the header flanges today in CAD. We first taking a tracing of the Header gasket and then scan it into Cad where we then straighten out some of the lines and take it down to the local CNC shop where they cut it out for us. It only costs me $40! The headers in total should cost me about $200 in materials. I got a wicked deal on the stainless!

As far as the tranny goes I'm using a t56 just to see how long it takes to blow up then will maybe go to a Richmond 6-speed. The rearend is a Strange 9" with 3:55 gears.

Back to the turbo effeciancy maps, I know that you should aim for the smack dap in the middle on the map for the RPM range your looking for but how exactly do your read those things? What are the numbers along the outerside of the rings? Sorry, I know that sounds like a dumb question, it's just my first attempt at a turbo engine!

 

you could get away with twin MP t-70's. They will make plenty of power and are a hell of a lot cheaper than the gt42's. You could also go with a PT-88 single and make just as much power...ask me how i know