kylemm1002

iTrader: (6)

This is my first FI build so I'll be taking slow. The plan originally was to swap a heads/cam ls1 6speed into my 95z. But I recently got into a 4.8 for a great deal and always wanted a turbo car.

This is defenetly a budget build and will probably take place over winter. But I'm collecting as many parts as I can to minimize down time.

Motor is 70k miles 100% complete 4.8. Plan is to single turbo front mount. Stand the radiator up for clearance. Going to use the popular griffin radiator.

I don't really want to get in the engine if I don't have to. Going to keep power steering and the alt as only assc. Going to run an ls6 intake.

Here is my problem. I want to swap a 6 speed in the car but im not sure about a boosted car and manual Trans. Its going to be a street car that sees the track a few times a year. Goal is about 500 hp. What turbo would you recommend? I want something that's fun to drive and a keep in my the budget. I don't mind upgrading if I get the bug to go faster.

Was looking at all the eBay gt45 and on3 stuff but not sure what's a good quality charger for the price. And being I'm going with a 6 speed im not sure what size is best.

LS1NOVA

iTrader: (12)

Id spend a little more and get a Precision 76 with the .81ar. You can find those for around $800-1000 used on Supra forums or Ebay. Then if you if want more power or change over to a 5.3/6.0 later, you can swap out the exhaust housing for the .96. An ON3 76 or Turbonetics TC 76 or 78 would get you in the ballgame but wouldnt support as much down the road.

foose04

iTrader: (4)

I used to have a MP70, P-Trim with a .81 open t4 with a 5 speed. Truck was a blast to drive on the street, but my 5 speed just couldn't pop the gears like I wanted. I later went 4l80 and to a 76mm. However with the stick, the 70mm is perfect.

Here's the old vid and dyno graph, don't mind the 67mm part, it was actually a MP70 unit.

Video:
Dyno Graph: Truck had ls6 cam/valve springs, everything else stock.

kylemm1002

iTrader: (6)

Ok cool. Just trying to get an idea of what's the best thing. I really want to go with a 6speed just because it's a street toy and not a track car. But I might change my mind and go 4l80e if I can find one at a decent price. I'm just concerned with keeping boost up with a 6speed.

kylemm1002

iTrader: (6)

I was thinking the on3 76 would be good if I stated auto but not sure about it with a 6speed?

denmah

iTrader: (2)

300 dollar gt 45 will easily **** out 500 range on a manual trans even on a 4.8l

i like to use stock camshafts like the ls6 or LS9 cam.

get pack 1218 springs for 140 they use all stock hardware and work great for 20lbs

kylemm1002

iTrader: (6)

Ya was thinking ls6 cam. I'll look in to this sprigs to! Thanks!
Do you think that gt45 would be restrictive up top?

b20forlife

iTrader: (4)

Im also interested in this. How would a t76 do in a 6 speed? I have a 5.3 but would like to know if its to big or laggy for a manual trans? Sorry not trying to thread jak

denmah

iTrader: (2)

nope i peak power at like 6500rpm and me and my friends 4.8 truck both made over 600whp on that gt45

stock truck intake usually runs out of breath around 6000 it makes peak hp

car intake on the same motor and cam makes power to 6600 about...

the ls6 cam is great, but if you can spring for the money for the cam cover and relocate the cam pickup for like 250 all said and done its well worth it to upgrade to the ls9 cam in my opinion...

the gt45 i use is a divided 1.05 AR, as far as i know they only come in one size

kylemm1002

iTrader: (6)

Hell I might just throw it together with my auto Trans and see what happens. I'd just really hate to spend the time and money swapping to a t56 only to wish it was still an auto...
If I kept the auto I'd probably do a 3200-3400 stall and the on3 76mm...thoughts on that? Or just stick with the eBay gt45 and see what happens?

kylemm1002

iTrader: (6)

ok guys need some advice on this build. Im not 100% sold on this swap just yet.
As said the goal is 450ish-500. Right now my car is a decent bolt on ltx auto. Im wondering if you guys think is worth the extra $$$ down time to swap over to the 4.8 turbo versus building a decent ltx 355/383?

Im just looking for a nice street car that will get down the track a few times a year.
I already have the 4.8 and a ls1 k member so I just need harness ($800 after having it modified), fuel system and standing the radatior up. I plan on fabbing up the hot side and cold side myself so that will help save some money.

Its just hard when I could build the lt1 for less $$ but might fall short of my goal...always could spray it! But then also Ill still have the opti that could cause problems?

Right now budget is the problem. I could probably sell the 4.8 and have enough to get a start on heads/cam for my current lt1...I just cant find anyone local that will tune my obd1 lt.

Thoughts?

Wicked69

Dude, boost that 4.8, keep the auto and don't think twice. My $500 junk yard 5.3 ran for 7 months and 23lbs of boost before I blew it up. I just wanted to test the limits. It ran low 6's at a 118mph in the 1/8 in my daily driver chevelle. Car weighs nearly 4,000 lbs, got 15,000 miles, and over 20 mpg and I did almost all of it myself and most the tuning was done by me. For your goals you probably don't need but 10lbs of boost and should last for a while. I woudn't hesitate to get the On3 or GT turbo off ebay. Especially since you will run less than 20lbs of boost.

Adam123

iTrader: (1)

^^ Keep the auto it will keep your rear alive too!

Sarg

iTrader: (6)

You can get a harness from Psi conversions for $500 that should work just fine on your car. I would sell the Lt, use the auto on boost that little 4.8. You can throw in valve springs and hit 500 hp with no other mods to the motor.

kylemm1002

iTrader: (6)

The harness from psi is a stand alone so my factory gauges wont work correct?

Sarg

iTrader: (6)

It still had tach and speedo outputs I believe. If not it would be easy enough to wire them.