2BAD4U

iTrader: (1)

.68,.81,.96? What do you think? Im thinking .81

Chevy406

iTrader: (12)

You can't expect to get a difinitive answer without giving details on your power goals, street vs track use, vehicle weight, rpm range, etc.

I have a 408 in my '69 Nova with twin GTK-650 turbos and .68 A/R housings. Last year it put down 909 rwhp and ran 5.70s in the 1/8 mile with those .68 housings. I think at that level it could make a little more power with bigger exhaust housings. Maybe that gives you some insight as you plan your build...

2BAD4U

iTrader: (1)

Power goal isn't in mind... efficiency with being a 5.3 is... hp is just a number to as is boost. Or weight for that matter. But to be technical race weight will be between 3,295.12 to 3,296.10 depending on weather or not I drink that monster before I buckle up. But im more or less curious to what cubic inch to AR sizes people are using. As after this junk 5.3 pops ill be building a 427 lsx to throw in...

LS1NOVA

iTrader: (12)

.68 if you really care about spool, .81 if you care more about max power, or .96 if you're going to use nitrous to get er movin'.

denmah

iTrader: (2)

as far as i understand the turbine size is way more important than the .AR when choosing a turbo

vettewreck

iTrader: (1)

Im doing twin 61mm
.96 AR Turbine
.70 AR Compressor

98Camarod

iTrader: (43)

to help you out, if you're ordering turbonetics 6665's the .68 housing is on backorder. That's why I got mine with the .81 housings. Otherwise I would have got the .68's.

pwrtrip75

iTrader: (8)

How can this question be answered without knowing what size turbo?
If you are using tiny turbos use a bigger a/r and if you are using bigger turbos use a smaller a/r.

chevellepowered

iTrader: (37)

yes i agree , the turbine size is whats more important than a/r , fast spool , id stay in the 5x mm size 54mm etc , more up top power go with low 6x mm, 62mm etc i personally wouldnt go with any turbine bigger than 64mm , im doin a ly6 , 6.0 l92 heads , i plan on around 58-62mm turbine , .68 a/r, with compressor of around same size of turbine .. my ideal turbo for my setup would be 58mm turbine .68 a/r , 60mm compressor ..

also depends on stall converter , weight ,,etc , and what your plans on,, i never like going over 2600 stall,, i like to drive my vehicles .. , so i need some fast spool, and still have up top power ,,

oscs

iTrader: (19)

I'm going with two 61mm turbos with .68 A/R

sbcgenII

iTrader: (1)

tonypaul

iTrader: (2)

I have learned anything on this forum its the "combination" of everything.... Your turbo size should be about what your converter, gears, tires, cam, ect, work with....

krwyellowZ28

iTrader: (10)

Surprisingly helpful answers for a pretty vague starting post. I'm taking notes for my own build and this offers some good examples.