Correct Turbo Size?
09-22-2014, 07:38 PM
#1
Correct Turbo Size? Hey guys question. I have a 383ci LT1 with 10:5 CR and Ported TFS Heads, 226/226 custom cam 114LSA. My turbo is a Turbonetics 7875 with currently a .96 A/R but have recently ordered 1.15 A/R. Do you guys think that my turbo is to small for my ci and CR setup? I've been told by a couple people that the 78MM might too small. Thanks a lot!
09-22-2014, 09:50 PM
#2
That all depends on how much power your looking to make. I'm running the same size turbo, but the On3 version on a 347 and I'm told 700whp is likely around my max. If you can swing it, get a S480, there all the rage these days. I would but my hot side won't fit one.
09-22-2014, 10:02 PM
#4
Hey guys question. I have a 383ci LT1 with 10:5 CR and Ported TFS Heads, 226/226 custom cam 114LSA. My turbo is a Turbonetics 7875 with currently a .96 A/R but have recently ordered 1.15 A/R. Do you guys think that my turbo is to small for my ci and CR setup? I've been told by a couple people that the 78MM might too small. Thanks a lot!
With your cubes, I'd guess you'll max out that exh wheel/housing well before the comp. wheel. You'll also run into back pressure issues with that cam/turbo combo. Id be looking into S476/S480 with the big 96mm exh wheel and a larger AR housing.
09-23-2014, 08:49 AM
#6
Not saying it won’t “work”. But the title reads “Correct turbo size”. I’ll try and find the article. If I recall correctly a 1.10 T4 has a slightly larger than 1” diameter exit on each side of the scroll just before the turbine wheel. So roughly a 2” (ish) diameter restriction at the end of the pipes on a 6.3 liter engine doesn’t sound “correct” to me. Exhaust velocity would get up to the choking point quick and exh. back pressure would be less than ideal IMO.
09-23-2014, 08:56 AM
#7
How much power do you want and how soon do you want it? What kind of power are you making NA?
With your cubes, I'd guess you'll max out that exh wheel/housing well before the comp. wheel. You'll also run into back pressure issues with that cam/turbo combo. Id be looking into S476/S480 with the big 96mm exh wheel and a larger AR housing.
With your cubes, I'd guess you'll max out that exh wheel/housing well before the comp. wheel. You'll also run into back pressure issues with that cam/turbo combo. Id be looking into S476/S480 with the big 96mm exh wheel and a larger AR housing.
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09-23-2014, 09:18 AM
#9
The 78mm compressor wheel is plenty big for 700 or more HP but the tiny *** turbine and T4 is gonna kill you. Guys are makin 1100 or more on a 76mm and hoin 5.0's.
yours Might make insta boost but will choke out hard.
Is it 6 speed or auto? You should be using somthing in the S400 mid frame size with a minimum of a 83mm exh wheel up to a 96mm. like a S475 or somthing simmilar .
A 1.10 to 1.32 AR on that size wheel will make some serious power. Id sell it and hunt for a used BW. I see em all the time for cheap.
yours Might make insta boost but will choke out hard.
Is it 6 speed or auto? You should be using somthing in the S400 mid frame size with a minimum of a 83mm exh wheel up to a 96mm. like a S475 or somthing simmilar .
A 1.10 to 1.32 AR on that size wheel will make some serious power. Id sell it and hunt for a used BW. I see em all the time for cheap.
09-23-2014, 09:34 AM
#11
The 78mm compressor wheel is plenty big for 700 or more HP but the tiny *** turbine and T4 is gonna kill you. Guys are makin 1100 or more on a 76mm and hoin 5.0's.
yours Might make insta boost but will choke out hard.
Is it 6 speed or auto? You should be using somthing in the S400 mid frame size with a minimum of a 83mm exh wheel up to a 96mm. like a S475 or somthing simmilar .
A 1.10 to 1.32 AR on that size wheel will make some serious power. Id sell it and hunt for a used BW. I see em all the time for cheap.
yours Might make insta boost but will choke out hard.
Is it 6 speed or auto? You should be using somthing in the S400 mid frame size with a minimum of a 83mm exh wheel up to a 96mm. like a S475 or somthing simmilar .
A 1.10 to 1.32 AR on that size wheel will make some serious power. Id sell it and hunt for a used BW. I see em all the time for cheap.
09-23-2014, 11:12 AM
#13
And don't forgot, a good ported LT1 head prob flows less than a factory cast LSX stuff.
09-23-2014, 11:33 AM
#14
if you set the car up to run the smaller turbo you can still run good. the cam might be little much for higher back pressure but id get the tune good and go make a few runs with it. there is no reason you cant get low 10s with your turbo.
my nova is 3600# with me in the seat has a tc78 78/68 mm wheels on it a 206/212 cam in a 6.0 truck engine a 3000 stall and 3.23 gear on 28 by 10 tires and runs 10.50s at 10# boost and 11* timing on pumpgas with full exaust. shifting around 5500 rpm. with a better 60' and about 2 more lbs boost i think it will go 10.0s. if you use the power and not slip past it or try to rpm to high you can go fast with that turbo.
my nova is 3600# with me in the seat has a tc78 78/68 mm wheels on it a 206/212 cam in a 6.0 truck engine a 3000 stall and 3.23 gear on 28 by 10 tires and runs 10.50s at 10# boost and 11* timing on pumpgas with full exaust. shifting around 5500 rpm. with a better 60' and about 2 more lbs boost i think it will go 10.0s. if you use the power and not slip past it or try to rpm to high you can go fast with that turbo.
09-23-2014, 01:16 PM
#15
Again, I have no data to show my BP or drive pressure, but, a smaller turbo than yours pushed my 3600lb car to 140 traps at 10psi. Transient response on the street is nice, but, I know if I went to a larger turbo obviously I could make more power. Its all a tradeoff. Its not the optimal turbo but IMO that is based on how you want the car to drive.. racecar, dynoqueen, street car etc..
And don't forgot, a good ported LT1 head prob flows less than a factory cast LSX stuff.
And don't forgot, a good ported LT1 head prob flows less than a factory cast LSX stuff.
.
09-23-2014, 01:26 PM
#17
if you set the car up to run the smaller turbo you can still run good. the cam might be little much for higher back pressure but id get the tune good and go make a few runs with it. there is no reason you cant get low 10s with your turbo.
my nova is 3600# with me in the seat has a tc78 78/68 mm wheels on it a 206/212 cam in a 6.0 truck engine a 3000 stall and 3.23 gear on 28 by 10 tires and runs 10.50s at 10# boost and 11* timing on pumpgas with full exaust. shifting around 5500 rpm. with a better 60' and about 2 more lbs boost i think it will go 10.0s. if you use the power and not slip past it or try to rpm to high you can go fast with that turbo.
my nova is 3600# with me in the seat has a tc78 78/68 mm wheels on it a 206/212 cam in a 6.0 truck engine a 3000 stall and 3.23 gear on 28 by 10 tires and runs 10.50s at 10# boost and 11* timing on pumpgas with full exaust. shifting around 5500 rpm. with a better 60' and about 2 more lbs boost i think it will go 10.0s. if you use the power and not slip past it or try to rpm to high you can go fast with that turbo.