A/R opinions needed
03-01-2003, 08:27 PM
#1
0.0 BAR
Thread Starter
Join Date: Feb 2003
Posts: 0
A/R opinions needed
B16a with Forged Rods,9 somethin' compression pistons,and an AEM ems. Looking for 300hp with mid to high boost response from a T3 with about 13psi. Currently have 36 turbine and 48 compressor a/r....and having second thoughts about maybe going with a different a/r. (Mostly street, but definately for track as well.) I don't want to put this thing together and find out top end power levels off. I need experienced advice. Any will do. thanks
03-03-2003, 12:00 AM
#4
Administrator
Join Date: Dec 2002
Posts: 13,991
Re:A/R opinions needed
awww. you didnt like that?
You want me to tell you why? because we have done several turbo setups, and a .48 a/r on a STOCK B16a blows ***, the top end will fall short quickly. The high reving B16a makes most of its power on the top end, and the turbo will not be able to keep up with it.
I am running a hybrid T3/T4 .48ar (exh) .54ar (comp) on my stock LS/Vtec and it isnt the greatest top end.
You Will have problems with that turbo, yes the car will make more torque than it would without a turbo. But who likes to shift at 6 grand?
You want me to tell you why? because we have done several turbo setups, and a .48 a/r on a STOCK B16a blows ***, the top end will fall short quickly. The high reving B16a makes most of its power on the top end, and the turbo will not be able to keep up with it.
I am running a hybrid T3/T4 .48ar (exh) .54ar (comp) on my stock LS/Vtec and it isnt the greatest top end.
You Will have problems with that turbo, yes the car will make more torque than it would without a turbo. But who likes to shift at 6 grand?
03-03-2003, 12:25 AM
#5
3.0 BAR
Join Date: Dec 2002
Posts: 3,396
Re:A/R opinions needed
also buddy. heres an explanation on A/r
to easily grasp the idea of an A/R radio imagine the turbine housing as nothing more then a cone wrapped around a shaft to look like a snail. unwrap this cone and cut off the small end a short distance from the tip. the hole in the end of the cone is the discharge area. the area of this hole is the A or the A/R radio. the size of the hole is significatn, as it determines the velocity at which exhaust gases exit the turbine scroll and enter the turbine blades. for thus, the area of the exist is important in controlling the velocity of the gases and the actual speed of the turbine. it is necesaay to keep in mind that the area of this exist is the controlling factor in the bas side effect os exhaust back pressure and thus reversion into the combustion chamber.
it is further value to not that a larger R will effectivley give the turbine shaft greater torque with wich to drive the compressor whee. the same force applies with a greater lever arm (R) puts more torque into the shaft. this, on occasion, can allow a bigger compressor wheel if confitions so require. in practice, however, it is almost always the A that is changed, while the radius remains constant.
selecting what appreas to be a logical starting point for a A/R ratio is one thing but actualy getting the right one is yet another. trial and error is usually necessary. a resonable choice can be judged by the numbers, or to some extent by peformance and reponse. judging by the numbers requires measurement of exhaust manifold pressure, or turbine inlet pressure and comparison with boost pressure.
so basically a/r is the size of slot there is where the exhaust hits the exhaust fins. if this gap is big. the A/R will be large and the turbo will spool up slower. if the a/r is small the slot is small and high velocity is produced inturn creating fast spool. i hope that helps..
*cough* sticky. i am gonna draw up some diagrams.
to easily grasp the idea of an A/R radio imagine the turbine housing as nothing more then a cone wrapped around a shaft to look like a snail. unwrap this cone and cut off the small end a short distance from the tip. the hole in the end of the cone is the discharge area. the area of this hole is the A or the A/R radio. the size of the hole is significatn, as it determines the velocity at which exhaust gases exit the turbine scroll and enter the turbine blades. for thus, the area of the exist is important in controlling the velocity of the gases and the actual speed of the turbine. it is necesaay to keep in mind that the area of this exist is the controlling factor in the bas side effect os exhaust back pressure and thus reversion into the combustion chamber.
it is further value to not that a larger R will effectivley give the turbine shaft greater torque with wich to drive the compressor whee. the same force applies with a greater lever arm (R) puts more torque into the shaft. this, on occasion, can allow a bigger compressor wheel if confitions so require. in practice, however, it is almost always the A that is changed, while the radius remains constant.
selecting what appreas to be a logical starting point for a A/R ratio is one thing but actualy getting the right one is yet another. trial and error is usually necessary. a resonable choice can be judged by the numbers, or to some extent by peformance and reponse. judging by the numbers requires measurement of exhaust manifold pressure, or turbine inlet pressure and comparison with boost pressure.
so basically a/r is the size of slot there is where the exhaust hits the exhaust fins. if this gap is big. the A/R will be large and the turbo will spool up slower. if the a/r is small the slot is small and high velocity is produced inturn creating fast spool. i hope that helps..
*cough* sticky. i am gonna draw up some diagrams.
03-03-2003, 08:13 AM
#8
1.5 BAR
Join Date: Feb 2003
Posts: 828
Re:A/R opinions needed
I think the turbo you are looking for is the 83-86 T bird unit from a automatic car. This is a Garrett T3 with a .60 A/R compressor and a .48 A/R turbine. The manual trans cars had a .63 A/R turbine. This is my favorite turbo for street use as it makes great high RPM boost with very little lag. If you want a water and oil cooled center section, get the 85-86 turbo, 83-84 cars were oil cooled only.
03-03-2003, 11:01 PM
#9
0.0 BAR
Thread Starter
Join Date: Feb 2003
Posts: 0
Re:A/R opinions needed
Thanks for the help guys. So I will need a larger compressor a/r. If I go with a larger compressor a/r I should be able to build good top end boost. One more question:
When going with the larger compressor, can I keep the 36 turbine a/r? will keeping this produce less lag than going with a larger one, or will I "over rev" the turbo's shaft?
Thanks.
When going with the larger compressor, can I keep the 36 turbine a/r? will keeping this produce less lag than going with a larger one, or will I "over rev" the turbo's shaft?
Thanks.
