Ok i have decided to go a head and turbo my 84 z28. I need to know if a garrett t3 turbo would push anuff boost to a 305.Or if i should get a bigger turbo like a t88.Any info on what size i would need would be helpfull. thanks

 

Maybe if you use 2 of them. I will put it this way. My 2.3 liter thunderbird could benifit from a bit more than a t3 garett. Right now, I have a tiny t3 IHI turbo on it. Is there something specific you were looking at getting the garett from? I know some guys have done twin setups with thunderbird turbos and such.

Ben

 

My TT Iroc uses two T3s from late 80's volvos. They have .42A/R on the compressor housing, and .48A/R on the exhaust side. A/R is a term used to size turbo turbine housings, and can help in sizing them (larger A/R equals more flow potential for a given size turbo). My turbos are a little small for a 350 but should work decent for a mild 305.

A single T3 turbo will be too small for your 305. We will need more than just T3, T4, etc to help you size a turbo. Those terms just basically give the basic 'frame' size of the turbo.

 

Ok but the t3s do come in more sizes than one i think they go up to a 60 0r 70 size turbo .Not shure though i think i need a turbo that is about 60 or above for a single setup.I want about 10 psi of boost and i dont want to work the turbo two hard to get it.

 

Any T3 is too small for your 305, even the .60 A/R T3s found on some T-Birds (and from aftermarket sources) would be too small for a single application.

Do you have more specs for your turbo in question?

 

you need to use this formula to detirmine the amount of air (in cfm) you will need. then look for a turbo that will easily support that amount of air movement at the psi level you want.

(CIDxRPM)/3456=CFM

CID- cubich inches (in this case 305 obviously)
RPM<- obviously the rpm you want to see peak boost at

then just find your turbo.

 

Ok thanks for the info I will look up a turbo or maby two. That will push my little 305 with ease.And maby blow a head gasket

 

I thought it was where you want your redline at not where your boost will peak.

please help me and clarify

Jason

 

I would use that formula w/ your peak power, or redline. Depending on the turbo you use, peak boost could start real low, but you will continue to make peak boost clear throughout your powerband.

Ben

 

The turbine is the main influence on where (in the power band) boost comes in. When sizing the compressor, you need to plot more than one point. Plot several points, starting at the lowest point you plan to be running full boost up to the point you plan to shift. The compressor efficiency should complement the engine's torque curve. Once you have a compressor that works efficiently through the desired power band, then you choose a turbine wheel and housing to get the desired response without being too restrictive up top.

 

Thanks for the info...one more question about compressor maps. Where do you want your plotted points to fall into(60-75%)? To be more specific is it better to have your points more towards the right of the complete circle or over towards the left by the surge line. Knowing that surge is not good and should never be crossed but is it ok to be to the left of the complete circle?

Jason

 

it is better to be on the right side, you dont want to be in the surge line at all.