Picking the right turbo size?

[TwistedD85]

I'm just curious, picking up info for later when I can accually do all of this stuff. Could anyone maybe tell me just how i should pick my turbo size? Any variables, ect. Thanks for any help, I'm just trying to learn

 

[wicked93gs]

turbo sizing is based on CFM flow of the heads of the chosen engine, desired HP levels, etc, in general you'll need a single turbo pushing about 53lbs or twins pushing 26lbs (the bottom numbers on most compressor maps which have nothing to do with boost, thats the side numbers, pressure ratio) at the mininum level for around a 500hp goal at whatever pressure ratio you desire(IE atmospheric pressure) pressure ratio of 1 is eqaul to 1 bar or 14psi, 2 bar 28psi, etc, I calculated this optimal turbo size from information gleaned from maximum boost(a must have if your turbocharging)

 

[TwistedD85]

Hmm.. seems like something I'll either have to have more explaining on or have someone else on the forums help me with it Oh well, it'll be a while until I get it, I just wanted to be prepared so I could just go down my list I'll be making and just buy what I need as I go. Thanks for the help though, helped me understand the depth of choosing a turbo.

 

[luigisho]

There are turbo calculators out there to help choose the correct size for most any application and places like turbonetics will certainly help you select the proper size if you plan to purchase one from them.

 

[munkee]

Yeah, if your in the process of learning about it, definitely pick up a copy of Maximum Boost by Corky Bell. That will get you well on your way to understanding what it will take to design a complete system, not just choosing the size of the turbo.

 

[TwistedD85]

I'll look that up, thanks. I know how turbos work and all, I mean I think I can design a system (I -think- ), I just don't understand the limits, requirements and capacities of them. Though I'm sure I don't know squat besides they use exhaust turn one turbine to push air into the engine with another I gots me some learnin` ta do :corn:

 

[leahyz]

A/R Ratio

Anyone have an idea on how to select the right A/R ratio? I understand what it is, what a high and a low one will get you, but I have no idea on what is a best choice for a SHO motor. I was going to guess around .8-.9(exhaust). I have the understanding that it is difficult to estimate if possible, and most people just guess and check.

Also, I have read Corky's book, it is great. I also have a BSME and have taken turbo machinery classes, so I am reasonably well learned in this field... just a bit confused... Anyone with a turbo care to share what they are running, and what their thoughts are?


Z

 

[1slickRED89]

Anyone have an idea on how to select the right A/R ratio? I understand what it is, what a high and a low one will get you, but I have no idea on what is a best choice for a SHO motor. I was going to guess around .8-.9(exhaust). I have the understanding that it is difficult to estimate if possible, and most people just guess and check.

the lower the AR (.4 to .7) the faster one could expect the turbine to get up to speed, with the penalty of less total power. conversly a larger AR will make for longer times for spool up with the benifit of more total power (.8 to 1.4) if you have the book look at pages 10,11,25,31,32,33 and 34. the chart on 34 will expain everthing. if i was to buy a new turbo i would get a turbine AR something from .8 to 1.00 on a t4 frame, with a divided inlet to help things get up to speed.. Corey

 

[munkee]

Yeah, I believe it is basically trial and error. The turbo I have currently is a .81 a/r. Hopefully we'll know soon how well that works. I would think for the sho, something in the .6 range would be good but we'll see I guess. That might bring on the boost a little earlier than you need it too.

 

[SH0 N G0]

Im undecided on which a/r would would best for my turbo sho project. I dont want to goto low of an a/r and have it come in too soon and i dont want it to come in too late and be making full boost at 7k lol. Its between 3 for me; .68a/r with a t4 ******, .70 with a t3 ****** or .84 with a t3 ******. As munkee said i think the .68 a/r might come in too quick but im not sure. munkee let me know how that .81 a/r turns out...... toolman what a/r do you have on you 60-1 or is it a secret lol

 

[SHO--ripper]

I've got a .6 A/R on my T04 and it spools around 4k.

 

[munkee]

I've got a .6 A/R on my T04 and it spools around 4k.

Is that full boost at 4K or 1psi at 4k? Do you know what the turbine trim is?

Sho n go, I believe your going to want to stick with a t4 housing. The t3's are going to be on the small side. They might work with low boost but it will take a little work to change to a t4 if you want to make more power later. It's my opinion that a 60-1 hi-fi turbo with an "O" trim turbine and a .67 A/R housing should be a near perfect setup for running 5-9 psi. I could be wrong though. If I had more money and time I would try out a bunch of different turbos and then I could say "I know" instead of "I think".

 

[SH0 N G0]

SHO--ripper I've got a .6 A/R on my T04 and it spools around 4k.

SHO--ripper is that full boost at 4k? How is your turbo sho running? What kind of power numbers did you make with it at how many pounds of boost if you dont mind sharing... Munkee thanks for the advice... I think i am probably going to go with the .68 a/r with the T4 ****** on my 60-1, but I have quite a bit of time to think about it. Right now im just trying to do as much research as possible and hopefully be able to start ordering parts and doing my piping sometime in the summer. As of now im pretty sure on everything i want to get but just doing more research so i dont have to go back and rebuy things because of my lack of knowing what to get... Turbo sho here i come...

 

[SHO--ripper]

When i drove it without the boost gauge it felt like full boost at around 4k. I'm not sure what the trim the turbo is off the top of my head. I'm installing a boost gauge this weekend so i'll let you know on the boost.
No dyno time yet...

 

[SH0 N G0]

When you dyno your car let me know if your going to get your car dynoed at Pruven performance. I live down the street from them so maybe i can come see that beast of yours...

 

[SHO--ripper]

Where do you live? I'm hoping to go to the dyno at the end of april.

 

[SH0 N G0]

I live in milford. Thats where pruven is. about 20 minutes from the pike if that helps any...

 

[SHO--ripper]

I'll be sure to let you know when i go.
Now back to picking turbo sizes