Was looking into a small turbo setup (more of an amusement project than anything else) and see alot of used/rebuilt turbos out there called T3/T4 units.

How do you determine the compressor and turbine size needed for a given engine? In this case, probably a Chevy 305. For example, I found a Garrett-specific site with a calculator that indicated a 305 would like one of their GT-25 turbo units (up to 400hp apparently). But:

What do these "T3" and "T4" designations indicate-such units seem to be everywhere and were seemingly installed on every factory turbo out there (Hondas, Chryslers, etc. etc.)?

I'm new at this too Eric. Log onto www.turbomustangs.com (http://www.turbomustangs.com) and do a search on the site, lots of good help & information.



------------------
'81 Viper Blue Z-28
383 Stroker
11.33 @ 119.9 N/A
10.18 @ 133.8 N20

***New Project...SBC 400 w/ Twin T70 turbo's, blow-through carb'd***

Eric,
Considering this as a project as well, if I don't sell the Z. Turbomustangs is a must go to place as mentioned. Also talk to calereeves, (member here) who is messing with it besides grapeape.
I have been finding that switzer and holset turbos might be the way for me to go (Cheap and easy to find) I have not figured out flanges yet. There are a coupla folks on turbo mustangs who will sell you some headers for a 2nd gen.

Eric

What site did you find for turbo sizing?? how about a web address??

Here are a few turbo claculators.

http://www.rbracing-rsr.com/compression.htm

http://www.turbofast.com.au/javacalc.html

http://www.turbofast.com.au/TFmatch.html

http://www.turbofast.com.au/tfcalc.html

Hope it helps!!!

Well- I went to turbomustangs and read some FAQ with a link to an Australian outfit with an online turbo sizing calculator (compressor sizing only) and came up with, based on the FAQ's instructions- needing something called an "R60" turbo- which, based on the size of the engine- seemed to be way way off- like three sizes too large- I assume something like a Garrett 35 or 40-series unit would be plenty large. Never did find a good definition for what a "T3" or "T4" is/was. Frankly- internet investigation- while cheap- finance wise- is a huge time killer. I think I'll investigate further when I have a good 4-5 hours to kill some night.

<font face="Arial,Verdana" size="2">Originally posted by Eric:

Well- I went to turbomustangs and read some FAQ with a link to an Australian outfit with an online turbo sizing calculator (compressor sizing only) and came up with, based on the FAQ's instructions- needing something called an "R60" turbo- which, based on the size of the engine- seemed to be way way off- like three sizes too large- I assume something like a Garrett 35 or 40-series unit would be plenty large. Never did find a good definition for what a "T3" or "T4" is/was. Frankly- internet investigation- while cheap- finance wise- is a huge time killer. I think I'll investigate further when I have a good 4-5 hours to kill some night.</font>

look at this one
http://www.turbofast.com.au/TFmatch.html

Aha! That was the calculator I used based on that FAQ- I assume the instructions in the FAQ were a bit off- I noticed when I was entering info and watching the results that the instructions seemed to take some rather large assumptions on how that calculator actually worked.