does this sound right (turbo sizing)

[dannyho]

I've been doing this correctly, i think. and I've been comparing turbo maps to what I think my engine requirements will be and it seems I've founda great match, but as a engineering student i've been trained to find the answer using numbers, then step back and ask if it "sounds right".
essentially what i've come up with is that a turbo from a 2.0 liter engine with a 7000+ redline that is reputed to be capable of just under 300 Hp, would but nearly perfect for use in a twin setup for a 5.2L engine with a <6000 redline. I'm probably not looking to boost that high (less than 12 psi at most), no more than 550 hp, probably more like 450. so does that sound right to you guys?
I'll post a picture of the flow map with my estimated requirements overlayed.

[70TWO NOVA]

im not sure if thats fight or not you might try this site http://http://www.theturboforums.com/knowledge.php its pretty good ( its got maps, calculations, FAQ, and alot more), but im glad to see that you are doing it right and calculating it out, unlike the honda kids who seem to think a turbo is a turbo is a turbo and just bolt on anthing that looks like a hair drier. Its obvoisly a bit more complicated than that which they figure out when their head gaskets pop!

[camcojb]

http://www.theturboforums.com/knowledge.php

[dcozzi]

This is how I figured it out. It took about 4 pages of math but was very straightforward.

http://www.turbobygarrett.com/turbob...o_tech103.html

Only to find out I cannot afford to do it right.

[dannyho]

I posted a spreadsheet that did all the calculations for you, you input the boost level at specified rpm, and it shoots out airflow, in chart form in every type of unit. give it a search, would make a good reference tool if it doesnt get burried. It even takes into account ambient temperature, and the adiabatic efficiency of the turbo. By cropping and resizing the compressor maps, I could set it as the background of the excel chart to be the map and overlay the air flow requirements, really a great tool, (should be a sticky?)
I think I'm just gunna go for it with the turbo from that engine. It really does make sense I believe, the airflow needs to be higher to let that engine pull to it's redline. and on top of that the DSM guys have managed to push it to an honest 300 HP out of a single turbo 4 cyl. if it really doesnt work I can turn around and resell the turbos and fork over the real cash. but I'll worry about that bridge when i get there

[dcozzi]

I guess the only remaining question is, "Does your application land close to the center the boost island of two of those turbos, and live in the widest possible area of it for streetability?"

I wish I had your spreadsheet. It would have made my life easier.

[dannyho]

it *should*
and here's the link to the spreadsheet if someone comes across this and doesnt feel like searching
http://www.pro-touring.com/forum/showthread.php?t=28515