wondertruck

What is the best technique for determining the nessecary, or most beneficial size turbo for a twin turbo setup? With a 370ci mild compression motor (9.2:1) I had planned on a twin 60mm t3/t4 setup however I want to ensure that I have the most optimal system. What is the standard way of determining this information?

vanillagorilla

iTrader: (1)

This should help:

http://www.forcedinductions.com/consumption370.htm

If you're running twins, then the turbos added together need to be able to meet the demands of the mass flow rate (lb/min) numbers in the chart. To get the flow rate of the turbos, you need to look at its compressor map. Easier said than done, but check out forcedinductions.com's Turbo sizing section. It explains it very well.

parish8

iTrader: (6)

you need a hp goal or an et goal with your race weight for starters. from there is isn't too tuff to pick a turbo/turbos that works for ya. if it's a race truck you err on the large side(turbos in their sweet spot at max hp). if it is street truck err a little on the small side(turbos just large enough to get to your hp goal)

whats nuts about turbos is how well they work even when they are not ideal. a t76 on a 408 is way too small but soo much fun. a pair of gts70's are way oversided for a 408 but soo much fun , you get the idea.

Spoolin

iTrader: (8)

Lol, so basically your all set in the fun department if you go turbo!
welcome to the dark side!

Hawk179

iTrader: (1)

You determine by compressor MAPs and things like what cubes, what intake manifold are you running, ect. What is your goal RPM with them? Stuff like that is how you get there. It took me some time to pick the pair for Marks truck, and the other truck I am building as well. PArish is right though, when you are in the sweet spot, the sweet spot is a good place to be.

Rick

04Denali

Rick
You are the Man

wondertruck

I'm running a 370, ~4250# range, not a track only thing however it shall run like it is. A single 76 would probably be nice on it, I want to stay with the larger frame so I can upgrade later if I want. A friend nas an S88 that has been modded to 91mm, thought about building the kit using that as a mockup, and then going with the same frame 76mm. I would like to see ~750rwhp with a mild setup not pushing to hard.

Spoolin

iTrader: (8)

That set-up sounds awfully familiar...where have I seen that one before....hmmmmm??

Hawk179

iTrader: (1)

I think there is more for the trucks by going twins only because the trucks really do need the TQ more than the HP. In that case, in order to support more HP, you need more cubes. So when this happens, you can sacrifice alot of the bottom end by going a giant single front mount. So why not share the duty then? Keep the TQ right where it belongs, keep the gearing right, and keep the fun there. If its going to be a single, then stay small I say. You will have more fun with the smaller turbo. Also, look at the truck manifold as well, with this manifold, there is no point in trying to go past 6K.

Rick

wondertruck

thanks for the info Rick, great stuff. I'm running solid roller and a victor jr. manifold.