porperly sizing turbo...

[sLoWnStEaDy]

how the hell do you do it? for an example, a 383 SBC. how would you go about picking a good size for a twin turbo setup?
Would a pair of these be good? :
57trim
.63A/R turbine .50 A/R compressor
Turbine Wheel: exducer 2.48" / Major :2.89"
Compressor Wheel : exducer :2.07" / Major 2.36"

just curious as me and a couple buddies where just talkin about turbo sizes and such.

[Ricky]

a single turbo would make more power. i also cant answer you question sorry

[krustindumm]

estimate volumetric efficiency
calculate required airflow for desired power level
choose a compressor with flow characteristics to match

not sure on the turbine though. I suppose it's mostly a guess using the estimated flow plus fuel in lb/hr or something.

easiest way is to copy someone who has already tried it.

[Rollin on Dubs]

estimate volumetric efficiency
calculate required airflow for desired power level
choose a compressor with flow characteristics to match

not sure on the turbine though. I suppose it's mostly a guess using the estimated flow plus fuel in lb/hr or something.

easiest way is to copy someone who has already tried it.

Or the way guys pick cams, Pick the one that best fits the engine and its uses, then go the bottom of the page and get the big one!

Find the biggest turbo you can afford and then buy the one the next size up!

[Scott]

find the biggest one that fits under the hood, then get the next biggest one and cut to fit, go to the hardware store and buy some PVC tubing and start hacking some pipes

[Drifte]

easiest way is to ask someone with that motor what they have done. its easy for a dsmer to pick out a turbo...so many options. it all depends on mods however. like krustin said you have to know what the engine itself flows, and what your going for with the turbo. Big numbers with slow spool, or quick snappy response.

[SLVR7]

First you need to decide what power curve you want the motor to have. Switch to a single turbo. Do the math to figure out how many lbs/min and at what pressure ratio, then look at some compressure maps to see what fits your needs. And no .63 a/r will chock outa sbc.

[sLoWnStEaDy]

. And no .63 a/r will chock outa sbc.

chock? you mean choke? remember its a twin turbo setup, so the .63 would only be for FOUR of the cylinders. i was doin the most simple (and probably most WRONG way) i figured its a 5.7L, so rather than one that would handle that engine, just find two that would handle 1/2 of that. Meaning two turbos that would be the right size for say a 2.8L or so would work good on a 5.7....



people are using single turbos with .85 A/R turbines on SBC's, so wouldnt that pretty much be like running a pair .42 or so turbos? i have seen a couple twin turbos and they where running .69 or so for turbine. but they where making TONS of top end power not much down low as they didnt fully spool 'till like 3500RPM. with a 6K redline i think two smaller turbine turbos would make power sooner and be a little better (for bottom end power).

[sLoWnStEaDy]

HERE YA GO... on a 427 this guy is running two 60MM turbos with .50AR comp. and .58AR turb. just under 10psi here are his numbers... mine is only a 383 and the turbines would be bigger so i dont really get how they would choke it out...
some may have heard of him... Monty Williams the engine is in a corvette.

RPM........TQ.........HP
4100......757.9.....591.7
4200......759.7.....607.5
4300......757.1.....619.9
4400......755.6.....633.0
4500......757.9.....649.4
4600......773.2.....677.2
4700......789.4.....706.4
4800......801.5.....732.5
4900......822.5.....767.4
5000......843.5.....803.0
5100......859.3.....834.4
5200......871.4.....862.8
5300......873.5.....881.5
5400......878.0.....902.7
5500......888.5.....930.5
5600......905.5.....965.5
5700......904.0.....981.1
5800......910.0.....1005.0
5900......917.4.....1030.6
6000......922.3.....1053.7

[Fire Hawk]

I forgor about this site here until just a min ago. http://www.grapeaperacing.com/

He pretty much has I think everything you need to know to get it figured out.

http://www.grapeaperacing.com/GrapeApeRacing/tech/turbochargers.pdf

I think that's a pretty good wright up on how to pick what you need.

[boxmakingman]

got to ebay
type in "chevy turbo"
purchase cheapest turbo

DONE!

[DustinsDuster]

a 383 isnt 5.7 L. a 350 is 5.7L. 383 is like 6.3L

[Stutz]

Are u actually going to twin turbo that 383 from the firebird u bought?