What turbo would you run under a gt4202?

morkable

morkable

Just Over Broke
Joined
Jan 30, 2008
Messages
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I am going to build up a set of twins this winter, I have a Gt4202 (1.01 AR 74mm) I am going to use this as the top turbo, what would you guys run as a primary for this?

Also, is there any guys out there that run the primary in a forward posistion, somewheres around where the battery used to be, behind the headlight? If so could you post some pics, and describe how you designed the bracing for this. Also how you designed your hot pipe would be awesome too.

Thanks

Kevin
 
morkable said:
I am going to build up a set of twins this winter, I have a Gt4202 (1.01 AR 74mm) I am going to use this as the top turbo, what would you guys run as a primary for this?

Also, is there any guys out there that run the primary in a forward posistion, somewheres around where the battery used to be, behind the headlight? If so could you post some pics, and describe how you designed the bracing for this. Also how you designed your hot pipe would be awesome too.

Thanks

Kevin
Click to expand...

If you want to put the primary up front, turn the top charger around to make the hot pipe shorter...then the cold pipe can loop around to the rear of the top charger.

That's how I'll be laying mine out anyway!

Chris
 
Anything in the 100mm - 106mm class:
GT5541R
Thumper T106
S510
HX-82 in the 4.1" variety

Or in the triple variety
Anything in the 65-67mm class:
Pair of GT4094R's
Pair of S465's
Pair of HX-52's
 
basic rule of thumb for large sequential turbos, multiply the secondary inducer size by 1.414 (square root of 2) to get an idea for the size of the primary.
 
I like to look at the compressor map, and when you get to the right side of the manifold chargers map, you should just be coming into good efficiency in the atmospheric charger.

So with a GT4202 you are at the right side of the map at ~90lbs/min (the true edge is ~96lbs/min, but you have dropped from about 74% to about 64%. The GT5541 @ 90lbs/min is just coming into swing at between 71-75%. Depending on what size turbine housing it is running, and therefore where it is spooling.
 
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