wastegate on twins

[mainer]

i'm building twins with an s475 and my stock IHI on my 02 lb7.


everyone is putting an external gate around the primary turbo but i'm not seeing any backpressure results posted.

basically i'm questioning the need for the wastegate as a ton of the dodges are running identical turbos with same a/r and not running a gate. they are also running 20psi more boost and not reporting any backpressure issues.


any input would be excellent as i cant get a straight answer out of anyone.... all the people doing DIY twins just seem to be following everyone else and throwing in the external gate and not really knowing how or if its affecting the setup

 

[diamondshocks]

most guys are running boost adjuster from the larger turbo through the wastegate to not overboost the large turbo

 

[mainer]

yes but on single cp3 there isnt enough fuel to overspool the big turbo i dont think.... and 95% of the twins out there are stock motor single cp3 street driven trucks

 

[Noreaster]

everyone is putting an external gate around the primary turbo but i'm not seeing any backpressure results posted.

basically i'm questioning the need for the wastegate as a ton of the dodges are running identical turbos with same a/r and not running a gate. they are also running 20psi more boost and not reporting any backpressure issues.

Got to have some way to keep the psi at a safe level for the head gaskets & rods. If you didnt gate it could use a BOV to control pressure.
Dodges need head studs after 30psi to keep from lifting their heads, so they can take the higher pressures & also have restrictive heads that will have higher boost with less airflow compared to a Dmax.

 

[dmaxvaz]

got to have some way to keep the psi at a safe level for the head gaskets & rods. If you didnt gate it could use a bov to control pressure.
Dodges need head studs after 30psi to keep from lifting their heads, so they can take the higher pressures & also have restrictive heads that will have higher boost with less airflow compared to a dmax.

dodges run more psi beacause of the RESTRICTIVE intake/head. Dodges need headstuds at 50+ psi

 

[malibu795]

Got to have some way to keep the psi at a safe level for the head gaskets & rods. If you didnt gate it could use a BOV to control pressure.Dodges need head studs after 30psi to keep from lifting their heads, so they can take the higher pressures & also have restrictive heads that will have higher boost with less airflow compared to a Dmax.

NO! very bad way of controlling boost.... risk overspeeding the turbo that.

 

[bullfrogjohnson]

Youe will definately need gates, We just put a set of twins on my buddies lb7 and you definately need the gates to tune the truck and get the drive pressures right. When we first setup the gates after the install we thought it would be close to 1:1 but it was more like 2:1 and it has taken alot of time messing with the gates to get it remotley close to 1:1

 

[mainer]

well i can tune my stock ihi gate to get that making the boost I want.


explain to me why the early mpi kits like duratothemax (ben) has do not have a gate around the primary then?? and those early primary chargers are quite a bit smaller than what i'm using s475.... and he can only make about 46psi with single cp3