Engine/Transmission (1994 - 1998) turbo questions

[JAmos]

Do larger exhaust housings on a turbo just help to lower egt's or do they make any more power? I would think they wouldnt make any more power since the compressor size is still the same. More air mass or volume from a bigger compressor housing & wheel is how to get more power right?(with more fuel also)



Changing to a bigger exhaust housing just lessens exhaust restrictions and moves the peak boost farther up the rpm range right? It also ads more lag time. I guess there might be a small increase from eliminating some exhaust restriction but I dont think very much? Jordan

 

[JAmos]

Ok I know the great minds out there must have some input on this. One thing I forgot to mention is turbo drive pressure. I know with smaller exhaust housings that the drive pressure is alot higher, but dont know how much. Jordan

 

[pwerwagn]

A larger housing will decrease EGT, therefore allowing you to add more fuel, and make more power. I dont believe that a housing itself will add much power, if any at all, unless maybe you are over your current housings limits? Yes, the larger housing will make more lag also, but that can be overcome with fuel also. A smaller housing will create more drive pressure. I think a 35 is somewhere in the 2:1 range (2x as much drive pressure as boost pressure). Not sure though how much the difference will be between a 12 and a 16cm housing in relation to drive pressure.

 

[HoleshotHolset]

If you're planning on adding a 16cm² housing for EGT reduction - save your money and buy a bigger turbo - or add twins! Bolting on a bigger housing will get you the following:



1) Slower spool

2) ~$150 lighter wallet

3) The same max EGT you had before - but the time it takes to get there will be very, very slightly more.

4) Lower drive pressure

5) Less responsive on the highway, around town, etc.



Bigger housings are great when used with twins, but just bolting on a bigger housing (going from a 12cm² to a 16cm²) was a big waste of money on my '94 and my Dad's '98.



Matt