I have a W250 (4x4) with A518, stock converter, 3.55 gears & a 14 cm gated housing, mine runs around 4 psi boost at 75 mph. Mileage is 16 - 17 in town, 18 - 19 on highway (75 mph). Peak boost is around 24 psi.

 

I installed a sps phatshaft 62/12 with a 12cm hsg. I was talked out of a 14 because the 14 would be laggier on the bottom end. I would assume it would be the same on the oem. With the 14 on the oem all your doing is increasing housing size which would seem to help your egts and top end. I'm confused

 

Yes a 12 will spool quicker than a 14 housing..............99% of the time. It didn't on my truck. I loved my 14 housing for my hx-35.
If you plan on keeping stock injectors you will be fine with a cheap non-gated 14. You don't need/want to bleed off extra boost until you get up around 35+ psi using a 14 housing. In fact my truck ran cooler with the wastegate actuator blocked. I ran it that way until the day I sold it making 38psi.

 

I ran around 5 psi with my 16 with 4inch straight pipe

 

and now I am running a 14 non gated with the stock non intercooled H1C and run 10 psi at 65 mph. it spools a lot faster than my 16 did with the same peak boost, the 14 just gets there faster.

 

I don't mean to hijack, but what housing would be the best for a 5 speed and 4:10's, with city and highway in mind?

Thanks

 

Definatly a 12cm gated housing for what you have. Engine RPM has nothing to do with turbo spool, it goes by engine load. With low 4.10 gearing you are taking away alot of the engine load so the 12 would be ideal.



I ended up with a $70 12cm wg housing and it is awesome. Boost set at 32psi and gets there quick. EGT stays around 1000* in 1st through 4th gear, but in 5th gear it climbs to 1200* by 85mph and will get to 1400* at 100mph+. I want to get the bigger intercooler in and see if it cools down some.

 

Really, that is sweet I had thought that it was dependent on engine rpm. Well That is a good piece of information. The 4:10's are a curse and yet a blessing