Hey everybody been looking at twin setups a lot and having a hard time deciding what to do. Right now i have a PS 64/65/14 and i could buy either a 74mm or 80mm from my buddy right now but i think that set up with the 80mm would be to laggey so i was wondering if i need a smaller turbo to run with it but still not sure to go with the 74mm or 80mm? Also i have a Jacobs Exhaust Brake on right now too so will i have to take that off to run twins?

 

If you are keeping the Phat shaft for the top turbo, then I would think that the 74 wheel on a bottom s400 would be what you would want. It will support the 700hp and spool faster than the 80mm. I am pretty sure you would have to lose the Jake brake... however, Pacbrake makes a unit that will work.

 

Thats what im wondering if i should sale the 64 and go with a 62 or keep the 64 but i want fast spool up and with the exhaust brake i'll just take it off and leave it off.

 

Well you will have to consider that while the turbo you have is entirely appropriate for a twin set up and will flow air from the primary nicely, it will spool a tad slower than you are used to it now, just because you put it in twins. (The fact the top turbo is now sucking air through the restriction of the bottom turbo before it spools and the corresponding exhaust restriction is what causes this extra lag). If you like the spool response from your phat shaft now and can live with that "tad" slower response using it in a twin... then great... use it. For the money it would cost you I would keep it. But, if you are worried about spool time... you might consider dropping a size. If you do that, I would look at the HTT line... I really like that stainless steel exhaust housing (13cm) with the dual wastegates in a twins application. I think the 62/65/13ss over s400 (74mm) will support the 700 hp quite nicely and give good spool habits.

 

Thanks for the input but i think i will drop a size cause i want instant spool up and i think i might call Nathan at MPI since i hear a lot about him and see what he thinks. Hopefully some other people chime in here. Right now i'm having trouble with my SB 3600 i called SB and they said it needs broke in since i just got it installed. I've never even got to see what my truck will do yet cause the clutch is always slipping never had smarty over #1.

 

Nathan will steer you right.

 

If your going with the 74mm the 62 would be fine but my buddy's got a 62 over a 80 and its a dog,takes way to long to light. In that case a 64 might get it going faster as the 62 seems a little small to suck the 80 going.

 

Thanks guys just trying to get some good ideas from the guys that now the best