EVO 16 / or should I say BIG 16G Rebuild w. questions,& External WG QUESTION!!!

Ok I know that is pointless to have an external wg on a big 16g, but i have one lying around a 38mm tial, and a 02 housing. I am quite used to the setup, I sent my turbo out for a rebuild and figured I might as well couple the 38mm on their.


The builder said that I have a MHI BIG 16G Wheel, with a EVO 3 COMPRESSOR HOUSING, and that he swapped MY EVOIII compressor housing for a MHI BIG 16G housing to eliminate the gap between the wheel and the compressor. He also said that its DEFINATELY a MHI 16G but the rest of the parts are from the EVOIII GT and someone swapped an MHI compressor in at one point.

I know the EvoIII housing is lighter and rarer, but does it make a difference if I have that housing over the mhi housing? with their be a faster spool time?

Another question is, I know I have a 34mm flapper internal in my turbo and the best way to run 38 off of the 02 housing is to remove the flapper and port it out to 38mm, but would the 4MM REALLLY make that much of a difference?
Can I just install the external WG on the 02 housing WITHOUT removing the flapper and porting it? How significant is this and am i really going to feel, or gain any gains out of this??

Any help appreciated Please!!!

 

BTW the DSM Wiseman JUSMX141 is rebuilding this turbo for me, well its actually done!

 

[IncorpoRatedX]

this really belongs in the newb section.

the 4mm can make a difference, but external in general makes a difference. I would suggest selling/trading for one that doesnt have a flapper or has a stock flapper in it, but thats just because i wouldnt want to ruin a 34mm set up.

as for the compressor housing, you want to run matched parts a gap will reduce the efficiency.

 

Yes exactly my point, I have done the research but I really want to go external even though it is not necessary. That 4mm difference would cause late spool up you would say??

 

[IncorpoRatedX]

no, the wastegate is closed during spool....

 

Ya but what I'm saying is that everyone says it will affect flow if I go external and don't remove the internal flapper and dont port it 4mm larger. How will it affect flow? Would I loose spool up time? Perfomance? Efficency??? If so how much?? If I'm at 5k rpm in 2nd gear at 20psi will that 4mm really affect me?? I want to go external but I don't want to hack up my turbo if not extremely necessary

 

[BrandonEchols]

Why do you want to go external?

 

If you go external you have to weld the internal flapper shut otherwise you will never spool. I guess someone might have told you that welding that would effect the flow of exhaust in that area, which may be true, but its a minimal effect at best. Regardless, there would be absolutely no point in porting it if you are switching to external. What they probably meant was that you could port your internal out 4 mm and get the same performance as an external.

 

[Barnes]

92Galant929: NO

He is talking about putting the external wastegate on the o2 housing, not the manifold. He is debating if he can just leave the flapper in there or if he has to remove it and port etc etc.

 

No dude I am running off of the 02 housing so I would have to do the opposite.

I wanna go bigger later donw the road and love the sound of the external dump. I also. Got the turbo rebuilt I want to insure a fail proof system.

Main point is I just want to go external period.

 

gotcha, sorry for any added confusion.

 

[Barnes]

Speculating, I think you could just port the exhaust housing (not the hole, where the flapper arm bumps the housing) enough to make sure the flapper can open up ALL the way. You could probably just leave it dangling and it wouldn't cause a problem. Or perhaps wire it open from the outside lever. I think one of the primary advantages of an external is not so much the size of the hole, but the nature of the valve. The flapper valve is itself a bit restrictive compared to the 'poppet' valve that an external is.

 

92galant92, no problem bro. Thanks for the help!

BarnesMobile, thanks for clearing this up for me. I know the flapper should not really affect flow but will be a bit restrictive. How restrictive I don't know. But I will try to shave on top by the arm to open up more.

Any other feedback is greatly welcomed and thank you guys all in advanced