Ya, the cover is bigger, but the MP compressor wheel is actually slightly bigger at 76.5mm x 103.5mm on the MP, but where the GT turbo will shine is with that bigger hot side. That's like having a bigger motor to drive that compressor with,

 

so when people refer to the compressor side, its always in reference to the compressor wheel dia?

cant wait to put it together and try'er out

 

Yep, it's generally the smaller, inlet or indusser size of the compressor wheel. The 102mm on your turbo is the exdusser size of the compressor wheel.

 

That's pretty misleading. I know what you said is true from reading around a bit, but the way Garrett labels these turbos is jacked. Check this out:

http://forcedinductions.com/help.htm

Digits 5-6 or 02 in the GT4202R's case corresponds to the compressor dia. So based off of what they call it, it should be a 102mm wheel. But I think in this case, the cover limits the wheel to an effective dia of 74mm. I bet all you would have to change is the cover if you want more out of it.

 

To the OP, you might get a hold of Stock48, he just bought a new t78 also, but with a divided 1.15 a/r turbine housing and now he wants a .96 a/r instead. That 1.15 would be better suited with your 408. He might be willing to swap with you.

Oh and that 38mm gate is most likely gonna be to small... Probable need at least a 44mm

 

Ya, Garrett seems to have their own little way of labeling their turbos, . Makes it confusing as hell. I told Chris about it when he was selling that turbo cuz he was going off Garretts sizing of it too. Why can't they just do things the way everyone else does,

 

Now let's start talking about the trim of the wheel and make it even more confusing.

To the OP: My GT70 had a 70mm impellor (inducer / compressor wheel) and was a P-Trim, 76 Trim turbine. Spool was minimal with the 408, even on a rear mount. I was hitting full boost at 3500rpm if I recall correctly. Boost started to come on earlier than that -- in the late 2k range but definitely by 3k, so I don't think you lag is going to even be noticeable.

Like Kyle said, just build for 2500-6000rpm range and you'll LOVE it

 

plan on it shifting aroung 6-6300 anyhow

 

You took the words out of my mouth.Far as im concearned anyone looking for drivability'power,and efficincy needs to talk with him.That truck is too underated imo.If I had the money I would damn near follow his build to a T if he be ok with that.

 

i have spoken on the phone with him (he is very helpful) and yes VERY UNDERRATED....