[Robert]

Originally Posted by wdodge45

Hi Robert,
I just got everything apart and will sending the units tomorrow. One last question pertaining to the 60-1 compressor housing and wheel upgrade to a 62-1. Why can't a bigger compressor housing and wheel be fitted onto a 60-1 like a T64 or 66 size? Sorry for being dumb but just know what fits what. Is this upgrade a F1 style wheel?
If I was to buy new turbos what would be your suggestion and why...I"m trying to think ahead if i"m not happy with this set-up when all is said and done.

Thanks,
Bill

The F1 wheels are turbine wheel designs only not compressor side wheels. You could certainly upgrade to a HP64 or HP66 compressor wheel if that is your preference. The main reason I recommended the 62-1 was cost/known performance. The larger compressor wheels in the HP line will change the spool characteristics you are used to. Even if you kept the same turbine wheels the HP compressor (64, 66, etc) wheels have a completely different flow profile than the 60 series do. I was of course operating under the presumption of keeping your cars boost curve, response, and general power distribution identical to what it is now just with more power being produced. Because the 60-1 and 62-1 share the same base architecture both wheels have identical flow profiles and boost curves just with one (the 62-1) producing more power per unit of pressure ratio than the other (60-1). You can actually see this on the compressor maps for the 60-1 and 62-1 here:

60-1:


62-1:


When you look at those maps you can see that the compressor efficiency islands have the same basic shape and curve to them. The 62-1 map is wider because it is larger and makes more power. Now compare that to the T66 compressor map here:



If you look at the maps side by side you can see the T66 will make more power but look closely at the efficiency island for the T66. It's a drastically different shape and curve. That same difference will be reflected in on throttle performance. Now that's not to say the T66 is a bad choice for your car. In fact the T66 is a pretty popular compressor for LS motors. More so its the delta between the 60 series flow map and the T66 that I'm alluding to. If you were to go with T66 wheels you would have more power potential than you would with the 62-1 but at the same time it will change the shape of the boost curve on your car and therefore your car will FEEL different when its climbing up to the boost threshold.

That's the tech side. The cost side is a bit simpler. Upgrading to the T66 will flat out cost more. Because the 62-1 is in the same family as the 60-1 the parts required to make the upgrade are less. A T66 upgrade would entail changing the bearing housing as well to accomodate the different wheel design and would end up costing you more. In all honesty if you wanted to go with a T66 I would recommend totally new turbos while you were at. The T66 compressor flows a lot more than the 60 series and I would have also recommended a turbine wheel upgrade as well. Main reason is that the T66 can flow so much more than the 62-1 that with the additional head room I would recommend a turbine wheel change to make sure you have enough power handling potential on the turbine side for when you ultimately start using that additional head room.

So long story short the 62-1 upgrade is cheaper and will keep things the same with regards to feel on the pedal but the larger compressors will cost yet make much more power albeit with a different overall feel.

In regards to a totally new turbo I would again want to know what your ultimate power goals are. Not just the 1500 HP target you have right now but thinking long term what is the most you would ever want to run in that car. I want to make sure whatever I recommend as a new turbo would be able to meet your goals now and later when the horsepower bug starts bitting you again.