another post about turbo selection.

[mazda_wes]

if you are keeping up with my ADD, you will know that i change my mind about every 30-45 seconds. this time, aptly so. someone in my area has a Precision SC50 hybrid t3/t4 turbo for sale. it's competition is a gt42 (which i have constantly gone back to during the course of my turbo selection). they are both journal spec's and the trim is pretty small on the SC50 compared to the gt42. the difference is that the gt42 is $900 (i am sure that i can do better than that, but that is the basic price that i am finding right now) and the SC50 is $650 (once again, i can probably do better than that by negotiating, but that is the base). the tightwad in me says just to save the extra $250 and get a cheap turbo that i still fairly large. the boost addict in me says, "bigger, better, faster, more, no matter the cost."

the boost addict is winning, but i want your opinion. i don't know anything about Precision, but everyone in the boinger forums vouches for them. i just know that what's good for the goose isn't always what's good for the gander, so i want to hear from some rotor heads that know the reputation of Precision.

[mazda_wes]

sorry, gt40 is what i am looking at. i don't know why i have been saying gt42

[WE3RX7]

T78 come on, come on....

[vex]

T60-1 or Bust. :p

[RETed]

Don't bother with ANYTHING T3 (hot side), period.


-Ted

[SpooledupRacing]

T60-1 Imo...

[classicauto]

how much power do you want to make? The GT40 with a decent exhaust housing can support 500whp at or over 20psi.

[Phoenix7]

is a T3 too small? Come on Ted, hook a brother up. I trust you when you say avoid it, but why?

[mazda_wes]

how much power do you want to make? The GT40 with a decent exhaust housing can support 500whp at or over 20psi.

i am going to control it about 15 psi-ish, but i don't want to run out of steam in the top end. when you push a turbo too hard, you are just blowing hot air into the engine. like i said, i just want to build once and be done. i don't want to keep building over and over.

[RETed]

is a T3 too small? Come on Ted, hook a brother up. I trust you when you say avoid it, but why?

It depends on what philosophy you believe in...

I believe in the less-backpressure-the-better group...
We try to keep the exhaust pressure versus intake pressure under 2:1 and try to shoot for a 1:1 as much as possible.
Thus, for 15psi of boost pressure, we try and keep the exhaust pressure under 30psi.
You need at least a T4 turbine side to do this.
Almost no T3 turbine side will allow for such low ratios - the Garrett GT-series GT35R's just make it.
Less backpressure -> better flow.


-Ted

[mazda_wes]

i think a 60 trim and a nice external wastegate will be what i am really aiming for. the gt40 will be perfect with the 52 trim compressor and 78 trim turbine, so i will look at the Precision and see what i think and use the gt40 as the fall back.

back to my original question, does anyone know how reliable a Precision is?

[SpooledupRacing]

precision performance?

long time ago I heard they used knock off turbotechnics.

[classicauto]

i am going to control it about 15 psi-ish, but i don't want to run out of steam in the top end. when you push a turbo too hard, you are just blowing hot air into the engine. like i said, i just want to build once and be done. i don't want to keep building over and over.

Again, how much power do you want to make? The stock turbo will make 250-260whp at 15psi, a GT35 will do 400whp at 15psi...........I don't care about pressure :)

[SpooledupRacing]

yeah when dealing with upgrading turbos etc you really need to have a HP figure in mind.

[mazda_wes]

okay, let's just say, in order to keep this moving and to get my answer, i am looking to keep it between 350-400.

anyways, are precision turbos pieces of crap or are they decent?

that is the main answer that i am looking for. i know that i can't expect to push a cheap turbo to high horsepower outputs without expecting to rebuild, but that isn't what i am even asking. if the turbo is crap, i don't want to use it no matter whether it would get me 1000 hp or no gains at all. i don't want a smoking turbo and i don't want an ongoing project.