Turbo sizing and spool question
#11
Registered User
My GTX3076R vband with 1.01ar sounds exactly what you're after. I drive around town out of boost but with more torque but from 4000 and upwards it really ramps up aggressively.
#12
Cruising with a GT3076R doesn't mean constant boost. It means that when you floor it, boost is there if you want it. If you don't floor it, it doesn't boost. I had one for years and did a ton of highway driving at 80 mph. Could still get 30 mpg. Then, in the mountains, I could easily and quickly pass floored S2000's who were in 4th gear while I was in 6th gear.
The dyno chart below is from a Dynojet in Denver, CO. You can see a GT3076R with 0.82 a/r not making a ton of power until after 5000 rpm. That's because these are inertial dynos. The only difference between the two runs is which gear I'm in. On a loaded dyno and in higher gears on the street, you can get full boost at 4k rpm/80 mph (this may take ~2 seconds- its not instant at this low rpm).
The S300SX FMW is similar. When highly loaded, it's boost threshold is identical to a GT3076R. For transient conditions, it's a bit laggier (as shown by the huge differences in boost vs. rpm based on gear in the chart below). From a stop, it takes a lot longer to spool- it definitely doesn't respond as quickly and does have a big turbo feel. With that said, you can still get into boost (a couple psi) during normal driving going up hills- a small turbo feel. It's an interesting mix of the two.
My recommendation- try what you have first- particularly if you have a >1.0 a/r hot side. The GTX3076R is tiny for enthusiasts, but it's enormous if you look at what a factory would put in a 2 or 2.2 liter engine.
Tim
The dyno chart below is from a Dynojet in Denver, CO. You can see a GT3076R with 0.82 a/r not making a ton of power until after 5000 rpm. That's because these are inertial dynos. The only difference between the two runs is which gear I'm in. On a loaded dyno and in higher gears on the street, you can get full boost at 4k rpm/80 mph (this may take ~2 seconds- its not instant at this low rpm).
The S300SX FMW is similar. When highly loaded, it's boost threshold is identical to a GT3076R. For transient conditions, it's a bit laggier (as shown by the huge differences in boost vs. rpm based on gear in the chart below). From a stop, it takes a lot longer to spool- it definitely doesn't respond as quickly and does have a big turbo feel. With that said, you can still get into boost (a couple psi) during normal driving going up hills- a small turbo feel. It's an interesting mix of the two.
My recommendation- try what you have first- particularly if you have a >1.0 a/r hot side. The GTX3076R is tiny for enthusiasts, but it's enormous if you look at what a factory would put in a 2 or 2.2 liter engine.
Tim
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