Joined
·
2,913 Posts
I just installed the Sound Performance SP74 turbo in place of the Turbonetics T-64 on my car. Power-related mods on my car are SP fuel system with 72 pound per hour injectors (750-ish cc), SP Cold Air Intake, GReddy "3-row" FMIC, RPS header, 3" DP, GT Spec cat-back, and HKS 264 cams. The SP74 has a 74-mm compressor wheel (at the inducer) and a .81 exhaust housing with Q-trim wheel.
I only drove the car for a few miles after completing the install last night, but I have to say that the turbo is awesome and spool is incredible for a turbo capable of suporting 825-850 RWHP. To give you an idea of the spool characteristics, I reset the peak hold on the GReddy boost gauge, then did tests in 2nd, 3rd, and 4th gears wherein I would nail the throttle at 3K RPM and then let off the instant the tachometer indicated the target ending RPM. From 3K to 4K RPM in 3rd it made approximately 9 PSI and I could tell that it was JUST beginning to cook. Not too bad for a 74-mm compressor wheel, and considering that the stock twins in sequential will only make 15 PSI under these conditions.
BUT, by 4500 RPM it made 23 PSI! In 4th it made 28.5+ PSI by 4500. I had the EVC EZ set at 2.0 kg/cm2, so I don't know how much more it would have made in 4th at 4500. I tried to test it in 2nd gear, but couldn't get much of a test because it kept blowing the tires away before 4500. It kinda hooked up a little in 2nd once and made about 18 PSI by 4500.
One other thing to keep in mind is that my tachometer indicates about 7150 when it hits the factory 6800 RPM rev limiter. I don't know what the actual RPM is when the tachometer is indicating 4500, but it is probably less than 4500 -- maybe around 4300 or so.
I definitely look forward to playing with it some more. I haven't done any pulls -- just a few short stabs of the throttle through a couple of gears -- but so far I think it's very impressive. I was hoping that it would spool decently early in the RPM range, and it definitely does. Considering the power-making potential of such a huge turbo, I'd say it spools incredibly well. It's pretty nice just going moderately through the gears -- not really nailing it. Where with the T-64 you can be pretty liberal with the throttle and still not have the power come on too explosively, you have to modulate more carefully with the SP74. If you don't, it just gets wild with boost (that's a good thing
). As you would expect from a turbo this size, power comes on like a 600 pound boot to the ass! I like it.
Steve
I only drove the car for a few miles after completing the install last night, but I have to say that the turbo is awesome and spool is incredible for a turbo capable of suporting 825-850 RWHP. To give you an idea of the spool characteristics, I reset the peak hold on the GReddy boost gauge, then did tests in 2nd, 3rd, and 4th gears wherein I would nail the throttle at 3K RPM and then let off the instant the tachometer indicated the target ending RPM. From 3K to 4K RPM in 3rd it made approximately 9 PSI and I could tell that it was JUST beginning to cook. Not too bad for a 74-mm compressor wheel, and considering that the stock twins in sequential will only make 15 PSI under these conditions.
BUT, by 4500 RPM it made 23 PSI! In 4th it made 28.5+ PSI by 4500. I had the EVC EZ set at 2.0 kg/cm2, so I don't know how much more it would have made in 4th at 4500. I tried to test it in 2nd gear, but couldn't get much of a test because it kept blowing the tires away before 4500. It kinda hooked up a little in 2nd once and made about 18 PSI by 4500.
One other thing to keep in mind is that my tachometer indicates about 7150 when it hits the factory 6800 RPM rev limiter. I don't know what the actual RPM is when the tachometer is indicating 4500, but it is probably less than 4500 -- maybe around 4300 or so.
I definitely look forward to playing with it some more. I haven't done any pulls -- just a few short stabs of the throttle through a couple of gears -- but so far I think it's very impressive. I was hoping that it would spool decently early in the RPM range, and it definitely does. Considering the power-making potential of such a huge turbo, I'd say it spools incredibly well. It's pretty nice just going moderately through the gears -- not really nailing it. Where with the T-64 you can be pretty liberal with the throttle and still not have the power come on too explosively, you have to modulate more carefully with the SP74. If you don't, it just gets wild with boost (that's a good thing
). As you would expect from a turbo this size, power comes on like a 600 pound boot to the ass! I like it. Steve
