I've been curious about how my 20v would respond to a couple of changes, particularly more intake plenum volume and a 7A exhaust cam, without any change in turbo, exhaust, or chiptuning.
The 7A exhaust cam is obvious, more lift and duration. Supposedly enough that it hurts turbo spool... more on that later.
The intake in question is a spare 3B part I had laying around. I cut it open and removed the bolt passthrough bosses from the inside, then had it put back together with a raised roof, sorta like an RS2 intake for a hell of a lot less.... not as pretty either.
When installed it looked like this.....
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Notice the "professional" tig work... the "professional" who did it bitched about how bad the casting quality was. Also notice how the end differs from the revised version below. Version 2.0 came about because I have a nice dent in my hood from a pair of launches.
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The welding on the revised area was done by Kevin at DTR in Florence KY while still installed. Notice how much cleaner the welds are and his actual welding time was less than 5 minutes!
The results of both were about what I suspected and go against what many say of the 7A exhaust cam.
Turbo spool... its changed alright, it hits HARDER. The large plenum volume could account for some of this but not all.
Midrange torque... oh yeah, much more. I was leaving 15ft stripes on the road the other night during some heavy launches... I run 235/45's on all 4 corners... Before the change I could barely keep the car from bogging on a launch unless I was slipping the clutch.
Drivability... improved, part throttle boost response is slightly quicker.
Fuel mileage... it improved a hair but I also installed new plugs that day so its probably a wash.
High RPM pull... the K24 bottleneck I hate so much is still there but its not quite as pronounced.
I'm very pleased with the results.
Next up... I have this K26 with an odd center section..... :wink:
The 7A exhaust cam is obvious, more lift and duration. Supposedly enough that it hurts turbo spool... more on that later.
The intake in question is a spare 3B part I had laying around. I cut it open and removed the bolt passthrough bosses from the inside, then had it put back together with a raised roof, sorta like an RS2 intake for a hell of a lot less.... not as pretty either.
When installed it looked like this.....
Notice the "professional" tig work... the "professional" who did it bitched about how bad the casting quality was. Also notice how the end differs from the revised version below. Version 2.0 came about because I have a nice dent in my hood from a pair of launches.
The welding on the revised area was done by Kevin at DTR in Florence KY while still installed. Notice how much cleaner the welds are and his actual welding time was less than 5 minutes!
The results of both were about what I suspected and go against what many say of the 7A exhaust cam.
Turbo spool... its changed alright, it hits HARDER. The large plenum volume could account for some of this but not all.
Midrange torque... oh yeah, much more. I was leaving 15ft stripes on the road the other night during some heavy launches... I run 235/45's on all 4 corners... Before the change I could barely keep the car from bogging on a launch unless I was slipping the clutch.
Drivability... improved, part throttle boost response is slightly quicker.
Fuel mileage... it improved a hair but I also installed new plugs that day so its probably a wash.
High RPM pull... the K24 bottleneck I hate so much is still there but its not quite as pronounced.
I'm very pleased with the results.
Next up... I have this K26 with an odd center section..... :wink:
