The car as the trusty "red top" SR20DET fitted. Brett has gone the extra mile and fitted aircon to his 510! Just fitting the rad/intercooler/condenser in the front of a 510 is a minor miracle. But he also has a miracle SR. First time on the customers/dyno netted some impressive numbers.
Some interesting stuff happened though. And here's an early lesson I learned. Before tuning any car everything has to be running right beforehand. Prime offenders are airflow meters (AFM) and fuel pumps. Lazy fuel pumps will cause artificially lean mixtures. As mixtures are usually leaned out when a factory ECU is re-mapped this can result in dangerously lean mixtures. The other problem is dirty airflow meters. Results can be either rich OR lean mixtures! I've seen both. In brett's case it went lean. So when the new maps were programmed it went extra lean! See the graphs below. This is an S13 SR20DET with standard turbo, AFM and injectors. It has a FMIC (modified GTiR item) and free flowing (but still quiet) 3" exhaust.
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| 12.5psi - Dirty AFM | 12.5psi - Clean AFM | 14psi - Clean AFM |
The lean mixtures resulted in a bit more power but it was too lean to be left that way. And as the AFM got dirtier the mixtures would lean even further. Final result after cleaning the AFM and adding some boost is on the right. Please note that these power levels are very healthy for a standard SR no matter how much the ECU is tweaked. Brett's car was always very healthy and the customers/dyno results back this up. Most S13 SR20DET's only give 160 or so in this state of tune. Nobody has been able to explain why this engine gave so much more.
We did have the opportunity to try the car on another customers/dyno and it made similar (slightly less) power. But that was pretty much it for standard hardware. The standard injectors and AFM won't let you get much more as both are nearing their maximum abilities. Naturally Brett wanted more so eventually he shelled out for a bigger turbo, injectors and AFM. He skipped the T28/S15 injectors/Z32 AFM level and went straight to GT2871R/550's/Z32 AFM.
He chose the 48 trim GT2871R with 0.64AR exhaust housing in the interests of boost response. By this stage he'd also gone to a Blitz EBC after having no end of problems with an Apexi unit. You can see the results of this in the middle graph. You can also see how the standard turbo cannot maintain 15psi past about 5000rpm while the larger turbo has airflow to spare. Although full boost is achieved around 500rpm later.
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| GT2871R at 12 and 16psi after tuning | GT2871R vs standard turbo | Data log for GT2871R |
Check out the log for the bigger turbo. I've started doing a log of engine parameters at the end of each tune. This gives a handy reference for later. Note how the Z32 AFM still has plenty of headroom (max voltage is 5.12V and this run only reached 4.4V) and the 550cc injectors are only at 75% duty cycle. So if Brett wanted more power he wouldn't need to touch AFM or injectors. Just increase boost and/or fit some healthier cams.