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Attached is the BIN file we developed during the March 3rd CT dyno day (see below links), using CalumSult's new Real Time ECU on a DynaPack loaded hub dyno. Also attached is an Excel spreadsheet with the torque, horsepower, and AFR numbers.
This engine is a stock-based build, done to SCCA's Improved Touring category, with the following mods:
- 1mm overbore, stock compression pistons
- 1/2 point compression via head and block milling
- Balanced and blueprinted
- Port-matched but *not* ported
- New cams, valves, rockers
- UOR crank pulley
- Hotshot Gen 6 header to 3" open exhaust
- JWT POP
- Stock injectors, FPR, ignition
- Stock flywheel, JWT PP and B14 disc
During our dyno day, we were using a handheld infrared pyrometer to measure EGTs at the primary header tubes. We noticed one cylinder (#2) was running 75-100 hotter than the rest. After we got it home I removed the injectors and sent them off to Marren Injection for inspection, cleaning, and overhaul. The data sheet on return showed a resultant ~4% increase in flow rate and a reduction in variability from 4% to 1%.
I ran this program last weekend at VIR, and the car was running pig rich. Whereas we were showing AFRs of mid-to-high 13s on the dyno prior to injection work, during this last race we were getting AFRs of mid-to-high 11s according to the NGK wideband (logged to DL-1). The spark plugs were BLACK. I dind't have time (or motivation) to mess with it that weekend, but at least we still won the race...
Soooo....I've got a test day and race weekend coming up next week. I'll diddle with the K-factor a bit to lean it out and try to get the AFR to at least the low-13s, and then after that I'll schedule a dyno day to tweak it to get better numbers... - GA
P.S., on edit: we're not using an O2 sensor. We're relying entirely on programming to handle this mixture.
Update: last race we changed the injector k-factor in this program to 30000 (thirty thousand) and the general A/FRs were much improved: low-13s a low RPM to low-12s at high RPM. However, they're not consistently "good" across the range so look for some dyno tuning soon on this.
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