Tuning Question - ZR-1 Net Registry Forums

jss06c6 · 11-14-2018

Dominic,

Need to talk to another tuner sir.. While working with my '91 on the Dyno today, we discovered that cylinder 7&8 showed temps on the header primaries at about 1200 degrees about 6-8 inches from the head. The other cylinders showed the same issue, but not as far down the header primary. Temp at the head (about one inch from the exhaust port) was about 400-500 F. This indicates that the fuel is still burning while being pushed out of the cylinder. Can we change the injector pulse timing on the LT-5? I need to bring it in sooner so that the fuel is in the combustion chamber long enough to burn completely. I can do this with OBDII.. Can we do this with our ECM? I took fuel out of the top end of the tune and brought the AFR into the sweet spot, 12.8-13.1 across the 2000 to 7000 rpm band. Gained about 15 hp at the wheels from the past last week. We're at 373 rwhp (inertia) and 369 rwhp (loaded 10%) now.

Car is strong and the HP is carrying 367 at 5200 to 369 at 6900 rpm, flat. Very powerful at the higher RPM band! Still climbing at 6900 rpm!

Would be grateful for your thoughts and if we have the ability to start the injectors a bit earlier in the combustion cycle. I'm wasting BTU's in the headers!

Steve

11-14-2018	#1
jss06c6 Join Date: Aug 2015 Location: Magnolia, Texas Posts: 884	Tuning Question Dominic, Need to talk to another tuner sir.. While working with my '91 on the Dyno today, we discovered that cylinder 7&8 showed temps on the header primaries at about 1200 degrees about 6-8 inches from the head. The other cylinders showed the same issue, but not as far down the header primary. Temp at the head (about one inch from the exhaust port) was about 400-500 F. This indicates that the fuel is still burning while being pushed out of the cylinder. Can we change the injector pulse timing on the LT-5? I need to bring it in sooner so that the fuel is in the combustion chamber long enough to burn completely. I can do this with OBDII.. Can we do this with our ECM? I took fuel out of the top end of the tune and brought the AFR into the sweet spot, 12.8-13.1 across the 2000 to 7000 rpm band. Gained about 15 hp at the wheels from the past last week. We're at 373 rwhp (inertia) and 369 rwhp (loaded 10%) now. Car is strong and the HP is carrying 367 at 5200 to 369 at 6900 rpm, flat. Very powerful at the higher RPM band! Still climbing at 6900 rpm! Would be grateful for your thoughts and if we have the ability to start the injectors a bit earlier in the combustion cycle. I'm wasting BTU's in the headers! Steve