Low power slow responce
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Teching In
Joined: Nov 2013
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Low power slow responce Been awhile since my last post, I hope someone can steer me in the correct direction?
I have A 2001 Chevy Silverado 2500HD 6.0 4x4 crew cab short box.
About two years ago, I completed my frame off restoration and during that process I replaced my stock engine with the following.
Summit 6.0 short block,460 HP Trickflow upper kit from Summit, Part Number: TFS-K306-485-460, Camshaft specs are 216/220 duration, .560 in./.560 in. lift, 114 lobe separation angle.
Cylinder heads Intake Runner Volume (cc):215cc Exhaust Runner Volume (cc):80cc Intake Valve Diameter (in):2.040 in. Exhaust Valves Diameter (in):1.575 in. Intake Valve Angle:13.50 Exhaust Valve Angle:13.50
I have headers, MSD Coils, 85 MM Throttle body, Dorman intake, stock fuel injectors, cold air intake, automatic transmission. I had Black Bear performance tune the computer.
My issue is, It seems that the response is way to slow from 700 RPM’s to 3000 RPM’s doesn't matter if I'm at idle or in gear, can someone please give me some recommendations on how to fix this.
I have A 2001 Chevy Silverado 2500HD 6.0 4x4 crew cab short box.
About two years ago, I completed my frame off restoration and during that process I replaced my stock engine with the following.
Summit 6.0 short block,460 HP Trickflow upper kit from Summit, Part Number: TFS-K306-485-460, Camshaft specs are 216/220 duration, .560 in./.560 in. lift, 114 lobe separation angle.
Cylinder heads Intake Runner Volume (cc):215cc Exhaust Runner Volume (cc):80cc Intake Valve Diameter (in):2.040 in. Exhaust Valves Diameter (in):1.575 in. Intake Valve Angle:13.50 Exhaust Valve Angle:13.50
I have headers, MSD Coils, 85 MM Throttle body, Dorman intake, stock fuel injectors, cold air intake, automatic transmission. I had Black Bear performance tune the computer.
My issue is, It seems that the response is way to slow from 700 RPM’s to 3000 RPM’s doesn't matter if I'm at idle or in gear, can someone please give me some recommendations on how to fix this.
" I had Black Bear performance tune the computer."
A mail order tune?
Without the ability to data log, make changes, and see what's really going on, it can be a long, drawn out process.
A mail order tune?
Without the ability to data log, make changes, and see what's really going on, it can be a long, drawn out process.
Couple of things to check -
- Trucks come (or came - haven't been into a newer
one) with pretty bad burst knock settings. Have seen
a truck that couldn't get out of its own way due to
this, as you try to run up the RPM the air mass change
(VE slope) hits the burst knock delta-cylinder-air
trigger threshold and pulls timing back even when
tip-in is long past. Look to stock car tune values for
a truck that isn't all about towing fuel economy.
Cam seems to make this worse as more of the RPM
range is "slope-y" rather than flat-top, VE-curve-wise.
Two, be sure that you are not seeing the Knock Learn
Factor driven up due to persistent knock detect. That
will hang a stone around your neck.
- Trucks come (or came - haven't been into a newer
one) with pretty bad burst knock settings. Have seen
a truck that couldn't get out of its own way due to
this, as you try to run up the RPM the air mass change
(VE slope) hits the burst knock delta-cylinder-air
trigger threshold and pulls timing back even when
tip-in is long past. Look to stock car tune values for
a truck that isn't all about towing fuel economy.
Cam seems to make this worse as more of the RPM
range is "slope-y" rather than flat-top, VE-curve-wise.
Two, be sure that you are not seeing the Knock Learn
Factor driven up due to persistent knock detect. That
will hang a stone around your neck.
Jimmyblue put up a good guess, but that is really the best to hope for at this point. Your mechanical combination sounds very reasonable, but your completely unknown tune is a variable that we can only offer "somewhat targeted" wild speculation about.
The right answer would be to start scanning with
emphasis on the net spark advance and all of the
various spark retard elements, plus knock learn factor.
Of course "seems slow" is a bit subjective. People
often seem to think their car should be faster just
because they did something that makes it louder.
emphasis on the net spark advance and all of the
various spark retard elements, plus knock learn factor.
Of course "seems slow" is a bit subjective. People
often seem to think their car should be faster just
because they did something that makes it louder.
