Nick 6.5
Active Member
So to start off this will be long winded! And if anyone is still with me at the end I really appreciate any input. So to start off my truck is originally a 2004 ccsb lb7 federal truck. Had the head gaskets start leaking and on top of that I needed injectors as well so I decided to convert my truck to Lly. Found a running engine and harness with low compression to use for donor parts. All sensors injectors turbo wiring came off this engine except the maf. I used my Maf from my lb7 engine. New fleece performance heads on my short block and verified I had good compression before tear down. Compression was at 380+/- 5 roughly for all the cylinders except 3/5 that were leaking into each other. Engine was basically stock except tune, cold air intake and batmo wheel and intake horn. Tune was a 60hp tune super basic and used it for everyday driving and towing. Never had any issues with overheating and got 18-19mpg unloaded highway when I had good injectors. That is hand calculated. Engine coolant temps were always low 165 on average(I drilled 2 small holes in the flat of one of the thermostats). While towing the hottest sine we got was 216 while towing in 112 degrees heat in Arizona. Egts on average were 650-850 flat and would spike 1200-1250 while pedaling if if the grade and load was steep enough.
So fast forward to the Lly engine running in my truck. Stock tune with egr delete. A few issues coolant temps spike tremendously while going up any grade. I hit 208 unloaded up a small grade at 75 degrees outside temp. Thermostats are from lb7. Trans temps are always low 146-185. Another Issue is that boost while towing at 70 is only 5-8 psi. Unloaded at 70 is only 1-2psi and will not go above 18psi to save my life. Also egts are 1100-1200 on flat ground. Hard to keep it under 1300. Same boat same load and highway with the lb7 I’d be at 8-13 psi normally with egts 8-900. I’ve tried searching the forums and cleaned the Maf with no change to numbers. I believe the Maf numbers are within spec for engine idling anyway. Also Checked the map and barro and I believe those numbers are in spec? Maybe the map is a little off but I’m not a pro. These two pics are of koeo and koer. Does anyone see anything out of the norm? Or does anyone have any ideas on things to check? A side note no codes no smoke no miss fires just no power. Runs like a smooth dog.
Keep in mind never had any cooling issues with the lb7 and 60hp tune and even had 100hp tunes with no issues. Factory lb7 radiator.
Now with Lly stock tune massive cooling issues. Also I’ve checked for boost leaks and found none being that I just have the engine out and all clamps still tight. Also balance rates are all in check with the worst injector being -1.5. To add visually all injectors look new with glassy machined body. Is there a design flaw in GM LLY heads? Is there something that I’m missing here? I really regret the whole swap. Should have stuck with lb7.
Mods for the Lly engine are batmo wheel, PPE manifolds and up pipes, banks l5p upgraded oil cooler, pusher intake y bridge, head studs with grade c gaskets, s&b turbo mouthpiece and AEM cold air intake.
So fast forward to the Lly engine running in my truck. Stock tune with egr delete. A few issues coolant temps spike tremendously while going up any grade. I hit 208 unloaded up a small grade at 75 degrees outside temp. Thermostats are from lb7. Trans temps are always low 146-185. Another Issue is that boost while towing at 70 is only 5-8 psi. Unloaded at 70 is only 1-2psi and will not go above 18psi to save my life. Also egts are 1100-1200 on flat ground. Hard to keep it under 1300. Same boat same load and highway with the lb7 I’d be at 8-13 psi normally with egts 8-900. I’ve tried searching the forums and cleaned the Maf with no change to numbers. I believe the Maf numbers are within spec for engine idling anyway. Also Checked the map and barro and I believe those numbers are in spec? Maybe the map is a little off but I’m not a pro. These two pics are of koeo and koer. Does anyone see anything out of the norm? Or does anyone have any ideas on things to check? A side note no codes no smoke no miss fires just no power. Runs like a smooth dog.
Keep in mind never had any cooling issues with the lb7 and 60hp tune and even had 100hp tunes with no issues. Factory lb7 radiator.
Now with Lly stock tune massive cooling issues. Also I’ve checked for boost leaks and found none being that I just have the engine out and all clamps still tight. Also balance rates are all in check with the worst injector being -1.5. To add visually all injectors look new with glassy machined body. Is there a design flaw in GM LLY heads? Is there something that I’m missing here? I really regret the whole swap. Should have stuck with lb7.
Mods for the Lly engine are batmo wheel, PPE manifolds and up pipes, banks l5p upgraded oil cooler, pusher intake y bridge, head studs with grade c gaskets, s&b turbo mouthpiece and AEM cold air intake.
