Originally Posted by John B

Why was I under the impression that Direct Injection requires fuel pressure of 2000+psi?

Originally Posted by vannatta20

Remember on Gen V's you have two fuel pumps. A mechanical pump on the engine in the valley cover and a low pressure in tank pump to provide fuel up to the engine. The mechanical pump is driven off the cam and provides 500 to 3000 psi. The variation is due to fuel requirements of the engine. idling they float around 500 psi. Wide open throttle on trucks it will hit 2000 psi. Lt4's at WOT will hit 3000 psi. This is due to the very narrow window to squirt enough fuel to support the horsepower. Higher pressure = more fuel.

The low side is simply to supply enough fuel to the high side. As long as the high side sees over 40 psi it will run. Now to support more power you need a good volume of fuel. I have found the standard aftermarket pumps that support 450 to 500 hp work great with them set at 57 psi. You can really set them from anywhere from 45 to 75 psi. The higher the pressure will work the pump harder and shorten the life of the pump.

You can see if your fuel requirements are working or not by watching commanded and desired high pressure fuel. If it is requesting 1500 psi and you only can make under that you might not have enough low side pump fueling. As well you can see low pressure. If the pressure falls below what you have it set to then your pump is not able to keep up with the demand.

Mitch

Swaptimeusa

Originally Posted by John B

Oh hell yes, BRAIN FART on my part! Forgot about needing larger lobes to drive the mechanical pump when upping the HP on the LT1/4/5 motors, thanks Mitch and great info by they way!

2nd question for you....how far off are LS1 header flanges/bolt holes compared to LT1/4 exhaust ports?

Originally Posted by vannatta20

The flanges are very close. We have used LS headers by cutting off the LS flange and welding LT Exhaust flanges on.

Originally Posted by Toddoky

The discrepancy in the cylinder head exhaust geometry goes beyond the manifold flange bolt pattern. The ports on the LT heads are shifted laterally almost an inch from the LS port position (the ports are closer to the front of the engine on the driver side and closer to the rear of the engine on the passenger side). The motor mount boss bolt pattern is also different on the LT engine family and the mounting bosses also protrude further out from the LT block.

Originally Posted by vannatta20

7. Fan Control- You can use PWM only on a factory ecu. Discrete does not work. I am using PWM with awesome results. It controls the fan speed based on A/C pressure and ECT. GM performance parts ecu uses a standard on/off signal. Update!! There is a trick to make a relay work to control a single speed fan. PM me for how to do this.

Originally Posted by Mulchboy

Hi guys. New here. Starting on a 19 Camaro SS/ 60's Impala build. I bought a sideswiped 19 camaro 6.2 di and 10 speed auto, so i have basically everything from a donor car. I picked up an art morrision air ride chassis that was a stalled project. So i have some pretty good bones. Looking at dirty dingo mounts and pulley system. Anybody have any suggestions before i get the checkbook out? I read that the factory mounts are good to eliminate vibration. where should i send the harness? who does the flashing. Is anyone doing adapters so I can use the factory brakes from the camaro. Im going to start to mock up the engine to see if i need a new oil pan. Ive done a lot of reading, but seems like there is a lot of knowledge here. Anybody that has tried this and has input please hit me up.

Originally Posted by vannatta20

I would like to start a thread where we can all gather basic swap info into the new LT1, LT4, L86, and L83 engines. All the info given below is what I have experienced. I have about 400 miles on the swap (2008 JK Wrangler) with no issues. I have now done about 10 gen v swaps as of 2018.


1. Fuel pressure requirements- So far the standard fuel pressure of around 57 psi works great. Fuel trims are dead on. Just make sure you have a pump that will support the engines power. I have tested using the Fuel Pressure control modules with great success. If using the FPCM use regulator for a non pwm pump. If using a PWM pump then do not use a regulator. Basically if you can monitor fuel pressure after the pump monitor it for any pressure drop. If no pressure drop then you are supplying the engine with enough fuel. Running a pump at 74 psi is not necessary at all.

2. Programming- I used hptuners to delete vats and any DTC codes that showed up. Get the matching ECU and BCM from the donor vehicle. You will have issues programming a new OS and VIN if you do not. (BCM needed for transmission tap shift control and the brake pedal position sensor if used) This ECU has so many complex tables be careful of any changes you do. If you use GM SPS service you can not program off vehicle. You will need the ECU, TCU, and BCM at least to program. You most likely will not be able to change the VIN but it will program the new OS. The 2016 model year ECU is NOT swap friendly.

3. Transmissions- I have only used the matching 6l80e and 8l90e transmissions. Everything works including tap shift and power modes. The new transmissions really make this an awesome combo. Early transmissions can be used as well along with manual transmissions. Be aware the flexplate and flywheel have a different bolt pattern.

4. Accessory Drive- We just added a power steering pump on a truck layout. Holley, ICT billet, and dirty dingo offer different drive solutions. If using DOD/AFM you will need to keep the vacuum pump.

5. Wiring Harness- I modded the harness myself and is not too hard. Please recommend any companies that currently make custom harnesses. Having it modded will be by far the cheapest and quickest solution.

6. Fuel pump signal- This is now can bus driven. For proper control us a fuel pressure control module. (UPDATE)!!!You can control the fuel pump via a relay. Connector E92 X1 with the blue face use pin 32 (grey wire) This is a positive turn on signal for your relay. So pin 86 use this wire. Pin 85 will be ground. 30 and 87 are power in and out to fuel pump.

7. Fan Control- You can use PWM only on a factory ecu. Discrete does not work. I am using PWM with awesome results. It controls the fan speed based on A/C pressure and ECT. GM performance parts ecu uses a standard on/off signal. Update!! There is a trick to make a relay work to control a single speed fan. PM me for how to do this.

8. Limp mode issues- I had no throttle without connecting the transmission computer up. If not using the matching transmission that came with the engine you will need to find a manual transmission tune. (If anyone finds a solution please post. GM's swap harness and ECU will not have this issue.

9. DOD/AFM- It is highly active with the stock tune. At 65 mph it can be in 4 cylinder mode. Cruising around town it will kick in all the time. Its loud and annoying to be honest. GM tuned the exhaust so you do not hear the change. For now I have it only working on steady cruises.

10. Engine Mounts- It is very important to use factory mounts if retaining AFM/DOD function. The mounts help absorb the extra vibrations. Please list any companies that make conversion mounts. I had a set made for the Jeep JK wrangler.

11. Gauges- Best bet is to use can bus driven gauges from dakota digital or speed hut. There is no VSS signal or tach signal from the ecu to drive a gauge

Originally Posted by dannyj661

hello. I have a lt swap I'm doing had speartech do the tune. Had ken wolkens do the harness. Truck starts and idles but when put in gear it's in limp mode I believe. The throttle is dead. I recieved the engine and trans from the customer looked as though it was originally together. The codes its giving are

P0073
u0101 lost common with tcm.
u0073
p12a6


I think the u0101 is the issue. What are your thoughts danny 661.212.0429. Fan work has been done for months this issues has been an issue trying to resolve for 6 months.

Originally Posted by vannatta20

Only code that really matters is the u101. You need to get a good scanner to see if you can read the transmission module. If the scanner can not read it you either have a wiring problem or a fried TCM. Check the can bus wires with ignition on at the tcm. They should be around 2.5 to 3 volts. They are a white wire and a white blue wire on the bottom of the tcm connector.

Originally Posted by dannyj661

On the trans the scanner says no communication with tcm.

The info below

Pin 10 white 3.2v steady
pin 11 1.68v blue steady
Pin 13 blue 2.3v fluctuate
Pin 14 white 2.5v fluctuates

Originally Posted by dannyj661

The battery is 12v key is like 11.8. I'll have to see if trans is humming.
attached is a pic of tranny information.