LT4 / LT1 complete engine swap
Thread Starter
Race Director
Joined: Apr 2000
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From: Texas
LT4 / LT1 complete engine swap
Anyone remove their LT1 and install a complete LT4? I'm not talking about bolting on the blower, I'm talking the full engine. If so, can you share some of the challenges regarding wiring and the cooling system.
I think I have a bad cylinder on my current engine (hope to sort that out in the next couple of weeks) so in the meantime I'm exploring all options, from rebuild the existing, to new or used LT1 short block, to dropping in a used but complete LT4 from a 2017 or later Z06.
This is not currently a money discussion. First I need to understand the technical requirements and issues.
I think I have a bad cylinder on my current engine (hope to sort that out in the next couple of weeks) so in the meantime I'm exploring all options, from rebuild the existing, to new or used LT1 short block, to dropping in a used but complete LT4 from a 2017 or later Z06.
This is not currently a money discussion. First I need to understand the technical requirements and issues.
Pro
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Thread Starter
Race Director
Joined: Apr 2000
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From: Texas
I know for instance the inlet tube is different between the LT1 and LT4. I can buy one of those albeit I likely have to buy the complete air cleaner assembly. In the programming I need to account for a different MAP sensor. The LT4 IAT sensor is separate while the LT1 sensor as I recall is is built into the MAF. Those are all tables I can copy over.....ditto timing, fueling, etc.
I'm trying to figure out what else is different between the two. For instance, I'm not familiar with the LT4 cooling system and what I'd have to do to install that.
Thread Starter
Race Director
Joined: Apr 2000
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From: Texas
Having said that, lots of folks running around with high hp and torque engines still using the GS gearing. While not ideal, I'd make due at least for awhile if this comes to pass.
Given the age of the platform, I'm surprised no one has done this. Figured with 2014s now 10 years old and the GS 7 years old that someone would have done more than bolting on the LT4 blower
Thread Starter
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From: Texas
I *think* I'm 95% sure it's basically a bolt-in...but I'd sure rather be 100% if I decide to head this direction vs a rebuild of the existing engine
Le Mans Master
Joined: Oct 2014
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From: Atlanta GA
It should be no different than when someone bolts an LT4 blower on an LT1 so the original PCM is still used....just updated tables. Trading notes with guys on the HP Tuners forum, that's what they do....copy over the LT4 tables and then update for any additional mods such as headers.
I *think* I'm 95% sure it's basically a bolt-in... but I'd sure rather be 100% if I decide to head this direction vs a rebuild of the existing engine
I *think* I'm 95% sure it's basically a bolt-in... but I'd sure rather be 100% if I decide to head this direction vs a rebuild of the existing engine
Dave
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Thread Starter
Race Director
Joined: Apr 2000
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From: Texas
That's a good question! With a full swap, but in particular for use on a road course, I think I'd have to add the factory Z06 cooling circuit with the intercooler pump and Hx plus something like a GSpeed kit for even more cooling. Not surprisingly, I'm of the opinion that making it work for street use is probably fairly straight forward. Making it work for the race track....it's going to take a bit more thought.
One other thing I'm still trying to sort out is the engine harness. I think the only difference is the IAT and MAF sensors....but I'm still not 100% sure.
I'm good with making "Assembly level" changes...ie engine swap. I'm not enthused about making a Frankenstein cooling system, wire harness, etc.
Hopefully we can get a day below 100* and I can run the compression check on the existing engine.
One other thing I'm still trying to sort out is the engine harness. I think the only difference is the IAT and MAF sensors....but I'm still not 100% sure.
I'm good with making "Assembly level" changes...ie engine swap. I'm not enthused about making a Frankenstein cooling system, wire harness, etc.
Hopefully we can get a day below 100* and I can run the compression check on the existing engine.
Le Mans Master
Joined: Oct 2014
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From: Atlanta GA
@96GS#007 , I'm not sure if you can use this IAT/Baro breakout harness . it comes with the 3 bar MAP sensor and an IAT sensor, this is what I used when I install my Centri
https://dsxtuning.com/products/iat-b...nt=30058995723
Good Luck keep us posted !
Dave
https://dsxtuning.com/products/iat-b...nt=30058995723
Good Luck keep us posted !
Dave
Pro
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I would contact https://lsa-conversion-store.myshopify.com/
I bought everything I needed from them when I did a lt4 on my lt1. I know you are planning on doing a whole engine swap. The only thing you would need is the harness and a different water pump for the blower. The water pump they use is an upgrade from the z06 oem. Then get a tune.
I bought everything I needed from them when I did a lt4 on my lt1. I know you are planning on doing a whole engine swap. The only thing you would need is the harness and a different water pump for the blower. The water pump they use is an upgrade from the z06 oem. Then get a tune.
Thread Starter
Race Director
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From: Texas
I would contact https://lsa-conversion-store.myshopify.com/
I bought everything I needed from them when I did a lt4 on my lt1. I know you are planning on doing a whole engine swap. The only thing you would need is the harness and a different water pump for the blower. The water pump they use is an upgrade from the z06 oem. Then get a tune.
I bought everything I needed from them when I did a lt4 on my lt1. I know you are planning on doing a whole engine swap. The only thing you would need is the harness and a different water pump for the blower. The water pump they use is an upgrade from the z06 oem. Then get a tune.
I ran a compression test today and 1 cylinder is 20% less than the others. Soooooooo....looks like I have a winter project.
Thread Starter
Race Director
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From: Texas
It's the cylinder. I was seeing 3psi of positive pressure in the crankcase. "Fixed" that with a massive vent system so it was no longer forcing oil out of the rear main. Now after a 20 minute track session I'm now draining up to 3/4 of a quart of oil out of the secondary catch can. The primary catch can has a drain-back line to the engine so that means I have a lot more oil getting past that's not being measured.
This all started after the plug wire popped off on track.
I should mention the heads are Frankenstein heads. Yeah....even new parts break but leaky valves don't fit the other symptoms.
This all started after the plug wire popped off on track.
I should mention the heads are Frankenstein heads. Yeah....even new parts break but leaky valves don't fit the other symptoms.
Thread Starter
Race Director
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From: Texas
Looks like the two wiring differences are the for the IAT and MAF since those functions are contained within the MAF sensor on the LT1 vs separate IAT and MAF sensors on the LT4. The other wiring difference would be the addition of the wiring for the intercooler pump. On top of that there are the added cooling lines for the intercooler.
I need to look to see how the intercooler pump operates....on with "key on"....ie just find a switched 12v source or is it controlled via the PCM. When I look at the tune I see there are min parameters for the Engine Run Time (ERT), IAT, and MAT so that's a good indicator it's PCM controlled which means more wiring.
Le Mans Master
Joined: Oct 2014
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From: Atlanta GA
As far as the IAT , the breakout harness link that I sent u works great , it also has the 3 bar MAP sensor , you plug that in where the old 1 bar sensor plugs in and then you take the 1 bar and plug it into the breakout harness , this now gives you your boost measurement based on real time relative air preasure. I still use my stock MAF sensor and I assume that you would just swap in a LT4 sensor. As far as the coolant pump , plenty of people have put the LT4 blower on a LT1 so I assumed it was just switched 12volt but I am sure someone has the " instructions "
I am staying close to this build because if I " pop" a piston I am going to go route also possibly
Keep us posted on your progress
Dave
I am staying close to this build because if I " pop" a piston I am going to go route also possibly
Keep us posted on your progress
Dave