LT1 Swap into 1986 IROC
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Joined: Feb 2022
Posts: 77
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From: New Jersey
Car: 1985 Z28 TPI 305
Engine: 5.0L VIN F TPI
Transmission: 700 R4
Axle/Gears: 3:23
LT1 Swap into 1986 IROC
My son purchased a 1986 IROC earlier this year. Car is LG4 with T-5 Manual He just acquired a 1995 Firebird Formula donor that is LT-1, T56 and LSD Disc Rear. Very nice donor car.
I am helping him plan the swap. We are sourcing a 1995 Corvette front harness to keep the AC and relocate everything to upper driver side, thereby avoid notching the cross member.
So, as I understand it, we will harvest the complete wire harness and use the LT1 ECM.
We will use a 1995 C-4 Corvette Water Pump to eliminate the oil cooler water connection on the 1995 Fired Bird Water Pump. This LT-1 does not have an oil cooler so currently there is a bypass from the water pump, direct to the Gen 4 Radiator.
Perform a VATS delete so he can use his current steering column.
The questions I have are as follows:
1. LT1 Steam vent pipe. We will keep this running through the throttle body as he plans to drive car year round and we live in NJ. We want to use the current Gen 3 IROC Radiator as it is new. Where do we mount the steam vent line since the IROC does not have a port to receive it. The Gen 4 LT1 radiator may fit but I would prefer not to use it. Are we looking at an aftermarket radiator or modifying the Gen 3. How would we add a port to an existing plastic tank radiator?
2. Air conditioning wiring. the Corvette AC system utilizes an orifice tube, similar to the third gen camaro. We plan to use the 3rd gen evaporator, orifice tube ad condenser (new) and a C-4 Vette compressor which will fit the front drive, and make up our own AC lines from combining the Gen 3 with the C-4 lines. Has anyone done this and can give advice how to wire up so fans kick on correctly, pressure switches etc?
3. Do we need the oil cooler bypass line for some other reason or the C-4 Vette Water Pump will be fine?
Aside from above, if we are missing any other issues that others have encountered and/or solved, please advise.
Thanks in advance.
PCOPP
I am helping him plan the swap. We are sourcing a 1995 Corvette front harness to keep the AC and relocate everything to upper driver side, thereby avoid notching the cross member.
So, as I understand it, we will harvest the complete wire harness and use the LT1 ECM.
We will use a 1995 C-4 Corvette Water Pump to eliminate the oil cooler water connection on the 1995 Fired Bird Water Pump. This LT-1 does not have an oil cooler so currently there is a bypass from the water pump, direct to the Gen 4 Radiator.
Perform a VATS delete so he can use his current steering column.
The questions I have are as follows:
1. LT1 Steam vent pipe. We will keep this running through the throttle body as he plans to drive car year round and we live in NJ. We want to use the current Gen 3 IROC Radiator as it is new. Where do we mount the steam vent line since the IROC does not have a port to receive it. The Gen 4 LT1 radiator may fit but I would prefer not to use it. Are we looking at an aftermarket radiator or modifying the Gen 3. How would we add a port to an existing plastic tank radiator?
2. Air conditioning wiring. the Corvette AC system utilizes an orifice tube, similar to the third gen camaro. We plan to use the 3rd gen evaporator, orifice tube ad condenser (new) and a C-4 Vette compressor which will fit the front drive, and make up our own AC lines from combining the Gen 3 with the C-4 lines. Has anyone done this and can give advice how to wire up so fans kick on correctly, pressure switches etc?
3. Do we need the oil cooler bypass line for some other reason or the C-4 Vette Water Pump will be fine?
Aside from above, if we are missing any other issues that others have encountered and/or solved, please advise.
Thanks in advance.
PCOPP
Member
Joined: Apr 2001
Posts: 225
Likes: 1
From: Phoenix, AZ
Car: 86 TA
Re: LT1 Swap into 1986 IROC
1. The best bet would be to use an upper radiator hose from a 94 fbody and follow the factory routing. It will have a hose that you can use for the TB/steam pipe.
http://shbox.com/1/93-94_hoses.jpg
http://shbox.com/1/heater_hoses_93-94.jpg
Here is the 95-97 setup as well so you can see the difference.
http://shbox.com/1/95-97_hoses.jpg
http://shbox.com/1/heater_hoses.jpg
FYI it has been stated that it's for deicing the throttle body many times, but really it's most likely for heating up the throttle body as quick as possible to help keep the emissions down. I've been messing with f-bodies for years and have yet to hear of anyone have an iced throttle body after a bypass. I've started mine in 10* quite a few times without issue. I would do the TB bypass, run the 94 upper hose and use the breakout hose from it for the steam pipe.
2. I have mine wired up just like the factory setup on a 95. The stock PCM has two wires that will go to your fan relays for activation. When the temp hits the threshold I have it set at in the PCM tuning they come on, they also come on when the AC is activated.
3. Oil cooler is absolutely not needed for most applications. Plenty of people have removed them for clearance or to rid the system of unnecessary leaks.
http://shbox.com/1/93-94_hoses.jpg
http://shbox.com/1/heater_hoses_93-94.jpg
Here is the 95-97 setup as well so you can see the difference.
http://shbox.com/1/95-97_hoses.jpg
http://shbox.com/1/heater_hoses.jpg
FYI it has been stated that it's for deicing the throttle body many times, but really it's most likely for heating up the throttle body as quick as possible to help keep the emissions down. I've been messing with f-bodies for years and have yet to hear of anyone have an iced throttle body after a bypass. I've started mine in 10* quite a few times without issue. I would do the TB bypass, run the 94 upper hose and use the breakout hose from it for the steam pipe.
2. I have mine wired up just like the factory setup on a 95. The stock PCM has two wires that will go to your fan relays for activation. When the temp hits the threshold I have it set at in the PCM tuning they come on, they also come on when the AC is activated.
3. Oil cooler is absolutely not needed for most applications. Plenty of people have removed them for clearance or to rid the system of unnecessary leaks.
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