So you want to put a LT4 supercharger on your L83/L86

SlowGMC · May 11, 2020

so you want to supercharge your l83 and don't want to spend 6-7k on a aftermarket kit. The LT4 supercharger could be an easier option for your l83 or l86 engine. I started out wanting to turbo my truck but after days and days of reading I decided to go ahead and try the LT4 SC route. I decided this route based solely on my preference and not because one way is better than the other.

ADM performance sells a whole kit to supercharge your truck. You could buy the kit with or without the supercharger. I decided I wanted to buy everything piece by piece so I could learn in the process. I didn't want someone doing all the work for me. Also I think it comes out to be a cheaper when you source all the parts yourself. I have and will be purchasing parts from ADM Performance because they offer some great products and sometimes the only product you may need to supercharger your truck.

So step one for me was to get the truck ready for the supercharger by buying all the supporting mods I would need. This list isn't all inclusive but will give anyone an idea of what they will need should they want to go forced induction on their engine.

1. Upgraded driveshaft (stock one piece drive shaft is known to blow up at speeds over 100mph on the dyno. Some people still currently run their stock driveshaft with no issues. Just remember the stock driveshaft was never intended to be used on a forced induction engine. I didn't want to risk blowing my driveshaft up so I went with a 2 piece drive shaft rated for 800hp.)

2. Headers and Y pipe ( you can run your stock headers and y pipe, I decided not to go this route because upgraded headers allow for lower heat Temps in the SC and better breathing of the engine)

3. E-85 conversion ( e85 conversion is to keep cooler Temps when boosting an NA engine. Especially in my area where e85 is plentiful and I don't have to worry about where I'm going to fill up everyday. I know some people don't have e85 around them and will supercharge their truck and run 91 oct pump gas. This is a optional modification that I felt would be beneficial for my build)

4. Tuning platform (I bought hp tuners and it is a amazing platform to make any and all adjustments to your tune. I am not sure what else is avaliable to us in regards to tuning because a handheld programmer just wouldn't do the job here with all the changes you need to make inside the tune to incorporate the injectors, supercharger, map sensor ect...)

5. Cold air intake (I currently have the k&n Blackhawk intake and I'm not sure if I'm going to be able to use it with the supercharger due to the supercharger putting the throttle body in a different location/ angle. ADM sells a kit that will allow you to use your factory airbox and I may go this route and just upgrade the filter)

6. Injectors (stock injectors will not be able to flow enough fuel for the supercharger. Our only upgrade option at this time for a decent price is lt4 injectors which are made to work with this supercharger. Be advised they are currently very hard to find and are on back order from GM)

7. Wideband (you will absolutely need a wideband gauge to be able to see what the engine is doing with all this new found air! I bought the AEM wideband kit and it plugs into the OBD port under the dash and it works great!

I bought the autolite steering column mount for it. The steering column mount isn't perfect by no means and required some drilling and sanding to get a decent fitment)

I think that about covers all the supporting mods I have done to ensure best reliability and performance from the engine/supercharger.

I have been told that I also need to go with the LT4 HPFP because the stock l83 HPFP won't be able to supply adequate fuel. I talked to ADM performance and On3 turbo and they all said it would be fine at the boost levels I plan to run so we will see. I sure would hate to have to remove the supercharger to upgrade the fuel pump. So I am currently undecided if I will upgrade it or not.

This will be all for my first post. Next post will be of all the stuff you will need to buy that will allow you to get that lt4 supercharger mounted and running on the truck.

lovelessjl · May 11, 2020

Sounds like you've got everything well in hand.

I would suggest upgrading to the lt4 fuel pump, you're gonna be in the valley to swap the injectors already anyways. It's a really simple 2 bolt in and out swap. I'd hate to see you end up running out of fuel especially when running e85, since you have to flow 30% more than with gasoline. But if the experts say you're good, then it's probably not necessary. I'm just a fan of over building things.

Can't wait to hear what you think when you get her done!

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SlowGMC · May 11, 2020

7 minutes ago, lovelessjl said:

Sounds like you've got everything well in hand.

I would suggest upgrading to the lt4 fuel pump, you're gonna be in the valley to swap the injectors already anyways. It's a really simple 2 bolt in and out swap. I'd hate to see you end up running out of fuel especially when running e85, since you have to flow 30% more than with gasoline. But if the experts say you're good, then it's probably not necessary. I'm just a fan of over building things.

Can't wait to hear what you think when you get her done!

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Thanks for your input. I have the same mentality in regards to the fuel pump. It's always better to be safe than sorry. I will most likely end up getting the lt4 fuel pump. I am going to start looking at prices and see where is the best deal to be had.

SlowGMC · May 11, 2020

this 2nd post will cover the parts you will need to install the LT4 supercharger. There is two way I have heard of you can do this. You can either use the tall adapter plates that are sold by ICT billet or you can use the smaller ones that are actually for a LT1 engine not the l83/l86. If you use the smaller adapter plates you would need to buy a lt4 valley cover, lt4 water pump, and a lot of other stuff to make it work. I didn't look into this to far so I cant answer any questions regarding it. I bought the tall adapter plates from ICT billet and these are the parts you would need to install the supercharger.

1. 2014-2016 LT4 supercharger from a corvette (do not buy the supercharger from a CTS-V it wont work, make sure its the proper year supercharger as well. The 17-19 LT4 supercharger will not work.)

2. Tall adapter plates from ICT billet (I don't know of any other company that sells these.)

3. LT4 Throttle body and gasket

3. LT4 Throttle body adapter ( rotates the TB to the 11 o clock position to allow clearance of the l83 water pipe)

4. Throttle body extension harness ( stock harness wont reach new TB position)

5. coolant sensor relocation kit ( coolant sensor has to be relocated because the supercharger/TB hits the sensor plug on the water pipe. The sensor gets relocated to the driver side of the engine where the block coolant passage is.

6. coolant sensor extension harness ( need to extend the coolant senor harness to reach new location)

7. MAP sensor and breakout harness ( you will need a new map sensor to read boost and a IAT breakout harness to reach the new map location on the supercharger and to move your IAT temps out of your MAF)

8. EVAP extension harness ( extends the evap harness to the new location on the supercharger)

9. belt, pulley and hub ( the stock pulley on the supercharger doesn't have the correct offset for l83/l86 engine. you will need a new hub and pulley to match the offset of the l83//l86 engine and the correct size belt to run the supercharger. All of this I bought through ADM)

10. Idler pulley bracket (This idler pulley bracket allows the belt to be ran to the supercharger, I bought this from ICT billet)

10. Heat exchanger, heat exchanger hoses, heat exchanger pump ( I bought all this from ADM but it can be sourced elsewhere depending on preference and how you want to route everything)

I think that about covers everything that is needed. I am sure I am missing some small things but those are the major components you will need. This is where I am at currently in my build. I don't have everything gathered that I need to finish the installation of the supercharger. I am hoping that I have all the parts by the end of the month and will be able to install the supercharger soon.

Edited July 2, 2020 by SlowGMC

SlowGMC · May 13, 2020

quick update. I talked to my tuner about the hpfp and he said it was a toss up if its needed or not for ethanol, that the stock hpfp would be fine on pump gas. So I will be purchasing the lt4 hpfp which is about 700$. I have also ordered the coolant sensor relocation kit from ADM performance

So once that's in, I'll get it installed and the fuel pump. Then all that's left is to install the supercharger.

Something I left off this list that may or may not be necessary is a boost guage. I have purchased one and bought a gauge pod for it that mounts it in the dash to keep a factory look to it.

teaser picture included

Edited May 13, 2020 by SlowGMC

SlowGMC · May 17, 2020

Supercharger is officially finished and ready to go on the truck!

ICT Billet TIAP sensor port plug

Lt4 throttle body

ICT LT4 throttle body adapter/rotator

LT4 Map sensor

ADM hub and pulley

2014-2016 LT4 SC Lid

Lt4 sc gasket set part#12679527

lovelessjl · May 17, 2020

Sweet! Just about time to start skinning knuckles.

Helpful tip for removing the intake manifold, unbokt the manifold cover, then unbolt the manifold itself. At that point you can pull the manifold out from under the cover. There are a couple harness tie downs on the back of the cover that make it almost impossible to remove with the manifold.

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SlowGMC · May 17, 2020

5 hours ago, lovelessjl said:

Sweet! Just about time to start skinning knuckles.

Helpful tip for removing the intake manifold, unbokt the manifold cover, then unbolt the manifold itself. At that point you can pull the manifold out from under the cover. There are a couple harness tie downs on the back of the cover that make it almost impossible to remove with the manifold.

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I installed the lt4 injectors last weekend and didn't put that intake manifold cover back on the engine to make it easier to remove the intake manifold at a later time.

lovelessjl · May 17, 2020

Nice, I put mine back on, but I removed the plastic piece that holds the harness. Stupid place to tie up a harness.

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SlowGMC · May 17, 2020

24 minutes ago, lovelessjl said:

Nice, I put mine back on, but I removed the plastic piece that holds the harness. Stupid place to tie up a harness.

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Yea. I bought the special tool that supposed to make it easier to remove the tie downs but the plastic cover kept bending. I just yanked on it until it came out.

I actually planned on putting it back on the intake manifold but I forgot about it. I installed the manifold and torqued it down and realized i forgot it. By then was to late to try to put it on lol.

SlowGMC · May 25, 2020

lt4 hpfp on the way! I plan on installing it this coming weekend along with the ADM coolant sensor relocation kit that came in a couple days ago. Should be the last loose ends that I have before the supercharger is ready to go on. I got my boost gauge as well from glow shift and got it mounted in my custom gauge pod. Looks pretty sweet!

SlowGMC · May 28, 2020

Look what came in today!

Lt4 fuel pump. I have been told by several sources the stock fuel pump will handle around 550hp but if you plan to run E-85 it will not be able to keep up with the extra demand in fuel.

Edited July 2, 2020 by SlowGMC

SlowGMC · May 30, 2020

Fuel pump and coolant sensor relocation have been installed. I also got a free coolant shower in the process was refreshing. So it's the official countdown to putting on the supercharger now! I'm getting excited about it.

SlowGMC · July 2, 2020

sorry for the lack of updates been a busy time for me with other things goins on. Update on the truck. I had to buy all new lt4 injectors because the ones I originally purchased were having issues due to having two different part numbers and not being able to tune the truck. Got that issue fixed and now I am waiting on my shipment which has the GM varimax IC pump and harnesses for it.

There's two pump you can run for the lt4 supercharger. Bosch and Varimax are the two brands that are mostly used. The varimax pump flows more than then Bosch pump so I went with that one. You will need a custom wiring harness for the ic pump because it only needs to run with the engine on. Several companies make the harness for it. Once those come in ill snap some pictures.

SlowGMC · July 6, 2020

GM varimax Pump, intercooler pump harness and evap extension/trigger harness has arrived from west michigan automotive. They do something different no other companies have done and their kit came with all the wiring you need for the intercooler pump, the correct plug for the new varimax pump and a special plug on the evap extension harness that triggers the pump on. All I had to do is connect the ground and power wires and connect the hoses and its ready to go.