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Pontiac GTO 2004-2006 The Modern Goat

Going from supercharger to twin or single turbo.

 
Old 11-18-2018, 02:45 AM
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Default Going from supercharger to twin or single turbo.

My current powerdyne supercharger just isnít cutting it anymore and am thinking of going the turbo route, preferably twins if possible. No pulleys to deal with and slipping/ broken belts.

I currently have an iron block lq9 6.0 with 317 heads with an n/a cam which Iíll be switching out for a turbo cam once I get my turbo parts. Iím gonna piece a kit together, all Iíll need is the turbo(s), wastegate and manifolds.ill be upgrading the fuel pump, injectors too. I already have an intercooler and bov That i use for my blower set up. Iím having a hard time Finding the right manifolds as I need to keep the a/c especially here in fl.

What turbo manifolds have you guys used on your gtoís that let you keep a/c and doesnít require relocating accessories Most likely Iíll be going twin turbo and I already have plenty of space for them since I relocated my battery a month ago. I have access to a shop and can fab up and weld parts if needed, saving a lot of money in the long run.

What size turbos should I go with? Iíll be keeping the boost down and gradually I up as I strengthen the drive line.

Anything else I should know before taking the plunge?

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Old 11-18-2018, 10:21 AM
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I still think this is the best way to go keeping AC and ABS: https://ls1tech.com/forums/forced-in...keeping-c.html
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Old 11-25-2018, 03:47 AM
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Twins are a nuisance in most cases. You have double the headache in almost every regard with no benefit. An lq9 will spin a single fast enough to never worry about lag, and you only do half the plumbing fab work. With a battery relocate, you could use the driver side gto manifold and a truck manifold for a passenger side single log setup that would retain A/C. Or you could remove the hood and do an up and forward china tube header twin setup with a couple of 96mm turbos that look large enough to eat children and deal with the minor drivability issues that may entail. I probably skipped over some options in between.
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Old 12-01-2018, 03:51 PM
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Originally Posted by ACCLR8N View Post
I still think this is the best way to go keeping AC and ABS: https://ls1tech.com/forums/forced-in...keeping-c.html
Nice thread, I have the return-less system on my gto, what should i get for my fuel system upgrades? what pump?
So far tonight I'm gonna order:
Deka 80lb injectors
The truck manifolds you mentioned
A 78/75 on3 turbo
44mm wastegate from wyntonm
Maybe a btr stage 2 turbo cam kit or an ls9 cam.
Then I'll be able to get a better visual on what its gonna take to get it done.
I was debating on doing the crossover to the rear but i see that a front run crossover may work as well so i might just do that.
I still have the oil feed/ return lines to do but ill do that after the manifolds are in and fabbed up to fit the turbo.


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Old 12-02-2018, 08:59 AM
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Bare with me as i have little experience with turbos and am learning as i go with this build but what psi waste gate would i need? at the moment i don't know how many psi of boost my engine will like or be set at so any help would be appreciated. I'm going to use my same Tial Q bov I used with my previous centri supercharger set up, I'm assuming I'm gonna need a different spring because the spring the bov came with was for supercharged applications only. now that I'm going turbo what psi spring would you recommend?
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Old 12-02-2018, 06:02 PM
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If you do a return style fuel system and 60lb injectors, you won't have to scale your tune. I am running a DW65C fuel pump. They have a DW300c now that flows even more and still fits in the fuel bucket. This is on 93 octane. If you plan to go E85 then you will need 30% more fuel.

Wastegate I would recommend keeping boost under 12psi unless you are forged. That seems to be where people start getting into trouble on stock long blocks. I started with a 4psi while I dialed in my tune. My tires won't hold the 7psi I am currently, so I haven't bothered to turn it up...yet.

BOV should work the same. Connect the reference hose to the manifold after the throttle body so it sees low pressure when the throttle snaps shut.
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Old 12-02-2018, 06:36 PM
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That ON3 78/75 turbine side is smallish. Granted, people are making a 1000hp with it but you will see boost fall off as back pressure increases. I have been eyeing the CXRacing Gt45R as a potential upgrade. https://www.ebay.com/itm/CXRacing-GT...-/181106806132

Keep in mind, the turbo is going to make more power at the same boost that your belt driven compressor did.
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Old 12-02-2018, 07:06 PM
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Originally Posted by ACCLR8N View Post
If you do a return style fuel system and 60lb injectors, you won't have to scale your tune. I am running a DW65C fuel pump. They have a DW300c now that flows even more and still fits in the fuel bucket. This is on 93 octane. If you plan to go E85 then you will need 30% more fuel.

Wastegate I would recommend keeping boost under 12psi unless you are forged. That seems to be where people start getting into trouble on stock long blocks. I started with a 4psi while I dialed in my tune. My tires won't hold the 7psi I am currently, so I haven't bothered to turn it up...yet.

BOV should work the same. Connect the reference hose to the manifold after the throttle body so it sees low pressure when the throttle snaps shut.
I ordered a 44mm wastegate from wyntonm last night and it says 4 psi. Does that mean Iím limited to 4 psi of boost??

I also ordered the on3 78/75 turbo with oil plates and gaskets, some v band clamps, t4 flange , aem wideband o2, a oil feed plate that goes above the oil filter that is flat and tapped to 1/8 npt, an -10an weldable bung for the oil return. Iím a little confused with the oil restriction feed plates and if I need them or not.

About the fuel system, i guess I will have to run a return to the fuel rail. Luckily I have an aftermarket fuel rail and the return exit side is just capped off. Would I just have to run a line back to the tank to make it a return system or is there more?

Iíd like to run e85 in the future. I havenít ordered them yet but Iím planning on using 80lb deja injectors so I have room to grow. Will the dw300c pump work with the 80lb injectors?

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Old 12-02-2018, 07:40 PM
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Originally Posted by ACCLR8N View Post
If you do a return style fuel system and 60lb injectors, you won't have to scale your tune. I am running a DW65C fuel pump. They have a DW300c now that flows even more and still fits in the fuel bucket. This is on 93 octane. If you plan to go E85 then you will need 30% more fuel.

Wastegate I would recommend keeping boost under 12psi unless you are forged. That seems to be where people start getting into trouble on stock long blocks. I started with a 4psi while I dialed in my tune. My tires won't hold the 7psi I am currently, so I haven't bothered to turn it up...yet.

BOV should work the same. Connect the reference hose to the manifold after the throttle body so it sees low pressure when the throttle snaps shut.

Is a return system necessary for boost? can't i add a boost a pump?
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Old 12-03-2018, 09:40 AM
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Originally Posted by ACCLR8N View Post
That ON3 78/75 turbine side is smallish. Granted, people are making a 1000hp with it but you will see boost fall off as back pressure increases. I have been eyeing the CXRacing Gt45R as a potential upgrade. https://www.ebay.com/itm/CXRacing-GT...-/181106806132

Keep in mind, the turbo is going to make more power at the same boost that your belt driven compressor did.
GT45 isn't much of an upgrade over a 78/75... you talking 2mm on compressor and turbine. For $100 cheaper then the cost of that GT45 you can get an 88/84 gaining 10mm compressor and 9mm turbine.

https://www.on3performance.com/shop/...harger-1050hp/
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Old 12-03-2018, 10:24 AM
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Originally Posted by Javi7808 View Post
My current powerdyne supercharger just isnít cutting it anymore and am thinking of going the turbo route, preferably twins if possible. No pulleys to deal with and slipping/ broken belts.

I currently have an iron block lq9 6.0 with 317 heads with an n/a cam which Iíll be switching out for a turbo cam once I get my turbo parts. Iím gonna piece a kit together, all Iíll need is the turbo(s), wastegate and manifolds.ill be upgrading the fuel pump, injectors too. I already have an intercooler and bov That i use for my blower set up. Iím having a hard time Finding the right manifolds as I need to keep the a/c especially here in fl.

What turbo manifolds have you guys used on your gtoís that let you keep a/c and doesnít require relocating accessories Most likely Iíll be going twin turbo and I already have plenty of space for them since I relocated my battery a month ago. I have access to a shop and can fab up and weld parts if needed, saving a lot of money in the long run.

What size turbos should I go with? Iíll be keeping the boost down and gradually I up as I strengthen the drive line.

Anything else I should know before taking the plunge?


Have you seen my single turbo build thread on my GTO? I still have ac and I have zero issues with heat. I built my own manifold and used a shorty header on the passenger side.
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Old 12-03-2018, 10:35 AM
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Heres my thread. may help you. I do need to update it. I'll do that shortly.....I'm changing turbos...

https://ls1tech.com/forums/forced-in...o-build-6.html

Last edited by Kfxguy; 12-03-2018 at 10:55 AM.
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Old 12-03-2018, 11:22 AM
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Originally Posted by Javi7808 View Post


I ordered a 44mm wastegate from wyntonm last night and it says 4 psi. Does that mean Iím limited to 4 psi of boost??

I also ordered the on3 78/75 turbo with oil plates and gaskets, some v band clamps, t4 flange , aem wideband o2, a oil feed plate that goes above the oil filter that is flat and tapped to 1/8 npt, an -10an weldable bung for the oil return. Iím a little confused with the oil restriction feed plates and if I need them or not.

About the fuel system, i guess I will have to run a return to the fuel rail. Luckily I have an aftermarket fuel rail and the return exit side is just capped off. Would I just have to run a line back to the tank to make it a return system or is there more?

Iíd like to run e85 in the future. I havenít ordered them yet but Iím planning on using 80lb deja injectors so I have room to grow. Will the dw300c pump work with the 80lb injectors?

You can get electronic boost controllers to modify the 4psi. You can also add Tial springs to it (I did). Manual boost controllers are unstable increasing boost more than 50%. The manual controllers become erratic with temperature changes.

No, you don't need a return system. Just easier to tune and easier on your fuel pump. Your pump is operating full blast all the time and at idle/cruising most of that fuel is just being returned to the tank internally. Also the stock system operates at 58psi (4 bar) while your injectors are rated at 43.5psi (3 bar). I doubt you will need a boost-a-pump. I assume you are not trying to get 1000hp on E85? Might be a bad assumption on my part. A +600hp GTO needs a lot of upgrades.

My fuel system returns fuel from the front mounted regulator. There are lots of ways to do it. The GTO's regulator is built into the fuel bucket. You have to block that off if you are going to do anything different.

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Old 12-03-2018, 11:32 AM
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Originally Posted by SLOW SEDAN View Post
GT45 isn't much of an upgrade over a 78/75... you talking 2mm on compressor and turbine. For $100 cheaper then the cost of that GT45 you can get an 88/84 gaining 10mm compressor and 9mm turbine.

https://www.on3performance.com/shop/...harger-1050hp/
I am seeing greatly different turbine specs than you are reporting. The LS motors usually want at least an 84mm turbine on a single to keep back pressure down and fuel economy high. The GT45's have nice big 87mm turbines. I haven't; seen larger without going to a T6 flange. The ON3 75mm turbine will spin up faster and the back pressure isn't terrible at low boost.

Car Craft did a test a couple years ago swapping out a Whipple for a 7?/75 turbo. I have kept that article. The blower needed 29 psi to hit the 1K mark while the turbo did it at 19psi. That is the efficiency of a turbo system. They did note the boost was falling off however they guessed due to back pressure.
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Old 12-03-2018, 11:45 AM
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Set the power goal, RPM, etc. and then spec the turbo. I wouldn't bother with the GT45 either for lower boost on a street car. If you're only ever going to run single digit boost then put a smaller turbo in there and let it spool stupid fast without worrying about backpressure.
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Old 12-03-2018, 01:34 PM
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Originally Posted by ACCLR8N View Post
I am seeing greatly different turbine specs than you are reporting. The LS motors usually want at least an 84mm turbine on a single to keep back pressure down and fuel economy high. The GT45's have nice big 87mm turbines. I haven't; seen larger without going to a T6 flange. The ON3 75mm turbine will spin up faster and the back pressure isn't terrible at low boost.
Did you look at the specs in the link you posted? What you linked to on ebay is an 80mm compressor with a 77 turbine, like I said not much of an upgrade from a 78/75.

Compressor Wheel (Major/Exducer)80/108mm
Turbine Wheel (Major/Inducer) 77.4/88.9 mm
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Old 12-03-2018, 05:22 PM
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What cam do you have? what are your power goals?
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Old 12-03-2018, 11:16 PM
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Originally Posted by Kfxguy View Post
What cam do you have? what are your power goals?
i currently have a Howardís cam: 226/234 109 lsa

Iím looking to order a BTR stage 2 turbo cam kit with the springs and pushrods included pretty soon.

For now my goal is at 500 to 600hp.
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Old 12-03-2018, 11:55 PM
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Originally Posted by ACCLR8N View Post
You can get electronic boost controllers to modify the 4psi. You can also add Tial springs to it (I did). Manual boost controllers are unstable increasing boost more than 50%. The manual controllers become erratic with temperature changes.

No, you don't need a return system. Just easier to tune and easier on your fuel pump. Your pump is operating full blast all the time and at idle/cruising most of that fuel is just being returned to the tank internally. Also the stock system operates at 58psi (4 bar) while your injectors are rated at 43.5psi (3 bar). I doubt you will need a boost-a-pump. I assume you are not trying to get 1000hp on E85? Might be a bad assumption on my part. A +600hp GTO needs a lot of upgrades.

My fuel system returns fuel from the front mounted regulator. There are lots of ways to do it. The GTO's regulator is built into the fuel bucket. You have to block that off if you are going to do anything different.

Yeah, Iím definitely gonna order an electronic boost controller, donít want any issues in the future.

My goal is 500 to 600hp, probably wonít run e85 as Iím not looking to make 1000hp.

Now for the fuel part, this is where I get confused. I thought you couldnít use the stock fuel system for boost? You say my stock system will work? Iíve heard that Iíll need at least 60lb injectors? I have a set of gray 12561462 injectors in the car, I believe theyíre 28#s maybe?

Also, Iím liking the return system option.i donít want to overwork anything. With a return fuel system I would have to run a return line from the fuel rail coming off an fpr back to the tank, then cap off the built in regulator in the bucket right? Still learning this particular part. But if my stock system will work, that would be great! Thatíll save me some money for my hp tuners kit and other odds and ends.

Last edited by Javi7808; 12-04-2018 at 12:00 AM.
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Old 12-04-2018, 08:47 AM
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Originally Posted by Javi7808 View Post



Yeah, I’m definitely gonna order an electronic boost controller, don’t want any issues in the future.

My goal is 500 to 600hp, probably won’t run e85 as I’m not looking to make 1000hp.

Now for the fuel part, this is where I get confused. I thought you couldn’t use the stock fuel system for boost? You say my stock system will work? I’ve heard that I’ll need at least 60lb injectors? I have a set of gray 12561462 injectors in the car, I believe they’re 28#s maybe?

Also, I’m liking the return system option.i don’t want to overwork anything. With a return fuel system I would have to run a return line from the fuel rail coming off an fpr back to the tank, then cap off the built in regulator in the bucket right? Still learning this particular part. But if my stock system will work, that would be great! That’ll save me some money for my hp tuners kit and other odds and ends.
You should read through my thread. It tells you everything I have and so far its working fine. There should be no reason not to beleive that i'm not at 550-600rear at 10psi. Once you go turbo, you;ll soon find that you'll want to be able to control the boost how you see fit. I was confused as to what controller i needed to get. I only wanted to do it once because you'll have $400 or more tied up in it. I researched for a few weeks, watched videos and asked questions. I found out that what i needed was a controller that had true boost by gear. The eboost2 advertises that it has this but after reading up up in, I came to the conclusion that it doesnt have a true boost by gear, its times or something like that. It doesnt know what gear you are actually in. the setup I chose actually knows what gear im in. It also give you room to grow, supporting many other functions. And it cost less money than all the other systems. simple 4 wire hookup.

I chose an aeromotive pump because they are known for being one of the best fuel pump manufacturers out there. I have not converted to return style system yet. so far it works perfect.

Last edited by Kfxguy; 12-04-2018 at 09:31 AM.
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