Help navigating turbo maze for LQ4
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Teching In
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Help navigating turbo maze for LQ4 I am looking to finally boost my LQ4 in my 2500HD truck. Being that my vehicle weighs 6500 lbs, I am struggling to make a decision on a turbo. The motor has 150K on it, so I don't want to punish it too hard, but I do understand it's due for a refurbished pretty soon. Currently looking at a TC 70 or TC 76. I am getting my hot section and downpipe from RM Performance, just need to decide on a turbo. I know most folks go supercharged on a truck, but the efficiency and engineering of a turbo system is more appealing to me. I enjoy driving a turbo vehicle and feeling that umph when it starts to boost, it's also a good way to terrorize my wife.
Goals
1. Make 450ish HP at wheels
2. Boost very low in RPM range
3. Maintain daily driver status
4. Not melt the motor when I tow, which is maybe once a year.
5. Keep the boost at ~7 PSI to nurse my motor into retirement.
I know I am looking for a small turbo, so it will spool quickly, but just don't want to go too small and choke the exhaust.
Would super appreciate any direction or help.
Goals
1. Make 450ish HP at wheels
2. Boost very low in RPM range
3. Maintain daily driver status
4. Not melt the motor when I tow, which is maybe once a year.
5. Keep the boost at ~7 PSI to nurse my motor into retirement.
I know I am looking for a small turbo, so it will spool quickly, but just don't want to go too small and choke the exhaust.
Would super appreciate any direction or help.
I had this same idea to do to my 2500HD LQ4. I love the trucks! 4L80e. 14 bolt rear. The trucks are very solid. Mine was a crew cab short bed, so I figured with the mile long steel 2 piece driveshaft, and completely bone stock, the truck probably made around 225whp. Best guess. What I was wanting to do, was do a simple and cheap turbo setup on it, and try to target 450whp. Most people stop me there and say, "What? only 450whp? But every LS vehicle that has a turbo on it instantly makes 1000?"
But think about it like this. You are literally doubling the power output of the truck. It will definitely be noticeable. Your towing is going to be a cakewalk with double the power and probably more than double the torque. And then with 450whp, you could imagine that the whole setup should be very reliable indeed. Plus, like is the nature of turbos, when you do become addicted to it, and want more power, it is just a manual boost controller or a turbo swap away from making any amount of power you would like.
So with that being said, this is the turbo I was going to look into. Should spool super fast, and should make the 450whp goal easy enough.
http://www.vsracing.net/catalog/prod...oducts_id=1323
Good luck.
But think about it like this. You are literally doubling the power output of the truck. It will definitely be noticeable. Your towing is going to be a cakewalk with double the power and probably more than double the torque. And then with 450whp, you could imagine that the whole setup should be very reliable indeed. Plus, like is the nature of turbos, when you do become addicted to it, and want more power, it is just a manual boost controller or a turbo swap away from making any amount of power you would like.
So with that being said, this is the turbo I was going to look into. Should spool super fast, and should make the 450whp goal easy enough.
http://www.vsracing.net/catalog/prod...oducts_id=1323
Good luck.
The 67mm Garrett turbos that were an "upgrade" on the kits Livernois used to sell are perfectly sized for what you want to do. That size turbo will allow the LQ4 to brake boost a few psi at launch, but not completely choke the fun out of your top end. With transmission upgrades, several full weight Escalades were running in the 12's 1/4 mile. I know firsthand from helping install and then tuning one of those kits with that turbo on my neighbors escalade. The instant available torque combined with AWD ripped the tailshaft out of multiple built 4l60's before upgrading to a 4l80. With the stock fuel pump and 42" injectors we ran out of fuel before the turbo choked out. I set the transmission maximum shift rpm to just under the point where fuel pressure dropped off until the fuel supply could be upgraded. The truck is still driving around like that 10 years later. BTW, don't count on 150k miles being anywhere near needing to be refurbished. I waited until 120K miles to whipple supercharge my Silverado, and it is still fine at almost 330k miles.
I have done a on3 kit on a 2500 hd. there are a few things that are different. the front bumper brackets need a lot of cutting to make the intercooler fit. we used a 76/65 turbo and ran it fairly hard. the torque converter will need swapped if you go to 10 pounds or so boost. makes the truck pull like a dmax.
Thread Starter
Teching In
Joined: Jul 2016
Posts: 39
Likes: 0
I had this same idea to do to my 2500HD LQ4. I love the trucks! 4L80e. 14 bolt rear. The trucks are very solid. Mine was a crew cab short bed, so I figured with the mile long steel 2 piece driveshaft, and completely bone stock, the truck probably made around 225whp. Best guess. What I was wanting to do, was do a simple and cheap turbo setup on it, and try to target 450whp. Most people stop me there and say, "What? only 450whp? But every LS vehicle that has a turbo on it instantly makes 1000?"
But think about it like this. You are literally doubling the power output of the truck. It will definitely be noticeable. Your towing is going to be a cakewalk with double the power and probably more than double the torque. And then with 450whp, you could imagine that the whole setup should be very reliable indeed. Plus, like is the nature of turbos, when you do become addicted to it, and want more power, it is just a manual boost controller or a turbo swap away from making any amount of power you would like.
So with that being said, this is the turbo I was going to look into. Should spool super fast, and should make the 450whp goal easy enough.
http://www.vsracing.net/catalog/prod...oducts_id=1323
Good luck.
But think about it like this. You are literally doubling the power output of the truck. It will definitely be noticeable. Your towing is going to be a cakewalk with double the power and probably more than double the torque. And then with 450whp, you could imagine that the whole setup should be very reliable indeed. Plus, like is the nature of turbos, when you do become addicted to it, and want more power, it is just a manual boost controller or a turbo swap away from making any amount of power you would like.
So with that being said, this is the turbo I was going to look into. Should spool super fast, and should make the 450whp goal easy enough.
http://www.vsracing.net/catalog/prod...oducts_id=1323
Good luck.
The 67mm Garrett turbos that were an "upgrade" on the kits Livernois used to sell are perfectly sized for what you want to do.... The truck is still driving around like that 10 years later. BTW, don't count on 150k miles being anywhere near needing to be refurbished. I waited until 120K miles to whipple supercharge my Silverado, and it is still fine at almost 330k miles.
I have done a on3 kit on a 2500 hd. there are a few things that are different. the front bumper brackets need a lot of cutting to make the intercooler fit. we used a 76/65 turbo and ran it fairly hard. the torque converter will need swapped if you go to 10 pounds or so boost. makes the truck pull like a dmax.
This site rocks, please keep it coming.
Thread Starter
Teching In
Joined: Jul 2016
Posts: 39
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GT4094R
Compressor ind diameter 67.80
Compressor exd diameter 94.00
Turbine diameter 77.00
HP 450-800
Displacement 2.0-6.0
A/R 0.85
EDIT: That sucker is $2000!!! The search continues...
Last edited by I R Gunnr; Jul 7, 2016 at 09:43 PM.
I gave you a firsthand real world account of 1 specific turbo because I am not an expert on turbo specs. There are so many choices in configuration between hot and cold side wheel sizes, covers, etc., that I could not give a decent answer for any turbo I haven't used. I can barely read a compressor map, and I still need a calculator to figure out what it means for a given combo. Something you should know, however, is that if you use a premade kit, you need to stick with the size turbo the kit was made for. Changing turbo size can mean downpipe and other fitment issues that require a degree of fabrication that negate any upside to buying a prefabbed kit.
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I bought the truck new back in 2005, didn't have the money for the diesel at the time so went with the 6.0L. It's been great, I've fallen in love with the LS series motors, so durable and unlimited ability to upgrade. Your thought process is the same as mine, make reasonable horsepower, have fun, but have a truck that will continue to last. Thanks for the input, that looks like a good size turbo, I'm just still a little leery of the on3 and VS racing stuff, being that they are 1/2 the price of everyone else. Might take the plunge , definitely work a second look.
Last edited by 93camaro_zzz; Jul 11, 2016 at 03:27 PM.
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I ran a precision T4 6775 .96 on my 5.7 and loved it. the responsiveness was pretty close to N/Aish. I'm about to switch it to my 6.0 to see how she likes it.
but it'll start making boost around 1800rpms, 7psi by 2800. torque curve made it fun to drive. torque was 400ftlbs @2500, 500-590ftlbs from 3500-6500rpms.
but it'll start making boost around 1800rpms, 7psi by 2800. torque curve made it fun to drive. torque was 400ftlbs @2500, 500-590ftlbs from 3500-6500rpms.
I ran a precision T4 6775 .96 on my 5.7 and loved it. the responsiveness was pretty close to N/Aish. I'm about to switch it to my 6.0 to see how she likes it.
but it'll start making boost around 1800rpms, 7psi by 2800. torque curve made it fun to drive. torque was 400ftlbs @2500, 500-590ftlbs from 3500-6500rpms.
but it'll start making boost around 1800rpms, 7psi by 2800. torque curve made it fun to drive. torque was 400ftlbs @2500, 500-590ftlbs from 3500-6500rpms.
that's on the LS6 longblock, E85, 7psi. 227/227 cam, I was street tuned after that so i dont know what it did on 13psi. will be copying and pasting on the LS2 here soon enough.
Thread Starter
Teching In
Joined: Jul 2016
Posts: 39
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I ran a precision T4 6775 .96 on my 5.7 and loved it. the responsiveness was pretty close to N/Aish. I'm about to switch it to my 6.0 to see how she likes it.
but it'll start making boost around 1800rpms, 7psi by 2800. torque curve made it fun to drive. torque was 400ftlbs @2500, 500-590ftlbs from 3500-6500rpms.
but it'll start making boost around 1800rpms, 7psi by 2800. torque curve made it fun to drive. torque was 400ftlbs @2500, 500-590ftlbs from 3500-6500rpms.
Andrew