Reliable boost levels
06-13-2017, 04:58 PM
#1
5th Gear
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Reliable boost levels
I have a Silverado with the 6.2/8L90 combo. From what I understand compared to the LT1 in the c7 vette I have slightly smaller injectors, and different intake/exhaust manifold, but the long block is identical to the Lt-1. Right now I have the Eforce with the stock 3.5” pulley. For the vette they sell a stg 2 which includes a 3.25 pulley for about 9psi. I wanted to upgrade my truck with the same smaller pulley and the truck forums don't seam to have much info on this. I figured this forum has more people that push their motors. With the higher compression ratio of theses DI motors, what are people finding they will take reliably (key word, not just a couple dyno pulls and done) for boost (intake and exhaust dependent of course) before they let go? I’m assuming the hypereutectic pistons are the weak point like usual. I also know fuel will be an issue, but I'll tackle that with the LT4 parts after get boost where I want it.
06-14-2017, 10:22 AM
#2
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I have a Silverado with the 6.2/8L90 combo. From what I understand compared to the LT1 in the c7 vette I have slightly smaller injectors, and different intake/exhaust manifold, but the long block is identical to the Lt-1. Right now I have the Eforce with the stock 3.5” pulley. For the vette they sell a stg 2 which includes a 3.25 pulley for about 9psi. I wanted to upgrade my truck with the same smaller pulley and the truck forums don't seam to have much info on this. I figured this forum has more people that push their motors. With the higher compression ratio of theses DI motors, what are people finding they will take reliably (key word, not just a couple dyno pulls and done) for boost (intake and exhaust dependent of course) before they let go? I’m assuming the hypereutectic pistons are the weak point like usual. I also know fuel will be an issue, but I'll tackle that with the LT4 parts after get boost where I want it.
Do all of this at the same time I don't understand what you mean on this last will tackle that on the last sentence of yours.
I have the lt1 stock exhaust I would sale you cheap if you want are that your stock stuff is going to do is just build up more boost in the stock stuff. If you put headers & pull your back cats will lower the boost #...
Robert
06-14-2017, 10:26 AM
#3
Le Mans Master
I have a Silverado with the 6.2/8L90 combo. From what I understand compared to the LT1 in the c7 vette I have slightly smaller injectors, and different intake/exhaust manifold, but the long block is identical to the Lt-1. Right now I have the Eforce with the stock 3.5” pulley. For the vette they sell a stg 2 which includes a 3.25 pulley for about 9psi. I wanted to upgrade my truck with the same smaller pulley and the truck forums don't seam to have much info on this. I figured this forum has more people that push their motors. With the higher compression ratio of theses DI motors, what are people finding they will take reliably (key word, not just a couple dyno pulls and done) for boost (intake and exhaust dependent of course) before they let go? I’m assuming the hypereutectic pistons are the weak point like usual. I also know fuel will be an issue, but I'll tackle that with the LT4 parts after get boost where I want it.
It's not so much a fuel issue its a cylinder pressure issue with the stock pistons. I wouldn't run more than 11 psi and I would have the LT4 fueling and meth. I currently run about 14 psi but I have a all forged shortblock.
06-14-2017, 09:50 PM
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You should be good man on the boost level but with that truck with smaller exhaust & inj do all that at the same time. PLUS FOR SURE THE LT4 INJ & PUMP for your set up the truck stuff will not work you will 100% run out of fuel on the stock stuff.
Do all of this at the same time I don't understand what you mean on this last will tackle that on the last sentence of yours.
I have the lt1 stock exhaust I would sale you cheap if you want are that your stock stuff is going to do is just build up more boost in the stock stuff. If you put headers & pull your back cats will lower the boost #... Robert
Do all of this at the same time I don't understand what you mean on this last will tackle that on the last sentence of yours.
I have the lt1 stock exhaust I would sale you cheap if you want are that your stock stuff is going to do is just build up more boost in the stock stuff. If you put headers & pull your back cats will lower the boost #...
RobertWhat other mods do you have and do you know what boost you are running?
06-15-2017, 12:59 AM
#7
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About the limit we're seeing on the stock shortblock is 9-11 psi. Many people running around with the novi1500 and no restrictor plate which is about 10 psi. However these setups run meth to supplement.
It's not so much a fuel issue its a cylinder pressure issue with the stock pistons. I wouldn't run more than 11 psi and I would have the LT4 fueling and meth. I currently run about 14 psi but I have a all forged shortblock.
It's not so much a fuel issue its a cylinder pressure issue with the stock pistons. I wouldn't run more than 11 psi and I would have the LT4 fueling and meth. I currently run about 14 psi but I have a all forged shortblock.
06-21-2017, 02:08 AM
#8
I'm running 14.5psi on stock bottom end on stock/injectors and fuel pump. I'm also running dual nozzle meth. I have about 25k miles on this setup.
Built shortblock, larger head unit, and fueling are the next steps.
Built shortblock, larger head unit, and fueling are the next steps.
Last edited by ilivas; 06-21-2017 at 02:09 AM.
06-21-2017, 10:24 AM
#10
Le Mans Master
06-21-2017, 05:14 PM
#12
Originally Posted by FYREANT
Who tuned it? Sounds like you got one hell of a tune to hold that!
11.5:1 AFR safely and only 11* of timing to keep it conservative.
I have 53k miles total on the car.
Last edited by ilivas; 06-21-2017 at 05:17 PM.
06-21-2017, 05:15 PM
#13
06-22-2017, 01:26 AM
#17
Originally Posted by FYREANT
Wow. That sounds very familiar! I have 52K on mine when I pulled it to rebuild for more power. Lol
06-23-2017, 10:37 PM
#18
06-26-2017, 06:44 AM
#20
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Well it looks like I'm taking the plunge and adding meth for not just the fuel, but also the cleaning of the intake valves, lower iats and increased octane etc. I'm gonna use Alky Control with 100% meth and use the windshield washer tank as the meth bottle so I have a low warning light. I can get VP M1 about 15 minutes from my house so depending on how much I use it shouldn't be a problem. The timing tables are going to be used with iats to help as a failsafe if the meth stops working. I have dash command so I'm going to set up a audio/visual warning when I'm above 2psi of boost and AFR/iat's go out of wack. Never though I'd have a drug problem, but I hope this meth stuff works