What turbo for a LQ4 Tow Rig??
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I am in the process of building a tow rig. The platform is a 1987 Chevy V3500 Crew cab 4x4. The truck will have a lq4/80e and 4.10 gears in the dana 60 and 14 bolt rear. I will fit the biggest intercooler I can in the front and buy a good meth kit. The fuel will be 93 octane, single walbro 450 and deka 80's. Big power isn't the goal for this truck nor do I want to be in boost constantly. What would you guys use??
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I have a 2003 2500HD (LQ4/4L80e/8 lug 14 bolt) and I also have considered turboing it. For me, I was thinking between a 70mm-76mm. I was actually leaning more towards the 76. From my experience with towing, you dont need the turbo to spool in 0.02 milliseconds, there is ALOT of load on the motor when towing. But like you said a larger turbo will make the power you want at a lower boost level, and be more resistant to unnecessary spooling when you are not towing. My truck makes 300 flywheel hp right now, and I was thinking if I could have it at the 450rwhp but hopefully at or over 500 torque, that would be pretty good with me I think. That would be about a 225rwhp increase over stock. I should notice the difference.
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#6
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Try not to get caught up by the idea that a bigger turbo will always make your desired power at a lower boost level. This is untrue; a turbo's isentropic efficiency does not begin decreasing as soon as it crosses into a pressure ratio range greater than 1:1. In fact it is quite the opposite. Some turbos need a ratio of 2:1 or more to really breathe well, so the efficiency of the turbo will increase to an extent while boost is increased.
Also, while considering 'load' on the turbo, don't forget to factor in RPM, as that is as much a part of load as throttle position is. If you use a turbo that is too large, you may not be able to build enough boost to make it useful while towing. For example on my own truck, my twin setup is just a hair too large to really make enough torque to pull large hills without downshifting under 65mph or so. I discovered this when my cruise control decided it should downshift and go full throttle up a hill with a 5k pound load...it got my attention really quick
At 65mph, I'm under 2000rpms...its just not enough exhaust to drive the turbos. It would take hills with no issue at 75mph, but you're not always towing at that speed. So a smaller turbo is absolutely beneficial when the primary goal is maintaining torque at low RPM.
Also, while considering 'load' on the turbo, don't forget to factor in RPM, as that is as much a part of load as throttle position is. If you use a turbo that is too large, you may not be able to build enough boost to make it useful while towing. For example on my own truck, my twin setup is just a hair too large to really make enough torque to pull large hills without downshifting under 65mph or so. I discovered this when my cruise control decided it should downshift and go full throttle up a hill with a 5k pound load...it got my attention really quick
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Ok so I have this little master power 70 with a .96ar on my rcsb and I am ready to move to bigger turbo on that truck... how would the mp70 fit the bill for my towing application? I have read that backpressure issues would make greater EGT's but 8-10psi on this cammed lq4 should give me plenty of power to tow with.
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Ok so I have this little master power 70 with a .96ar on my rcsb and I am ready to move to bigger turbo on that truck... how would the mp70 fit the bill for my towing application? I have read that backpressure issues would make greater EGT's but 8-10psi on this cammed lq4 should give me plenty of power to tow with.
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I am in the process of building a tow rig. The platform is a 1987 Chevy V3500 Crew cab 4x4. The truck will have a lq4/80e and 4.10 gears in the dana 60 and 14 bolt rear. I will fit the biggest intercooler I can in the front and buy a good meth kit. The fuel will be 93 octane, single walbro 450 and deka 80's. Big power isn't the goal for this truck nor do I want to be in boost constantly. What would you guys use??![Lurk](https://ls1tech.com/forums/images/smilies3/lurk.gif)
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#12
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I have always wondered and wanted to do this myself. build a turbo LS motor to pull with. I would error on the small side of a turbo so you are making more power down low and don't need to spin 4500-5000 rpm up every hill.
I wonder how it would compare to a diesel? I'm assuming towing large loads with a gas engine with turbo is not going to get very good mileage.
I wonder how it would compare to a diesel? I'm assuming towing large loads with a gas engine with turbo is not going to get very good mileage.
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I know Kurt tows some heavy **** with a gas turbo. I remember reading about him running a second radiator but can't find it.
Here is some info about his tow rig: https://ls1tech.com/forums/forced-in...comes-end.html
Here is some info about his tow rig: https://ls1tech.com/forums/forced-in...comes-end.html
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I totally agree, I have to pull my transam on a trailer up the side of a mountain to get to my local race track with the truck in my sig, and there is one part that is a very long stretch of a big incline, and I can't keep into the throttle the whole way or else the temps raise to over 230*. My truck is stock though.... unfortunately.
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#20
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Don't think you need a baby turbo to get quick spool. I have a s480 with the 92mm turbine on my lil 5.3 and I see positive pressure before 2500 Rpms and full boost before 3800 Rpms. This is a t6 1.10 ar turbine.
Last edited by Sarg; 10-03-2013 at 06:13 AM. Reason: dang autocorrect