How wide (and low) can the powerband be?
Thread Starter
Teching In
Joined: Apr 2019
Posts: 40
Likes: 1
From: northern MN, moving to twin cities area soon
How wide (and low) can the powerband be? I started the Ecoboost LS thread and the first phase of brain picking sort of petered out but i'm also rethinking my original goals and plans a bit. Which is great, need to do all that thinkin' before I start buying stuff locked into a plan!
I've decided the least important part of my commitment was to diesel like torque when this is a truck that has to do a job so I wanted to open the floor a little more and ideally get some more feedback. I will try to be less wordy this time.
CURRENT PLANNED BUILD:
- Turbocharging a 5.3L Gen3 V8 is the only fixed part - I know a 6.0L would give easier and flatter torque but wanted to save some money there and make the power with and altitude compensate with the turbo
- Forged 4340 rods and forged pistons - specifics to be decided
- Goal (and Ceiling) making 450-550lb/ft of torque "as flat and wide as a table" - this is for transmission life among other things and because i've decided it's enough. Prefer lower as this is for a tow vehicle not a sports car - i'd rather have 1500-5500rpm than 2500-6500rpm.
- Water or water/methanol injection using a 5 gallon DEF tank repurposed
- Intercooler probably taken from a Duramax
- Reliability matters and budget is just trying to be reasonably thrifty
- Reused and repurposed junkyard parts are just fine.
What would you choose for things like turbos and camshaft or other power parts? Consider things like the reliability of the turbocharger under minutes of uphill load so no chinese turbos, that the heads might last longer if they stay iron heads even if losing a little compression, etc.
I'm led to believe twin turbos will spool faster than a single turbo despite the cost, maybe even twin scroll turbos on each side as long as cost isn't excessive.
I've decided the least important part of my commitment was to diesel like torque when this is a truck that has to do a job so I wanted to open the floor a little more and ideally get some more feedback. I will try to be less wordy this time.
CURRENT PLANNED BUILD:
- Turbocharging a 5.3L Gen3 V8 is the only fixed part - I know a 6.0L would give easier and flatter torque but wanted to save some money there and make the power with and altitude compensate with the turbo
- Forged 4340 rods and forged pistons - specifics to be decided
- Goal (and Ceiling) making 450-550lb/ft of torque "as flat and wide as a table" - this is for transmission life among other things and because i've decided it's enough. Prefer lower as this is for a tow vehicle not a sports car - i'd rather have 1500-5500rpm than 2500-6500rpm.
- Water or water/methanol injection using a 5 gallon DEF tank repurposed
- Intercooler probably taken from a Duramax
- Reliability matters and budget is just trying to be reasonably thrifty
- Reused and repurposed junkyard parts are just fine.
What would you choose for things like turbos and camshaft or other power parts? Consider things like the reliability of the turbocharger under minutes of uphill load so no chinese turbos, that the heads might last longer if they stay iron heads even if losing a little compression, etc.
I'm led to believe twin turbos will spool faster than a single turbo despite the cost, maybe even twin scroll turbos on each side as long as cost isn't excessive.
Forget about spool time. With the type of build you have planned, the size turbo you are going to use means that a single will be able to brake boost several pounds on a stock torque converter. This translates to nearly instant off idle boost when towing. Twins, dual scrolls, ball bearing, etc. will all be a waste of money.
TECH Enthusiast
Joined: Feb 2020
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Likes: 210
Problem is you're not going to find much dyno info for rpms under ~3000 rpm. My thoughts are you're going to have to make a compromise between spool time and back pressure as think that high BP on long hill pulls is going to get the exhaust valve temps up high ( not sure if this is true or if w/m will help to control this also) keep the cam small , maybe < 210° intake to make for very good na response so that instant boost is not as necessary. Lift under .550 for use with inexpensive ls6 springs or under .500 for stock springs or just leave the stock cam in it to start. Going to tune it yourself? Thinking that logging while actually towing is going to be necessary to get the timing right and maximize performance and reliability- again, just my thoughts
TECH Enthusiast
Joined: Mar 2013
Posts: 503
Likes: 39
Question for OP. Lets say you have a truck that is geared so that going along at 60 MPH for instance in third gear the engine is at peak horsepower (let us assume that means less than peak torque) and in fourth gear it is at peak torque. Do you know in which gear you are going to be able to pull the heaviest load and why (assuming again the same mph with third being peak hp and fourth being peak torque)? The reason I ask is your seeming focus on torque.
Thread Starter
Teching In
Joined: Apr 2019
Posts: 40
Likes: 1
From: northern MN, moving to twin cities area soon
Question for OP. Lets say you have a truck that is geared so that going along at 60 MPH for instance in third gear the engine is at peak horsepower (let us assume that means less than peak torque) and in fourth gear it is at peak torque. Do you know in which gear you are going to be able to pull the heaviest load and why (assuming again the same mph with third being peak hp and fourth being peak torque)? The reason I ask is your seeming focus on torque.
Power for hours (over the engine lifespan) is just about not having to worry about keeping my foot in it than maxing the load at 60mph. Scariest tow I ever had was actually thru outer Cincinnati at rush hour where if I didn't keep up 75mph on the right people would honk and swarm around me like a logjam. Once past I slowed down to 55-60 again.
