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N/A 408 stroker lq9 expectations

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Old 10-29-2018, 10:36 PM
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Default N/A 408 stroker lq9 expectations

I’m currently in the process of building a lq9 stroker and I was wondering if anyone could give me any idea of their reliability, recommendations, and fuel mileage. I understand that it’s a high displacement engine not a Prius, but I’m hoping to see at least 10mpg tuned. My truck is a 03 Sierra 1500 ext cab with a 3” lift on 33s with 3.73 gears and 1 3/4 long tubes and a flow master 40 series currently and here’s some of my parts list:
Gen 3 408 short block from TSP
TSP N/A bald eagle cam
Yank TT3000 stall
stage 2.5 5.3L heads with PAC .660” dual springs
factory rocker arms with CHE bushings
holley mid ram Intake
lsx e-fan harness and e-fan setup
gm high performance oil pump
rollmaster double roller
ls7 lifters and trays
the truck will never see a track but I do like to show out from time to time, and I do mild off-roading.
Old 10-30-2018, 07:58 AM
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I dont see why it wouldnt get better than 10mpg. My neighbor has an 8.1 Suburban that can eek out 13 on a mild day, so I'd think a 6.67L with better heads could jam the same, provided your foot isnt matted.
Old 10-30-2018, 10:31 AM
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Originally Posted by arthursc2
I dont see why it wouldnt get better than 10mpg. My neighbor has an 8.1 Suburban that can eek out 13 on a mild day, so I'd think a 6.67L with better heads could jam the same, provided your foot isnt matted.
see what concerned me with the fuel mileage is that my factory lm7 5.3 gets 10mpg on a good day but it’s at 189K and hasn’t been tuned so I was hoping that was the issue
Old 10-30-2018, 10:59 AM
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Huh, something is wrong with it for sure. I can get 13-15 out of my cam'd/tuned 5.3 w/ 188k. If Im real nice to it, 17 on a downhill at 65mph trip haha.
Old 10-30-2018, 07:02 PM
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shoot, i've got 193k on my cam/exhaust 5.3 and average 15mpg mixed driving with 33s & 4.30s
even with dished pistons, you're probably high 11.x:1 CR with 5.3 heads. that'll help a bit on efficiency compared to ours, too.
Old 10-30-2018, 07:38 PM
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Originally Posted by _zebra
shoot, i've got 193k on my cam/exhaust 5.3 and average 15mpg mixed driving with 33s & 4.30s
even with dished pistons, you're probably high 11.x:1 CR with 5.3 heads. that'll help a bit on efficiency compared to ours, too.
I hope so. I’ll be happy just to see double digits tbh I’ve done learned to balance my checks around it
Old 10-30-2018, 08:11 PM
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My 408 with ls3 heads got a good 11mpg which sucked lol
Old 10-31-2018, 08:44 AM
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Your trucks all probably weigh more than my reg cab long bed 2500, and bigger tires and gearing also make the comparison even more apples to oranges, but here goes. I have been driving around N/A all summer and I get almost 14 mpg on the highway. When the blower is on it doesn't change the highway mileage anyway.
Old 10-31-2018, 09:06 AM
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I get 11mpg highway and city with a bone stock 4.8 and a blower.
Old 10-31-2018, 06:51 PM
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Originally Posted by dantheman1540
I get 11mpg highway and city with a bone stock 4.8 and a blower.
and 35s, right?


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