Lucy gets a modern powerplant - The 1947 - Present Chevrolet & GMC Truck Message Board Network

RustyBucket · 01-03-2016, 12:28 PM

It'll be interesting to see how your 5.3 does on fuel mileage with no O.D. What rear gear ratio is your truck? I have an '02 GMC 6.0 and when I tow I don't use overdrive .... the mileage is UGLY. I know the 6.0 is thirstier than the 5.3 and the '02 truck is heavy. I like the LS motors but wonder if the better economy isn't due a lot to computer engine management and overdrive. I have a mild 454/TKO500 combination in my Blazer. It'll give a little better than 15mpg at a steady 75mph... OR ... you can blast it around in the lower gears and get 7 or 8, but it's a lot more fun.
Please keep posting on your project, enjoying your progress.

LooseyLucy71 · 01-04-2016, 03:27 AM

Quote:

Originally Posted by RustyBucket

It'll be interesting to see how your 5.3 does on fuel mileage with no O.D. What rear gear ratio is your truck? I have an '02 GMC 6.0 and when I tow I don't use overdrive .... the mileage is UGLY. I know the 6.0 is thirstier than the 5.3 and the '02 truck is heavy. I like the LS motors but wonder if the better economy isn't due a lot to computer engine management and overdrive. I have a mild 454/TKO500 combination in my Blazer. It'll give a little better than 15mpg at a steady 75mph... OR ... you can blast it around in the lower gears and get 7 or 8, but it's a lot more fun.
Please keep posting on your project, enjoying your progress.

I have 3.08s out back. As I probably mentioned earlier the next big step after swapping the 5.3 in is to change the TH400 out for an NV4500. When I installed the posi I put the 3.08s in to give me around 2,000 RPM with the NV4500 at 75, which is about where my 04 with the 4L60 will run down the highway in OD. I'll definitely be tracking mileage both ripping around town and cruising the highway. Definitely looking forward to getting her running soon!

01-03-2016, 12:28 PM	#1
RustyBucket Registered User Join Date: Jul 2009 Location: Space Coast, Fl. Posts: 1,055	Re: Lucy gets a modern powerplant It'll be interesting to see how your 5.3 does on fuel mileage with no O.D. What rear gear ratio is your truck? I have an '02 GMC 6.0 and when I tow I don't use overdrive .... the mileage is UGLY. I know the 6.0 is thirstier than the 5.3 and the '02 truck is heavy. I like the LS motors but wonder if the better economy isn't due a lot to computer engine management and overdrive. I have a mild 454/TKO500 combination in my Blazer. It'll give a little better than 15mpg at a steady 75mph... OR ... you can blast it around in the lower gears and get 7 or 8, but it's a lot more fun. Please keep posting on your project, enjoying your progress. __________________ Dad always said, "Son, WISH IN ONE HAND, and ......." -------------------------------------- -------------------------------------- Current toy trucks: '71 GMC 1500 SUPER CUSTOM short/step, orig. dk. blue, 350/700r, ps,pb, A/C '72 Blazer 2wd, ochre & white, 454, tremecTKO 500 5spd. ps, pb, A/C, tilt Last 10yrs of hobby vehicles, had a FEW more in the 50yrs. before these: '66 Plymouth Belvedere City of Miami cop car clone. '70 Nova 406"sb, 13.5-1, solid roller, Brodix, p.glide/t.brake, back halved, 9" Ford, spool 4.88, cage,ladder bar/coilover, 10.5 tire....... SOLD!! '67 C10 short/step side mount spare -- SOLD!! '72 Jimmy 2wd, 350/350, ps, pb, fun driver, lots of bondo & a shiny red paint job..... SOLD!! '69 Nova 350, 4spd, A/C, ps, p.b, ...SOLD!!



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