5.7 vortec mpg

[CRF450R]

I got the factory Z71 package so I got the 3:73 with the 14 bolt and a locker. Im running stock tire size as I hate lifted trucks and just cause I hate lowered trucks aswell I don't believe in screwing with the factory suspension height I like them sitting as they come off the assembly line. Other then the 3" dual exhaust with the double H-pipe and bottles she's all stock.

 

[Supercharged111]

Cold air intake would make trivial difference at most. It pulls air from the same place so the only thing it would do is reduce restriction due to rough edges on the intake tube. The throttle body is a bit of a bottleneck. It may also be worth looking into a new intake manifold. I'll be putting a new intake manifold and headers on mine with the 383. Current engine has a bit of piston slap during warm up, so I'm not adding a ton of power to this block.

MPFI may help with the cold start issue you have, it doesn't get much colder than 20* here in Dallas and even then it's rare, so not much experience with real cold weather here, but it always starts up within a second of engaging the starter.

I do have a slight issue with idle that just started, wonder if anybody could weigh in on it. Occasionally after startup the idle will cycle between 500 and 800rpm. It's intermittent, but I've tested vacuum and fuel pressure all good. I did recently replace my exhaust, manifold back (new flowmaster cats, magnaflow side exit cat-back). New O2 sensors as well. Reset all bolts to spec after having it installed for a month. Does a new set of cats and/or O2 sensors require the ECM to be reset?

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TB is not a restriction on a small block truck at WOT. Just that lip that ***** off your part throttle.

 

[RawbDidIt]

TB is not a restriction on a small block truck at WOT. Just that lip that ***** off your part throttle.

The throttle body is the narrowest point in the intake system, stands to reason an additional half inch or so of diameter would increase air flow through the system. Whether or not the fuel system has enough overhead to take advantage of that available airflow remains to be seen, but the anecdotal evidence of the two users with experience is enough for me to take a chance with it. Especially with my future plans of putting in a 383, and the relative low cost of the part.

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[RawbDidIt]

3.73 w 265/75R 16

Hmmm... I do run taller tires (33") and most of my miles are city, but I'm never in stop and go traffic. Is the added weight offset by aerodynamics with the suburban? So many people reporting mileage in the same ballpark, then yours comes in 33% higher, what are we doing wrong?

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[Supercharged111]

The throttle body is the narrowest point in the intake system, stands to reason an additional half inch or so of diameter would increase air flow through the system. Whether or not the fuel system has enough overhead to take advantage of that available airflow remains to be seen, but the anecdotal evidence of the two users with experience is enough for me to take a chance with it. Especially with my future plans of putting in a 383, and the relative low cost of the part.

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Sounds good in your head, but not true.

 

[RawbDidIt]

Sounds good in your head, but not true.

Any chance you'd be willing to share anything other than "you're wrong"? It's not exactly constructive.

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[evilunclegrimace]

Hmmm... I do run taller tires (33") and most of my miles are city, but I'm never in stop and go traffic. Is the added weight offset by aerodynamics with the suburban? So many people reporting mileage in the same ballpark, then yours comes in 33% higher, what are we doing wrong?

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A) you are running around in the city and that is stop and go driving.
B) it is possible that a heavy throttle foot is contributing to lower MPG's and
C) I was running around 2,000 -2,200 RPM's for hours at a time on cruise control.

 

[RawbDidIt]

A) you are running around in the city and that is stop and go driving.
B) it is possible that a heavy throttle foot is contributing to lower MPG's and
C) I was running around 2,000 -2,200 RPM's for hours at a time on cruise control.

All true, just seems like a large jump in mileage especially considering everybody else's experience as well. I was hoping you had some profound knowledge we didn't. Turns out I just need to stop driving like an idiot. I was really hoping otherwise, I like driving like an idiot [emoji3]

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[PlayingWithTBI]

That's funny but, I wouldn't call it "drive like an idiot", I'd call it exploring my options and capabilities.

 

[RawbDidIt]

That's too many words. Besides driving like an idiot only has negative connotations if you let it.

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