1991 C1500 TURBO 5.3/4L80E

[RDF1]

Drove it around last night for about 20 miles. Had to add a touch of trans fluid but so far so good. Drove it home and made it back to work. Adjusting the tune slowly.
Gotta put a new PCV valve in and find a bolt to fit the dipstick holddown, along with make some real mounts for the Radiator and Efan.
Still gotta build a reservior for the water air intercooler.

 

[RDF1]

Dual 22" monitors at work sure do make it easier to adjust the tune. So i just log the truck and when i get time at work ill copy the tune and log over. Make adjustments and then copy the tune back over to the laptop and flash it in before i leave.

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[RDF1]

Got the GPS out at lucnh and found out the Speedo is off. I guessed and got it close. but appears it has 4.10s instead of 3.73 gear. So thats no fun.
Once i get the new rear tires on and finish tuning it ill decide what ratio i really want to go with.
At first i wanted 3.08 or 3.23s since its going to be a daily first and track toy second. But most my daily drive is back roads since i live in the country, and its nice to keep the converter locked crusing.

 

[Christian Steffen]

You thinking 4.10s will yield too high of a cruise rpm?

 

[RDF1]

Yea I'll know more when I put the new rear tires on and double check my speedometer with gps. It has 275/60/15's (28") on it now. New tires are 275/60/17's (30").
I'd rather see 1800-1900 at 70. I know it's got enough grunt to push it along that low of rpms.
My other truck with the cammed 6.0 and same turbo got its best mileage at 2000 rpm at 70 and it weighed 5100#. 265/65/17 and 3.42 gear with a 4l80e.

Hoping this truck is closer to 4000#.

Plus a higher (3.23) gear loads the turbo better for playing around.


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[RDF1]

You thinking 4.10s will yield too high of a cruise rpm?

4.10 30" tire shows 2425rpms at 70mph.
4.10 28" tire shows 2585 rpms at 70mph.

 

[RDF1]

Couldn't find a socket cap bolt to hold the dipstick tube in. Ended up making a spacer so the regular bolt head wouldn't hit the manifold flange.

Got that done. Put new pcv valve in the driver valve cover.
Now thinking bout drill and tap both valve covers and run hoses to a catch can and do some check valve voodoo so the filter can be hooked up. If I get any oil on the compressor, I'll rethink it.

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[Christian Steffen]

Yea I'll know more when I put the new rear tires on and double check my speedometer with gps. It has 275/60/15's (28") on it now. New tires are 275/60/17's (30").
I'd rather see 1800-1900 at 70. I know it's got enough grunt to push it along that low of rpms.
My other truck with the cammed 6.0 and same turbo got its best mileage at 2000 rpm at 70 and it weighed 5100#. 265/65/17 and 3.42 gear with a 4l80e.

Hoping this truck is closer to 4000#.

Plus a higher (3.23) gear loads the turbo better for playing around.


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Yeah if it's that light and you're running tires that are smallish, I don't blame you for wanting something shorter than 4.1.

 

[RDF1]

Got a buddy at work that has a 3.08 rear end in his truck and swapping a 12 bolt in. I'm gonna see if I can borrow it and cruise for a couple weeks to see if it's bad or good.

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[RDF1]

Got another Buddy with a 3.42 rear that's out of his truck right now I can test. It's got the same Eaton LSD my axle has so i know it's good.
The 3.08 rear has a open so it's only going in for gas milage testing and top end pulls.

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