Yet another GMC build

[dsraven]

start with a good power wash.
also, before installation, flush out the cooler lines and replace the cooler.all that stuff is stuck in that old cooler. some will put a filter inline but I am not on that side of the fence, personally. I have seen a hydraulic shop flush new lines and then blow a plug down the line with compressed air to clear any solvent from the line and see if the plug comes out clean or if the line needs more flushing. they use what looks like a roll up ear plug.

[dsraven]

I have also seen a cut away of a previously flushed plate style trans cooler. it still had lots of debris in the plates. a new cooler is cheap insurance.

[dsraven]

you're gonna be soooo tired of ATF soon.

[OKGMC4]

Took the trans apart and all the frictions and steels looked perfect so put them back in. The only damage found was a chewed up converter snout, the stator bushing was banged up, and the front seal came out in little pieces. I replaced the bad parts and put it back in and it’s been driving perfect for almost 200 miles now. Not really sure why it blew the front seal out in the first place. The bad news is I’m not 100 percent thrilled with the 5.3 power. Seems to have about what my cammed 6.0 had naturally aspirated. Not bad, but I ain’t scared yet. Thinking of gapping the 6.0 rings and swapping it. More cubes, little more compression, more cam, and more boost should thoroughly scare / thrill me.

[OKGMC4]

I pulled the heads off the 6.0 and regapped the rings. I changed the Texas Speed 224R out for a mild custom turbo grind from Cam motion. I changed the wastegate springs for 12lbs. Pulled the 5.3 and pushed in the 6.0. The idle needed raised from 650 to 750 and I think I need to lean the idle out a little below 13.6 where the tuner set it. But the power so far is ridiculous. I only pushed it to half throttle and it’s walking sideways while still accelerating and shifting. I believe I finally have the scary power I’ve always wanted. Need to look into wider stickier tires now.

[6DoF]

[Kevin_C]

Looking great! I saw this video the other day and thought of your truck. I was a bit surprised by his current brake and suspension set up.

https://www.youtube.com/watch?v=nf1MItkMMKM

[OKGMC4]

Originally Posted by Kevin_C

Looking great! I saw this video the other day and thought of your truck. I was a bit surprised by his current brake and suspension set up.

https://www.youtube.com/watch?v=nf1MItkMMKM

Man that thing is a beast!

[OKGMC4]

Really wanted to make sure my tune was safe for the engine so I had it dyno tuned this morning. The verdict…
605 hp
656 ft lbs.
I think it has more than enough power now. My poor 275/40zr18 tires agree. I had backed down to 10lb wastegate springs because I was afraid to lean out up top. I’d rather give up some power than burn it up at 12lbs boost.

[6DoF]

haha, yeah, the makings of a tire smoke show

[OKGMC4]

I thought my brakes were ok. Good at low and medium pedal, but hard at panic stop levels. Truck would slow down but not like it should. I only had 14 inches of vacuum at idle. And also not much vacuum being made under boost. I took out my 30 year old 4th gen f body vacuum booster and installed a new universal hydro boost, using the firewall bracket off the vacuum booster. I can now lock all four tires up and slide if need be. Pedal feels strange, never had hydro boost before.

[OKGMC4]

Also never posted a video before so will try here. I have the first dyno pull after the turbo 6.0 install. Don't know why I didn't record them all, just didn't. Since then, I have extended the tailpipe all the way to the rear and swapped the bullet muffler for a Dynomax 3.5" Ultraflow muffler. I would not say the truck is quiet, but it is twice as quiet in the cab now.

https://www.youtube.com/watch?v=XfJldrXsr6g


Hopefully this link works?

[dsraven]

Hydroboost is awesome.

[6DoF]

hydroboost feels different for sure ... but it's like putting an 6-71 blower on your brake booster! having the stopping power of a rig built to drive around at 12,000gvw, but only rolling 4000, works out reeaaalll nice

[dsraven]

AND, its the same all the time unless the engine dies or you blow a hydraulic hose, then you have one boosted brake application before the manual brake feel comes back.

[OKGMC4]

I was car 454 at the track today. Wanted to see how it went with a new set of drag radials on the rear. Best time was 11.7 and I am happy about that.

[6DoF]

NICE!! hard to complain about a solid 11sec truck!

having issues anywhere, or anything you'd change to try for faster?

[OKGMC4]

Originally Posted by 6DoF

NICE!! hard to complain about a solid 11sec truck!

having issues anywhere, or anything you'd change to try for faster?

Could go with a stall converter but the radials might not hold anymore. Could also try more timing or boost with E85 but I like running pump gas and also drag radials might not hold. It would either hook or spin a half turn and go. Just about perfect. The Nittos are expensive but work. Plus, because the tech guy passed me without even looking under hood, I was later warned that if I get faster than 11.5 they will require a roll bar installed. Not sure I want that. Yet. Still would like to make it work on a road course. But I need more brakes, lower in the rear which means frame mods, and track tires. How cool would it be to go track with a bunch of Corvettes and BMWs in an ancient pickup truck?

[6DoF]

ooooo, i always forget that 11.5 is the breakover ... 11.7 is fawkin MINT!

the cornering game can be a deep hole too. moving weight, alignment adjustments, getting springs/shocks/bars tuned just right. worth it.

[Kevin_C]

Thats awsome. I live down the road from New England dragway. Hoping to run mine down the track next year.

[OKGMC4]

Originally Posted by Kevin_C

Thats awsome. I live down the road from New England dragway. Hoping to run mine down the track next year.

Can’t wait to see the time slip!

[OKGMC4]

Want to start improving handling. The truck understeers pretty badly on turn in and I think it is partially due to the rear sitting 2.5” higher than the front. I’m going to make some changes to attempt to fix it.

[OKGMC4]

I'm also going to have to raise the gas tank a bit, and cut the pretty bed floor, and probably modify the exhaust some more. The toe rods need to be relocated downward. Definitely going to go more aggressive on wheel alignment and tires. Looking to move from 275/40r18 to 295/35r18 in a stickier compound. Lots to do.

[6DoF]

my wife's base C7 always pushed bad into corners when we'd go play at the low-key autocross, turns out it just needed a rear sway bar. the base car comes with the lightest front bar and no rear bar. at the suggestion of a guy who races them and did a whole comparison study on what worked well together, we got the stiffest rear bar. made a significant change for the better.

[OKGMC4]

Originally Posted by 6DoF

my wife's base C7 always pushed bad into corners when we'd go play at the low-key autocross, turns out it just needed a rear sway bar. the base car comes with the lightest front bar and no rear bar. at the suggestion of a guy who races them and did a whole comparison study on what worked well together, we got the stiffest rear bar. made a significant change for the better.

Interesting you mention rear bar. I was thinking to put one on but my massive oversteer coming out of a turn makes me second guess that. I thought lowering the rear and reducing rear bar helped corner exit oversteer?