2004 Casper Tahoe

[Casper 2004 Tahoe]

Recently purchased this 2004 Tahoe as a platform to start a new fun project with, and also to do truck stuff :-D.

I'm still learning about the truck, but this is what it has, to the best of my current understanding.
The motor has been swapped. there is a 6.0L out of a van, recently rebuilt. LS3 heads, LS9 injectors, LS9 supercharger with LSA lid and stock pulley. Stock PCM tuned with HP tuners. I have forgotten the cam specs, but I was told it was a Lingenfelter cam with specs very similar to a stock LS9 cam. Stock airbox is very quiet.

The truck has been lowered and has some stiffer shocks, but it all seems to work and nothing rubs or rattles.

Transmission is a stock 4l80, freshly rebuilt. Converter is a cheap, as of yet unknown brand 2600 Stall.
Rear is a rebuilt stock 10 bolt with Detroit Locker? (can't remember if the guy said TruTrac or Detroit Locker and do not know how to tell without opening it up) and 4.11
All drivetrain has around 6000 miles.

What needs to change, the exhaust is shorty headers to a stock Y pipe with cats to a single 3 inch into a giant Magnaflow muffler, then out to a dual 3 inch, then Y into a single 3 inch dump at the rear. All welded up nicely, but it kinda sounds like a stock exhaust with a hole in the muffler and at around 3,000 RPM it is already wooshing like it needs more exhaust lol. It needs long tubes and a proper exhaust.

The tune is good enough for driving around and sets no codes, but it was NOT dyno tuned, so that needs to be done, likely after the other work.

Motor is 9.6 to 1 and the stock pulley is only giving me 7 PSI. would like to see 10, but will be talking to Speed Inc to see what else I may need to do first since I will probably be taking it to them to tune.

Aftercooler is right in the front and works, but the tank is tiny, I may buy an aftermarket one or make one to fit in the second batter spot.

The transmission shifts need work. It lingers in gears at part throttle for longer than I would like.
The first to second shift is set to lift throttle before shifting at WOT so the truck lays on its face before shifting, possibly to save drivetrain. Shift points are at 5800 RPM, prior owner was OCD about reliability and didn't care about squeezing performance out of it.

Stock steel driveshaft with 1310 Ujoints may be swapped in favor of something sturdier.

I know the 14 bolt is almost a direct replacement. I will consider this swap if the 10 bolt becomes a problem.

Looking forward to doing some truck stuff and messing with people at the track occasionally.

 

[gat0r]

nice
interested to see how it comes along, after tune & such

 

[Casper 2004 Tahoe]

nice
interested to see how it comes along, after tune & such

Me too :-D

 

[bottomline2000]

Recently purchased this 2004 Tahoe as a platform to start a new fun project with, and also to do truck stuff :-D.

I'm still learning about the truck, but this is what it has, to the best of my current understanding.
The motor has been swapped. there is a 6.0L out of a van, recently rebuilt. LS3 heads, LS9 injectors, LS9 supercharger with LSA lid and stock pulley. Stock PCM tuned with HP tuners. I have forgotten the cam specs, but I was told it was a Lingenfelter cam with specs very similar to a stock LS9 cam. Stock airbox is very quiet.

The truck has been lowered and has some stiffer shocks, but it all seems to work and nothing rubs or rattles.

Transmission is a stock 4l80, freshly rebuilt. Converter is a cheap, as of yet unknown brand 2600 Stall.
Rear is a rebuilt stock 10 bolt with Detroit Locker? (can't remember if the guy said TruTrac or Detroit Locker and do not know how to tell without opening it up) and 4.11
All drivetrain has around 6000 miles.

What needs to change, the exhaust is shorty headers to a stock Y pipe with cats to a single 3 inch into a giant Magnaflow muffler, then out to a dual 3 inch, then Y into a single 3 inch dump at the rear. All welded up nicely, but it kinda sounds like a stock exhaust with a hole in the muffler and at around 3,000 RPM it is already wooshing like it needs more exhaust lol. It needs long tubes and a proper exhaust.

The tune is good enough for driving around and sets no codes, but it was NOT dyno tuned, so that needs to be done, likely after the other work.

Motor is 9.6 to 1 and the stock pulley is only giving me 7 PSI. would like to see 10, but will be talking to Speed Inc to see what else I may need to do first since I will probably be taking it to them to tune.

Aftercooler is right in the front and works, but the tank is tiny, I may buy an aftermarket one or make one to fit in the second batter spot.

The transmission shifts need work. It lingers in gears at part throttle for longer than I would like.
The first to second shift is set to lift throttle before shifting at WOT so the truck lays on its face before shifting, possibly to save drivetrain. Shift points are at 5800 RPM, prior owner was OCD about reliability and didn't care about squeezing performance out of it.

Stock steel driveshaft with 1310 Ujoints may be swapped in favor of something sturdier.

I know the 14 bolt is almost a direct replacement. I will consider this swap if the 10 bolt becomes a problem.

Looking forward to doing some truck stuff and messing with people at the track occasionally.

View attachment 183680 View attachment 183681 View attachment 183682

Cool to see a lsa blower in play on one of our trucks. Been toying with the idea just to keep it a factory mod truck. I have a stock 4l85 with a transgo shift kit. U don't have to much to an 80e to get it to hold big power, just dual feed it which is what the transgo kit does and drill the valve body plate to adjust shift firmess. I have my torque management disabled and mine shifts smooth with no delays.

I think the 80s are kinda lazy in Stock form and that may be what u are feeling. I need those 4.11 gears in my life lol.


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[Countryboy07]

Sleeper! PTM door handles and bumper cap would do wonders in the looks department.

 

[Casper 2004 Tahoe]

Sleeper! PTM door handles and bumper cap would do wonders in the looks department.

I know, I considered it

 

[Casper 2004 Tahoe]

Cool to see a lsa blower in play on one of our trucks. Been toying with the idea just to keep it a factory mod truck. I have a stock 4l85 with a transgo shift kit. U don't have to much to an 80e to get it to hold big power, just dual feed it which is what the transgo kit does and drill the valve body plate to adjust shift firmess. I have my torque management disabled and mine shifts smooth with no delays.

I think the 80s are kinda lazy in Stock form and that may be what u are feeling. I need those 4.11 gears in my life lol.


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Thanks for the info, I will add this to my growing list of stuff to look at.

And the 4.11s are nice, what is not nice is cruising at 80 at almost 3000 RPM.

 

[bottomline2000]

Thanks for the info, I will add this to my growing list of stuff to look at.

And the 4.11s are nice, what is not nice is cruising at 80 at almost 3000 RPM.

Dammit, I was going to ask u about the OD gear and rpm. I have a taller tire 295/35/24 so I hope I can keep my rpm under 2300 and limit cruise speed to 70-75mph.

I'll say this regarding the transgo kit. If you already have one u may want to consider reversing the pressure relief mod and using a sonnax valve instead. If u do add one don't drill your valve body. This will make sense if you look into it. Some older 80s were known to have runaway line pressures that could break parts and Crack the case. The sonnax valve relieves this pressure. The transgo relief mod can fail and cause you to burn your trans up from low line pressure.

There are a lot of little mods u can do and it can be a beast that can hanlde that lsa blower at full rip but u need to find out what u have first.

btw, hat kind of fuel mileage are you seeing with this combo?

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[Casper 2004 Tahoe]

Dammit, I was going to ask u about the OD gear and rpm. I have a taller tire 295/35/24 so I hope I can keep my rpm under 2300 and limit cruise speed to 70-75mph.

I'll say this regarding the transgo kit. If you already have one u may want to consider reversing the pressure relief mod and using a sonnax valve instead. If u do add one don't drill your valve body. This will make sense if you look into it. Some older 80s were known to have runaway line pressures that could break parts and Crack the case. The sonnax valve relieves this pressure. The transgo relief mod can fail and cause you to burn your trans up from low line pressure.

There are a lot of little mods u can do and it can be a beast that can hanlde that lsa blower at full rip but u need to find out what u have first.

btw, hat kind of fuel mileage are you seeing with this combo?

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You may be able to pull that off. Right now I am at 2500 RPM at 70 mph, if your tire is taller, you may be in that ballpark.

I certainly need to find out for sure what I have. I was told this was a completely stock, rebuilt 4l80. The more I hear and read about these, the better i feel but I have no automatic transmission experience.

This is the first automatic car I have ever owned so I have a lot of catching up to do. I did ask about a shift kit since shifts are quite firm at part throttle. He told me there was no shift kit, and he tried backing down the shift firmness with HP turners but realized that someone had turned up the pump pressure in the transmission, so he left it. As I understand it, it's only a matter of pulling the pan and backing pump pressure down to normal, then the shift firmness can be adjusted better.

The guy who built this was not the guy who sold it to me, so I was collecting information from two people. The guy who built it seemed to know what he was talking about, but in all my conversations, I forgot to ask, specifically, what the owner was afraid of breaking that he had the shifting set up this way.

Thanks for the information about the valve body and pressures. I am an automatic noob so any information you can give me in that arena will be greatly appreciated.


Fuel mileage? LOL Let's just say I will not be selling my Mazdaspeed 3 anytime soon. :-D Even modded, that car is around 30. I have not actually checked mileage, but I can get a judgement by how much money I have been dumping in it's fuel tank compared to my other cars. Honestly, I am sure the tune is not great, and fuel mileage may improve with a better tune.

I did run this at the track to get a baseline before I start working on it, it was over 95 degrees that day (In Michigan in September!) and the truck felt lazy between 80 and 100 mph which showed at the track. I think I gave the kid in the BMW 135 next to me PSTD. :-D

It was consistent though between 14.0 and 13.91 @ 98 mph. It weighed 5182 lbs with my 180 lb self in there. 60ft was better than I expected, stock tire pressure on those old all terrains, 2.0 60ft.

Truck seemed like it layed down flat forever in each first to second gear shift. I do need to move my shift points up, it feels like power is still there when it shifts and the second to third shift seems earky so the truck starts second gear below the power band then feels like it is pulling strong again around 1000 ft.

I'm used to racing manual cars, so with nothing more to do than press the gas pedal, I could concentrate on the light and was treeing the crap out of everyone :-D.

 

[bottomline2000]

If you are in contact with the trans builder then you are halfway there. My trans is running my stock pressure and is completely stock minus the shift kit and pump mods. It's butter smooth at part throttle, better than my 4l60. Once I get into it the shifts are nice and tight, but not harsh. Torque management is making it fall on its face between shifts. A waste of time in an 80e. I don't have any and there is no delayed shifting.

I have never opened a transmission before and did all the mods myself. The shift firmness is controlled by holes in the valve body plate. There are specific sizes to drill to get different results..my drill sizes
1-2nd gear -.110
2-3rd gear- no check ball
4-4th gear-. 125

You can literally tailor it to shift how you like. These figures are from one of the top 80e builders in the country so I trusted him and used them. Worked out great.

Turning up the pump pressure may cause more problems and may explain why you have firm shifts at part throttle. I think they are trying to get more holding capacity with the clutches, but I don't think that's the right way to do it.

My truck is much quicker with the 80e than it was with the 60. It doesn't lose any momentum between shifts and just runs thru the gears. A little adjusting and I'm sure you'll be down in the 12s.


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