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I’m wondering if it is even a good idea to install an aftermarket turbo on a stock LB7? The only thing I have done to my LB7 is install EFI Live tunes and a 5 inch turbo back exhaust. The truck is at 172k miles and runs great.

I have a feeling the answer is no, but just wanted to see others opinions.
well, it depends what you want out of the truck. If your happy with it how it is then obviously the answer would be no. However if you use the truck to tow, and want more power, or lower EGT's, swapping the turbo may make sense, or if you want to blow the doors off civics at red lights, a turbo might make sense. Just depends what you want out of the truck. Personally i dont see a reason NOT to do it, so if its something that you want, go for it. The fuel will be your limiting factor still though unless your have improvements to the fuel system. A lift pump will not make a huge difference in that regard. Lift pumps take the load of lifting fuel from the tank to the pump off the CP3, but they do not even remotely come close to the output pressure of a CP3, so while they may help along a hurt CP3, its not like your going to support 100 over sticks just by adding a lift pump (not that your saying that, just making a point for clarity)


I see. I plan to add a few upgrades to my truck in the distance future lol like a built trans. Good to know an aftermarket turbo would roast the stock transmission.

On another note, these turbos with the 64mm, 68mm and so on... Do they require a different sized inlet tube?

The transmission on an LB7 can take about 50 HP over stock reliably. Some push that to 100 over without issue, but personally i think your on borrowed time there. However the failures in the transmission tend to happen more when you hit the go pedal on the highway, since those gears are not built to take that kind of load. You are unlikely to roast the low gears on a mild tune unless you really just beat the hell out of the truck. Bolting a new turbo on is not going to roast your transmission, that is all on your right foot and the 7-8 pounds of goo between your ears. What it will do though is give you the ability to roast the transmission should you make that choice.

It would be better to build the trans first, however depending on your needs for the truck, that is not always required. Were you trying to get more low end torque for towing, the transmission would probably be fine with a aftermarket turbo so long as you were aware of what kind of load you were putting on the truck. However if you want to be more care free with your right foot, a trans build would be a better investment before the turbo.





Lastly, if the goal is sound, and only sound, put a batmo or similar compressor on the factory turbo, add the PPE boost valve and put a metal intake on it, and assuming its not cali emissions, it should be very noticeable even with the windows up. Thats basically what i ran on my 01, except i had a plastic banks intake and even with the music on in the cab i could hear the turbo sing. That setup though did not really make any major performance gains, so its about 500$ for noise. I think i picked up maybe 2 PSI of boost from that whole arrangement.
 

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Put a Bigger airhorn on, remove the resonator if its still there(plug the whole) 2in rubber plumbing cap, Put a PPE waste gate restrictor in-line with the waste gate. You will have whine. No need for a bigger turbo. If you must, get you a different input fan think Bat-mo is one I seen. There are others, as well as bigger fans with bigger housings. Do the cheap stuff first. Lift pump, with a sump kit will cure that fuel gauge problem. I would go Fass and delete the factory filter, or leave it for more filtration.
 

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I agree with others about the transmission. I have an 02 and when I unexpectedly had to replace the engine I of course added other goodies. After an LBZ pump, .45 over sac injectors, a fleece 63 turbo, high flow up pipes and down pipes, 5” exhaust and efi live I destroyed the transmission the first time I towed my toyhauler. Knew it was coming but still sucked
 

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So are these trannys basically maxed out for the power they can handle from the factory?
I could see doubling HP being an issue but adding 100hp seems to be the breaking point I keep reading. It’s unfortunate since it seems so easy to add the power to the motor.
 

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They don't over-engineer for factory power output. If you leave the power output at factory settings and maintain the equipment, then it will last a long time.

But you have to realize, 100hp isn't small potatoes. Yes it is when you're talking big power or performance-wise, but a stock truck turned up 100hp is a big deal on stock components.

My LB7 is over double what it was from the factory. But, that hasn't come without a price. Two transmission builds, a driveshaft, injectors, turbo, a rear end, an engine build... it all adds up, and it adds up in a hurry in the diesel world.
 

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They don't over-engineer for factory power output. If you leave the power output at factory settings and maintain the equipment, then it will last a long time.

But you have to realize, 100hp isn't small potatoes. Yes it is when you're talking big power or performance-wise, but a stock truck turned up 100hp is a big deal on stock components.

My LB7 is over double what it was from the factory. But, that hasn't come without a price. Two transmission builds, a driveshaft, injectors, turbo, a rear end, an engine build... it all adds up, and it adds up in a hurry in the diesel world.
Oh I’m learning about the high costs real fast, my wallet is still smoking haha

What does an average rebuild of the 5 speeds cost and I’m assuming there’s some additions that would need them up as well?
 

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If you're going to be in it going through to rebuild it, then you might as well actually build it to hold some power versus a stock rebuild. I would suggest using a SunCoast kit that includes internals and use one of their triple disk converters. A GMAX5 kit and 1058 converter is what mine is, and it works awesome for me. Seems like the going rate, parts and labor, is somewhere north of 5k any where that is a quality establishment.
 

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So are these trannys basically maxed out for the power they can handle from the factory?
I could see doubling HP being an issue but adding 100hp seems to be the breaking point I keep reading. It’s unfortunate since it seems so easy to add the power to the motor.
The transmission has plenty of overhead for the truck as built so that it will likely not fail in the life of the truck. It is an excelent transmission but its not built for the loads that a built engine puts on them. Just like the engine needs a bigger turbo, injectors, pump ect to make more power, the transmission needs upgraded converters, plates, valve modifications ect to hold the power. Its really no different.
 

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If you dont do the valve body you can do it yourself find a old Core rebuild the transmission then when you pull yours switch the valve body. I've done some of the older ones from back in the day but they didnt have electronics. That was in 1987 and most of them where older out of international bus's and trash trucks. They did have lock up convertors though.
 

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There are plenty of videos you could watch as well. Pull the front first then flip it pull the rear the clutches and drum is in the rear. Then the Valve body leave the bolts in the body its easier going back together. I would not do a 5 speed either do the 6 speed its a better tranny in my opinion. I never minded doing GM stuff 350/400/700R4, but the ford C4 I never had luck with. I recently did a 4L60 for my middle son's truck with a 454 and it was pretty easy. Might buy a book and make some extra $$ once you get good at it. I do anyway.
I do notice mine goes into reverse hard, Im hoping it gets better over time. Its a 5 speed but when I find me a 6 speed core reasonable I may change it and put the shift flipper on the column. Nice to dream a little as well!!
You can get a new 6 speed Valve Body and TCM for about $1900.00. If you have a Edge CTS it will show the gear as well.
 

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The push buttom manual shift is an easy switch. I havent looked into the 5 spd to 6spd swap but i know a few years ago it was a valvebody change and tcm from suncoast or SoCal that was locked to them. Around 1700 bucks iirc.
 

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As a fellow LB7 owner running tunes and a lift pump plan a 5k transmission. Another weak spot on our trucks when you bump up the HP are the head gaskets. I had to upgrade that as well. I don't beat on my truck and it doesn't even have 100k miles yet. Do the turbo and a tranny, it will be fun to drive!
 

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I thought I read here the 5 to 6 speed swap was expensive and not worth it.
Very much not worth it. Over $2200 just for the parts, plus fluid and installation. The 300rpm drop just isn't worth it

As a fellow LB7 owner running tunes and a lift pump plan a 5k transmission. Another weak spot on our trucks when you bump up the HP are the head gaskets. I had to upgrade that as well. I don't beat on my truck and it doesn't even have 100k miles yet. Do the turbo and a tranny, it will be fun to drive!
This is kind of a loaded comment... I've been on both sides of the fence here. I've done head gaskets on stock trucks with around 100k miles... and then my truck had 266k miles when I tore the engine down and the gaskets were fine- after 100k miles with bigger injectors and 40k miles with a bigger charger and making some good power. I shortened the rods on stock head gaskets and bolts. So just because you turn it up doesn't mean you will have head gasket issues. But, don't get pissed if it does happen, because anything is possible
 

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Sun Coast does still have the Module and Valve body kit, Im thinking this will be my next big expense. Like said before the RPM drop at Hwy speed is what I like as well as the up/down shift button with tow selector change over. Its probably never going to be cost effective, but my truck is my labor of love. I wont do tunes, unless I ever refresh the engine.
 

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Sun Coast does still have the Module and Valve body kit, Im thinking this will be my next big expense. Like said before the RPM drop at Hwy speed is what I like as well as the up/down shift button with tow selector change over. Its probably never going to be cost effective, but my truck is my labor of love. I wont do tunes, unless I ever refresh the engine.
You could just do the Fleece TapShift and have the shift control. It actually comes in pretty handy sometimes. And doing the TapShift is WAY cheaper than the 6spd conversion, and just that ability is way more useful than the 6spd too

Being you have a 2003 I think its just a plug-n-play on the TapShift install. 01-02 trucks require a tcm reflash with the overdrive lockout tune, but 03-later trucks i'm pretty sure are just plug-n-play
 
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