Stock GMC Sierra, new twin turbo kit installed, need advice and tune.

[Anthony5.3]

So I have a stock 2008 GMC sierra that I installed a twin turbo kit onto, everything is done the truck starts and drives just fine and I have the wastegates basically open so it builds no boost. So it runs and drives like it did before I installed the TwinTurbo kit, but I need help as far as tuning it to except boost pressure. This is all fairly new to me and I just ordered the HP tuner pro and should have it in a few days I'm looking to find if someone already has a tune out there for a 5.3 GEN 4 twin turbo. My goal is just to run about 8 to 10 pounds of boost and keep everything on the truck stock unless I want to upgrade later on and add more boost but this is a daily driver and only boosted it to gain power for pulling my boat across the pass and of course having some fun too. Please help me! Tia

[5FDP]

I hope you bought injectors and a fuel pump for that thing. You could only get away with no fuel pump if you have a Flex fuel pump, otherwise you will never have enough fuel flow. They are good for 500-550hp or so.

What MAP sensor did you buy? You'll have to set that up in the tune.

Running MAF or no MAF with this setup??

[Anthony5.3]

It's all stock, it originally had a mass airflow sensor right next to the airbox and now that is in line from the intercooler. I will not be changing injectors or feel pump I just want to get the most power out of it I can using all stock components I didn't purchase a map sensor

[GHuggins]

Your going to need to go speed density, otherwise you'll have cutting out issues even with MAF and VE both tuned correctly... ALSO stock fuel system is only good for about 5 to 6 psi absolutely maximum... Besides the stock map depending on year model and altitude is only good for around 3 to 5 psi... So either at least replace the injectors and map or go with really low boost output... Up to you...

[5FDP]

You need injectors and a 2 BAR map sensor.

Like the man said, you might see 3-4psi of boost without more fuel. More air = more fuel, more power = more fuel.

Nobody wants to see you blow your engine because you didn't have the right parts. We can try and help you with questions and tuning but you need to have everything else up to snuff before you even can begin.

[Anthony5.3]

Ok cool, so I need a 2 bar map sensor and injectors? What kind of injectors? Do you know a model number or brand?
And the map sensor, does it replace something? Or does it need to be wired into something and if so what?

[Anthony5.3]

Also where do you install the map sensor? Is there a particular place that most people install them ? also after some quick research I found some injectors that are 650cc Deleen injectors.

[Anthony5.3]

By the way a huge thank you to all the comments and support I'm getting already I've been completely lost until I ran across HP tuner and this Forum

[5FDP]

You can buy a Chevy Cobalt 2 bar MAP sensor, they are direct plug and play. Remove your old one and replace it with the 2 bar sensor. Then change the MAP sensor linear and offset settings in the tune for the 2 bar map sensor. That is all there is to it for that part.

Quality injectors with proper data will be wanted. Injector dynamics, fuel injector clinic and deatchwerks injectors are some of the better ones on the market that come with the data you will need. Look for 60-80lb/hr injectors at the minumum. I know deatchwerks sells 72lb/hr injectors that would be perfect for the power you are after.

If your truck is a flex fuel truck you will not need a fuel pump upgrade unless you decide to reach for more power than around 550ish. If your truck is not a factory flex fuel vehicle, you will also need to purchase a fuel pump.

[Paz]

Edit- 5FDP beat me to it

Your stock map sensor should be just behind the throttle body, should be able to get a 2 or 2.5bar replacement that is just plug and play (after you updated the tune data of course).

Whatever injectors you get make sure they have good reliable data for GM.

[Anthony5.3]

Awesome! So do I get rid of the maf sensor completely? (the inline sensor that was near the airbox)

[Anthony5.3]

And what is a good fuel pump? It's not a flex fuel rig*

[GHuggins]

You can either upgrade the pump or go with oversized injectors to compensate for the pump output - always better to go a little over than under anyway... BAP's tend to burn up stock pumps so definitely don't recommend that route... You can use a GM 3 bar map straight out of a ZL1 lid - you may or may not need the wire connector to go with it? You can keep the MAF and just use it for the iat readings - no need to completely remove it... Just has to be killed in the tune... The bov's are the only reason why you have to kill the MAF in the first place - them opening and closing causes the MAF to drop out and thus cutting fuel during in and out of throttle events... Reason why the OE has almost completely gone away from them on turbo applications unless they're in the inlet side of the turbo's...

[Anthony5.3]

Wow interesting. So I can just get a set of injectors and I should be fine. To be honest I don't want to push it over 600hp because of running all stock internals and running gear.
Also does anyone have a tune that I can load into the truck that will be close to where I need to be? Then I can just data log it and fine tune it from there?

[GHuggins]

Injectors will compensate to a degree - as long as your keeping it in the 600 flywheel range - you may be OK... I've tuned centrifugal setups only building about 4 to 6 psi and used stock pumps and injectors, so injectors would be a big improvement... Those typically put down in the 430rwhp range with a 6 speed and doing right around 70% duty cycle on the injectors just to give you an idea... So at 600 on the flywheel - you'll be somewhere around 450 to 500 at the tire...

There are decently priced high output pumps out there, if you want to go that route - it's entirely up to you...

[Anthony5.3]

Ok great, and any idea on a base tune?

[5FDP]

The stock tune is your base, this will need a ton of work past that.

Not much anyone can just whip up and hand out.

The simple stuff will be setting up the new MAP sensor and Fuel Injector settings, past that it's all going to be custom to that vehicle.

[Anthony5.3]

By data logging and tuning over and over?

[Anthony5.3]

Do you know how to set up the 2 bar map sensor and injector settings on HP tuner pro ?

[5FDP]

I believe the 2 BAR map settings are 200kpa and 10.33 offset.

The injectors you buy will come with the data you need to plug into the tune. They should tell you what tables you need to change.