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i just finished a turbo build on a 2011 sierra 4.8 and i have been driving it around here and there checking out what it's doing and what parts are worth swapping out.
first and foremost I would say change your plugs/wires The reason I'm saying change your plugs and wires is; I did the same thing as what you're doing now. I put heat socks on and everything. The straight boot on the end of the stock plug wire is way too close to the log manifold and it will melt the wire down the road and have you scratching your head on why it's running like ****. What I did was I bought plugs and wires for a LT1(90s) they come with 90 degree boots and you can come from underneath the log manifold as apposed to coming down from the top. They come fairly long(different lengths) you would use your best judgement to how you would route them. The stock LT1 plugs are only 7MM but they should be fine if you're plugs are gapped and you're not putting huge power to it.
also I wanted to mention the VVT - I went ahead and deleted my VVT by putting a LS2 timing cover/sprocket on there and got rid of the single bolt VVT cam and went with a traditional 3 bolt cam. I purchased a LJMS stage 2 turbo cam and I grabbed a set of BTR dual valve springs. Upgraded the push rods while I was in there.
Theres a couple other things I was going to mention;
Have you looked at injectors?
Have you talked to someone that has turbod a SFI NNBS truck?
i just finished a turbo build on a 2011 sierra 4.8 and i have been driving it around here and there checking out what it's doing and what parts are worth swapping out.
first and foremost I would say change your plugs/wires The reason I'm saying change your plugs and wires is; I did the same thing as what you're doing now. I put heat socks on and everything. The straight boot on the end of the stock plug wire is way too close to the log manifold and it will melt the wire down the road and have you scratching your head on why it's running like ****. What I did was I bought plugs and wires for a LT1(90s) they come with 90 degree boots and you can come from underneath the log manifold as apposed to coming down from the top. They come fairly long(different lengths) you would use your best judgement to how you would route them. The stock LT1 plugs are only 7MM but they should be fine if you're plugs are gapped and you're not putting huge power to it.
also I wanted to mention the VVT - I went ahead and deleted my VVT by putting a LS2 timing cover/sprocket on there and got rid of the single bolt VVT cam and went with a traditional 3 bolt cam. I purchased a LJMS stage 2 turbo cam and I grabbed a set of BTR dual valve springs. Upgraded the push rods while I was in there.
Theres a couple other things I was going to mention;
Have you looked at injectors?
Have you talked to someone that has turbod a SFI NNBS truck?
Thank you.
You can't see it under the insulators, but those are Taylor 9mm wires which have a good bit of angle to them already. The wires basically run straight up from the plugs. I'ts more the insulator touching than the wire itself. I'm going to try to make them live like this before dumping more $$ into it.
The plugs are stock LT4(supercharged DI 6.2) pieces.
Originally Posted by FFDP
His is direct injection. Little different details in the injector department and tuning for a DI.
Correct. On3 says the stock pump/injectors on the 5.3 should be safe to about 500 RWHP. I'll be happy making anywhere between 450-ish range so hopefully this will be something I don't need to upgrade. Looks like a LT4 pump or a cam(or both) should give me 10%-20% more overhead so there is a little room to grow before injectors. I think?
Geoff @ EPS is a friend and will be handling the tune.
A big advantage of Direct Injection is that you don't have to run a super rich fuel mixture either. Port fuel cars just as examples are normal 12.5 NA and 11.5 boosted as a general target air to fuel ratio. Some like richer than other of course.
Then with DI running low 12's with moderate boost levels is pretty normal and nearly 13.0 with NA because of where the fuel is being injected. This alone saves on fuel and headroom for the injector.
A big advantage of Direct Injection is that you don't have to run a super rich fuel mixture either. Port fuel cars just as examples are normal 12.5 NA and 11.5 boosted as a general target air to fuel ratio. Some like richer than other of course.
Then with DI running low 12's with moderate boost levels is pretty normal and nearly 13.0 with NA because of where the fuel is being injected. This alone saves on fuel and headroom for the injector.
I have high hopes for DI. Pretty impressive to increase output by 50-75% and not upgrade fuel system in any way. At least I get some compensation for that GD noisy pump! The day after I bought the truck I thought I had a bad lifter. In stock form, it's a bit embarrassing in a tight drive through that echos. Now there will be so much extra noise it hopefully will fade away.
Originally Posted by Choda
Nice write up, keep it going
Thanks for the encouragement. I often only get an hour or two at a time around two jobs, but hopefully the holidays will allow a *little* more shop time.
I had some of the Accel ceramic boot plug wires on the shelf so I decided to try them out. Wasted the little precious time I had tonight on these worthless pieces of garbage. First, even with dielectric grease it was EXERCISE to get the things to snap on to the plugs. #3 wire on the passenger side basically wouldn't fit due to the angle of the boot(and remember these are ceramic and don't give a bit). Went to pull them off and re-think things and two of the metal crimp ends came out of the boots and stuck on the plugs. They were so tight on the plugs it took me some time with the pliers to get them off. These might make good decorations on the tree this year but that's about it.
On3 is sending me a set of their plug wires with 90 degree boots that are long enough to hit the plugs from the bottom and feed up the firewall back to the coils, keeping them out of the major heat. I'll still use the woven cerami-something boot protectors as extra insurance.
Thanks to "Worktruck" in his post above for pushing me in this direction; once I called On3 about it they indicated they do all their vehicles that way and highly recommend it(to everyone except me when I was buying my kit? )
The fore O2 on the driver side fits great as does the crossover(now installed and tightened). Crossover fits great around the front driveshaft and under the pan and such. Not too tight but doesn't hang real low, either.
The fore O2 on the passenger(turbo) side is going to be a bit different as the bung is a few inches away from the head in the manifold. The plug is tied up with the aft plug(that won't be used; this kit deletes the cats and Y entirely) and clipped to the frame. Pop it out and then divorce it from the other wire it is clipped to. Should know shortly if it will reach or if we're getting an O2 extension.
On3 includes 3/8-16 bolts and metal lock nuts(the pinch type) to mount the turbo. I wanted something to quickly mock up to clock the turbo before I took it off for final tightening so got some non-locking of the same nuts. BTW, Lowe's has an amazing assortment of fasteners compared to Home Depot. They even have the pinch/lock nuts in 3/8-24 which I may buy for future R&R as I've had much better luck with finer-thread bolts staying tight after many heat cycles.
Hopefully starting on the cold side tomorrow so that I can fully clock both sides of the turbo and get on with things.
Their "race" intercooler is beastly. Weighs about 35lbs and is big enough to make me worry about how well my A/C will work next summer. And the struggle is real; many years in Louisiana summer starts around Christmas Eve.
It will mount about an inch higher than that to the diagonal crossbars behind it; for now just resting on the bumper.
11-16-2017, 06:22 PM
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