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I wanted to create a thread for this truck. It’s a very simple truck and is a lot of fun on the street.
My goal for this truck was to create a fullsize Syclone if GM had made one in modern times. I wanted a NBS truck like a Silverado SS, but it always bugged me that they were no RCSB. I found this one in TX with 70k miles. It’s a 4.8 which I wanted as the Syclone was 4.3 albeit V6.
NP149 tcase Stainless exhaust AWD dyno Silverado SS front diff
Sorry to keep you hanging. I had to convert some photos to work with the site.
VSR 70/70 .96 FLT built 4L65 Circle D 3000 stall Huron Speed V4 kit
FUEL - 1000 cc FIC from Huron. 2 hellcat pumps in the Huron hanger. -8 and -6 lines to Flexfuel to TBSS intake and fasster rails using fasster fittings and fpr and RH lines left from another project.
POWERTRAIN - 4.8, 862 heads, stock everything except for tbss intake. FLT stage 6 or something trans. Huron trucool trans cooler. Circle D converter, 3000 stall. NP149 reman. Upgraded front and read shafts. Stock open rear for now.
Huron speed V4 kit with intercooler. VSR 70/70 .96 turbo. Precision gate and bov. Had to have a few pipes remade. Speed density tune. Stock P59 ecm with HPT. Fully tuned for flex.
NNBS fan upgrade
Innovate Motorsports ethanol/boost/afr gauge
Newest Silverado brake upgrade
Atomic Fab front coilover install (removed keys and torsion bars)
Slightly dropped with basic Belltech bs.
About 500 awhp/500 awtq @ 10 pounds
12.47 @ 113 on the street
Next plans:
Maybe trutrac or quick performance rear but so far not much spin with this powertrain. Slow 2.0 60 fts.
4.8 cam and springs. Not sure which one to get. Leaning towards milder the better. Want great idle, just opened up a bit. Not sure where I will land there. Holdener says BTR torque cam maybe? I am thinking @Summitracing SUM-8720 or ghost cam at the biggest? Not sure as its kind of a weird combo trying to remain streetable and I already have 3k stall. @ddnspider what did you run in your 4.8 turbo truck?
4.8 cam and springs. Not sure which one to get. Leaning towards milder the better. Want great idle, just opened up a bit. Not sure where I will land there.
i had a triple 12 in my 4.8 in the awd truck and liked it.
my next go to is the 'sloppy stage 1'/elgin 1838. in my wagon i swapped from that to the SS2/elgin 1840 and dont like it, planning to swap the 1838 back in. the awd truck has it now and if i wasnt planning a complete motor swap id be planning to swap the cam out.
I have 11 PSI on a 4.8 using the Texas Speed 212/218 .550" Low-Lift cam.
Feels good, runs strong up to 6400 rpm, a little soft below 2400 rpm with stock torque converter.
I'm still on the stock cam. When I decide to upgrade it'll be with Summits Torkinator truck cam for sure. I think Holdener had a video where they changed nothing but the cam and it picked up 100hp and gained everywhere. Just awesome.
I'm still on the stock cam. When I decide to upgrade it'll be with Summits Torkinator truck cam for sure. I think Holdener had a video where they changed nothing but the cam and it picked up 100hp and gained everywhere. Just awesome.
I like Summit's cams, but I have also heard Holdener say that the Torkinator is too big for a 4.8 if you want street drivability. It seems like many enjoy something in the mid 2 teens with lower lift.
From Summit's intro thread to the cams: "SUM-8728R1Big Truck Torkinator, 212 int. / 218 exh. 110 LSA +3 adv. .600 int. / .585 exh., -1 I/O, 33 I/C, 42 E/O, -4 E/C, -5 overlap. This thing is all attitude. It's for the guy looking for a True tow cam with 33 abdc intake closing, but also wants a bit of an idle to it AND we've pushed this to .600 lift. This cam has more torque and power production than anything else we've seen on the market. The truck lobes are designed for long spring and valvetrain life and our new SUM-174004 .600 lift beehive springs are the perfect match! This would make an excellent turbo cam with 4.8 for instance. Also good for a turbo car where the owner is looking for good streetability and wants to retain the stock stall converter."
So what does that mean if I already have a 3k converter? The Ghost cam seems to be a fan favorite, but that is 222/230 and .600/.585 lift. I'm not sure if there are any turbo 4.8 guys running that one, but it seems if you want to err on the side of streetability that the Torkinator might be the way to go.
I like Summit's cams, but I have also heard Holdener say that the Torkinator is too big for a 4.8 if you want street drivability. It seems like many enjoy something in the mid 2 teens with lower lift.
From Summit's intro thread to the cams: "SUM-8728R1Big Truck Torkinator, 212 int. / 218 exh. 110 LSA +3 adv. .600 int. / .585 exh., -1 I/O, 33 I/C, 42 E/O, -4 E/C, -5 overlap. This thing is all attitude. It's for the guy looking for a True tow cam with 33 abdc intake closing, but also wants a bit of an idle to it AND we've pushed this to .600 lift. This cam has more torque and power production than anything else we've seen on the market. The truck lobes are designed for long spring and valvetrain life and our new SUM-174004 .600 lift beehive springs are the perfect match! This would make an excellent turbo cam with 4.8 for instance. Also good for a turbo car where the owner is looking for good streetability and wants to retain the stock stall converter."
So what does that mean if I already have a 3k converter? The Ghost cam seems to be a fan favorite, but that is 222/230 and .600/.585 lift. I'm not sure if there are any turbo 4.8 guys running that one, but it seems if you want to err on the side of streetability that the Torkinator might be the way to go.
You're confusing something. The Torkinator is the smallest of the cams. It's going to drive the best hands down.
SUM-8727R1 Truck Torkinator, 200 int. / 205 exh. 113 LSA+ 4 adv. .550 int. / .550 exh., -9 I/O, 29 I/C, 40 E/O, -14 E/C, -23 overlap. Note this intake closing point is 29 abdc a full four degrees eariler than SUM-8718R1. This wll shift the powerband down even further BUT with .050 extra lift, that's going to help through the range and keep it still fairly strong all the way to 6k rpm. It's designed for use with our SUM-174002 LS6 springs.
You're confusing something. The Torkinator is the smallest of the cams. It's going to drive the best hands down.
SUM-8727R1 Truck Torkinator, 200 int. / 205 exh. 113 LSA+ 4 adv. .550 int. / .550 exh., -9 I/O, 29 I/C, 40 E/O, -14 E/C, -23 overlap. Note this intake closing point is 29 abdc a full four degrees eariler than SUM-8718R1. This wll shift the powerband down even further BUT with .050 extra lift, that's going to help through the range and keep it still fairly strong all the way to 6k rpm. It's designed for use with our SUM-174002 LS6 springs.
I'm still on the stock cam. When I decide to upgrade it'll be with Summits Torkinator truck cam for sure. I think Holdener had a video where they changed nothing but the cam and it picked up 100hp and gained everywhere. Just awesome.
I just put the btr stage 2 4.8 turbo cam in mine. It’s taking the place of an ss2. G42 turbo (80/75)
Shooting for 850whp on kill. I’ll update when it’s running again.
Even though it has a stall, it's heavy so it will drive much better with the smaller cams for sure. I think cams like the ghost cam would be a bit much for what you are looking for, you want to be in the low/mid teens duration range and low ICL/LSA to bump up the bottom/midrange of the little 4.8. I think of the smaller cams you mentioned I'd pick the https://www.summitracing.com/parts/sum-8728r1 as it will still drive decent, probably make a noticeable difference in the midrange over the smaller truck cam and you have a stall already. If you want it to be more stealth probably pick the https://www.summitracing.com/parts/sum-8727r1 though.
Last edited by slowride; Sep 21, 2023 at 10:42 AM.
I think 8720 is the biggest i would go. I wish more real world experience was out there for these but i don’t know any one running 8720 or the torkinators. I’m sure it’s splitting hairs but since it isn’t a daily driver, I will likely try 8720. Luckily I don’t have to decide for another month or so as I’m going to drive it the rest of the Fall as is.
That's basically the same or close specs to the Ws6store hi lift hot cam also. That should work I did't realize you were thinking about going that large. It's going to act a bit larger being in a 4.8 though.
I really like the 4.8. I think its very underrated, but too many people neuter their best qualities right out of the gate. They need to rev to make power. Plain and simple. Wimpy cam and wimpy stall will never allow it to do what it does best. Which is pull like an SOB from 5-8k for very little $.
I get you don’t want a race car. But the 4.8 is more of a race engine because it needs that RPM. It will never 60’ and make boost and power as it should down low without it. Without a trans brake, you need the converter to flash high 3700+ to make that turbo light off instantly and make real boost and power off the line. Without that, it will never do what you want IMO. If you want a stump puller low rom build. You need a larger motor. Build a 370” ls on the side (or even bigger) and drop it in down the road. It would likely be fine with your current setup.
I’d take all power gains and claims coming from Holdner w a grain of salt. You *might* see 30hp from a cam at the wheels, and even that is doubtful. You aren’t gonna see 100hp and NA 4.8’s and 5.3’s aren’t making 400-500hp as you routinely see on his channel. At least those numbers aren’t relevant to a turbo ls setup once its in a car.
A healthy NA 6.0 with a cam is making like 350ish wheel through an 80e. His dyno cell data is VERY misleading. Can’t count the amount of people coming up to me telling you they make 500hp with their cam only 4.8's and 5.3’s and want 1000hp on 15lbs. That’s not how it works.
Step 1 is always pick your power or ET goal. What are you wanting it to run?
Last edited by Forcefed86; Sep 21, 2023 at 02:36 PM.
I don’t get why people are afraid of loose converters and rpm. With lock up converters, higher stall isn’t an issue. And actually, the way turbo converters are made these days a high stall converter can run very well on the street IMO. I run an extremely loose PTC unit and a glide. I street drive it everywhere and its great. No hot fluids, couples well… and I light off twin .96 T4 78/75s easy with a cam only SBE. 5.3. So IMO, a MUCH looser stall (like the loosest Circle D makes) with a tightish LSA cam and decent duration would be the best fit and least amount of rework for you. Even without a cam it would make a HUGE difference. Because you need a high stall and rpm to make power, tiny cams don’t do much. You want to look at 5kish and up power band with a 4.8. I don’t care what the curve looks like below that for a street strip toy. So while you may gain a little from 5k to redline with a small cam… you gain a lot more with a relatively “big cam”.
If you look at the past 10 years you’ll see a trend in small bore turbo LS cams. They are ground on a tighter and tighter LSA. Id rather error on the side of too tight than too loose. Less power to be lost if it’s a little tight. Somewhere in the 109-111 range would be great. You are tying one had behind your back with converter choices, then shooting yourself in the foot by limiting cam choices. I know it’s a pain, but if you pull that converter and send it out, you’ll be money and performance ahead. Much more so than playing with cams and other parts.
Optionally if you wanted the setup to really shine, you want a decent T6 turbo that can actually breathe well at high rpm. A trans brake is a night/day difference as well. But I get that’s not for everyone. 1.32 T6 S475 is hands down a better turbo than the 78/75 IMO. A stg2 summit cam and t6 1.32 S480 worked very well on my 4.8.
A 2.0 60’ is really bad, even for a 2wd setup. What tires do you run? How much boost can you make on the line?
I don’t get why people are afraid of loose converters and rpm. With lock up converters, higher stall isn’t an issue. And actually, the way turbo converters are made these days a high stall converter can run very well on the street IMO. I run an extremely loose PTC unit and a glide. I street drive it everywhere and its great. No hot fluids, couples well… and I light off twin .96 T4 78/75s easy with a cam only SBE. 5.3. So IMO, a MUCH looser stall (like the loosest Circle D makes) with a tightish LSA cam and decent duration would be the best fit and least amount of rework for you. Even without a cam it would make a HUGE difference. Because you need a high stall and rpm to make power, tiny cams don’t do much. You want to look at 5kish and up power band with a 4.8. I don’t care what the curve looks like below that for a street strip toy. So while you may gain a little from 5k to redline with a small cam… you gain a lot more with a relatively “big cam”.
If you look at the past 10 years you’ll see a trend in small bore turbo LS cams. They are ground on a tighter and tighter LSA. Id rather error on the side of too tight than too loose. Less power to be lost if it’s a little tight. Somewhere in the 109-111 range would be great. You are tying one had behind your back with converter choices, then shooting yourself in the foot by limiting cam choices. I know it’s a pain, but if you pull that converter and send it out, you’ll be money and performance ahead. Much more so than playing with cams and other parts.
Optionally if you wanted the setup to really shine, you want a decent T6 turbo that can actually breathe well at high rpm. A trans brake is a night/day difference as well. But I get that’s not for everyone. 1.32 T6 S475 is hands down a better turbo than the 78/75 IMO. A stg2 summit cam and t6 1.32 S480 worked very well on my 4.8.
A 2.0 60’ is really bad, even for a 2wd setup. What tires do you run? How much boost can you make on the line?
Probably that stock open rear diff is killing his 60 ft.
One tire fire not ftw lol.
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2003 Sierra sycloned 
