Xtremes10

So I'm planning out my 5.3 twin turbo build and here's what I'm going for.

LM7 5.3 refreshed valve springs, small cam, truck intake, bigger injectors

Here's where I get a little lost, I'm looking for a set of twins since it's going to be wide open and exposed mainly for a cool/wow factor, kinda the idea of the truck in general. I'd be happy with 450hp but anything above that isn't bad either as long as I can stick to 93.

I've been told so many different turbos to use or not use my heads spinning. Here's where I'm at- was told hx35's are way too much turbo, hy35's would be ok as well as he341's, told gt35's would be too big for me while another guy said they'd work well for me. I'm not looking to break any records just to make some good power, and the cool factor. It's a budget build so I'm not looking into $1500 turbos either. It's going to be mated with a th400 to an 8.8 with what I believe are 3.27 gears.

Advice? Comments? Ideas? I'm open to suggestions and any help on this one

tta656

iTrader: (5)

ok first you goal is not 450 anymore............ 2 ebay gt35 turbos

your new goal is to have 576hp and 800tq and here is how you do it ...anyone tells you its too small or to big tell them to shove it because here is the proof...

https://ls1tech.com/forums/forced-in...too-small.html

Tjabo

HY35s are too small in terms of flow potential, despite being heavy sumbitches. HX35s are probably too small for you too, and they are harder to find for good prices because they are appropriately sized for a larger audience.

Since Matt found those GT35s to be a little small, maybe try some CXRacing 67mm turbos. I saw them on eBay for $323 shipped per turbo recently.

The whole "I want to run pump gas" thing is a little counter-intuitive. Bigger turbos are actually less octane sensitive because generally speaking they spool a little later where the detonation threshold is a little higher, and they also tend to run a little lower intake temps... GENERALLY SPEAKING. Lol

T76s10

iTrader: (6)

something isnt right in matts truck. theirs someone else on here and his friend is using them on an lq4 and made 750hp on a dynojet. talking to liljohn thinks its because hes on 12deg timing. your setup is similiar to mine, th400, 3.27's, twin gt35's, except i have a lq4. those gt35's are definately not too big for a 4.8/5.3. if people are putting 6262's on bigger cubed engines and making over 1000whp i find it hard to believe these 6162's will choke out that early. i have big exhaust ports in my heads, tubular manifolds, and im going to run around 17deg timing in boost which should keep backpressure down. maybe ill pull it on the dyno sometime this summer just to get some results.

Xtremes10

I'm pretty much building it to be fun and sound like a jet engine going down the road if I'm totally honest. I mean the thing has a bullet hole in the door and was painted by a brush with enamel paint sometime in the 40-50's lol

The plan is a big pro street tire to give it a pretty wicked look and make it drive able hence no big cam or stall no spool ect ect

The gt35's sound like a good option as well as the 67mm turbos, what about the on3 turbos? The hx35's can be had for cheap still but you guys don't think there's enough turbo for twins for 5-600hp?

T76s10

iTrader: (6)

I think the 67's will be a little lazy like on3's 70's. Wicked on here is using a couple 70's on his 5.3 and they take a bit to spool but he likes them. He's also well past 5-600 horse also. I know someone on here with a couple hx35's in his blazer and they spool fast but i don't know much about them. I'm debating about bigger turbos because i am not positive if these gt35's will be big enough. I think they ate perfect for 4.8/5.3 and I'm thinking about switching to a little bigger turbo. If your interested in them pm me they are brand new only mocked up.

Xtremes10

Shot you a PM, I'm trying to get a list of what all I should get when I buy the turbos. 60# injectors, should I use tubular manifolds or reverse and flip the factory manifolds? Fittings? What wastegates?

Tjabo

Absolutely, that is PLENTY of turbo for more than that level of power. Being as they're diesel turbos though, they are more efficient at higher pressure ratios than you'll be wanting to run. But still, plenty of turbo.

Xtremes10

I'm torn between the gt35's, on3 70mm's and my buddy insisting that those two are too big and too cheap and I should be running a genuine he341 or hy35....

Tjabo

Hopefully others will chime in.

Your buddy is taking an old-school approach that doesn't necessarily reflect the feelings of a lot of the people on this forum. That's not to say he's *wrong*, just that a lot of people on here who maybe used to feel that same way, don't seem to anymore.

Xtremes10

And that's sorta what's giving me issues cause it's a total budget build the entire vehicle is meant to be cheaper than a full out hot rod and meant to be driven and had fun with, I don't care if it most efficiently uses the turbos or if they're genuine or not but he's also going to be doing a lot of the fab work and has a large knowledge of turbos so I try to take his opinion highly hopefully I'll hear more tomorrow

T76s10

iTrader: (6)

Those 70's are honestly a turbo for a bigger cubed engine. Wicked is pretty close to 900-1000hp range with his 4000Lb chevelle. They were lazy on his 5.3 but he has it to get the best times at the track. You can find his vids on YouTube search sinister 5.3 to get an idea of how it will spool. I'm not saying all this just because i want to get rid of my gt35's for bigger turbos I'm just saying if you want quick spool and turbos that won't fall off in your combo the gt35's will work perfect with the 6162 wheels

UberTruck

iTrader: (1)

Twin ebay 67mm's will work great.

Black98s10

I'm going to be running 67's on my 5.3L s10. I had my cam custom spec'd to help spool the turbos faster. If you wrap your hot side piping, it would help with spool time.you're running the same setup I will be.

boostedsl2

If all you want is 450~500, you could always look at twin 57 trim to4e or 60-1. They are old school, mild price, garrett and will easily support your goal. They also come with a million options so you can tweak your setup later without buying all new turbos. T3 backsides would be fine too.

Xtremes10

How would you guys feel about a big single say mounted above the passenger side head? Keep in mind it's going to be a traditional fenderless, hoodless type rat rod hence why I thought twins would be cooler but I think I could make a big single look ok if I mounted it back by the cowl and up high. Someone suggested maybe a s472 with a t6 would work well and be cheap and a nice brand name turbo to boot

boostedsl2

I would look at a T4 S372 or a T4 T67. That's with the power range you posted above. If you want to pony up some more $$, the billet precision turbos or borg warner EFR's are putting out some impressive numbers.

I've personally got an S480 going on my 5.3 with a t4 1.25 a/r, but i went that big only because i had the turbo from a previous build. If i were going to go out an pick up a turbo, i'd be looking for something a little smaller (67mm~76mm comp with t4 backside). My goal is 600whp street and maybe grow to 800whp.

Garrett/precision/turbonetics/comp all run about the same size frame and are going to be smaller then anything borg warner. It appears that it won't matter in your setup. figured i mention it.