S475 vs S480 over stock

[thunder550]

Been doing a lot of reading about twin over stock setups. I was pretty well set on a S475 but then started reading that people have had good experiences with the 480 in regards to spool up and top end. Also been reading though that it might require wastegating around the stock turbo to keep drive pressure in check. Can anyone share their experiences either way? I was planning on building my own piping and I'm not excited about the added complexity of the wastegate. Can the 475 be run completely without a wastegate? Would the 480 require gating around either turbo?

 

[DmaxRvRrat]

Sub'd for some good info! :thumb:

 

[countrycorey]

You shouldn't need a wastegate from what I've seen and read, but I guess it would depend on how hard you plan on pushing your setup. Yes, both can be run without a wastegate.


Corey

 

[Harbin_22]

I ran a billet 475/stocker setup on my stock motor for 20,000miles. I ran 11.6@119 around 68-6900#'s on street tires. Went [email protected] 1/8 miles around 6,400#'s. Made 65#'s boost to 75ish#'s drive. Spooled awesome and had enough power to break a rod with 40% Inj and dual pumps around 2650 pulse. It wasn't out of air yet. Through the traps at maybe 1250-1300°. Actually debating on turning my truck down some and going back to that setup.

 

[onebaddmaxxx]

There really isnt any complexity of adding the wastegate. You simply weld your flange in on your hot pipe for the valley to the s400, and have a small pipe dump right into the downpipe. Or you can dump it externally doesnt matter. Not much to setting one up. usually they come with springs to adjust pressure, or you can put a turn knob inline to the boost feed and you can turn it to adjust

 

[Chevy1925]

you will not need a gate on the 475 or 480 untill you push the 475/480 over 40-50psi which you will never see unless you have the vanes on the stock turbo set wrong. you might actually need a gate on the stock turbo before the 475/480 so you dont over drive the stocker but thats on some big sticks turned way up, well beyond what a stock motor would see or last under.

the 480 i noticed woke up the top end on the truck more than the 475 did (thats straight swap, no tuning changes). the 475 spooled a hair quicker but nothing i really notice and im picky about lag. both setups pulled hard and clean up 45% overs at 2100 all day long. on a 3000uS, its pretty smokey in the summer, cleans up more in the winter. either way, you will push enough boost to pop an intercooler down the road.

i wouldnt give up the 480 but i do miss the whistle of the 475.

 

[thunder550]

What kind of RPM are you turning James? And is that 45-50 psi you are talking about on the low pressure turbo only, or combined boost?

 

[Chevy1925]

What kind of RPM are you turning James? And is that 45-50 psi you are talking about on the low pressure turbo only, or combined boost?

3600rpm shift points but ill see 3800 by the time it shifts. anything over that you feel it fall off some. 45-50 is the low pressure only when you need to start looking at gating it. put it like this, on my DD tune at 2100uS i see 17psi out of the 480 and 52psi total boost, my wastegate does not open. Well atleast the regulator is set that way, drive pressure may be opening it but ive not loaded the big tune to see yet.

the setup i have in my truck right now and this DD tune would be an absolute blast in your truck. 2500lbs less is a big difference

 

[SilveradoTwins02]

sub ed

 

[Harbin_22]

2650 pulse would make around 33-35#'s boost from my 475 and 65 total. If you have an LLY turbo, it has a bigger exhaust side so you should better numbers than I did

 

[56taskforce]

My thoughts were to gate the stock turbo and have it dump back in between the The two. Kind of a half compound half series setup.

 

[Harbin_22]

No reason to gate the stock turbo. Just need good tuning that will keep the vanes where they need to be

 

[02ilduramax]

Subd

 

[thunder550]

Hmmm so it sounds like I would do well with either one. How much of a difference did the 480 make over the 475 on the top end?

 

[Chevy1925]

what use to feel like dieing off a bit at 3200rpm is now gone. pulls better all the way to 3600-3800. for the little bit of price difference, id go 480.

 

[Burn Down]

If your not doing a built engine I see no need in the 80mm... The 75mm will do everything you need quicker and cheaper. Unless you can score a really good deal on an 80mm or plan on building the engine later I would stick with a 75mm. I have had both on a stock engine and thought the 75 over stock was way more fun.

 

[duratothemax]

Years ago I ran a stock LLY VVT with S480 twins. I had no complaints, worked great. No wastegate.

 

[NinjaMax]

Fwiw ive been running the 475/stocker for close to 20k miles on my lly...I'm seeing max so far 60lbs of boost and dynod 550hp..only added studs and a lift pump. Respectable numbers for being a mile high.

 

[56taskforce]

Are these T-4 or T-6 frame turbans? If T6 where is the best place to make the transition from 3" to 4" ? As close to the stock turbo or the atmospheric?
I have a very nicely made billet T-6 to round pipe flange and 3" long 3" to 4" stainless transition but am thinking I should be using a T-4 S-475 instead???

 

[countrycorey]

They're T6


Corey