I have been wanting to add boost to my engine for a long time but the transmission was the limiting factor being a 4L65E.
After finding out that these can finally be built to hold up to 1200rwhp reliably thanks to technology and engineering improvements and in house customisations from Performabuilt.
I will be looking at importing one of these most likely toward the end of the year.
I would like to hear folks opinion on whether a supercharger, single turbo, or twin turbo setup is best?
What would you choose and why?
Each has it's pros and con I guess.
I am aiming for around 800rwhp which will be easy to achieve as I already have an LS 408 stroker engine making over 600hp.
I know I will have to change camshafts again to match the boost of my choice.
I am probably looking at running around 15psi of boost.
I want it to be reliable so I don't want to run too much boost.

 

Depends where you want the power, how much room you have, cooling capacity, etc....

My fav is single turbo, but I don’t have any experience with any, so....

 

Everyone is going to have their own opinions including myself. But regardless several questions need to be ask.

What type of vehicle is it?
What do you use it for? Street car or race car
Auto/manual trans? If auto what stall
Rear gear
I know you said you already have a 408 making 600hp, is that to the tire?
What's the compression ratio?
What fuel do you plan on using?

 

proper turbo application is the epitome of elegance and efficiency. No other option provides such benefits with little to no draw backs besides mind boggling potential for 2000*F spaghetti tubes running all over the place.

If you can fabricate properly for it, the turbo is the 100% win in almost every venue except perhaps rock climbing and certain exotic fuel applications.

Supercharger take energy directly from the crankshaft, which means the rod/piston/crank all needed to 'deal with' that energy, as much as 80-120hp is absorbs using traditional setups.
So for example:
675rwhp supercharged engine, is really making 900bhp because: (900 * .15) + ~90hp to spin the blower = 225 horsepower lost to the drivetrain/blower
750rwhp turbocharged engine, is really making 880bhp because (880 * .15 = 132) 132 horsepower lost to the drivetrain leaves 750rwhp

So in the turbo application, you are putting down 75 more horsepower average, and the engine is seeing 20 horsepower less stress to do that.
You can turn the turbo application down to 675rwhp and have around 100hp less stress on the engine than the supercharged engine has at the same output.
How much longer will it last thanks to that?

high exhaust gas pressure
The high exhaust gas pressure generated from turbocharging has a rod cap life extending property which allows turbo engines to spin higher RPM more safely, it improves the engine's longevity outlook for racing.

Turbocharging also takes the $$$ out of the engine. You can use a $300 (cheap) engine to make 700rwhp or more,
example: this fellow has done around 20 such setups

No need for high lift cams, port work, special intakes, you can even use factory exhaust manifolds sometimes.
Turbocharging is also easier to 'position' as you can decide where you want the dang thing (in the back of the car? in the fender?) And that helps with cooling because it gives plenty of options for pipe routes that take it through nice heat exchangers and the ability to properly insulate the exhaust side, hot areas from cold areas.

Fabrication is the key. If you have a 3-phase tig and $$ for materials. More than you will ever spend buying a kit.
Why not the kit, why not used parts?
Kits are for experienced turbo users. The idea is facilitate assembly at the potential cost of durability. Wategates that won't work properly, manifolds developed cracked, turbo bearings go bad, but the kits are cheap and the users have welders and knowledge for repairing those little issues which comes up 20-30% of the time when using cheap kits.

lowest cost novice option is full self-fabrication, no kits. 25 hour of work, gas shielded mig welder, Buy a flange, use oem manifolds, scavenge stainless junkyard tube from Volvo cars 2.5" some of it is nicely oval. Take heat shields from random cars, some of them are nicely large. Insulate and shield the turbine.

I followed my own advice and still using Gen1 version of what I just described as a novice using a gas shielded Mig with lowest budget, this is the cheapest option with the possibility for high success rate since ~2008 and welders became affordable that actually work for these jobs and many have been successful.

The point though is to fail, have something break/crack/melt/warp and learn a lesson. Gen1 leads to Gen2. The repair or re-invention of what once almost worked. And by then you've been driving for 10 years already.
The only way to skip this step is to jump directly to 3-phase tig welder & ~50 to 100 hours instead of 20 hours welding pipe. Actually you can spend 500 hours welding pipes for an appropriately stunning setup. That is the beauty of the turbocharging method: It both improves the engine performance and gives the owner a chance to show highest level of plumbing exerse... top level stuff is in hot pasta. Package a turbo properly and it will last 250,000 miles.

Before owning a turbo car, you should own a turbo car. Buy and maintain a factory turbo vehicle (2.0L usually) and learn the pcv system and ignition components, trigger system and use this knowledge when attempting first diy turbo application on a V8

 

Damn, so many options.
I do like the idea of having the turbos.
Is it possible to fit 2 different sized turbos?
One smaller one that comes on earlier and a larger one that comes on later and after a certain RPM they are both working at once?

 

What you're describing is a compound turbo setup. It's not really advantageous on a V8 as you already have plenty of exhaust volume. It's mostly seen with small displacement 4 cylinders that are using a smaller turbo to feed/spool the big one.

If boost lag is an issue, I'd rather go with shorter charge piping, changing the cam, and changing the exhaust housing a/r instead of compounding boost. A single S475 will make all the power you'd want in a street car and spool fairly well. If you throw a single S480 with a T6 1.32 a/r housing on a 5.3L, it's going to be slow to spool. Just match the parts well.

 

I don't know much about turbo's with sizing etc.
It's all new to me.
I only have basic knowledge.
I still don't know if I should go single or twin turbo.
I test drove the new 2019 BMW M5 competition last week which has the 4.0 litre twin scroll turbo engine with the Hot V setup.
No noticeable turbo lag.
What I did notice though, is that the torque is very strong from 1500rpm+ in fact much stronger than what the power figures say.
This holds it's max torque from 1800rpm all the way to about 5800rpm so the power band is very wide.
Personally I want this from 2500rpm- 6500rpm because being a stroker engine it will have enough torque in the low end anyway.
Can this be achieved and what setup would I need?

 

I love turbos, but packaging them is obviously more complicated. On a 90º V engine, dropping a blower and intercooler into the valley makes a LOT of sense.

 

BMW has millions and years in that setup ,,, its a twin scroll and I believe variable vane
with active pressure and turbine RPM management.. There is a reason that car is north of 110 grand..
they failed many times before they got it right,, The twin turbo 3 series recall for example.
Its also a shared housing,, there is a really fancy schmancy internal layout thats pretty trick.
The replacement turbo alone is like 15K I've heard,,

 

Damn, these german's and their trickery.
The 4.0 litre turbo in the mercedes AMG is the same way I think or similar.
I wonder what they think when they look at our engines. Haha
But does anyone know if it's possible to get a turbo setup in an LS to have max torque band from 2500-6500rpm?

 

I'm a fan of any thing that DOES NOT sit on top of your engine IE roots style blowers, Magnuson, elderbrock those kinds heat is too much of an issue, I like the procharger set ups

 

And the Japs with their trickery - Both Mazda and Toyota have built complicated sequential turbo systems... And usually, the correct answer is to simply replace with the correct sized single.

Of course it's possible, just depends on how sophisticated you want the plumbing/valving and control system to be - and how much effort you wanna put in to get it calibrated correctly.

What most of the domestic turbo cars (ie ecoboost/ecotec) do, is choose a little turbo that is perky and boosts the low speed torque a lot. Of course, a little turbo like that is going to run out of steam on the high end - but you end up with a very flat torque curve. You can trade off that bottom end response and torque and pick up a lot of high speed torque/power - but there ain't no such thing as a free lunch!

 

So would you be better off going with a single turbo or twin turbo to achieve this?
I think the best would be a compromise of the two.
Get a really strong torque curve all over and sacrifice a little too end power.
Hell, it's going to make a ton more power any way.

 

I like this. Realistically, how much time in a street-driven vehicle is spent at the upper end of the rev range?
Build for strong mid & upper, but emphasize the mid, as that's what you will be using more than anything. My .02...

 

Agreed because you will still get crazy top end anyway.

 

I call that a win-win.....

 

Single vs twin is generally a packaging thing, not performance.

BMW artificially creates a flat torque curve because that is the response they want from their engines. With a different tune you'd see massive torque gain down low, and a little bump up top.

You can do the same with an LS engine. It is simply boost and timing control to create the response you're looking for.

 

Nothing wrong with roots style superchargers They make great power and heat isn't an issue with a intercooler, Turbo gets the nod for max power and efficiency then twin screw blowers/ centrifugal superchargers and TVS style are about equal and then traditional roots 6/71 - 14/71 .
I run a traditional roots with an Enderle Bugcatcher converted to EFI and runs E85. Heat is a non issue, The intake is cool to the touch when it's running and the blower itself is cold enough to cause condensation to build on it. The problem with tradition roots blower is that they are large and not very efficient but still capable of making huge torque numbers down low and decent numbers up top.
I also have a LSA supercharger on a LY6 6.0 and 6-speed, it's driven daily if the weather cooperates and it's a blast to drive , No lag between shifts and It makes more power than I can use on the street. I can run 2nd gear from 20mph to just under 80mph and can break the tires loose anywhere in-between.
I've had turbo cars in the past and they were fun also, I just like the torque and simplicity of my blower motors.

 

I know the pro's of turbos, blowers and centrifugals.
Turbo's are the most efficient and might actually yield an increase in fuel economy in daily driven application if the turbo is making great low end torque.
Blowers have power everywhere but are the least efficient.

 

You aren't getting 1200rwhp reliably out of a 4L60. I would say 900rwhp and it's a wear item.

And that's an FLT Level VII or RPM Level X or whatever. 4L80 is a different beast... but has it's own set of problems with converters. TH400 would be the best choice.

Until you have that down, picking a power adder is sort of moot.

But if you decide to go for 900rwhp... a PT7675 or D1X gets you into that 800+rwhp range on pump gas or more on the corn. I would probably look at something like that. Or an F1A with lower boost...