Radix or STS for a 408?
 

If you were to build a 408 (hypothetically), which boost would you prefer - Radix, or STS - and why?

I would do sts out of those 2. You have more room to grow with the turbo choices. I believe you would max the radix out quick on a 408. You could get the gt70 kit and run some good boost on the 408.

Radix, of course.

Turbo for sure. Like Beeftip said GT70 or 76

Thanks, guys, for you input thus far.

If you would, when you reply, please give the reasoning behind your recommendation. I'd really like to see what's behind your thinking. :thumb:

just put a procharger. make it easy on your self :)

I don't believe a Radix can support the CFM needed to make it worthwhile on a 408. The STS could easily do so with the upgraded piping and bigger turbo. One good aspect is the lag won't be so noticable on the big motor due to the great low end power.

So out of those I would definately go STS.

Another factor is where you want the power. IMO a roots style would be a waste on a big cubed motor because traction will be limited. Why not make the motor more efficient in the midrange and top end instead.

Kevin you need to go turbo if you want that big of a motor. On top of that, a turbo kit will cost less then an equivalant supercharger that can support the 408.

Besides, it's damn nice to be able to adjust boost in the cabin, and you can really get into the tuning to have low boost low octane maps, and high boost race maps, and econo maps.

If you do decide on the STS route, or another flavor of Turbo, I may take that Radix off your hands. My condo sale is coming up and I'll have some cash hopefully. Forget my wedding, I have priorities. :devil:

3 things

1. how much cfm would you guess would be needed for this setup?
2. If Kevin really wanted to, I bet he could get that AV to hook like no other.
3. I bet that STS would pull like a freight train at freeway speeds and he does drive the highways quite a bit. (did I just say something nice about the gutter turbos? :twak: ........ok I'm back :angel: )

This is where the properly sized turbo will make all the difference, as well as a good tune, as you can advance the timing at low RPM to aid in spooling.

Or you could do a twin turbo setup. :eyes: Lots of power with less lag :burn:

Yes you did, Your slowly coming to your senses :jest: Nothing against the Radix Grippy, Just for big cube engines you would be better off with a turbo. Weather it's STS or like stated above any flavor. Ask Parish ;)

With a 408 I'd go turbo. As stated already, enough torque in the cubes to get her moving then make the horsepower with the greater boost capacity of a turbo.

Well, you know I disagree, lots of reasons, maybe I'll post some of them later.
One wheel down, four left :bang: I love polishing them :eyes: besides, can't show up to the track without a coat of 1/4 mile wax and shiney wheels :devil:

some experts disagree with this, I have heard from more than one that the sooner the mass is moving the better, more 1/4 mile type scenario though.

I would LOVE Kevin to get a 408 and a Turbo :devil:

:jest: I'm sure you'll come up with some :bs: while shining them wheels.

Back to the topic. Grippy Does Magnacharger make a bigger charger?

:offtopic:

Seriously, I'm not up to date on the Radix. Do they make a bigger charger for larger cube engines?

They can support up to a 6.0L engine per their website. I don't think that the Radix or MP112 can do any better though as they are pretty compact in size and you would be restricted and out of volumetric efficiency. But to not go larger then 6.0L you maybe fine if not looking to run big boost.

I wish they would publish more specs of their superchargers rather then pretty efficiency graphs.

If there is any supercharger to consider, I think it was mentioned already, a Pro Charger.

I just went to Eatons site and the M112 is the largest they make. I thought they had something bigger. I guess that's what i get for thinking :jest:

There was a vid of an AV with 2 Radix style compressors on it a while ago, I think that's the only way you could really get the full potential out of a supercharged 408, But I woulds also go turbo for the same reasons mentioned above.

sts with a gt76...full boost all the way to 6500 rpms :) if you dont get skeered :devil:

The radix is a great product that will work with alot of setups and could definetly make 500 rwhp but depending what kind of numbers you want i would go with the sts or another turbo set up or even a stacked twin setup, That will help out wit lag. Don't get me wrong i have read alot of great things on the radix but turbo hp is unlimited depending on the $$ you have to spend.An for a 408 setup i would do the turbo thing. My 02

Hey I'm a Procharger man myself. Slap youa D-1SC Procharger and you will get a lot of H.P. out of that 408. But between the radix / or turbo.... I go with the Turbo hands down. You will have a lot more options to choose from with that setup.

I've had a big cube motor with the Radix. It's a nice combo, don't believe all the BS from the keyboard jockeys. It will build more than 8lbs of boost with a 3" pulley.

What you'll get with the Radix is gobs of TQ and great throttle response. If you pick the right cam (valve event timing is very important) for this setup you'll have a better daily driver than if you go turbo IMHO.

I went from the Radix to a GT42 with a 84mm exducer. Now my motor makes 500+ NA on the engine dyno and until boost comes in it doesn't come close to the Radix's instant boost. IMHO if I kept the boost @ 8lbs the Radix would win in a drag race or from a roll every time. But my Turbo really makes me smile when you feel 12-18 pounds of boost pushing you foward.

Radix Best all around performer with ease of install and little to no additional maintenance. Works fine in the rain, no oiling issues or things to add. It comes with everything you need to run.

Rear turbo... If you like to tinker a bit and turn up the boost you'll go faster.. Unless you blow some N02 into the Radix.

You can't go wrong with either setup...

and I thought I was alone...................... :cheers:

funny how building a combo that works together correctly can work out so well :drive:

How much you paid him to say that? :jest: I figured somebody out there was making power with the big cubes with a Radix. Ripped427 that's what we want to here.

That turbo sounds a little small for a 408, if you're looking for best overall performance.


Anyway, what about a nice 3.3L intercooled Whipple. :chug:

a radix for your case. solid and reliable. if you aren't out to build a race truck type 408 the radix will feed it just fine. a mild cammed 408 with small port heads and a radix will make for off idle torque that just can't be made with a turbo setup. with the weight of your avalanche and emissions being an issue i'd certainly go with the radix. the radix even works well at the track...

:werd:

what about a nice 3.3L intercooled Whipple. :chug:[/QUOTE]



this is what i've heard as well.... :judge:

that about sums it up I would be suprised if you could get over 4lbs out of a radix on a 408 from everything I have heard. I know alot of people love em but Im just not sold on em. Too many out there with a 5.3 and a radix that arent making power like they should be.

I would look into a livernoise, W2W, or ctmotorsports kit if I was gonna do it right. who wouldnt want to make parish type power of at least somewhere close to it.

Wow, interesting....it almost seems civilized in here. I'm not sure I'm on the right board. :confused: :jest:

In the AV I really have no problems with traction.....at 5800 lbs (6050 lbs with me in it) with my stock 5-link and 25" of rubber in the back, I grip pretty well, thank you very much. Once I get up to NorCal I will be getting some custom rear coils that are 1" lower and made to hook. At that point the issue will be the 10-bolt, not traction.

As far as a centrifugal blower, doesn't that give you the worst of both worlds? The parasitic loss of a belt-driven SC, together with the lag of a turbo, right? Why would I want to do that? :loco:

Ideally I'd get a low compression 408 and that 3.3L manifold-mounted Whipple from those guys down under at Starr. But since I'm not made of money, and seeing as they're charging North of $10K just for the 2.3L version, I don't even want to know the price of it's Big Brother.

So until such time that I land that big contract (and move away from the CARB cops) I think these are my choices - STS or Radix.

Zippy presents an interesting argument for a Radixed-408....don't overcam it, cam it just right. It would be nice to have power everywhere - the low-end, all-over torque that a 408 would provide (with a 220/224 or so), together with the low-end, all-over torque of a Radix. That does sound like a dreamy daily driver.

But the turbo is also appealing, for different reasons. Nothing feels quite like a V-8 turbo. Heck, even a 4-cyl or 6-cyl turbo is pretty amazing to drive. Not to mention the turbo would likely be a little quieter, and get a little better gas mileage. Hmm....

Sure thing, :jest: :jest: You were joking right..

I like the keyboard jockey comment...

I've had a centrifugal, I've been N/A, then Nitrous, now turbo'd and I've seen plenty of Radix combos at the track. I'm not over impressed till you start spraying them. I've also seen just as many problems with the kit as I have any other. IMO figure out where you want the power and what kind of feel you're looking for and go from there. At least you have CARB legal choices now. :)

kevin, the hell with emissions lets worry about that in about 4 years :drive:
I have never felt a radix before (rode in a L with upgraded pulleys, that was nice), but i think you will like the 408 with the STS. Off the line im sure a radix may pull on you but when that GT70 kicks in, HOLD ON!!!! Hell if you were closer i'd take you for a ride, it would help your decision a little more :drive: Anyway you decide the 408 will be nice :chug:

You're in NorCal, right? Perhaps I'll come up early to get my springs and you can show me what you got. Whaddaya say?

His truck wont be ready by then. Hell that thing is never going to run right again. :p

Rocklin is 5min up the road from my house if you wanna ride in a real STS truck... Wait, mine wont be finished by then either. :cry: