Willie B.

I'm in the mist of doing my 5.3/4l60e swap in to my 91 camaro, BOOST is difinitly in the plans. I currently have two rb25det turbos i pulled from running smokless skylines during my time in japan. But so far all i heard is those turbos suck and like to come apart a high boost. I only want to run 5-8 psi on the 5.3. And i figure that if they run 5 psi each on 2.5L then they can handle 5 psi together on a 5.3 Just what to know you guys would do, stick with what you have and make it work or ditch them and get a supercharger. ( i like pockets setup something to thing about.)

blackbmagic

5-8 psi. Thats a baby boost number go with a supercharger. It will get you that number no problem and it will be across the board. 5-8 psi on a small turbo like that is not worth it.

Stangski09

iTrader: (10)

There's no reason why he couldn't start with those to get the feel of a twin turbo v8, then eventually add larger turbos.

junkcltr

iTrader: (1)

Why is 5-8 PSI worth it with the SC, but not with the TC? I thought boost was boost? Are you talking about efficiency?

The two small turbos will make 8 PSI at a much lower RPM than the SC. The TC will get you max. PSI across the board, not the SC. The SC is linear and the small TCs will make max boost much faster.

junkcltr

iTrader: (1)

A stock 5.3 is going to over-speed / over-rev the turbos and destroy them and possibly the engine. The alternative is to set the rev limiter at 4000 RPM or less. The fun part is they would probably spool around 1200-1500 RPM.
A V6 supercharger is also too small.
An appropriate sized TC doesn't cost that much if you shop around.......or locate a M112 SC.

ZZ3Astro

I've had everything from NA to nitrous, roots blowers and turbos. I've always avoided centrifugal blowers, mainly for belt problems I have seen many people have (typically brand specific and mostly a problem on cheaper units) but also because of limited mounting options vs accessories you can keep and the sometimes annoying sounds they can make.

Of course I have a turbo so I am somewhat biased at this point, but there is nothing sweeter sounding than a turbo V8 going down the track. Especially a LS turbo car like the 4th gen I saw at the track Sunday!

Not sure as far as using those specific turbos you have. I'm really sold on singles but perhaps a twin rear-mount would work for those two turbos. Of course then you run up your costs with a oil return system and more tubing. It won't be cheap either way to do it right.

blackbmagic

two tiny turbos on a 5.3 are going to max out real quick. They will over spin, efficiency goes out the window. They will reach 8lbs very quickly. Its not true on every platform but boost isnt always how it sounds. By running a small turbo at 18psi you are actually increasing the chances of engine damage then running a larger turbo or supercharger at 10 pounds and making way more power.

With forced induction its about volume a larger turbo at a lower psi will produce more air per cubic inch than a smaller turbo at a higher psi. When you over spin a small turbo you are adding heat and friction into play as well.

With a blower you can produce a smaller amount of boost more efficiently. If you want to produce more boost somewhere from 12-20 you could go with a larger turbo setup. Its all preference where you want to make your power and what type of setup you have.

junkcltr

iTrader: (1)

It is fun watching them go down the track. I think it is great when they put a giant cammed loud-a$$ big tire race car (N/A engine of course) up against a stock sounding turbo powered v8 with little tires. Lights turn green and the race car makes a bunch of noise like an old chevy 8' bed P/U truck with cherry-bombs while the turbo car sails by it. Not to mention usually driven to the track and gets 20+ MPG.

OP,
If you can stand all that noise the SC will make then maybe give it a try. If you want a nice stock sounding rig then go with the turbo. Personally, I can't stand all that noise a SC makes when not making any power (idle, cruise, etc).
Those twins equate to a single that is around 50mm on the compressor side, but the turbines are really small. Maxed out at 350-400HP.........so I would rev limit it if you use them. Or better yet, just put a 60mm+ single on it.

Willie B.

I think it will be in my best interest to save some money an get a good turbo and do a single setup. I will just use the one i have now for mock up as where i want the new unit to sit. What size turbo do you guys recommend for the 5.3?

bunmod

depends on if you are at a circuit race or drag race for my opinion between the two, I'd prefer the SC for a circuit since you have that boost in and coming out of a corner, for a straight track all the way down a TC hands down because after a certain rpm the SC doesn't have much use and everyday driving i would use a TC. Another thing between the two, an SC will be much cheaper than a TC setup. of course i could go on all day about pros and cons of both so ill cut it short

ZZ3Astro

Good point bunmod, TC would likely make circuit racing more difficult. With the right ECU setup (such as the megasquirt's TPS based boost control) it could be made manageable, but when the torque comes in it kind of has a life of its own and comes in hard when it does. I'm actually going to take mine to an area SCCA event and see what happens in the corners though!

Willie B.

Mostly my car would be drivin for street/ little drift(got hook on it while in japan)/drag. BUT a SC is out of the budget (wife wont let me drop 3-4 grand at once.) Which is why i decided to go turbo. Even with a fairly new turbo and intercooler i dont see myself spending from than 1000 maybe 1200 for a kit and thats plus tuning. Mostly my whole build was done by me. Man if i was to go N/A i would be done by now and i haven't spent more than $1000 total and that for engine, trans, wiring, mounts(custom made), and rear end. I hate to say it and (my wife nose it) "I'M just cheap

Willie B.

But if anyone has or knows someone with a SC for a LSX for a good price. Let me know send a few pics and state of condition.

junkcltr

iTrader: (1)

$1200 for the turbo kit including tuning? What ECM and software package are you using? None of the OBDII stuff that I know of is cheap. $300-$500 just for the software.
Used LM7, harness, acc, pump, etc for under $1K sounds right. Trans included for that price isn't going to last at all. DIY turbo kit with fuel parts and IC is going to run you $1000-1500 if you shop wisely.
If you have the engine out right now I would put the oil return fitting on the pan. Other than that you can just drop it in NA and get it running first. Then worry about making the kit after.

bunmod

I dont know if its possible with a V8 with a TC setup but you can retard the timing to get a better reaction with a turbo through the corners, but i think that's only for 4 bangers, something called a misfiring system. also I believe you'll feel it if you are watching for it, a slight drag coming out of the corner it will be worse since you dont have a manual to down shift and a clutch to hold the RPM just right so you don't lose too much boost

junkcltr

iTrader: (1)

The timing retard is hard on the exhaust valves though. With ZZ3Astro's setup I don't think it will have a problem. The turbo is just about a perfect match for doing that kind of racing.