I have read countless threads about rear mount turbos since Feb2010. The biggest problem that I see is that the exhaust needs to be wrapped and either untouched or reduced to 2.5”.

So my plan:
-Use a Water/Air intercooler coupled with a water pump, oil intercooler, and an ice box for drag days and for normal use will just be a large sump, water only circulating at 5lbs.
-Use stand alone oiling system for turbo. Mocul oil pump, oil cooler, and a small reservoir to store oil and all for an easy oil change, maybe 1-2 qts max. Yes with a check valve. (is it possible to make this high/low like STS?)
-Use -8/-10 AN PTFE lines for oil and water. Maybe add an oil intercooler for the engine’s oil as well for added protection.
-Use catch can and route pcv and brake booster lines all the way to the back and connect them to the intake.
-Preferably all 2.5” aluminum piping for cold side.
-Use ebay water meth kit, $250-$300, activated at 5 PSI.
-Siemens 60lb injectors with walbro 255lph pump.
-Tune car with HPTuners with custom 2 bar OS and use an actual 2 BAR MAP sensor. I read shooting for 11.5 AFR and 16 degrees of timing should put me at a good safe spot.
-AutoMeter UltraLite II's, fuel press, boost, and AFR gauge with Bosch LSU4.2(I have heard good and bad things about mounting this close to the manifolds, is putting the sensor a couple of inches past the turbo the best thing to do? I would think it would read leaner then actual AFR due to the fact it will be very close to the outside air.)

Currently the car has a 9” rear end, Chromoly LCA’s, Chromoly panhard bar, Chromoly torque arm, and a FAST 90/90 sitting on the side(should I sell this and use the money towards the build?) Will be adding custom subframe connectors from Bobby Shayhan in Cabot, AR, tower brace, clutch, driveshaft, QA1 shocks, and probably some ET drag radials.

What else am I missing? Do I need to upgrade my valvetrain at all? Should this setup be pushing about 550RWHP at 10lbs? What type of turbo would any of you recommend that has the potential of 600RWHP?

All advice is welcome and I am open to maybe you should just stay NA and be happy with 450 lol. I'll attach some of my findings, my ls1specs sheet is a little personal because it is my own randomness but it may help someone one day so I'll add it as well, just don't be too critical on it due to the fact it gets changed daily and not everything is up to date, sometimes I forget some things. The ls1spec sheet needs to be changed to .xlsx and the rearmountguide needs to be changed to .pdf.

Hopefully the infamous Zombie and Longrange4u can step in and help me...

 

unless you were planning on finding a deal on a used sts kit i would just stay away. i just ordered a front mount kit from josh at kyturbo for 5500 bucks. that includes a precision billet 76mm turbo (tons better then sts), front mount intercooler, burkhart bumper support, and stainless headers. its not that sts cant make power, its just the scavenging pump and pipe routing and so on...

For only a little more money you can have a superior kit in every way... just dont buy into sts thinking its cheap. actually no FI is cheap... lol

 

There were a couple rear mount kits going for about 2k in the classifieds.

 

If your going to do it. A 70 to 75mm turbo should achieve those numbers and help keep some of the lag down.

 

I did see some STS kits going for sale and even made a couple of offers but my problem is if I get the actual STS kit I would up replacing the turbo, maybe the oil pump, all the lines, still have to modify the cold side for the water-air intercooler, doesn't include the gauges or wideband, doesnt include the fuel injectors, nor does it include the fuel pump...at least almost all the ones that I have seen, so 2k for a kit here and add another 2-3k and it is still close to what I was going to spend for new parts. This is just based on what I have seen.

Has anybody replaced their fuel lines with some stainless steel tubing as well? Do you think this is needed for the added volume? How hard is it to do?

I appreciate everybodies help.

 

Question: Are you looking for simplicity, power, and reliability? If so then the KISS method would be preferred with rear mounts. Air to Water intercooling is not really all that necessary because the charge temps are way lower as long as you use a standard intercooler. I would suggest a simple meth kit for additional "race" days. Standalone oil kits are complicated. It is much easier to just use engine oil pressure and a Turbowerx or Mocal pump to recirculate the oil. Maybe I am biased, but I can't see paying 4k for a turbo, BOV, oil pump, pipes and clamps. You can save a ton of money by building the setup yourself and source all your parts. This way you have more $ to spend on tune, fuel, and other mods. Keep the stock exhaust and headers wrap em up. Don't forget the turbo blanket. Look at the twinscroll turbos and quick spool valves to keep lag times down. The more mods you throw at it, the more expensive it gets!

At the end of the day if it gets too complicated then I fully agree that a front mount kit maybe using truck manifolds and Vbands would be the way to go.

 

KISS method? I figured the stand alone oiling system would help my turbo last longer and cooler, why is it so complicated? A warning system, cooler, pump, some lines, and a small sump right?

I'll take a look at some of those turbos.

 

It is just much easier to use the vehicle oil pressure system to deliver the oil and one pump to send it back to the crankcase. Some standalones use two pumps and a fan to cool the oil as well as a sump. Some of the pumps are so loud that you don't need a warning sytem either. You will know when it stops working
Whatever you choose just make sure a good tune and fuel system follow.

 

my buddy Scott made about 530 with a T67/.81 on a bone stock motor and maxed out at about 680 with a forged motor. both on 100oct. fuel... don't forget the stock manifolds!

 

Do you remember how many pounds he was pushing? What other upgrades did he have? Before forging the motor.

 

Alright just made an offer to a guy to get his rear mount setup, just gotta get all the gauges $550+ for the ultra lite II's, walbro, 60lb injectors, map sensor, and from what you guys said if I just want to push 5#'s for now I don't need the meth nor the water-air intercooler so that will save me about $700 for now and will upgrade later before I turn the boost up.

 

I'm running 5 lbs without ic or meth. Runs great, only hurts power on really hot days.

 

^Do not, I repeat do not forgoe any type of IC on a street driven car, really on any car unless E85, race gas, or methanol is the fuel of choice for the reason he said on hot days. Even on cool days it won't be at peak performance.

I'd still go with the meth kit and forgo the a/w and use an a2a i/c.

Go with a 70-76mm turbo, master power and turbonetics make good affordable units.

I would still talk to Josh at KYTP and get a quote on one of his kits with manifolds unless you must keep a/c.

 

My IATs run about 50* over ambient temp. Would not hurt to drop that a little with an intercooler.

 

Far as fueling there are a ton of ways to go. Nasty fuel system makes a good set up. But pricey... If you know what your doing you can save a lot of money by ordering everything from summit or jegs. Anywho... It is not wise especially on force induction. But I ran a 200 dry shot with stock injectors, fuel lines and fuel pump. Now im not telling you to do that by any means. I think the high elevation saved me. But in my opinion you should be okay to around 500ish. But id try and atleast throw a 255lph pump in.

 

So does anyone think the Fast 90/90 is worth keeping or should I sell it? What would be the hp difference at 5..10?

 

I wouldn't keep it. Sell it for an LS6 (stronger) and use the extra funds for the turbo stuff.

 

My A2W intercooler keeps mine about 11-15 above ambient while crusing and helps to keep the charge cooler longer while boosting on it. I dd mine with 93 octane, it dosent run as good on hot days but still way better than no intercooler at all IMO...

 

Ebay air to air intercooler would work fine for ya. Also put a new set of valve springs in it to keep the valves closed under higher boost levels.

 

The rearmounts work well. You just have to make sure get the exhaust velocity needed to spool the turbo and the retain the heat. We just finished a customers T/A that is a rearmount. Started life as a STS kit, but turned into a custom kit shortly after.

With the forged 346,4l80e transmission and a 9in. rear end with 20in. wheels we made 665rwhp with the 76mm turbo.

The upside to the rearmount kit is no underhood heat, all factory accesories remain. The bad, a little slower spool time, but that can be a good thing. We can footbrake this rearmount turbo car and spool the turbo. Full boost is around 4500rpm. If this is your first time with a rearmount, conventional wisdom about your exhaust system that you would think would be better, is not.


Chris