well i am wanting to do a rearmount, but i dont know where to start. i have all the tools and resources to build my own kit so thats what i will do. i would like to hear about others rearmount setup and how you like them. i hear a lot of bad talk about rearmounts but im not building a racecar, and i want a cheaper turbo kit.

can you all help me make a parts list of what i need? also i am looking at a single 70mm turbo is that too big? like i said its not a racecar, but want somethings pretty quick. Do the rearmounts react ok with nitrous also, i have a small shot that i will like to run also. thanks for any help you can give me.

 

70mm would be perfect for an STS stock cubed motor. Start by looking at the parts the STS kit comes with to get a good idea of the parts you will need. You can build your kit so it flows better and have better ground clearance than the stock STS kit. About the nitrous, I wouldn't spray any shot when boosted on a stock bottom end. It just seems too risky, although some have had success doing both stock. Turbo it first, if you want more, build it and up the boost, if you want more spray it then.

 

If you are capable of building a rear-mount, then you are most likely capable of building a front mount. The front mount will be better. The appearance of simplicity with a rear mount is ONLY an appearance. If you buy a ready made (STS) kit, the install IS easier, but a custom build negates that. BTW, I have an STS kit on one of my vehicles. It works, but now that I have experience with other builds, I would never buy one again.

 

There are a lot of good threads on fabbing a rear-mount kit. The 2 most important things to consider are oil control (feeding the turbine the proper amount of oil) and charge cooling.

Look at Zombie's threads on the topic. Lots of great info. LongRange4U has some great threads with pics of his high HP custom fabbed rer mount.

Fabbing the piping should be fairly straightforward if you have the welding experience + cutting tools for the pipes (sounds like you do).

Check this thread I did a while back on oil control issues: It'll give you good ideas on how to run a return oil system if nothing else. https://ls1tech.com/forums/forced-in...ust-pipes.html

Wiring is pretty darn easy on a DIY. Wire the Mocal pump to the fuel pump relay (at the distribution block) on the driver side just in front of the rear axle. Use a good chassis ground in the same general area. For a warning system (if the pump quits), run a 2nd set of wiring through the pump to an idiot light mounted on the dash (I had one above the radio). In short....if the light is on, the pump is getting voltage, and probably working. STS uses a buzzer system, but you'll need pressure switches or a flow switch to set that system up.

Running the PCV is also a critical step. Several posts on this. Frost has good diagrams on the topic.

Intercooling can be accomplished a few ways. Find the old TRT FMIC for the STS, get an "e-bay" FMIC, or check with one of many sponsors (EPP, SpeedInc) to adapt one of their coolers. Meth is a viable alternative. Cooling is a must mainly cause the charge pipe will run near/along the y-pipe and this negates a lot of the natural cooling the pipe would otherwise provide being under the car.

You can get good HP with the rear mount, but it isn't really that much cheaper (if at all) vs fabbing your own front mount. They can have issues with lackluster track performance on M6 cars due to the loss of pressure to turn the turbo between gearshifts. Exhaust wrapping becomes critical, which adds to the cost. The overall HP gain I always thought was the same, but I have noted that unles done just right the lag will cost some power "under the cirve" vs the traditional frontmount. It's main pros (the rearmount) are in packaging and it's a no-brainer to keep AC with this system.

The hidden costs of the rearmount tend to be the same as the frontmount. Sufficient valvesprings to avoid float at high RPM, good fuel delivery (I recommend going straight to 60lb injectors, at least from my experience), good fuel pumps, etc. All this adds up if not already done.

The rear-mount will not play well with N2O on a stock shortblock, unless the shot is very small and being used as a charge cooler vs a power adder. Even then, it's a lot of stress on the engine.

Finally, tuning is critical (as with ny other FI setup).

As I tell everyone....good luck. There's lots of little things that can make the project frustrating at times.

 

^ damn man thats a lot, i really appreciate it.
yeah i understand that i could be putting a lot of stress on the motor, but i dont have plans on making it last, just for a couple months in the summer time. Then i have plans of a forged 346, that should be pretty sweet. I have always wanted a rearmount on my car since i got it, but i did other things to it first, so now im ready to do it. i like frontmounts, but theres something about rears i love, i think because they are more hidden and keep a clean engine bay, also having a/c helps, this is a street car!

yes again i do have everything to do this, only thing i dont have is a pipe bender. that isnt a big deal though being i can figure my bends out and get that done by a local for cheap. The fuel part i have thought all of that in and i thinking of a dual fuel pump but idk, and maybe a little extra injector being i plan on spraying the car also(being the engine will be forged at some point) I talked to a local and i probably wont spray the car with the turbo being my stock bottom end probably wont handle it. i dont want to take the chance of starving my turbo from oil. It also might not be hard to flip that switch either so i dont know how that will work out