Duckmang

I have an inline 6, 3.0L engine that I'm planning to turbo. The car is a heavy AWD wagon with 3:29 gears and a 4spd auto. I plan to run relatively low boost, 6-8 PSI. The factory fuel system is good to approximately 300HP. I'd be shooting for around 260-280 HP. My biggest concern is having it spool well from a low RPM.

The current (not yet turbo-ed) engine breathes really well in the upper revs, 3-6k (6200 redline) I've done a nice valve job with some attention to the ports and chambers. In addition I've fitted a larger throttle body (70mm). I also run the stock cam 3 degrees advanced. That's to help get enough low end torque to get the heavy wagon moving.

I have a T3 manifold sorted for the engine and now need to select a turbo. I'm leaning towards an AR.48 turbine housing b/c I want to get boost as quickly as I can off idle. Is the .48 too small for a 3.0L? The calculators put me around 400CFM @ 6-7PSI at the current redline. Assuming that I squeeze the .48 turbine on it, what should I look for in a compressor? Do I keep it small since I'll aready be spinnning the poop out of the shaft in the small turbine housing? The engine is set up to breathe well, is a larger compressor appropriate? Keep in mind this intends to be a relatively low boost set-up and I'd readily trade 40HP at redline for 40lb/ft @ 2500.

Opinions please

busa4

a t3 .48 exhaust a/r is pretty small for a 3.0. if you want low rpm boost then thats the way to go. you will definitely max out that turbo quickly and it will over spin at high engine rpm and most likely kill itself. i would sacrifice some low end rpm boost and get the .68 a/r exhaust housing. that should spin up ~2000-2500 rpm which to me would be better. as far as the compressor housing since your not looking for high hp numbers a .40ar compressor housing should do the trick.

Duckmang

Thanks for the input. Not sure if I was gonna get any replies with a post count of 1.

I have to say that I'm still leaning towards the .48 despite the better advise. I am planning to use an internal wastegate housing. I am wondering if anyone has any numbers as to how much CFM the wastegate port will flow wide open...? If the turbine and wastegate together meet my 400 CFM @ redline then I'd assume it'd live ...unless somebody can tell me otherwise.

I've read a little bit about porting the housing. I'll definately be in there with a die grinder. I've done a fair bit of porting and valve work on cyl heads so I'm not too intimidated by that but I'd appreciate any pointers on how to best port the housing for a bit better flow without sacrificing spool up. Since I'm in there I figure I'll try to get a litte better flow from the wastegate port too. It will be dumping into a 3" pipe with a catalyst and two mufflers so downstream is pretty well taken care of.

The last thing I am thinking is to lower my shift points. I've got adjustments that can be done relatively easy. If it can get some ***** down low then it wont really need to be revved to the moon. I get the feeling that the key to this setup will be balancing the trans with the engines new powerband.

Duckmang

Thought I'd post some pics of the progress. I've got a good used .42/.48 garrett and began mocking up my lines. So far I've got the feed line, and drain line finished. Not pictured is some bracketry I've fabbed to support the downpipe attachment point. Also I've fabricated an EGR mount and line. I know, I know, but I want it to at least look emissions compliant. It will have to pass an emissions inspection after all.

Still to do: finish fabbing the inlet piping and air flow meter connection. Fabricate my boost enrichment device. I have an old electronic piggyback for CIS boost enrichment that I plan to use but I will also fabricate another device to add fuel when on boost. (which with this tiny turbo should be all the frickin' time)

busa4

looking good. keep posting pics of the progress.

Duckmang

Managed some more time in the shop and got a few things done. I've got the air flow meter adaptor built. I bent some aluminum stock and welded up a nice "hat", see first pic. Second pic is the cross pipe and hat mocked up in the car. I haven't fabricated a hold down for it yet. Will probably hold it with two studs from the inside. Last pic is current setup on the mockup engine.

busa4

nice. question for you. since you can weld aluminum, why did you go with a steel boost pipe?

Duckmang

Mainly because it was what I had handy. The EGR valve is bolted to the pipe via a 3/8" thick flange that was tigged on. Steel was the better choice there. Besides this isn't a peak HP bragging rights kinda build. More of an "area under the curve" kinda build. Remember, this is a relatively heavy AWD wagon.