Perth-WRX.com - Yeti sled

Been out in the shed welding like a mad man. Ive decided to go a low mount turbo setup under the engine. The foglight mount turbo idea is shelved and ive been full steam ahead making this. Its a little project i call ''LOW HANGING FRUIT''.

Heres how it stands now.

[img]https://farm9.staticflickr.com/8440/28969053940_9ac78ca2af_k.jpg[/img]

[img]https://farm9.staticflickr.com/8387/28634180894_1c813063a1_k.jpg[/img]

[img]https://farm9.staticflickr.com/8436/29086688076_98b56d2ba2_k.jpg[/img]

[img]https://farm9.staticflickr.com/8345/28639552753_e14c36b10f_k.jpg[/img]

[img]https://farm9.staticflickr.com/8210/29227395506_dee66cabcd_k.jpg[/img]

[img]https://farm9.staticflickr.com/8033/29153529222_ce9842eb18_k.jpg[/img]

[img]https://farm9.staticflickr.com/8451/29261702975_2b836deeef_k.jpg[/img]

Ive thought long and hard about low mount / front mount / twist mount / bumper mount turbo setups. And i chose this location for a few reasons. This location has one of the shortest pipe routing i can imagine. Both for exhaust in and out, and air in, boost out. The exhaust run is basically straight out of the heads, merge, then in into the turbo. Even a V mount setup with turbo dead center infront of the engine would not be much shorter.

Because the turbo is directly below the drivers head, the compressed air pipe into the FMIC will be incredibly short. Just a short loop around to the bumper and in. And coming out of the FMIC and up to the reversed manifold will also be incredibly direct compared to a conventional Subaru FMIC setup.

Because the turbo inlet is angled into the gap between U brace and chassis, it is literally a few inchs into where the filter will be. Ive literally got a 45° 4" tube bend as the turbo inlet pipe. About the only way youd could have a shorter inlet pipe is with the filter stuck on the turbo direct. Or no filter at all.

Exhaust out of the turbo is also a very straight run. I simply have a few small bends under the crossmember. Then its straight pipe all the way to the muffler. A foglight mount or front mount turbo could have a side exit exhaust which would literally be about a foot or 2 long. And i did consider those options. But with RAC already closed down due to noise issues, i thought a muffler would be a sensible choice.

Not only that. With my low mounted setup, all the wieght is near central, and its all very low CoG. Something i realised i could massively improve on over a stock subaru setup.

The only draw back is the need for a scavenge pump to drain the turbo. Its added wieght and expense and complication. But i see no way around it unless I V-mount / front mount the turbo. Or stick with a conventional twist mount. I have ordered a mocal gear drive oil pump from Merlin Motorsport in the UK. Nicely priced, and from a reputable brand, not some ebay hunk of s#it.

I took some of Dazs advice and I re-made the headers to give more clearance to the sump. The pipe work isnt quite equal length. But its very close. I extended the loops out on the drivers side pipework to help get equal length runners. I could have pulled them in alot shorter.

I am also going to weld a Brace between the drivers head flange and the pipe work just before the turbo entry. This is to reduce the risk of cracking from having the turbo wieght hanging off the pipe work. I did not use any flex bellows before the turbo. I had planned on doing so, but there simply isnt enough space.

The fab process on these was alot longer, as i spent alot of time pollishing the internal surfaces for a nice smooth transition between sections. Went through many carbide burrs, flap wheels, and flex hones trying to maximise the internal surface smoothness.

The Intake is basically built. All thats left is too slip a new 4inch air filter on the end of the elbow. I have a very large K&N coming. If my measure ments are correct it should fit nicely in the front corner of the bumper. I will also make up a rubber isolated mount for the elbow too. And i might weld on some ports for the catchcan. (Or i might just vent it to atmo?)

The dump pipe is slowly taking shape. A few more sections and it will clear all the engine crossmembers and various under bracing. Once its clear of that, i will join in a 3" flex bellow, and then a 3" V-band. Then it should be pretty easy to make a new mid pipe to match to my existing Hi-tech muffler. And then small stuff like weld in hangers and O2 sensor sockets.

The dump pipe is 3" out of the turbo, then tapers up to 4" and back down to 3" again. Carefully hugging the underside of the car as close as possible. The 4" section is a small collector to catch the turbulant exhaust coming out of the turbo and allow it to accelerate along the dump pipe. I have read that this can help with performance for turbo systems. A bit like a ball mouth on a standard TBE.

For the wastegate, im undecided if i will plum back, or screamer pipe it? My heart says screamer, but my brain says plum back. (For noise considerations. MC Motorsport has officially stopped doing events at the RAC track due to noise issues.) If plumb back, the piping will exit and hook around under the turbo, then join back into the dump just after the 4"section.

I still need to fabricate a oil drain mini sump for the turbo. I have some 5" dome end caps, that i will weld into a flat circular tank. That will form the body of the sump. Hard part is finding space for it. I am quickly running out of room down there.

And of course the front mount intercooler will need to be fitted and piping made. I will see what i can salvage from the piping kit that came with the FMIC, and if the bits line up enough, i will try my hand at alluminium welding it to fit propper. But i may end up just using more stainless steel if i cant operate the AC TIG to a high enough standard.