anothernord
08-14-2012, 04:34 PM
What happens when you find an exhaust leak on your swapped/turbofrankenstein'd Subaru? You pull off the entire manifold/turbo to replace the gaskets and port and polish everything, of course.
Here's what I bought:
Harbor Freight Die Grinder - $35
3/8" Double Cut Burr (1/4" shank) - $15
Harbor Freight grinding stone set - $5
Grimmspeed gaskets all the way to the turbo - $75
The idea with porting is to open up the areas near flanges to match the sizes of the ports, as well as remove abrubt transitions between pipes. The only exception where I didn't match the ports was right off the headers. The collectors are made to have a large diameter than the exhaust ports on the heads to create and "anti-reversion lip", which apparently aids in scavenging by creating a low pressure zone.
Lots of people do what's called a "gasket match" on all the ports. While this might give you more gains on a dyno graph, it will not help your spool or low-end, because you're increasing the volume of the exhaust piping pre-turbo. Basically, I just smoothed out all the "steps", opened and matched all of the pipe diameters (caliper required).
One more thing: While polishing the ports to a mirror-smooth finish looks cool and probably helps a small bit in the power/spool department, it really isn't worth the massive increase in labor time. The gas traveling through the pipe doesn't really care about the finish of the walls, unless you dimple it like a golf ball. Focus on the size and shape of the port more than the finish.
Basic Procedure:
Use the carbide burr to the majority of your cutting, then smooth it out with the stones. If you really want to clean it up, use 80 and 100 grit cartridge rolls, followed by flapper wheels for a nice finish.
After disassembling everything, you get a bunch of parts:
https://sl-i.net/FORUM/images/imported/2012/08/20120808_144720_351-1.jpg
Here's the inlet to the turbo:
https://sl-i.net/FORUM/images/imported/2012/08/IMG_3240-1.jpg
Outlet of turbo: (frosted mini wheats necessary for maximum wrenching energy)
https://sl-i.net/FORUM/images/imported/2012/08/IMG_3237-1.jpg
Yay
https://sl-i.net/FORUM/images/imported/2012/08/20120810_142605_323-1.jpg
Notice that it isn't ported quite as large as the gasket. That's ok.
https://sl-i.net/FORUM/images/imported/2012/08/20120810_113353_768-1.jpg
Removed the sharp lip on the exducer: Not much materal to take off here.
https://sl-i.net/FORUM/images/imported/2012/08/IMG_3239-1.jpg
GAINS:
-Improved low end torque - I estimate 10-15 ft-lbs from idle to 3000 RPM. The first test drive, I went to pull the car out of the garage, and immediately noticed there was more grunt. Cool!
-Faster spool - 400-500 RPM. I have a VF34 on a JDM 2.0, using the stock manifold with an STi UP. Previously, full boost was around 3700, now I'm at about 3300 or so, as observed it datalogs.
-Ability to piss of friends through bragging
I'd call this a "street" port and polish. By doubling your labor time, I'm sure you could see even more gains, but for about $130, and 6 hours of work time plus assembly and dissasembly, you can get some nice gains. If you have the time. :cool:
Happy modding.
Here's what I bought:
Harbor Freight Die Grinder - $35
3/8" Double Cut Burr (1/4" shank) - $15
Harbor Freight grinding stone set - $5
Grimmspeed gaskets all the way to the turbo - $75
The idea with porting is to open up the areas near flanges to match the sizes of the ports, as well as remove abrubt transitions between pipes. The only exception where I didn't match the ports was right off the headers. The collectors are made to have a large diameter than the exhaust ports on the heads to create and "anti-reversion lip", which apparently aids in scavenging by creating a low pressure zone.
Lots of people do what's called a "gasket match" on all the ports. While this might give you more gains on a dyno graph, it will not help your spool or low-end, because you're increasing the volume of the exhaust piping pre-turbo. Basically, I just smoothed out all the "steps", opened and matched all of the pipe diameters (caliper required).
One more thing: While polishing the ports to a mirror-smooth finish looks cool and probably helps a small bit in the power/spool department, it really isn't worth the massive increase in labor time. The gas traveling through the pipe doesn't really care about the finish of the walls, unless you dimple it like a golf ball. Focus on the size and shape of the port more than the finish.
Basic Procedure:
Use the carbide burr to the majority of your cutting, then smooth it out with the stones. If you really want to clean it up, use 80 and 100 grit cartridge rolls, followed by flapper wheels for a nice finish.
After disassembling everything, you get a bunch of parts:
https://sl-i.net/FORUM/images/imported/2012/08/20120808_144720_351-1.jpg
Here's the inlet to the turbo:
https://sl-i.net/FORUM/images/imported/2012/08/IMG_3240-1.jpg
Outlet of turbo: (frosted mini wheats necessary for maximum wrenching energy)
https://sl-i.net/FORUM/images/imported/2012/08/IMG_3237-1.jpg
Yay
https://sl-i.net/FORUM/images/imported/2012/08/20120810_142605_323-1.jpg
Notice that it isn't ported quite as large as the gasket. That's ok.
https://sl-i.net/FORUM/images/imported/2012/08/20120810_113353_768-1.jpg
Removed the sharp lip on the exducer: Not much materal to take off here.
https://sl-i.net/FORUM/images/imported/2012/08/IMG_3239-1.jpg
GAINS:
-Improved low end torque - I estimate 10-15 ft-lbs from idle to 3000 RPM. The first test drive, I went to pull the car out of the garage, and immediately noticed there was more grunt. Cool!
-Faster spool - 400-500 RPM. I have a VF34 on a JDM 2.0, using the stock manifold with an STi UP. Previously, full boost was around 3700, now I'm at about 3300 or so, as observed it datalogs.
-Ability to piss of friends through bragging
I'd call this a "street" port and polish. By doubling your labor time, I'm sure you could see even more gains, but for about $130, and 6 hours of work time plus assembly and dissasembly, you can get some nice gains. If you have the time. :cool:
Happy modding.