Author Topic: Porting/gas flowing  (Read 173 times)

March 08, 2018, 04:07:42 PM
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Maybe this is a dumb question: for a 2011 forester XT, if I want to tow better, am more interested in low-mid range performance, what would you recommend?

I'm thinking to keep the standard TD04 turbo. I already have a nice downpipe and decatted exaust (fitted by SAC, with uniq chip).
I'm thinking to
a) get a Chett tune and let them remove the uniq chip;
b) make what I have more efficient and run cooler. This is where some people speak "porting". Also not sure if a better intercooler is needed.

Any thoughts on this?

March 08, 2018, 04:23:17 PM
Reply #1


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Hi Roan

To answer your question, yes. Do the Chett Tune.
If you towing then you should look at getting the EGT to stay down. It is something a lot of folk overlook.
You can go STi IC and that will help a little bit.
Porting the heads is a massive expense for very little gain.
If you still like the TD04 turbo then consider fitting a Water Methanol Injection System.
It will keep the EGT down and aid in the cooling by a long shot. Much more economical and more torque to be had.
We at Intent Performance can fit it for you prior to a visit to CHett.
PM me for details.
Oh 82 785 Nine 277
Forester XT 2008 MT
VF48, STi IC, 76mm Bell mouth TNT Free flow, GFB EBC, Coolboost WMI, WHP built and Chett Tuned. Blue Wasabi V3.0

March 08, 2018, 05:40:11 PM
Reply #2


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Dunno if this has been done by anyone in SA but, the Oz and USA guys often swop in the dual range box from the non turbo models. Gives a lot better towing gear ratio.
You still have to go the Chett route anyway.

March 10, 2018, 12:38:38 AM
Reply #3


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Porting and polishing the heads on a turbo charged vehicle will get you negligible gains, even getting larger cams wont do that much as the intake is already pressurised.

On the subaru boxer engine it will mean the engine has to be pulled out and two heads need to be removed and machined, meaning the labour/parts and cost of actually porting the heads will be a lot higher than simply fitting a used VF42/48 or whatever you can find and having Chett tune it.

If I was in your position I would probably get outback with a larger engine for towing only.

If you really want to keep your forester and go for a bit more power I would build it like this:

Get a STi turbo and have the turbo housing ceramic coated inside and out, have the exhaust manifold and downpipe also ceramic coated inside and out to reduce the under bonnet temps. Fit a big top mount intercooler from a STi, add a meth injection kit to keep the intake and exhaust temperature as low as possible. Have Chett tune it on 93 and ask him to tune it conservatively and run the midrange especially rich.

Then fit a OBDII reader and monitor the temperatures when towing.

March 14, 2018, 07:33:31 AM
Reply #4


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Or you can go this route.