Dulagarl: the Lifted H6 Forester

^ thanks for the tip. I don't currently have any way of monitoring oil temps, but will look into it.

NEWS:

Raptor H6 headers have arrived. Exhaust place visited today and have booked in for March. Headers will be shortened to improve ground clearance. Overall exhaust clearance will also improve. I am going a complete stainless system from the headers to the muffler. It will cost a bit, but its better than replacing mild steel in 4 years time. Straight through muffler and the new headers will improve performance.

Then its time for a dyno run and tune....

Will the shorter headers perk up the rumble a bit?

The straight through muffler will add some volume lol. Interested to see how the headers go

I've got a free-flow system - it's too bloody loud!! It drones terribly under load so I'll have to add something to tame it a bit.

A centre resonator should quieten it up

This looks really well done.. Get some videos up!

ALMOSTunseen said:

Will the shorter headers perk up the rumble a bit?

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No. It doesn't rumble. It's a H6. It sounds like this...

[ame="https://www.youtube.com/watch?v=GlQeNdpiqmA"]H6 Forester, big desert June 2013. - YouTube[/ame]

NachaLuva said:

The straight through muffler will add some volume lol. Interested to see how the headers go

Click to expand...

yes it will, but...

ALMOSTunseen said:

A centre resonator should quieten it up

Click to expand...

exactly. He's putting in a louvered resonator, so the increase in volume will only be about 5%. Given its got some leaks at the moment, it should balance out.

Thanks for that vid, sounds sweet!!!!!!!!!!

The old exhaust had a few holes in it, the muffler was stuffed, and I wasn’t happy about the clearance. As well as that, I had been advised to get some Raptor H6 headers, so I decided it was time for a revamp.

Before:



I decided that for a little extra expense stainless steel was the go. The Raptor headers are stainless steel, and the first step was to shorten them at the engine end to make sure I didn’t lose any clearance. The next step was to integrate them to the rest of the system. As they were supplied, the flange would have been right at the crossmember, and this was not acceptable. Instead, the flanges were removed, and welded to a spare set of H6 cats I had lying around.

I was concerned that the system was already loud, and I didn’t want it louder. A way of dealing with this was to put in a larger louvered resonator. At the same time a 16 inch muffler went in.

The end result? It looks like this….



Here’s the larger resonator:


The left side headers:


and the right side headers:


here’s the work from the headers to the flange on the left side. Note that there is a flange for each side, which means when working I don’t have to remove both headers and the y pipe in one piece. There are also flex joins on each side, which make the system more capable of dealing with knocks (previously there was only one flex join). I also like the way the OEM cats have been integrated. Very neat. Note that the flange is after the front crossmember but before the rear / gearbox crossmember.



Same goes for the right side:


After the flanges, the Y pipe nicely follows the contour of the gearbox crossmember. Very neat.



Note that there is also a bung for a wideband oxygen sensor which is currently plugged with a bolt. This is for tuning purposes. Car is booked for a dyno run and tune next week.

Those who know the car will remember that the exhaust used to be the lowest point. Now, the exhaust is tucked up nicely close to the underbody:


It’s also much more direct: fewer ups, downs, and turns from front to back:


So how does it perform? Already, without a tune I have noticed the following differences:

Its quieter, and has a more refined note. Here’s a brief vid of it coming off the hoist:

https://www.youtube.com/watch?v=cn87w-zEUKM&feature=youtu.be

It has more torque at low revs: I can drive over speed humps in 3rd gear at 1000 rpm, and easily accelerate away. I can idle around town in 4th gear at 1000 rpm and accelerate without pinging. Its also more responsive: First gear is over and done with quickly, and as a consequence second gear is less dramatic. It has changed the car more than I had thought possible.

A big shout out to Roy at Autoxcess, who did the exhaust work. Great bloke, great work. You can find him here:

https://www.autoxcess.com.au/

Really looking forward to the tune next week.

Very nice job!

Very, very smart looking, Greg :biggrin:.

When you are on your back like a turtle, your car will look very pretty indeed. Seriously, I hope that never happens, but it looks to be a really top notch job. Neat and clean looking.

Is there a reason the headers all join in at the same point?

That is some serious bling! Cant wait to see it out on the tracks again

RB the merge collector is positioned so that the cats can remain in standard position. I think that's the answer.

https://www.raptorsc.com.au/subaru6.html

^ Thanks. Just wondering about it.

All the old works extractors I have seen/used went to considerable effort to ensure that the length of each branch took the full capacity of the exhaust stroke (therefore the term "full bore" extractors) and also that they joined in the position where the individual exhaust gas streams were in harmony with each other - i.e. "tuned".

Of course, modern engines are far more finely built and designed than most of the cars that I have owned in the past, and the science of gas flow is far better understood now than it was in my youth (fluid dynamics).

Geez, my '68 LC used a 1929 design Chev engine as its starting point. Truth be told, that starting point was very close to the finishing point! I improved its fuel economy by a massive 37% to 300+% just by using my own design inlet manifold and changing the carby from a Zenith or Stromberg downdraught to 2x 1¾" SU side draught! Just guessed at the jetting required! It worked a treat ... Went from about 4 mpg to about 13.5 mpg towing a tandem horse float around the Adelaide Hills, and from around 13.5 to 18.5 mpg on the freeway.

But I have two questions:
Did you wear an onion on your belt as was the fashion at the time?
Was the toaster turned to 3 : medium brown?

Of course ... :rotfl:

I love the look of this Foz and its offroading ability!

I look forward to seeing more shots of it out in action

https://www.youtube.com/watch?v=bEUIZ1-8xzI&feature=youtu.be

Dyno run yesterday...

What kind of power specs is the beast putting down?

Power was 102 KW at the wheel before the tune. Now 113 atw. When the motor was first put in it was reported at 120KW at the wheel. Chasers say their dyno is conservative, and I'm not sure how load would affect it, but I had most of my camping gear in it as a true test (e.g 100 amp battery, fridge, drawers full of tools 'n ****). Also, front LSD may have made a difference to the figure from Godzilla in QLD.

Torque gains were significant. Road test today saw highway driving with some stop start and some big hills, returned over 9.5 KM per litre. Same run pre tune and headers returned just under 8km per litre. The magical 10 km per litre is in sight. The thing drives really well now. Also getting more out of VVT / Cams.

Around town it seems to be using a lot less juice. I think the main reason for this was that acceleration enrichment was too high.

Irrespective of the differences between the Godzilla dyno and the Chasers dyno, I have an approx 10% gain in power from the tune, probably more compared to the old headers. Also have over 15% gain in torque. Pretty happy with the result.