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Old 03-13-2013, 10:56 AM   #198
Member#: 198281
Join Date: Dec 2008
Chapter/Region: MAIC
Location: Virginia
2005 WRX/STi
WRB of course


Originally Posted by kellygnsd View Post
That's pretty slick. Did you do any back to back testing against the virgin 4" inlet though?
No. The only thing I can tell you is the turbo sounded more 'chirpy' on light throttle lift and light tip-in felt slightly better. Placebo effect maybe?

Originally Posted by manitou View Post
The compressor flange looks to be v-band compatable, correct?

Not to take anything away from this low mount kit but turbos spool so fast in the stock location or rotated stock location with your headers that it may be difficult to justify the cost of the low mount kit with smaller/ mid size turbos for the gains. I think this low mount will shine, the bigger you go turbo wise because the shorter piping will aid in spool up of the big guys! Kind of like what Junior is doing with the PTE6766 and his soon to be forward facing front mount location. Talk about short and efficient piping! I love what you're doing though and I'll bet the 3576 will shine on your kit!

Think about the waste gate exhaust though, it's a shame to route it back into the down pipe and loose some of the gains. Look at the discussion in the external waste gate muffler thread that we have been having! I'll post up a link here.
Compressor flange is made for a standard 3" silicone tube. Space is tight and this was really the only option because no hard tubing is used on the inlet.

I can't entirely disagree with the performance of our headers in stock location, but you can't compare your setup here. It's VERY different. You've got the long rod block, built D25 heads (with bigger valves to boot) , I'm going to guess no cat as well and probably a bunch of ther stuff too I've got a SB with forged pistons/rods and higher pressure valve springs in the heads with a catted exhaust. That's it. For comparison sake the kit makes more power sooner in the revs than a 3071 on any other kit (rotated or OEM location) I've seen and similar peak power to the bigger 3076. The bolt-on-ness and combination of streetability (super good spool characteristics) with 400whp capability was the goal. Maybe I'm shooting for the wrong demographic?

Originally Posted by manitou View Post
I read through ALL of it. Not one single before/after dyno. This would have been great to see. More specifically, a plot showing recirc vs to atm

At 400whp I'm not concerned that I'm leaving a lot on the table power wise going recirc. The EWG has a long dump tube, it's is tied into the exhaust at an pleasurable angle, plus it is tied in after the cat.

So the concern is going above 400whp and still being as quiet as the possible. An additional muffler on the gate is not the path I want to take. I'd MUCH rather run exhaust and EWG into a collector and appropriately size up the exhaust from there, say from 3" to 3.5" (or whater the math says it should be). I know the dual muffled setup works, but for some reason it's not tickling me the right way. More thought required

Originally Posted by reid-o View Post
Plus one of the competing theories about the value of features like split pulse is the increased total volume from running two long secondaries to the stock location. One could argue that the increased volume would limit the effect. The idea is not so much low mount as it is reduced header volume while increasing efficiency. It just so happens that most designs will put the collector closer to the ports.
True. The thoery has merit, but I question the effectiveness of 'tratitional rotated twin scroll' setups in Subarus because the secondaries are vastly longer that than the primaries. It seems like the headers were made this way to fit the confines of the available space marketing to the 'must have TS!' market and no one thought to ask "does this setup have gains to warrant the massive price of admission?"

Originally Posted by manitou View Post
I agree with you Reid but the results Chris has posted of the 3071 are not impressive in spool characteristics and HP. Maybe it's the tune but the gains in spool and response will be bigger with bigger turbos because of the efficiency in the design and volume. My 58 lb stock location turbo acts like a VF on steroids with the Holy header. I think I have a good balance of stuff in my build, you can ask Junior about that. I'm not trying to discourage or discounts what Chris is doing, it's all good but it will get better with bigger turbos!
Again... you gotta compare similar setups; pump, stock heads, catted, etc...

Originally Posted by reid-o View Post
If you're going to be experimenting with twinscroll of the same compressor turbine combination please plumb in a backpressure sensor or if you feel rich a shaft speed sensor. I know you're going to argue that it's not necessary for the average consumer, but your customers are not average anyway. The best test I've seen to date was done on the supra forums, but there were too many variables to draw strong conclusions. It's always good to have other data sets other than outcome data.

I don't have any comments on your designs and always enjoy your posts. I'm curious about your solutions to single wastegate twinscroll.
Oh I know there's nothing average about Suby owners, we are a quirky crowd In all honesty, that kind of data stays here. Reason being, it opens up a HUGE can of worns. As-is I avoid custom work like it's the plague and providing info like that opens the flood gates to those that want our products "prefect" by "fixing" a miniscule pressure differential across the primaries. I can see the PMs already... "Can you make me a header that doesn't have .00X pressure differential, I need this build to be perfect!" I'd have to lump this in with my ever expanding inbox of "I like the design of your headers, but can you make it with 2" primaries and 2.5" secondaries, I'm shooting for 450whp and those small primaries/secondaries won't flow enough."

For now you'll have to have some faith and trust in that we cross our T's and dot our I's and hopefully the 'outcome data' will be all good.

The TS single WG solution is pretty cool and it might even catch on as a fabrication piece for the DIYers out there. Or at least I think it's cool Our first cast part too. Basically right before the turbine housing it runs a port from each runner to the WG, so the WG port is split into two and runs into the exhaust runners, secondaries. It's tipped at an angle for good flow characteristics (can't say how much I DESPISE WG's stubbed in at 90!). The divider goes into the WG all the way to the WG's valve for minimal cross contamination of gasses. It's made correctly to a T3. I say correctly because I ordered 2 different off-the-shelf T3 flanges and the profiles (specifically the corner radii) did not match the housing . It will also not require the squeezing, hammering or otherwise mashing of tube to fit a T3 flange, because it IS the flange. It goes from round to the rectangular-ish port shape in a nice smooth transition
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