pl0x

They are v3 sti heads with 272 franklin cams, and i think upgraded springs but cannot confirm as I brought the long block complete. Should be able to flow more based on other people results, but heads restricting the flow is my suspicion.

Plox: 280kW ATW @ 28PSI - 492 NM Torque Model: 92 RS Legacy BC5 Displacement: 2.0l Mods: gtx3071 gen 1 with mamba twin scroll 0.82 AR housing/ 880cc Side Feeds / bl/bp ts headers with twist adapter / 3Inch with 2 x coby & muffler / 550x230x65 FMIC / vipec i88 / post IC 50/50 water/meth injection / 272 Franklin reground cams / adjustable cam gears Fuel: BP 98 Top line is 28psi with water meth Middle is 24ish psi no water meth Dashed lines are old single scroll gt3076 0.63 housing 23psi no water meth Couldn't pull any more than 280kw, torque drops off significantly, next to no top end gain adding boost and timing. Injectors weren't the limiting factor (yet), appears there is a airflow restriction. Pressure testing results (on high boost): Exhaust port egbp 40psi pre turbo but post wastegate egbp 35psi post turbo egbp 5psi turbo outlet/pre intercooler 34psi final boost/manifold pressure 28psi Back to back core vs no core @ 40% open loop wastegate duty test showed 22psi with core 26psi without (so ~4psi of intake pressure drop is the IC, this added 20 degrees of IAT even with WM and made the car run mid 10 afr rather than the normal mid 11, and seemed to bring the boost threshold 200rpm earlier) I've been "internet" advised IC is to thin and causing a restriction. Any opinions on this? I have a suspicion the cams aren't what they should be, are a bad grind, or are dialed in wrong. Any opinions on what could be the restriction or tests to suggest?

Also what inter cooler size and what brand and AR exhaust housing? Plox: 280kW ATW @ 28PSI - 492 NM Torque Model: 92 RS Legacy BC5 Displacement: 2.0l Mods: gtx3071 gen 1 with mamba twin scroll 0.82 AR housing/ 880cc Side Feeds / bl/bp ts headers with twist adapter / 3Inch with 2 x coby & muffler / 550x230x65 FMIC / vipec i88 / post IC 50/50 water/meth injection / 272 Franklin reground cams / adjustable cam gears Fuel: BP 98 Top line is 28psi with water meth Middle is 24ish psi no water meth Dashed lines are old single scroll gt3076 0.63 housing 23psi no water meth

I've got two of the more expensive "gold" model ones from Repco, Repco brand. You would really struggle to tear and have lasted sitting in the weather for longer than I like to admit.

Manifold patterns are due to the head version/phase, not short block. I'm sure the engine builder will have the best advice.

I've got both TT turbos (which I thought were off a BE5) in the garage taking up space. Pm me if you'd like me to check if one is a vf26.

Good point. Also from memory it's not spongy without vacuum (car running), even the initial sponginess isn't as prevalent.

My BC5 with ABS has always been pretty spongy with 1 1/16" - 4 pot front 2 pot rear. Cert guy wanted it firmer and more travel once firm for the cert and suggested the master cylinder to be replaced. A brand new cylinder netted the same result. I'm wondering if the firewall flex has something to do with it.

Interested. Really it's a question of does it detonate/knock on Mobil if it's tuned on BP or vise versus. I've used both Mobil and BP in my BP98 tuned cars. No issues that i'm aware of, but that doesn't mean there isn't any (I don't have any knock gear on my cars to compare). I believe there is a difference between Gull and BP due to ethanol content, but have heard conflicting story's of which is better. One friend said his car see less knock on Gull, but have heard others say it's tuned on Gull so fine to run BP.

Didn't think it'd be that high either. At that price I'd wrap, and just replace them if they rusted to failure. Carry on with glad wrap around the header wrap during oil changes.

Isn't wrap/hpc as much about keeping heat in (heat=energy=turbo spool) as it is protecting things around it? People say wrap causes rusted as it traps moisture, also on subaru's it's more of pain in the ass than normal as it sits below the oil filter (oil drips onto wrap). I'm not sure if it's just sales pitch but HPC sounds pretty good, heat protection plus better performance benefits. Anyone seen actual proof of HPC coated performance gains?

I suspect that low power reading would have been done after back to back runs to show how much power it makes once the top mount intercooler is heat soaked already, so the 35kw increase possibly isn't as good as it sounds. More that with a FMIC it can actually maintain that power, not degrade pull after pull. The lag/response difference (or lack of) is some proof I hadn't seen before.

See Prestige Tuning & Motorsport's post on facebook today? Additional front mount lag looks like 100rpm or so. Factory location turbo and manifold, basically longest routing and large volume to fill. Given those results I'd be trying to get as little pressure drop and not really be concerned with volume to fill (with in reason), so 2.75" all round shouldn't hurt.

I'm sure there has been much more advanced study/calc's done on this, would be good to find and have a read. But i'm sure for the majority pretty much what @Gripless said above, bends are bads, pipe sizes should be in between the turbo outlet and the TB inlet size. Mines not quite what you're describing, but the hot side does have about 450 degrees of bends in it. After having reading through this and getting my head around it, I think i'll have another attempt.

People have always said flipping manifolds reduces the "lag", I've never seen any back to back results so unsure if it's true or if it's mainly placebo,. I guess it would take out around 180 degrees of bends and 1m of piping, so definitely reducing some area to fill and pressure loss.

Good to know. Just checked a few old logs and I'd guess mine are slightly undersized for my goals. 880cc making 280kw @75% with the help of water/meth

Also struggling to get my head around this. I think the bold below is the most accurate/best statement from the top thread, I'm unsure about his filling calc but I suspect the extra difference in time to fill from 2" to 2.75" over the short length of hot side IC piping would be barely noticeable. I think basically we are trying to get the air from the turbo to the intake with as little pressure drop as possible. Pressure loss is generally a factor of velocity and roughness/restrictions (with the same flow - smaller pipe means higher velocity, higher velocity means higher friction losses) When talking about restrictions other than friction on IC pipe walls, the smaller the diameter pipe has a bigger the restriction (i.e 2" 90 degree bend causes more pressure drop than a 2.75" 90 even at the same velocity, when you take into account the higher velocity from smaller pipe it compounds) Imo you want to be at the point where it’s not causing a significant pressure drop, but also not overkill. But I don't know where that is I think you are right on cold side, I'd probably go 2.75" hot side just to know it's not causing any pressure drop/restriction.

Title kind of sums it up

Actually you could be right, I may have cut a circlip grove into the rhs one further up the spline. Too long ago.

For my rear diff, these are the axles I needed but were hard to find: these are what I used in the end, I cut the extra length off the right one, they clipped in and no issues so far:

Front? can you cut one of the axle stubs? I remember with my 6sp conversion I had cut one of my axles stubs down, but I think it was the rear to suit the 3.9 r160

Pretty sure the rear covers have different length studs, but you can use the rear cover from your existing diff. Driveshaft/diff yoke bolt pattern can also change so check that it matches before buying. Unsure about axles, majority are the same if you are sticking with the r160 I believe (which you are by the sounds of it)

Second hand info so check it out for yourself but I believe if it sits the ethanol adsorbs water which lowers the octane rating. Unsure how long it takes to be a significant issue.

Unsure how true, but have read people say when it's high revving all the time you need to slow the water down through the rad (rather than speed up - drilling thermostat). Obviously you had an issue prior to drilling though so not actually any help. Fenix rad, 1 factory fan, water cooled turbo & fmic with no issues, although very minor track work compared.

Oh yea, Holset turbine housings don't do a/r.