Jump to content
SAU Community

Recommended Posts

  • 2 months later...
  • Replies 97
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted Images

hi guys, resurecting an oldish thread.

i like the idea and did some research. i have found a guy in the usa who modifies yours existing t4 twin scroll exhaust housing. so basically he cuts out the divider and fit a pivoted flap in there, similar to the spool valve. differences here are.

the valve is in the exhaust housing so you still keep the twin scroll manifold and no sandwich plate to fit, so dump pipe still fits

also the flap is at 45 degrees when closed so make a nice transcient flow of exhaust gas and creates no blockage or hotspots.

i am going to be sending my rear housing to him for mods so will try to update on the results.

i like th spool valve idea but not there design, i would imagine massive heat build up behind the closed flap where this idea eliminates this.

any thoughts on this type of design guys??.

bernie

It's a good idea for a road car but I bet with tracking the car or even aggressive street use it would overheat parts, warp pieces, and cause problems. Some wrc cars didn't even use twin scroll turbos as the heat and pressure would cause one side to push over and block the other side.

i thought this but you can have it in stainless or inconel....

this is an email clip from him to me.

We have two models. The standard model comes with stainless steel 304L internals, and the pro version comes with nickel 600 (Inconel) internals. The pro version provides peace of mind for those who think they will be running in very high horsepower and temperature environments. Both models come with all required bracketry and the actuator so the unit is a complete bolt-on kit.

Edited by rockabilly

just waiting for prices mate. will post up the two prices when i get them.. think its similar to the sp one by the time you have posted your housing there,its been modded and posted back. will update when i hear more..

i do know though that on a 3000gto with a gt42 turbo. 20psi was acheived by 4300rpm with the valve and its been on the car now 5 years no issues..

Edited by rockabilly

thats what i saw when i looked at it BoostdR.. i can see any great hotspots on this set up, he says when idling the gate is in the closed position until positive pressure is reached to the level of the spring you choose, also on gear changes as boost drops the same again, it closes and you have major instant responce. i will try it out and see how it goes. the guy works for a living and this has been a 6 year project for him, he could not find suitable people to make the valve cheap enough so he bought his own cnc milling machine and made it himself..

Edited by rockabilly
  • 3 weeks later...

anymore results people?

it looks like a ghetto variable vanye setup to me, worse backpressure than a normal vv turbo but it has to spool better there's no way about it, you are halving the usable area of the turbo, will probably pose some restriction in the top end but my thinking is it will be completely worth it.

honestly I dont think it is that dodgy at all, surely the flow couldn't be much more turbulent than a normal dodgy log manifold or unequal length aftermarket one, and even if it is, it can't increase backpressure any more than just running a stock turbo.

Thats pretty cool, I approve of this method - had actually been trying to come up with a good way of achieving basically the same thing but never posted anything. It still looks a bit more whorey than what I'd like to do, but I can't really knock it too hard. Would be very interesting to see videos of it in action :)

The thing which makes me curious is what affect the back pressure has on engine efficiency and tuning to suit, if you are letting it build to 20psi before opening the second scroll then I'd imagine that back pressure is getting very high - then it will suddenly drop substantially when the second scroll opens. It'd be interesting to see the torque curve.

Ditto. However backpressure changes suddenly only if you suddenly switch it from fully closed to fully open. With a proper pressure source this setup should stabilize the back pressure for some engine rev range, while the valve opens gradually, and when it's fully open, backpressure rises again.

Actually if intake manifold pressure is used as a source, gradually opening valve does not stabilize back pressure, but rather reduces its rate of rise, as you have to maintain expantion ratio in order to keep level of boost. So many variables :wacko:

Edited by Legionnaire

The gradual opening thing is something which worries me a little, if its tuned on a dyno there is an assumption that at any particular boost level the valve will be so far open and timing will be adjusted to optimise that.

I am prone to overthink things, but I know with swingvalves there is a bit of a delay (most people with internal wastegates get a little bit of a boost spike on gearshifts) but what if you shift at high rpm with this setup? Conceivable that if the swing valve is set to 20psi, where it hits at around 4300rpm on the dyno- but rpm drop to 5000rpm on the gear shift and shoot straight up to 26psi.... there could be a very brief moment where you have 26psi of take pressure, a gazillion psi of exhaust manifold pressure and the ignition advance to suit something with perhaps have a gazillion psi of exhaust manifold pressure.

Could make for a pretty unfriendly engine environment in a track car, though just pondering out loud really.

The gradual opening thing is something which worries me a little, if its tuned on a dyno there is an assumption that at any particular boost level the valve will be so far open and timing will be adjusted to optimise that.

I am prone to overthink things, but I know with swingvalves there is a bit of a delay (most people with internal wastegates get a little bit of a boost spike on gearshifts) but what if you shift at high rpm with this setup? Conceivable that if the swing valve is set to 20psi, where it hits at around 4300rpm on the dyno- but rpm drop to 5000rpm on the gear shift and shoot straight up to 26psi.... there could be a very brief moment where you have 26psi of take pressure, a gazillion psi of exhaust manifold pressure and the ignition advance to suit something with perhaps have a gazillion psi of exhaust manifold pressure.

Could make for a pretty unfriendly engine environment in a track car, though just pondering out loud really.

may or may not be an issue, if is you'd something that takes into account rpm and boost pressure, I imagine most decent aftermarket computers could offer something like this, or if you run it with rpm only you would need a decent boost controller that can compensate for it, depends what is slower the wastegate actuator or the flap actuator, the fastest one should be doing the most control, I imagine the wastegate would be the fastest so unlikely it'd prove a huge issue.

Just means you'd need a competent tuner who can test all possible scenarios and ensure stable boost and no detonation, couldn't be too difficult.

I can't see backpressure being a huge issue, you'd just tune the gate to open slowly once full boost is it, cause if you did it too fast boost would drop/dip.

Edited by Rolls

Lithium, Also pondering out loud, just as you are, but I wonder if track 997 porsche turbos use VGT turbines. Just as this "quick spool" valve I don't think VGTs are suitable for a track car, unless of course it uses water cooled exhaust housings.

As for extremely high backpressures in certain circumstances - just to make sure I understand - 26psi in intake due to boost overshoot because of wastegate delay and gazillion exhaust psi due to spool valve operating lag, so both wastegate and spool valve are clorsed, but throttle is fully open and rpms are high? Is this correct? Timing may not be extremely advanced as when MAP-based ECU sees 26 psi when it expects only 20, it either shifts timing right back or cuts it off temporarily, but either way reacts before backpressure rises, on AFM-controlled ECUs... hm, I have to think about this... Dunno how PFC accesses its ignition tables, in factory ECU maximum load is seen when engine torque peaks... so 26 psi is irrelevant, is flow high in these conditions you described?

Anyway, that's exaclty why I wrote about importance of choosing a proper pressure source. I think we should use exhaust manifold pressure as a reference for the swing valve instead of intake manifold pressure.

Just means you'd need a competent tuner who can test all possible scenarios and ensure stable boost and no detonation, couldn't be too difficult

The problem is that some ECUs may be unable to tell the difference between normal and dangerous operating window beacuse of the way they access load points.

Edited by Legionnaire

Urk. I have a small novel forming in my head, but just a couple of points to ponder on.

1/ If a tuner tunes to cover all scenarios in this kind of situation, they have no sensor for exhaust manifold pressure - so the only way they can make it guaranteed safe for all scenarios is tuning the whole thing as though everything is flowing through a single scroll. That would be aweful, exhaust pressure would be through the roof - if it could even maintain full boost like that. There would be minimal timing at high rpm/high boost and the car may as well have a much smaller turbo.

2/ An equivalent flowing twin scroll setup tends to take noticeably more timing/make more power through the middle of the rev range than a single entry manifold. Thats comparing two efficient setups.... what happens if you turn a twin scroll into a single scroll with half the flow potential, and 3 cylinders have an exhaust flow which could either take a pair of 90 degree bends going into the turbine housing, or just go straight in - while the other side just goes straight in.

Hey Rolls, I know what A/R is.

If you change the cross-sectional area of a 3d object the volume will change. Quick spool valve is not changing the A/R. I'm sceptical that blowing half the turbine wheel will give quicker spool.

Anyway if quick spool valves really work go buy one and prove me wrong.

Hey Rolls, I know what A/R is.

If you change the cross-sectional area of a 3d object the volume will change. Quick spool valve is not changing the A/R. I'm sceptical that blowing half the turbine wheel will give quicker spool.

Anyway if quick spool valves really work go buy one and prove me wrong.

By blowing half the turbo you are effectively changing the a/r as there is less volume.

Urk. I have a small novel forming in my head, but just a couple of points to ponder on.

1/ If a tuner tunes to cover all scenarios in this kind of situation, they have no sensor for exhaust manifold pressure - so the only way they can make it guaranteed safe for all scenarios is tuning the whole thing as though everything is flowing through a single scroll. That would be aweful, exhaust pressure would be through the roof - if it could even maintain full boost like that. There would be minimal timing at high rpm/high boost and the car may as well have a much smaller turbo.

If you jam it shut all the time (why?) it will be like running a smaller turbo as you are only utilising half the blade area, then when it opens it is like using a larger turbo.

2/ An equivalent flowing twin scroll setup tends to take noticeably more timing/make more power through the middle of the rev range than a single entry manifold. Thats comparing two efficient setups.... what happens if you turn a twin scroll into a single scroll with half the flow potential, and 3 cylinders have an exhaust flow which could either take a pair of 90 degree bends going into the turbine housing, or just go straight in - while the other side just goes straight in.

You use a standard manifold, no way in hell you use a twin scroll manifold, I imagine you'd cook 3 pistons if you tried doing that.

The concept makes sense to me, it just depends how negative the effect of turbulence is.

Edited by Rolls

anti lag would work better...

But I'm skeptical about these type of devices, you might get better pulse onto the Turbine wheel but you're also only doing it on half the surface area....

it'd be like one high pressure hose squirting a water wheel as opposed to two hoses using half the pressure on the wheel. Maybe if that one hose had a better mechanical advantage over the wheel then it'd be better...

More unbiased testing is required! If someone wants to donate a twin scroll turbo I'll be more than happy to test it ;)

Edited by zoidbergmerc
If you jam it shut all the time (why?) it will be like running a smaller turbo as you are only utilising half the blade area, then when it opens it is like using a larger turbo.

I explained it. I'll try and do it slower/clearer - even though you almost answered your own question.

When anyone who has half a clue upgrades their turbo, they retune their car to suit - right? So if you are going to have a setup which alternates between a bigger or smaller turbo and there is no way the ECU knows exactly which point in the transation the flapper is at, what tune should it use?

You use a standard manifold, no way in hell you use a twin scroll manifold, I imagine you'd cook 3 pistons if you tried doing that.

FFS, I forgot why I stopped partaking in tech threads in forums for a while. I'm not going to bother with my huge speel now - thanks for saving me some time. To make what I said make sense, read the thread - specifically the posts by Rockabilly I was referring to. Its all here.

I don't get how you guys don't see that this is essentially just blocking off part of the turbo making it seem like a smaller turbo, then when the valve opens it utilises the other half of the turbo as well, eg a larger turbo. Mazda did it on their series 4 rx7s apparently and there are loads of dyno vids on youtube showing how it works

Strange how people always made their Mazdas more reliable by binning the stock turbo setups.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • Update 3: Hi all It's been a while. Quite a lot of things happened in the meantime, among other things the car is (almost) back together and ready to be started again. Things that I fixed or changed: Full turbo removal, fitting back the OEM turbo oil hardlines. Had to do quite a bit of research and parts shopping to get every last piece that I need and make it work with the GT2860 turbos, but it does work and is not hard to do. Proves that the previous owner(s) just did not want to. While I was there I set the preload for the wastegates to 0,9bar to hopefully make it easier for the tuner to hit the 370hp I need for the legal inspections that will follow later on. Boost can always go up if necessary. Fitted a AN10 line from the catch can to the intake hose to make the catchcan and hopefully the cam covers a slight vacuum to have less restrictive oil returns from the head and not have mud build up as harshly in the lines and catch can. Removed the entire front interior just shy of the dashboard itself to clean up some of the absolutely horrendous wiring, (hopefully) fix the bumpy tacho and put in LED bulbs while I was there. Also put in bulbs where there was none before, like the airbag one. I also used that chance to remove the LED rpm gauge on the steering column, which was also wired in absolute horror show fashion. Moved the 4in1 Prosport gauge from sitting in front of the OEM oil pressure gauge to the center console vents, I used a 3D printed vent piece to hold that gauge there. The HKB steering wheel boss was likely on incorrectly as I sometimes noticed the indicator reset being uneven for left vs. right. In the meantime also installed an airbag delete resistor, as one should. Installed Cube Speed premium short shifter. Feels pretty nice, hope it'll work great too when I actually get to drive. Also put on a fancy Dragon Ball shift knob, cause why not. My buddy was kind enough to weld the rust hole in the back, it was basically rusted through in the lowermost corner of the passenger side trunk area where the wheel arch, trunk panel and rear quarter all meet. Obviously there is still a lot of crustiness in various areas but as long as it's not rusted out I'll just treat and isolate the corrosion and pretend it's not there. Also had to put down a new ground wire for the rear subframe as the original one was BARELY there. Probably a bit controversial depending on who you ask about this... but I ended up just covering the crack in the side of the engine block, the one above the oil feed, with JB Weld. I used a generous amount and roughed up the whole area with a Dremel before, so I hope this will hold the coolant where it should be for the foreseeable future. Did a cam cover gasket job as the half moons were a bit leaky, and there too one could see the people who worked on this car before me were absolute tools. The same half moons were probably used like 3 times without even cleaning the old RTV off. Dremeled out the inside of the flange where the turbine housing mates onto the exhaust manifolds so the diameter matches, as the OEM exhaust manifolds are even narrower than the turbine housings as we all know. Even if this doesn't do much, I had them out anyways, so can't harm. Ideally one would port-match both the turbo and the manifold to the gasket size but I really didn't feel up to disassembling the turbine housings. Wrapped turbo outlet dumps in heat wrap band. Will do the frontpipe again as well as now the oil leak which promted me to tear apart half the engine in the first place is hopefully fixed. Fitted an ATI super damper to get rid of the worn old harmonic balancer. Surely one of the easiest and most worth to do mods. But torquing that ARP bolt to spec was a bitch without being able to lock the flywheel. Did some minor adjustments in the ECU tables to change some things I didn't like, like the launch control that was ALWAYS active. Treated rusty spots and surface corrosion on places I could get to and on many spots under the car, not pretty or ideal but good enough for now. Removed the N1 rear spats and the carbon surrounding for the tailpipe to put them back on with new adhesive as the old one was lifting in many spots, not pretty. Took out the passenger rear lamp housing... what do you know. Amateur work screwed me again here as they were glued in hard and removing it took a lot of force, so I broke one of the housing bolts off. And when removing the adhesive from the chassis the paint came right off too. Thankfully all the damaged area won't be visible later, but whoever did the very limited bodywork on this car needs to have their limbs chopped off piece by piece.   Quite a list if I do say so myself, but a lot of time was spent just discovering new shit that is wrong with the car and finding a solution or parts to fix it. My last problem that I now have the headache of dealing with is that the exhaust studs on the turbo outlets are M10x1.25 threaded, but the previous owner already put on regular M10 nuts so the threads are... weird. I only found this out the hard way. So now I will just try if I can in any way fit the front pipe regardless, if not I'll have to redo the studs with the turbos installed. Lesson learned for the future: Redo ALL studs you put your hands on, especially if they are old and the previous owners were inept maniacs. Thanks for reading if you did, will update when the engine runs again. Hope nothing breaks or leaks and I can do a test drive.
    • No those pads are DBA too  but they have colors too. I look at the and imo the green "street" are the best.
    • I’m not sure what happened I told them about sonic tunes free OTS tune and the next the I know .. I was booted..   To funny 
    • Yea - I mean I've seen my fuel pump which is decades old and uh, while I'm not saying this with real knowledge... but I sure get the ick at using anything in the fuel system that produced the state of that pump. Many years ago I went through multiple pumps (and strainers) before I dropped the tank to clean it out with extreme violence. I'm talking the car would do maybe 50km before coming to a halt, which resulted in me cleaning out the filter with some brake cleaner and going on my way. None of my stuff ever looked like what came out of your fuel tank. I don't think I'd be happy with it unless every single component was replaced (or at least checked/cleaned/confirmed to be clean here).
    • I'm not going to recommend an EBC pad. I don't like them. Just about anything else would suit me better. I've been using Intima pads for a while now.
×
×
  • Create New...