219 replies to this topic

[Soop]

Its pointless being skeptical with no evidence eitherway. As a rule I'm skeptical of everything out of the ordinary. That said, I've only every seen (really) shit curves from B4's. So I don't know.

[BigWillieStyles]

Its pointless being skeptical with no evidence eitherway. As a rule I'm skeptical of everything out of the ordinary. That said, I've only every seen (really) shit curves from B4's. So I don't know.

Just for you Soop, another B4 with mild mods - See link from ozlib -> My link

[acres]

Alright, just spent alot of today trolling other forums sussing out how these other sequential systems work and although I couldn't find any info on the porka setup, I did find plenty of details on the rx-7 and supra systems. Mechanically they aren't really all that different to the subaru setup, it seems the key difference is in how the pre-spool and I/C valve are managed. The Supra places it's I/C valve directly on the compressor outlet of the secondary and rather than use a differential pressure sensor to determine when it opens this valve it just seems to operate at a slight delay from when the ecv opens. This system just seems to take advantage of the increased capacity & pulses and just assumes that the secondary will be at full boost. Excess pressure build up during this  pre-spool stage is vented via a one way check valve. The Mazda system has the same capacity problem as the subaru however this seems to overcome this by better managing pre-spool. It begins pre-spool at 3000rpm and doesn't open th I/C valve till 4500rpm. With 1500rpm (as opposed to subarus 300-500rpm) worth of pre-spool the secondary is almost at full boost when the valve opens so VOD is hardly noticable (1-2 psi drop) just as Big Willie Styles described his RX-7. The Mazda uses a bypass valve similar to the Subaru to vent excess boost in pre-spool.
This has sort of confirmed for me what I was going to try anyway to combat the vod. Which is to initiate the pre-spool sooner and delay the I/C valve opening till a higher rpm.

Only info I could find on the Porsche was that pre-spool and changeover occurred higher in the rev range - after 4000rpm. But nothing on how the system operates.

[skillionaire]

Hi,

Try teamspeed.com for some tech. on the P-car system.

Cheers,
Nik

[Billsy]

this is a very interesting thread, and its good to see others attempting what is essentially a massive time consuming experiment.
with it done correctly, the right turbos for the setup and the right tune i see no reason why a TT cant be very successful even on a 2L.
unfortunately my TT experiments are over as i bought a house and am selling the car.
But i had collected 90% of the parts for a rather complicated compound/sequential setup using 2 garrett's aiming at 300atw.

the limit i reached was either the under manifold pipe or the turbos flow capacity, im not sure which as i didnt get round to changing the pipe to find out.
the 2L made more peak power at higher RPM, but the 2.2 had a broader delivery and went like stink with no vod at all.
after about a month i ran it parallel with 2 secondarys, which made it a lightswitch at dead on 4200rpm, but boost kept tapering off top end making me think it was the intake pipe that couldnt supply the turbos.

the keys to the success i sure is to ditch the subaru designed ECV and control the flow with a free flowing valve such as a large ceramic ball valve or high temp stainless butterfly after the turbo.
i found these available, but at very high cost for something that i wouldnt worry about failing.
and the IC valve (if your design has one) needs to be operated by the pressure from the staging turbo, not a setpoint controlled by an ECU which in the stock setup always opens too early (its part of how ecutek gets it so smooth by retiming it)
and obviously to have the right turbos for the application. the better the system works the bigger the turbos can be.

if anyone in adel wants to be a guinnea pig, let me know. i still want to build this monster

[allpaw4]

Hey guys, just a quick one about my graph - that is the newer graph, and if you look closer at it, there are less points it uses to make the curve - due to the smooth curve of the twin scroll. The older graph which hasnt been posted uses much more plot points, and shows the VOD does still exist, albeit much much less.

But on topic, this thread is awesome, very keen to see where it gets to. I too thought about this, and asked a few questions on ozlib with the basis of a 2.5, but after talking to regency, the idea was canned due to them not willing to let me register it after I was finished. Best of luck with it!

Billsy - how much help were you after? Send me a PM with what bits you have and what you would need to make it happen. I have to say, I am somewhat curious. Only point is, it will have to be done on the sly. If the missus finds out this is in the works, I'm a dead man

Cheers,
Ben

[acres]

Yes I have thought about replacing the ecv with a butterfly valve. Once I get around to making the headers I would like to implement a larger butterfly. The stock ecv seems to be quite restrictive without porting it out. I have looked at the apexi butterfly type ecv and they seem practical. The plate looks a decent thickness so it should tolerate the heat. Would you mind sharing a link to any decent stainless butterflys you've found?
Billsy did you ever modify your I/C valve to operate off positive pressure? I'm curious as to the effectiveness of this as I have thought about it but the problem I saw with it was getting it to operate smoothly. Too soft a springrate and it would open too early, cause reversion, close again and repeat the process. Too hard a spring rate and the valve would never open until the secondary is boosting higher than the primary, this would cause massive surge I would think. The bypass valve would also have to be modified to operate as a regular BOV taking its signal from the manifold so low rpm pre-spool would be compromised. If you have made this work I would love to hear how you did it?

Compound would be cool. But won't intake temps reach massive, probably dangerous levels? Will you lower compression ratios to combat this? Or just manage it with good cooling and a conservative tune? I'd be very interested to see the results of such a system.

Nik, teamspeed.com was a good place for a perve but unfortunately they had very little info on the elusive 959.

[zanzarah]

Billsy passive one way ICV
http://www.ozliberty...g-the-tt-10075/

[Billsy]

The stock ecv seems to be quite restrictive without porting it out.

its downright terrible, both in design and as far as fluid dynamics goes, it creates massive turbulence even when ported it leaves much to be desired

Billsy did you ever modify your I/C valve to operate off positive pressure? I'm curious as to the effectiveness of this as I have thought about it but the problem I saw with it was getting it to operate smoothly. Too soft a springrate and it would open too early, cause reversion, close again and repeat the process. Too hard a spring rate and the valve would never open until the secondary is boosting higher than the primary, this would cause massive surge I would think. The bypass valve would also have to be modified to operate as a regular BOV taking its signal from the manifold so low rpm pre-spool would be compromised. If you have made this work I would love to hear how you did it?

it was basically as in this pic, and it explains itself, the pressure from the primary keps it closed, when the secondary has something to contribute it just opens and self adjusts to the flow of each turbo.
it worked VERY well, and allowed me to controll changeover with just one signal wire from the ecu or switch on the dash. (with vac line modifications aswell) it eliminates the valve timing fuckups that subaru tuned into the ecus

i made it from 40 and 50mm stainless tube, stainless hinge and valve flap.

Compound would be cool. But won't intake temps reach massive, probably dangerous levels? Will you lower compression ratios to combat this? Or just manage it with good cooling and a conservative tune? I'd be very interested to see the results of such a system.

the compound would only be during primary operation and once the much larger turbo kicks in the primary is bypassed, using similar passive valving as above it automatically goes back to the smaller turbo once the smaller one out flows the larger etc. its a modified version of what mercedes now use on their twin turbos, ive had it planned for about 5 years and it never really got off the ground

[acres]

Looks good. One question though. If it's free swinging like that does it tend to flap around uncontrollably in low boost situations? Such as backing off the throttle or changing gears? Or have you also used a magnet or really soft spring to ensure it stays closed during these situations. I suppose it could be positioned vertically and gravity would take care of that too.

Your compound system also sounds similar to Volkswagon's system on the golf super + turbocharged setup. Just thinking about it, and what a fiddly and frustrating job that will be trying to fit the pipework in!

[Billsy]

the free swing gate is fine as is. even at idle the primary creates enough pressure against the throttle to keep it closed, ive never heard it rattle. only with sharp throttle stabs from idle you di hear it open and shut again, but this also helps response at that initial point as its a shortcut for the low pressure air before the turbo gets going.
if it was upside down then gravity would eliminate your concern anyway.
also it has low pressure from the turbos intake (through the secondary)on the other side aswell to keep it shut. although the effect would be minimal.

along with the front mount it was the single best mod for smoothing out the TT transition

[acres]

Good stuff. I will definitely have to fabricate something like this then. Probably easiest to wait till the front mount goes in too though. Space is a bit tight with the top mount.
Ta
Aaron

[BigWillieStyles]

I dont really understand how the Electronic control valve can be ported? Can someone explain this to me? Is the little gate just trimmed to make it lighter and easier to open?

[acres]

ECV - exhaust control valve. In a way it resembles a big wastgate in appearance. You can bore out the hole to a larger diameter within the tolerance of the original flapper and there is even enough room to be able to fabricate a larger flapper valve which will enable you to bore it out even further. The original flapper already has a weight attached to it and positioned to aid opening of the valve.

[alexGT]

I would take dynographs of other people's cars with a grain of salt.

The only graphs you should be looking at is your own, going back to the same, consistent dyno.

Only then, you can compare your own graphs with yourself, and then gauge true gains.

Comparing one person's graphs from SA, to another person's in QLD is like pissing in the wind. It's messy, and achieves nothing.



There are no constants to compare against.

I'm sceptical of that curve

ken oath x1billionz. dyno is JUST A TUNING TOOL. it can be manipulated to show anything! a 100kw car can make 200kw on the dyno with hardly any work from the operator!

dyno smoothing is a very common practice. makes the customer happy

i admit it is a good power curve however ALL SEQUENTIAL TT's WILL HAVE CHANGEOVER. map a boost curve below that and will tell the story.

props to all the effort you are going to. DIY mods are epics wins big learning in them and sometimes a very little costs for some handy gains. great work!

[Chadza]

Further to the above dyno posts, someone mentioned a Torque curve- Torque CANNOT be measured accurately on a dyno, so any figure derived from a dyno run is not worth the paper its printed on.

[zanzarah]

I dont really understand how the Electronic control valve can be ported? Can someone explain this to me? Is the little gate just trimmed to make it lighter and easier to open?

There is a before and after pic of a ported ECV on this page:
http://www.subyclub....b4/page__st__40

[TTimpreza]

Just thought I would share what I have been up to over the past couple of weeks.
Rather than travelling down the tried and trusted path of binning the twins and strapping on a massive single I thought I might try and see just how far I can take the twin setup. This is just the first step and involves the 2 new turbos and intake pipe. Next step will be fitting a dual core vertical FMIC, bigger IC valve and I have an idea for a set of headers that I would like to try.



This is the 2 OEM turbos on top and the new hybrids below - secondary's on the left, primaries on the right. OEM is VF18/19 and the hybrids are TD04-13T/VF25 primary and TD04-13T/VF14 secondary. I have kept the wastegate on the secondary for future use. (might be necessary after the headers are done)



VF18 on the left, hybrid on the right. This clearly shows the difference in compressor size between the two.



Again, VF18 on the left, hybrid on the right. You can see the turbine wheel is much larger so flow should improve and it will be capable of driving the larger 13T comp wheel. The turbine wheel has been replaced with a TD04 wheel rather than the TD04L wheel which is used from factory. The 2 wheels share almost identical exducer's and inducer's however the standard TD04 wheel has a slightly shorter tip height. This reduces weight of the wheel and flow capabilites which should help reduce lag on spool up, particularly at changeover.



This is the 2 primaries again. Bit hard to tell but you can see that VF25 turbine housing on the hybrid is much smaller than the VF18. This reduced AR ratio should help with spool up as the TD04 core is journal bearing as opposed to the VF18's ball bearing core, also the physically larger wheels will now be much harder to drive too.



New intake pipe. I have made it from 2.5 inch mild steel and 63mm radiator hose and coated with a layer of high temp engine enamel. This is a total pain in the arse to fit as there is only just enough room for the standard plastic pipe as it is. I have had to delete plumback section for the BOV just before the primary, and also the crankcase breather that plumbs back into the OEM pipe just under the TB. This will insted be rerouted to a tee piece between the secondary bypass valve and intake pipe. PCV valve will also be deleted as I can't be bothered rerouting those hoses too (there just isn't enough room to work with). The 3 smaller pieces up top are 2 inch mild steel and are used from the compressor outlets -> TMIC.

The maths I have done suggest that airflow from these 2 puppies should be ample for a good power figure but I am in no way going to make any predictions yet. Just going to see if it actually works first - the turbos might respond poorly and it will just be a real pig to drive

P.S. apologies about the quality of pics, apparently the card in the camera was corrupted so I have just used my phone.

Ta
Aaron

good luck! but this hybrid turbos is come from what car?

[acres]

Thats a good pic showing the difference between a ported and standard ecv in the link that zanzarah posted.

TTimpreza, Turbos are a TD04L from the wrx. They are hybridised from switching out the turbine housings with those from the standard IHI VF turbos fitted to the TT engines. The housings have to be machined out to accept the larger turbine wheel from the TD04 turbo. Housings from any series of the TT engine can be used with the difference being varying A/R ratios.

[acres]

Ok, had a bit of spare time over the last couple of nights so I have now managed to fit everything where it needs to fit. All the necessary pipes, hoses, brackets, etc are cut, positioned and installed so the only thing left to do is lift the engine back into the engine bay. Some pics:



Primary turbo. Not the neatest setup but it will do for now. The compressor housing is rotated outwards in preperation for the FMIC. Combination of 50mm mild steel and radiator hose to loop it back towards the TMIC. This is why I have deleted the plumb back section for the BOV.



Secondary turbo. This was time consuming as the ECV actuator bracket collided with the larger compressor housing so that needed a section carved out of it. Then the wastegate actuator collided with everything so after trying 2 different sized actuators I just removed it and wired the wastegate shut. I don't need it yet anyway, it's just there to future proof further mods.



Above pics is the first actuator I tried, then a smaller actuator, then wired shut. The circled bit is where I hard to take a chunk out of the ecv bracket.

I should be able to get stuck into it again tonight so if all goes well I should be able to have it up and running within the next couple of nights.