Cold-side boost control
 

thought this was interesting; Turbosmart took their electronic straightgate 50mm butterfly wastegate valve and converted it to control boost on the intake cold-side for high power drag racing applications by allowing the turbo to run/hold at max allowable shaft speed and then controlling the boost/flow that the intake manifold sees (electronic BOV that is not simply on/off, controlled boost “leak”) rather than using an exhaust wastegate valve

https://www.turbosmart.com/boostgate50-is-here/

my mind got boosted up and spinning :suspect: and I can possibly see it being applied in other areas as well …
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Folks do this with smaller DBW throttle bodies as well. Mount it on the IC end tank and bleed of excess pressure as necessary.

The obvious issue is over spooling and grenading your turbo. This is the reason it's done on the exhaust side traditionally. You would definitely need to monitor compressor speed.

Usually used to stay on the stable side of surge line on the low flow side of the compressor map while staging drag cars. Massive power loss and temperature issues running the turbo flat out, generally not possible at stall rpm either on auto cars if the turbo is big enough to bother doing it.

^^I get it now, but wasn’t aware of it previously especially for a blow-off valve, per our recent discussion in your own aftermarket BW TT thread.

Though it seems to me a rally style fresh air ALS setup would make more sense. So maybe the FA-ALS pre-dates that method, but was less common then.
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I have like zero real life experience with this haha, but my thinking is this is good for drag racers during staging with throttle on but managing boost for launch. and ALS still might be better for its application of constantly going on during off throttle to keep spool up on turns and braking.

^^particularly for premix applications where the off-throttle fuel cut is turned off and dumping fuel into the manifold - ding-ding-ding

the primary difference being venting it to the turbo manifold rather than dumping to atmosphere. Both require monitoring and controlling turbo shaft speed.

which the advent of the electronic valve version allows finer control of the aggressiveness level wrt turbo durability.

in reality very few people have direct experience with it, and the few who do aren’t blabbing. The basics are easy to locate, but the devilish details are not simply googled up for all to see.
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^^I forgot to mention that the FA-ALS also serves as the BOV, but as with the additional drag style DBW TB, it diverts the intake air to the turbo manifold rather dumping it to atmosphere.

and for anyone possibly not comprehending what instant boost means at every tip of the throttle


RIP Ken Block 🙇‍♂️
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It also means your max flow is 100% dependent on the exhaust housing size, so you'll likely need to run a much larger housing than you would with a traditional wastegate. No problem with a drag car, but not great for everything else.

As soon as you dump boost, you have less exhaust flow, slowing the turbo. I don't think this adds any over-spin issues to the equation.

FA-ALS comes with its own set of challenges, sure is cool though. My favorite anti-lag setup is the Beattie hill climb car, uses a small helicopter turbine hooked up to the hot side to give boost at any RPM even with the engine off :)

Subaru WRC antilag was similar to using a helicopter emergency power unit turbine except it used a pulsejet stage instead of jet turbine in the exhaust between the engine and turbo.

https://cimg1.ibsrv.net/gimg/www.rx7...411d4f0b29.jpg

The rotary would be very well suited for this pulsejet ALS as it can run and make good power at very rich AFRs ( fuel for the pulsejet) with a good enough ignition system.

Can even be used Naturally Aspirated on a rotary as an post pulsejet exhaust ejector/pre pulsejet low pressure exhaust scavenge.


https://cimg4.ibsrv.net/gimg/www.rx7...c402510643.png

yeah, that’s the rocket device, it presents a more difficult control situation. Most have moved away from it to the FA-ALS setup instead for that reason.

mr2peak, I’d suggest you do some more research. The main concern of these devices is to prevent them from going out of control. They’re essentially a self feeding loop and can do that easily without the proper monitoring sensors, controls, and safety strategies in place. The only reason to run a larger housing is for more power at the top end without sacrificing the low end.

The device keeps the turbo spooled up at a certain speed rather than letting it wind down. There’s not much load on it in that scenario, basically it’s free-spooling wrt how much energy it’s being fed. Which greatly reduces the need to rev match when shifting. It’s a bypass throttle body control strategy that removes the engine from between the two.

Think of it this way. You’re braking into a slow corner where the engine might drop down 3,500 rpm at the slowest throttle application point, but the turbo is being kept spooled up as it were at the 6000 rpm point. It only engages there for a short period of time coming out of the corner and then the ALS strategy completely drops out as it if didn’t exist, until the next shift or corner slow down.

It really comes down to how much power you can put down effectively for the application and rule constraints. What you stated above is not entirely accurate. There’s also the launch boost advantage when that’s applicable as well. Which again, the aggressiveness of the system can be adjustable when configured as such. In that regard, a smaller housing may need less compared to a larger housing.

It only maintains a partial loading under certain circumstances depending on the control strategy and mode. The flow capacity of the housing doesn’t enter into it as you suggested.
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rx8 you misunderstood my comment.


Talking about cold-side boost control here


This part is about anti lag

Intake side only wastegating is moronic for 99.9% of applications. Less efficient, more heat generation.

Apart from drag, it could be nice to use as a "pop-off" type valve for safety in overboost if you have a wastegate failure. Would need to be on its own circuit to be useful

Most ECUs cut fuel and/or spark to prevent overboost, I think even a PowerFC can do it. That can accomplish the same goal without adding parts. More parts are more potential points of failure. On a drive-by-wire car, the ECU can close the throttle to avoid overboost. There's a good example posted here: https://www.rx7club.com/link-vi-pec-...ottle-1158807/

And for the fresh-air antilag fans, even if you like the broken-engine misfire sounds you might not like how it affects the maintenance schedule for turbochargers and exhaust manifolds. Antilag is only done on the big-budget rallycar builds, from what I hear it's not something most privateers would be able to afford.

Unless those other safeguards fail, or take too much time to react, or aren't configured properly.

All limiters should be implemented before before the starter solenoid is ever energised. If ecu load sensing fails your engine is gone anyway. If you want a reliable intake side pressure limiter it should be a dumb, single pressure interface (ie only the underside of the valve) relief valve anyhow, not something more complex, if you are scared of runaway boost.

Very few things take effect more quickly than a fuel or spark cut. If the ECU measures manifold pressure slowly or reacts slowly to dangerous conditions, IMHO that's a compelling reason to switch to a better ECU. And if the tuner configures things improperly, IMHO that's a compelling reason to switch to another tuner.

I think the compressor surge situation sounds like a good justification for adding parts to a system, and it might make sense to configure it to be used as another method for avoiding overboost if you've already got the parts installed. But I wouldn't add parts as the primary method of avoiding overboost.

apology for my error mr2peak, wish I could edit that out 😅

it seems to me there are a number of misunderstandings being stated above

perhaps some of you are thinking of the earlier ALS strategies than ran the additional air through the engine rather than the latest fresh air strategies that bypass and remove the engine from the equation to put air directly into the manifold.

and having mentioned it several times, but now another; the aggressiveness can be adjusted and this plays a large role along with many other factors on the durability factor. It can even be streetable and you won’t be lunching on turbos daily.

Running any turbo continuously at or near max allowable shaft speed is going to take it’s eventual toll, but there’s a lot of benefit to having it without pushing the turbo so hard as some top competition rally cars may.
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Those single "dumb" pop-off valves have been used in race series that have a limit on allowable boost. Seems they have been less than reliable, and it's either open, or closed, no actual control. Cold side e-gate gives more control, and could be set up as a separate system. Is it worth it to you? Probably not.

lol no worries

How many forum users are running full chassis methol cars with turbos bigger than the engine that actually need to ride the surge line on the 2 step/launch limiter? Likewise actually running very large turbos on rally cars where a partial throttle stop/bypass and enrich/retard isn't enough to keep it spooled? Very few places you can run old school rally cross spec cars these days.

I live in Thailand nobody is gonna stop you over a massive turbo. Shit, I see pickup trucks with hood dumps on the street on a fairly regular basis.

Just because you live somewhere you can’t do it, doesn’t mean other people have the same restrictions.

But yes, limited application. But, we are the tuner crowd, and we love to push limits

8374 is pretty much right on that surge line, plenty of people here running one

yes, and increasing the shaft speed moves the data point on the map away from the surge zone
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European Rallycross cars do this too, so they can run a giant turbo that makes 600hp and not surge at low engine speed. They redirect the airflow to the exhaust manifold and closely control turbocharger speed with a combination of this and fueling/ignition timing so the engine can spool the turbo without melting it down, since they need to be able to have good response coming off of a corner.

It is similar to bang-bang antilag but much more subtle in how it works, it isn't just in operation when off throttle. The turbo is kept spinning at its best speed and the valve is controlled to bleed off pressure as necessary to keep flow up and away from the surge line while allowing as much as possible into the engine.

Came across this elsewhere. Definitely takes up some real estate, but lots of options for control stratagies!

No idea who is building this, but if you're on the forum please pipe up lol

https://cimg0.ibsrv.net/gimg/www.rx7...f9230489a3.jpg
https://cimg1.ibsrv.net/gimg/www.rx7...4232c5ff75.jpg
https://cimg2.ibsrv.net/gimg/www.rx7...8fde498123.jpg

That is a lot of failure prone plumbing on the exhaust side when you can just direct your boost through the port air passage on the LIM just under the primary runners which exits through the inconel exhaust port sleeves for the stock airpump.

even the wastegates have wastegates!

That looks to be my roll cage fabricator's car. You can get a hold of him on instagram at @badcatengineering or @2798jmitchell. Not sure if he's on here.

Cool guy, he's got two first gens. The other is some crazy tube-chassis contraption that he made.

That definitely looks like the work of a roll cage fab guy!

I wanna know what he's thinking. I'd usually say I'll have what he's smoking, but that looks a bit beyond what I'm willing to put in my body.

if it’s T321 pipe rather than the usual T304 variety then it’s significantly stronger at higher temperature. Technically T321 16 Ga. tubing or Sch 5 pipe is strong enough compared to the Sch. 10 thickness that’s typically used for T304 pipe.

there are sound reasons for not trying to put anti-lag air that deep into the exhaust port compared to where it is on the manifold pipe. There technically isn’t anything wrong with what he did, but the anti-lag air supply lines could have been formed thin-wall tubing with NPT/tube fitting adapters on each end rather than welded pipe.

Welded pipe for those is overkill, but he likely had his own reasons for the choice. Likely it being self-supporting if I had to guess.
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Pretty sure it's just a showcase for his pie cuts.

I suppose you must of never had to fabricate large diameter intake tubing where a standard radius either didn’t work or were a lot harder to fit without having to throw several expensive bends away getting it just right.

I don’t think he’s intending to build a show car that just sits and looks pretty on the the convention center circuit. How about cutting the guy some slack. There are some things going on there that are rarely if ever seen on this forum. Right inline with the thread topic even.

The extra DBW TB isn’t intended as a decoration any more than the pie cuts.
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I'm not knocking his work, it's beautiful. A bit of a head scratcher though. I'm sure you know what his thinking is though since you're a clairvoyant

Don't have anything (of value) to add to this discussion regarding manifold design and the like but some of you might get a kick out of this. Spoke with the person who owns the car/fabricated the manifold this past weekend when we were scanning my interior and the main reason for the addition of a turbocharger was to reduce noise as his previous N/A setup was loud enough to require ear plugs whilst driving as mufflers alone were not sufficient to achieve the desired noise level.

Pulled the engine to fix a front seal leak and fit the e-gate. Space is tight! Need to chop a bit out of the mount, and cut / re-route the oil drain to fit properly. Unsure how it will clear the RHD steering rack, it's going to be tight engine might come out again to get the clearances right. We measured and eye-balled it, so fingers crossed the mount is clocked correctly the first time. Might need to put a Z bend in the rod, the angle is close enough make me a little nervous but far from locking up on the arm.

Still no answer from Full Race for the amp draw. The wires are small so it shouldn't be an issue but a real answer would be nice.


https://cimg9.ibsrv.net/gimg/www.rx7...009bd5618.jpeg

edit: nm, I may not be seeing it properly, try your best. You also beat me to the edit.
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Arm length is no problem, I have a few of them. Spacing out the mount just makes the oil drain issue worse.

Just realized I posted this in the cold side boost thread and not the e-gate thread.

I can clearly see the pies being used where the standard radius won’t work. Nothing clairvoyant there, only experience and common sense.
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definitely nothing clairvoyant going on there because it was pretty clear the one thing I wasn't questioning was his pie cuts

if you meant piping skills rather than pie cuts then that’s probably explains why I thought you were being critically sarcastic. In that case, my apology.
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both. All good. the plumbing set up is very interesting. I have no idea what is going on there. The work is obviously done by someone who is good at fab-ing tube