Gollum

Back to maps... So, in theory, with a system that's controlling flow through BOV control, can we program the BOV to not just blow off enough to prevent surge, but allow enough flow to let the compressor follow it's most effient path? (as long as pressure ratio request are met according the the PSI/RPM targets. Because we can set a target load line like this: http://www.squirrelpf.com/turbocalc/graph.php?version=4&pr0=1&pr1=1.07&pr2=1.78&pr3=2.5&pr4=2.5&pr5=2.5&pr6=2.5&pr7=2.5&airflow0=3.1&airflow1=3.1&airflow2=8.2&airflow3=15.7&airflow4=29.7&airflow5=42.4&airflow6=44.6&airflow7=46.2&product_id=42 So for this plot, it looks like 98,000rpm would be a good limit for the turbine. Then the BOV will be opening enough to make up the difference between the load line and where we want the compressor to end up. So say at the 1.5 pressure ratio, the engine would be at an estimated 6 lb/min of flow (for theory sake, i don't actually know), and then the BOV would be flowing around another 6lb/m to get past the surge line. What I'm still not quite understand is where the PSI the engine will see is actually going to end up. The engine will only "breathe" so much, hence the surge issues, but I'm assuming that if we vent JUST ENOUGH to bring the turbo out of surge range, then that will give us the MOST available PSI for the engine. If we were to vent MORE than needed to get into operable range for the compressor, then we'd be sacrificing more air than needed, thus also available usable PSI for the engine, right?

You know Tony, I'm VERY SORRY, but I hadn't read that sticky... Before that last post I'd just read 3 articles on surge, and you explained it better than all three COMBINED!!! Serious lack of UNDERSTANDING out there... One article was even from garrett's website and was just plain poorly written and not expansive enough. I see now that I was thinking of it reversed. Thank you. I can understand how people (and OEM'S) have stuck with a pure wastegate control for simplicity, but I'm seeing that now as a very sad reality. We have companies like nissan and BMW with throttles that are only used in warm up and then total valve timing control for "throttle change". This is only about a thousand times more complex than the BOV turbo pressure control we're talking about here. I'm also kinda lost as to why the OEM's don't do this since it would allow them to use a SMALLER hot side allowing some cost saving on materials, and also a smaller package. Seems like everything they're normally after.

I'm having ah ha moments, while creating more questions/problems for myself. I feel like I don't understand turbos at all anymore. It's one thing to understand the concept of how they work, it's another entirely to KNOW what's going to happens in a certain situation. Load created Compressor Surge = When the engine is requesting more air than the compressor is actually able to give, correct? This is why if your compressor is too large for your application at lower RPM if you full throttle it your compressor isn't up to speed yet and you hit the surge limit. The engine is suddenly drawing more air than the turbo has to give, now you have flow separation. Throttle change Compressor Surge = When the throttle is rapidly shut under boost conditions, causing air to reverse and force air back to the compressor, causing the compressor to be pushing against an "unmovable object" if you're thinking about it in fluid dynamics (I think) Now, I'm understanding (I think) why you don't need a second BOV. I believe this is because your BOV won't suddenly "close" or "open" just because you closed the throttle. But if you're at a peak PSI for a given RPM and you slam the throttle shut, the PSI will increase as your RPM's are dropping, and this will throw your BOV into an area of the map that it'll open anyways... correct? And for surge line following.... I'm thinking that in order to prevent surge, accord to how it's programmed, you'd be OPENING the BOV to let air IN if you're in surge terretory. IE: You're at 1000rpm in 5th gear and you opened the throttle to WOT. This would allow air into the engine bypassing the turbo acting as a restriction at this point, and then using that exhausted air to spool the turbo. Once the turbo is into non-surge area it will be creating PSI and the BOV will close to follow your requested PSI/RPM data. Looking back at the dyno you posted in the other thread, I believe they could have had full PSI much sooner, but they've tapered it the way they have in order to make the power more usable and come on smoother.

In most cases that I'm aware of, yes. Though there's many different block variants so I can't say they all swap with any real certainty.

i think MOST people were buying them "after the group buy" and where getting the group buy price. I think at this point it's more like "mention hybridZ and get a promo rate". It's been like 2 years now and he's still giving out the group buy price. Awesome guy if you ask me, despite the issues people have had at times getting a hold of him. He's never taken money and not delivered, and he's quite to ship out once he's got the money.

the Lincoln Mark 8, continental, mark 8 lsc, and aviator had DOHC mod motors,

Their classes seem pretty decently prices too. Too bad they're a solid hour and a half drive away. I wonder if there's anyone like them up in the sac area. I've actually considered trying to get in for classes at a school like Davis just for machine shop access, though that's a mighty expensive route to go.

So I'm back at it again!!! I'm working in solidworks this time around, and might even be able to manage some ghetto flow analyses going (I'm not nearly as versed as some like MONZTER on here). What got me back on this old idea of mine was that the more I learned about force induction systems the more I realize that runner length doesn't matter nearly as much as runner diameter. Sure in a NA trim length can have a huge impact, but when the intake is pressurized there isn't the same limitations when you're running on vacuum. I'll have to scan or take a pic of the intake dyno I referred o earlier in my last post a year and a half ago, but it's amazing how much better a short runner tunned for the 4th or 5th wave actually works in practice. Sure the 4th or 5th wave might not be as strong, but it has a much more even response between the waves and allows a much broader range of flow. A long runner tuned for the 2nd or 3rd harmonic has VERY strong harmonics, but their overall performance gets sacrificed greatly. You can really "see" how long OEM runners kill top end power in truck V8's and similar applications. Anyhoot, another reason I'm looking into this again is that I'm expecting to go E85 in the future, and plan on running NO intercooler. My plan is to actually find a way to run the intake piping from the compressor UNDER the engine and up towards the intake plenum, running a design similar to the last one posted with a throttle body in the middle. I'll probably have a similar air comb system as in that design but done a little differently. My estimated costs this time around are probably a bit more realistic at around $500, and that's if I can get some next to free time on a mill. We'll see if I can pull that one off. As people like MONZTER have said in other threads, doing one off machine work without cheap CNC access just doesn't make financial sense. It really is the key in doing DIY stuff like manifold flanges if you're just making it for yourself alone. Plans for the oil cap will be to move it between cylinders 3 and 4, and I will definitely be using a quick disconnect system, probably using heavy rubber with clamps. I figure if it's good enough for OEM's like BMW and Mercedes then it should be good enough for me if I engineer it right. This will require solid mounting on BOTH sides that basically get the runners within 1/16th of an inch or less and let the rubber at as a seal only, not a part of the runner. Same concept as quality intercooler piping really. Silicone couplers are NOT for getting pipes to meet to each other. I'll have some renders probably in about a month or so. I'm gonna wait until I at least get to where I was at before, which will take some time to build back up to. So far I've got a rough sketch of the flange and the runner.

Yea I was thinking that a compressor with a map that looked more like a squat pumpkin would be much easier to use in a control scheme like this. From what I'm understanding, it wouldn't be hard at all to program in a map to do this on megasquirt. It's just a basic table, same as spark or fuel. You have to big variables, speed and speed (opposed to speed and load for fuel) and a map that tells the ECU where to aim the wastegate. The complicated part is that you need TWO new tables. One for Wastegate control of the turbo and one for BOV control. I'm not exactly sure MS has enough room for that, I'll look into it though. As stated before, might be possible with some custom scripting done to the source code. Oh, and I'd been thinking about this... the BOV that's venting for a target PSI, being control by the ECU, can it also act as the BOV for when the throttle plate gets closed during shifts and coast down? I'd think you'd need a separate BOV just controlled by the manifold vacuum.

What I'm still not quite getting though tony, is that isn't the optimal speed for a turbo variable based upon the pressure ratio it's up against and also the air that's actually flowing? I thought that was kinda the point of a compressor map, so you can see if you engine will land the turbo in an efficient range. It does seem though that in theory by running high boost at the bottom and then tapering it back down at the top you actually STAY in the peak area of efficiency of the turbo easier.

So let's see if I understand this... at least kind of, as it comes to application. The more I've looked at compressor maps over the years the more I think I don't quite understand them completely. I think I grasp what it's displaying, but it seems like in application your load lines your draw won't be followed. They seem more like just a guess to where you'll end up. So according to this map/load line here: Compressor Picture Based on this config here (which might not be accurate volumetric efficiency for a relatively stock L28ET Config Now, according to the map, if the wastegate is fully closed I'll make 17psi by 2k. Sounds reasonable. But because these load lines are figured for wastegate control on the hot side, it says i'll be going way past the efficiency peak of the turbo by redline. BUT, if I'm controlling excess then I can make the turbo follow the "island" in the middle of the map, increasing RPM and pressure ratio as I reach redline, then vent the excess on the cold side, right? All that being said, that's WAY more turbo than you'd need for a meek 350hp on a stock L28ET. People have made 300 wheel on stock T3's, showing that a GT35 should be more than capable to blow up the stock bottom end.

It's also a pain to fit a BBF into a 65' stang, yet it fits quite nicely in a Z... The SOHC shouldn't have an issue fitting on the width. The Lincoln DOHC fits, so you're fine. Any fitment issues you'll have will be related to exhaust/steering and belly/x-member. From the looks of the fitments I've seen you'll have some clearance issues on the firewall that require the motor to sit forward a little, but it'll fit.

Thanks for the clarification Tony. That's along the lines that I was thinking as to why it would still be referred to as a BOV. Next question, or ponder. I'd assume there wouldn't be anything wrong with venting the air back into the inlet of the turbo, right? If anything I'd assume that'd actually be a GOOD thing helping the turbo to continue to spool easily and prevent compressor surge. So knowing what you know, do you foresee any issues getting megasquirt to control a system like this? I personally don't see any issues, just concerned I'll have to write a new version with the code for the loop. I must say I think I grasp that area under the curve is much better and important than peak numbers and making power where your gears can't utilize it. Obviously you still need some raw HP figures otherwise you have a torque only big rig that's mostly just useful for towing things and needs tons of gears to make use of that power. But we should all know and understand this. But that being said I'd rather have a 225hp V8 that makes peak torque more than 3k rpm bellow peak HP, than a 240hp NA 4 cylinder that makes peak torque about 2k before peak HP.

I didn't get into this in my last post but they're also obviously not setting their boost control method, whichever it may be, to max boost as early as possible, making the torque curve more tame down low. You can see it make it's jumps which leads me to think they would otherwise have problems keeping the engine controllable if they just fed it as much boost as the turbo was making.

Well turbos don't spool like that boost plot, so the boost HAS to be controlled through a BOV control like you're talking about. I'm curious to know how it's being actuated though. Because those steps in boost look like they're being electronically controlled the way they spike and then taper down. It looks the same the way an electronic boost controller usually can't quite hold boost at or bellow peak right as it opens. But the front of the ramp is completely different than an electronically controlled wastegate turbo control, especially for those power levels. Thank you for the insight though Tony. You da' man. It seems that controlling the turbo with a basic loop with a speed sensor is easy as cake! And upon a basic google search I found this - http://www.turbobygarrett.com/turbobygarrett/products/Accessories_continue_speed_sensor.html Seems like there might be others that agree with this form of turbo control.... surprise... A total side note, for arguments sake (which doesn't mean I disagree, just want clarification). Should we really be calling a BOV when it's being used for venting excess charge a BOV? Seesm like a Pop-off valve might be more accurate in this instance.

The new coyote is already proving capable of more power than the 5.4 GT motor. The heads flow MORE in a SMALLER package. Rebuild with SVT H bream rods and slightly lower compression pistons and I'm SURE that's a 1000hp engine. The block is a stronger design than the GT block too. Crank is better engineered imo. They'll be much more affordable in time as well. I'm not saying the GT motor isn't awesome, just that Ford really outdid themselves with the new 5.0

I find it SO funny that people bad talk the OHC ford motors so much. I've done it myself from time to time, but what it still comes down to for me is one big factor. Potential potential potential. Sure you CAN get a DART block 302 and make 600hp, but there's been many more blown 302 blocks at a mere 500hp than mod motors. It's much more solid platform, and what makes the 302 super-light weight it takes back in potential. The 302 is the best motor for getting an easy 300 wheel hp for sure. But a lincoln DOHC 4.6 can also make 300hp, and without changing many parts. For the 302 you'll most likely need decent heads, a cam, upper/lower intake, and tuning the sucker with something like megasquirt or tweecer. The mod motor will also need to be tuned, but just opening up the exhaust and intake, coupled with some other basic work will get you into the same HP range. Even the crappiest DOHC heads flow decently well, and have HUGE potential still with port work. And they're NOT as heavy as some people like to imagine. Sure they're BIG, but they're not THAT heavy. I'd argue it's better for weight and distribution of it compared to any of the modern DOHC inline 6 motors, which are common swaps on this site and highly drooled over... Read my lips (over the internet). The 302 isn't BAD, the RB and 2JZ aren't BAD, and the 4.6 isn't BAD either. Application application application application application. Past that it's preference. I say AWESOME, I'm GLAD to see another 4.6 swap in progress. Oh, and I bet you CAN fit the 5.4 liter. It'd just take a dry sump system and maybe some engine bay massaging.

Well I'm glad it was brought back up. Because I've been thinking about what you've been saying in regards to turbine speed/boost control in this thread tony and I'm still somewhat unclear on some things. What were you using to control the wastegate's movement? Was it basically a map based on the max flow of the engine at full RPM? If so how is part throttle flow calculated. Seems like this would be a serious headache to figure out, or is it just some basic tuning time to figure out? It makes sense that if you had a speed sensor on the turbine shaft that this is all an EASY thing to figure out. Just find the optimal RPM for the turbo and run the wastegate against that. You could even log the positioning and then make a map to follow to keep from any possible "control jitter" from happening. But without any way to tell what speed the turbo is really at it seems like it would be a challenge to tune. Also, how was this setup on the street? I'd image since you said it was akin to a supercharger setup, that it was quite tame if you kept your foot out of it, but had instant power with full throttle anything close to boost threshold, which was insanely low. I'd love to try this out on my car, and maybe even my friend's STI, since he hasn't been so happy with how hard boost comes on with just the stock electronic wastegate control. Adding a boost LEAK with a manual controller helped, but he's obviously loosing some threshold. But it makes it much more livable on the street. It doesn't help that he's a lead foot and knows it, but I think if he had more control like you have in a supercharged setup he'd be much happier overall. And he's certainly not going to be turning his boost DOWN anytime soon. He's hoping to get close to some records when it comes to using the stock turbo on a STI.

So tony, what coil-overs do I need for my car again? I honestly get his point though it took me several years to really take this concept to heart. We have so many threads of people asking "which engine should I go with" and "my stock brakes suck, where can I get some brembo's for my car?" These are questions that tell more about the person asking than we could possibly give them back in information. They don't really know what they're looking for and the best a good samaritan could do would be to point them towards finding the right question. Like the whole injector question. The real answer is that you can put as many injectors just about wherever you want and be ok. It's all in how you want to tune that system. For quite some time companies got away with basic throttle body injection on V8 engines. Sure it sucked like hell, but the problem wasn't in the inherent concept, but the way it was applied. So even in those cases someone might say "TBI sucks" showing their ignorance, because the idea doesn't suck, how it's been done sucks in many cases. A community can only be as strong as their communication allows them to be. If we fail to learn how to communicate then what we're doing here is pointless. Go hand around some serious F1 forums and you'll find many debates on how to use words and what their definitions should be. Because if we can't use words that mean the same thing to everyone then they're pointless. This thread has had some of the most spoon fed info I've ever seen from Tony, which is actually high praise that he's that interested in responding... Tony has more experience than many of us will ever come close to comprehending, and his advice and explanations shouldn't be taken lightly. That's not to say lift him up like a god or something. We have MANY people that are members here that are like Tony, which is why newcomers need to be so careful at times. Posting here is like getting to speak and ask questions at a panel discussion with race teams. Know your subject matter BEFORE standing up and making a fool of yourself. I say all this because I learned the hard way myself. Go back and read some of my earlier posts. I've been an utter newt at times.

You have no idea how beautiful that is to me right now. Thank you so much ron. It's now save on my PC FOREVER!!! Muwahaha!

I don't know about everyone else in this thread, but to me this reads like John's sense of humor. Though it's been well documented (as you've seen) the liners flow just fine. I'd never remove them as a flow issue, but you HAVE found an inherent issue with them (my very humble opinion). The NA motors will get those liners red hot, and they don't have nearly the exhaust manifold temp of a turbocharged engine. They're very thin little pieces of metal, and I think it was wise of nissan to go with a square port design without liners for the P90. Take the manifolds off, be smart on how to keep shavings from falling into the engine, and go to town. Remove those suckers.

If the guy tuning KNOWS haltech, AND he's verified haltech is setup properly, he should be able to tell you if the problem is pre or post haltech, which is what we've been looking for. My guess is that it's pre-haltech, and I'm betting since you're trying other dizzy's that haltech is being triggered by the sensor in the dizzy. This conclusion would mean it's a select few parts, but still many possibilities. Bad Dizzy (you've changed, but maybe they're both bad or the other you tried is different enough that it wouldn't be compatible with the same wiring scheme?) Bad coil - easy to test and see Bad wiring somewhere. This is what I'm betting there's a chance of it being. Double check ALL of your wiring and make sure your ignition switch is triggering the ignition relay correctly and that there's power getting to the coil..

What state are you in? My price would be the same, $100 + shipping.

I like opera, but i'm quite stuck with chrome. It just works for me best at the end of the day.

Hey ron, you happen to have a full dimension breakdown of that manifold flange? I assume it's got the larger diameter ports which are slightly raised, yea? If not that's ok, I'll figure it out on my own eventually, just would save me some time (not that what I'm working on will go to production, but it's fun non-the-less).