Sequential Turbo 3

[R34ztune]

Hi all,

I've been looking for a forum and place on sharing ideas about sequential turbo charging. Many forums I've seen on the Internet about turbocharging is mainly focusing on horse power. Sequential twin (or multiple) turbo setup goal is not just for high power but also taking care about low end grunt of an engine.

To make it sort, I will only talk about twin turbo setup to simplify the introduction of sequential turbo . The 1990's Mazda RX7 and Toyota Supra are well known setup of sequential turbo charging system. Tuners often change to twin parallel turbo or even one large turbo to replace the stock setup and achieve a high output engine. This doesn't mean the stock setup is no good, it is because tuner's goal is aim for high HP numbers with simplicity. Everyone who experience with turbochargers know that using a large turbo can achieve high horse power with sacrifice of low end torque. Sequential turbo charging is a way to optimize both low and top end power of an engine.

Take RX7 as an example, two turbo chargers exists in the system. These two turbo are the same size. The primary turbo works in all engine rev range. The secondary turbo only works in mid-high rev range. Since the 13B rotary engine is an engine having wide range rpm, it is an ideal motor to having a sequential setup to maximize the torque on each rpm range and deliver the most out of it. In low engine speed, both rotor's exhaust gas are pumped to the primary turbo, making the primary turbo spools up quickly so that the engine can have boost as soon as possible. When the engine speed goes higher, the primary turbo efficiency decreases and requires two turbo to work in parallel to generate enough boost for the engine. At this time, a flap in the exhaust manifold open wide and allow the exhaust gas of the second rotor to pump into the secondary turbo . At this stage, the engine just work as a parallel twin turbo system.

The disadvantage of sequential turbo setup is complication of piping work, control and known how of it. Nowadays we have a much better technology base then in 1990s. Does anyone know anybody in the world is doing some similar projects using a better design then the RX7 and Supra? I have been in this topic for many years, but I didn't have enough resources and time to build a prototype of it. I've done lots of design and research work in this area, but not seeing many of others is working on it. At the time I was studying, forum and blogs are not that common at all. Recently, I bought a R34-GTR, the engine revs from 1000 to 8500, with little modification it can go to 10000rpm. This engine is very tough. Currently, it is a parallel twin turbo setup and is missing low end grunt . I am looking to modify it to a sequential setup . I was trying to locate the Garret VNT (Variable Nozzle Turbine) turbochargers to achieve a similar goal, but can find very little information about it .

If anyone is in the field, please share.

 

[BrianPetersen]

VNT turbochargers are common on diesel engines, but in general, the VNT mechanism doesn't like the high EGT of a spark-ignition engine.

Study the turbo system on the BMW 335d, which is a current production vehicle with a turbodiesel 6 cylinder engine with a small and large turbo.

 

[yoshimitsuspeed]

I recently heard of a car that came from the factory twincharged. SC and turbo. I think it might have been a Mazda.
It seems to me most car companies are doing away with their flagship power monsters that would even use this. At least the Japanese companies and US car companies seem usually to prefer al motor or occasionally super chargers.
I have always loved Toyota and I am a little POd at them for ditching all their cool cars. The Supra, the Celica all-track and the MR2 were their cars that would make people drool and get them in the door. Now it's all bland eco cars and behemoth SUVs and trucks.
Mazda went NA when they went to the RX8 and went from having a badass full blown sports car to a sporty compromise car.

I am curious what your HP goals are and how much low end it's missing.
I always figure you should be able to find a quick spooling turbo that will get you to 300 HP on a smaller motor. Even more on a larger motor.
If you are going for more than that then you could be sacrificing some spool time. I also look at the overall RPM curve. Even if it has nothing from idle to 4k but spins to 10k RPM then you still have a 6k RPM powerband which from a racing or performance standpoint is more than enough. It could be a little doggy around town or for daily driving but then do you really want a 500 hp highly tuned car for that purpose?

 

[Warpspeed]

Sequential turbos are a nightmare to set up and get going. If it was easy, there would be a lot more sequential turbo production engines.

Forget VNT turbos on a gasoline engine. They too don't work very well, only Porsche have been game to try. VNT technolgy has been around for over thirty years, where are all the VNT production cars and race winners ?

If you want a very broad power band, turbocharging an already supercharged engine (twincharging) works well, and is quite easy to get going.

 

[R34ztune]

Sequential turbo is nightmare only because lack of electronic/microprocessor control . Nowadays, these electronic controllers are easily available, you get computers cheap and cheap microcontrollers like PICs. Anyone try to setup VNT/sequential turbo using mechanical way will fail. If you try to turn up the boost by bleeding the wastegate actuator line on a stock sequential turbo without reprogram the sequential turbo controller, it will not work. Because when the secondary turbo kicks-in (using the factory program), the pressure of the intake side is unexpectedly high. When the secondary turbo boost line open's up, the existing high pressure from the primary turbo will reverse the flow of the slower spinning secondary turbo. That's why it will not work for aftermarket tuners who doesn't know about microprocessor control.

Believe it or not. Car makers doesn't do much on automotive electronic or technology developments, most of them are done by other companies like Bosch/Mahle . If these companies doesn't have an off-the-shelf solution, then they won't use it. Porsche 997 turbo setup is done by BorgWarners . Every year I visit those automotive parts engineering exhibitions, these companies are always trying to sell their complete solutions to car makers. I've also seen VNT on gasoline engine solutions. Here is a picture of it.

I am a developer, always not a follower, if someone has done something, we take it as reference, which is good. If someone never did something, it doesn't mean that we can't do it right. Engineering is application of science. First we have to have an idea, then know the science, and collect real life figures, turn them into applications. Let's keep it up and find out the other unknown variables before someone or me to proceed for a prototype.

Its not a matter of how much HP I want on my car. I am not an individual trying to achieve high HP numbers on my car. I am from a company and group of people. We are distributor/importer and sell high performance parts to tuners. I am the engineering manager of the company. I personally own a Nissan R34-GTR it has lot of HKS/Nismo stuff in it, it has more power than I need. Our company and group of people own so many sports cars and high power cars. Porsche Cayene turbo, Porsche 996, R32 GTR, R33 GTR, Audi A4 DTM, Audi RS4, Golf GTI 2.0 Turbo.. Not to mention customer's cars . If we develop a solution, there are so many test platforms to test with . Achieving a smooth torque curve with high power output is always the goal, its an engineering problem of cost/efficiency/performance ratio.

Superchargers efficiency is too low, its not in consideration. Turbochargers is much more flexible. Think of supplying a supercharger kit, and the difference of supply a turbocharger+valves+electronics . The second can be easily to install in many types of cars.

I don't use to write forums and blog. Its even my first post. I am just trying to share my idea here and to see if anyone has done some engineering work about this recently. Its nice to hear some replies. Thanks.

 

[Warpspeed]

Nissan have spent a bundle developing their whole desirable range of fantastic twin turbo GTR cars from the 32 up to the 35 GTR.

Nissan diesels have run VNT turbos for decades, the Nissan R&D engineers have full access to the full range Garrett VNT technology.

Why do you suppose Nissan decided to avoid the VNT altogether for the Skylines and stay with ball bearing turbos ?
The level of computer sophistication on the 35 GTR is truly incredible, but still no VNT turbo. There is a lot more to getting one to work on a petrol engine than just writing a few lines of code.

 

[yoshimitsuspeed]

This is my opinion.
I'll use my MR2 as a example. It has a little 1.6 liter engine. I am running a DSM T25 which is good for close to 250 hp. The most boost I ran on my old motor was 12 PSI and it would make that somewhere between 2500 and 3000 RPM. You will notice I am most familiar with MHI turbos and will use them as reference.
a 14B is good for something like 300 hp and would still make full boost by 3500 or so. This would be a great setup for the street. There is really no need for a lot of power below this. Also 300 hp in a 2500 pound car and out of a 1.6 liter motor should be plenty for that kind of use.

A 16G will hit something like 20 psi by 4500 and is still making 12 at 3500. This means down low it will pull hard and above 4500 it will pull real damn hard. my motor will spin to 8k so that's still 3500 RPM of butt puckering power with minimal lag. That's plenty to use the gears to stay in the powerband. I wish I could pull up that dyno sheet (not my car) but the website is down.
As far as racing goes it's just not worth the extra weight, complication and extra parts that can fail when you can just use the gears to stay in the powerband.
As far as DD I would say the same thing plus do you really need that much power? Even if you do how long do you expect to get a motor to last pushing 200+ hp per liter?

For the most part I think twincharge is silly and I would put sequential in the same category.
There are only a couple instances where I have really felt the concept was practical. The one I can remember is a 600+ hp hill climb car where they needed a huge turbo to make the power and used a SC to keep some low end and to help spool the turbo.
If you are making less than 200 hp per liter you should be able to size a single turbo that met your power goals and still gave you good spool and drivability.

 

[Warpspeed]

You might be able to get full boost by 3,500 rpm and 300Hp, and driven absolutely flat out, it is probably a pretty exciting ride.

But what about driving in traffic at legal road speeds between 2,000 and 3,000 rpm ? For more sensible driving, a very broad flat torque curve with instant throttle response makes for a far more relaxing drive.

Big capacity American V8 pushrod engines are still very popular for that simple reason, they are so darned easy to drive, and still deliver the goods with plenty of easy power when required.

 

[yoshimitsuspeed]

How much power do you need for sensible driving? Really not that much.
If you need to pass or for whatever reason need to accelerate then you drop a gear and put it in the powerband.
Also if you are looking for a relaxing drive you shouldn't be driving a skyline or a supra. You are right for the driving you describe a motor targeted for lower RPM power may be better.
That said though I used a 1.6 as an example because for one I have one, for another it's a very common size for commuter cars. If the 300 hp turbo seems slow in the lower RPM then don't even think about the NA MR2 or econo civics. You have to rack those things to the moon just to get them out of their own way.
I also think it's funny that you put 3500rpm and flat out in the same sentence. With a car that revs to 8k 3500 is a bump above idle. I'll hit that in fifth gear at about 75 and I have the taller ratio transmission.

I'm also not bashing displacement or the many other options to increase and broaden your powerband. In fact that's sort of my point. Unless limited by a class of racing or something why would I twin charge my 1.6 4A-GE and try to push it to such limits when I could drop in a 1GR or 2GRfe and run just a few pounds of boost, have nearly instant spool, gobs of power and not be stressing the motor nearly as hard.

 

[patprimmer]

R34ztune

Before you say to much more about what car manufacturers actually do, a lot of people who post here work as OEM engineers or as engineers for OEM suppliers.

Oh, and Warpspeed is right.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[gruntguru]

How much power do you need for sensible driving? Really not that much. If you need to pass or for whatever reason need to accelerate then you drop a gear and put it in the powerband. Also if you are looking for a relaxing drive you shouldn't be driving a skyline or a supra. You are right for the driving you describe a motor targeted for lower RPM power may be better.That said though I used a 1.6 as an example because for one I have one, for another it's a very common size for commuter cars. If the 300 hp turbo seems slow in the lower RPM then don't even think about the NA MR2 or econo civics. You have to rack those things to the moon just to get them out of their own way. I also think it's funny that you put 3500rpm and flat out in the same sentence. With a car that revs to 8k 3500 is a bump above idle. I'll hit that in fifth gear at about 75 and I have the taller ratio transmission. I'm also not bashing displacement or the many other options to increase and broaden your powerband. In fact that's sort of my point. Unless limited by a class of racing or something why would I twin charge my 1.6 4A-GE and try to push it to such limits when I could drop in a 1GR or 2GRfe and run just a few pounds of boost, have nearly instant spool, gobs of power and not be stressing the motor nearly as hard.
Go back and read your post that Warpspeed was replying to. It was you that spoke of full boost at 3,500 rpm, of 300hp and of exciting rides. What he is talking about is a combination that will do both - an exciting ride when that's what you want or an easy drive when you don't feel like stirring the gearbox every time you want a bit of grunt. There are plenty of people who want the excitement available in a Skyline or Supra, but also want to drive according to the road rules and with courtesy for fellow motorists, which means they can can only use the available performance less than 10% of the time. Foe the other 90% they would like a car that is easy to drive!

I agree with Warpspeed's advice. To anyone considering sequential turbocharging, twincharging is a much better proposition offering better performance and numerous additional benefits for less effort.

Engineering is the art of creating things you need, from things you can get.

 

[naturalextraction]

R34ztune, I more agree with trying to gain overall efficiency from the conversion of thermal losses from as an efficient a process as possible. Agreed any time electronic controls can be incorporated in managing the means for gaining the efficiency, the better.

I've built/modified many turbo assemblies into hybrids from different compressor/turbine (manufactures) and impeller combinations. I also devised an adjustable device that works only in non-split housing turbines that help with spool up speed without limiting higher end boost performance. The mechanical systems input variables determine it's design and application.

As the norm, most requires the proper mathematical applications to formulate a proper and more accurate starting place. Sometimes finding the mechanical devices and or turbo combinations to achieve a lower torque gain becomes difficult. Short of having your own foundry to build the perfect turbo. Yet I've found some we've modified almost perfect per our applications and perform with a strong linear torque curve throughout the rpm range. The more important qualifier will depend on the mechanical configurations of the engine.

Good luck with your pursuit.

 

[R34ztune]

Thanks for all the replies. If more concrete technical information can be thrown out is even better. If anyone of you were working on OEM manufacturers, did anyone of you have experience design a factory turbo system and know what is the reason behind why factory people don't use VNT on gasoline applications? This is what I really want to know. Please give me some idea.

I don't believe exhaust gas temperature issues. How difficult is to make the vanes out of ceramics or even cast iron with some machining work? We have ceramic turbines in Skyline GTR since 1988 in R32. 1988 Shelby CSX used a Garrett VNT turbo in gasoline with electronic boost control. Look at

http://www.aerocharger.com

, Cocky Bell is the guy who wrote the book "Maximum Boost" and introduced the VATN Aerocharger more than a decade with gasoline (turbo charge a Honda NSX). I read the book in the 90s and it is almost twenty years from now. If you look closely the design of the vanes of the Aerocharger, the Garrett VNT vanes are even more rigid than the Aerocharger . The vanes in the Aerocharger just stamped with sheet meter with little spot weld into shape. If this thing can withstand gasoline EGT for the last 2 decades, why not Garrett VNT?

I don't want to mention Porsche 997 Turbo/GT2 because they use a slide vane BorgWarner VGT which is different. But even for VNT or VGT, I just can't see how EGT come into play, unless one of you guys have experience on it with gasoline which fail a VNT turbo due to EGT.

I just know a guy from NDperformance who use a Garrett GT35V on his Ford Mustang and have success. He is an electrnical engineer and developed his own microcontroller based VNT boost controller. He done his project a few years ago. It looks like aftermarket tuners to get away of VNT is due to lack of a decent off-the-shelf electronic or microcontroller based
controller for it. If you do a search about VNT turbo modification, almost every modification of VNT turbo throw the electronics away and change to a traditional vacum or wastegate style actuator mechanism.

I also have contact with the manufacturer of VNT vanes for Honeywell/Garrett, they are the major supplier of the Garrett factory in China . EGT problem is a myth, I think control is the truth. If the same factory is supplying turbine wheels and vanes, I cannot see the difference of casting the vanes out of the turbine material (they are steel, compare the stresses cause by thermal and centrifugal acceleration of the turbine and movement of the vanes).

After I post and started the thread, I got many replies. But none of the reply did supply any concrete technical reason or failure cases for VNT on gasoline. I know about Nissan, we own S14, R32, R33, R34, and R35 GTRs . We also own a bunch of VAG cars, Audi/Porsche/VW turbos . Our group distribute and supply automotive parts to tuning shops and motorsport teams. Its a pitty that I am the only engineer in the company, while other people are all business man, and administration . After talking to the guy how succeed in his VNT Ford Mustang conversion, my decision is to use two of the cars, one Audi and one GTR as a project car, so that we have one single turbo and one twin setup as experimental project for VNT in gasoline. If the project go success, then will persuade others to convert all the cars to VNT to gain more experience. Last step should convert these results to a product and market it.

I didn't answer the question of how many hp going to make. There is no answer for that. How many hp is going to make depends on size of turbo and compressor you choose, and how would you like in which RPM the engine run to. To me, it is totally worthless to build an engine over 1000hp and boost the RB26 til 10000rpm. This is a test for your deep pocket and making zero achievement. For the turbo size, I will choose the same compressor size as some existing turbo kits with a known torque curve. Because this will proof the improvement of the turbo lag on the torque curve.

We also have another project working on an electronic diverter valves (similar to blow-off-valve or recirculation valve, a common setup on stock VAG turbo cars). These can help to prevent overboost your engine by release the charged air by an electronic decision, and can take part of the work in a sequential secondary turbo spooling stage. Setting up a sequential VNT turbo is just a software achievement with an additional throttle body. Provided the VNT vanes of the secondary turbo can block all exhaust gas effectively.

We are sourcing the GTB2260VK (BMW/VAG OEM) turbos to arrive, and still need some support by Garrett about the compressor and turbine maps, also the electronic specifications of the actuator.

Honeywell is a very large company, I am still waiting for them to get the correct contact person to answer my questions. If I got any update from them, I will keep it posting. If anyone of you knowing anyone did any kind of VNT gasoline work, please bring something up.

I promote forward engineering, not reverse engineering. We studied all sorts of science and engineering, we use scientific method to solve technical problem. I don't know why Nissan don't go to VNT, but Porsche did . How a product comes out of a company have many business reasons behind. Nissan spent 20 years of development of the Toroidal CVT transmission. At the year it completed and released the Gloria (USA have a different name, I can't remember). The company got major share sold to Rennault. Where is the Toroidal CVT now? Some journalist and reporters even told that R35 GTR will use the toroidal CVT transmission. Why they don't put the best of the best in the top of the line of the car? Maybe they want to hide this secret weapon until someday it is necessary to use it. In Japan, some people has converted their Nissans to use the Toroidal CVT transmissions, these things fly. There are also many video in you tube about it too. The legend is real... I hope Nissan engineers can give me an answer of why not VNT? Maybe the proper answer for this is from their business management.

Let's keep focus on engineering rather than looking at the matter as a backyard hobby or DIY car modification. Questions like how I want to drive the car and how much hp really doesn't matter. The GTR has more than enough power to drive. My daily car is an Audi A4 DTM Quattro (2.0L turbo) and another family car, a Nissan Serena . So I already have too many cars that satisfy my need.

Just talk about driving a Nissan GTR ...
My driving experience about the GTR is a nightmare, slower than a bus when under 4000rpm, pulls like mad when over 5000rpm. There is no throttle control at all with six throttle butterflies, it just too sensitive at high engine speed. All the electronic LSD is only good when cornering or accelerating at the traction limit. The car has a guage to display the front wheel torque in terms of percentage. It appears it never go more than 10% or even zero at all time. I bought this GTR for experimentation. Audi is the car I prefer to drive with medium performance and very good driveability.

Apology to post such a long message. But I have to clarify the necessity of creating this thread. Otherwise, it will be another google result of VNT turbo myths.

 

[naturalextraction]

R34ztune, it's "Corky" Bell, unless you where being funny! On page 183 of his book "Maximum Boost" he discusses VATN turbos however does not get into any downsides yet explains the benefits to being utilized in the SICE. After a little research the main negatives I've found for the VATN is the corrosive buildup negating their function almost entirely, but usually after some considerable operating time. Also they are somewhat cost prohibitive related to utilization on average consumer production vehicles. This information though from forums and not of what I would consider a more valid testing facility. Without personal experience, why not use one.

 

[R34ztune]

As I promised, after having more indepth discussion with the related people who have experience with Garrett VNT in gasoline applications, the truth behind why factory not use Garrett VNT in gasoline is more concrete.

1. Control & Safety
Gasoline engines tend to have a higher rev range and volumetric efficiency. When achieving a good low end boost with VNT turbo, the turbine size will get maxed out in high RPMs. During this maxed out situation, the turbine speed becomes uncontrollable because VNT designs forces all exhaust gas to go through the turbine (no wastegate). By using VNT in gasoline and high rev engines, it is desirable to install an additional external wastegate as a safety device, or an electronic diverter valve (Like Audi/VW/Porsche). When overboost, the ECU will open up the diverter valve (like blow off valves, but recircuilating back to the compressor inlet) this way the system makes no boost.

2. Maintenance issues due to carbon build ups
Gasoline engines causes carbon build up on the vanes, eventually these vanes will cake and get seized or difficult to move. This also lead to a control issue because when carbon builds up (before it got seized), the vane controller need to be adaptive. If the vane fails to open, then it will cause safety issues as well. Diesel engine carbon tends to be powder, which is different. Frequent service and clean up together with an adaptive controller will still able to use VNT wtih gasoline.

The above 2 issues have nothing to do with exhaust gas temperature. I should start another thread for VNT turbocharger to focus on this topic. The Aerocharger company is not responsive, they will face the same issue as above, their front page have a CFM calculator (air flow rate calculator) based on your engine size, so I guess the maxed out situation can be avoided by selecting the correct turbo charger that will never get maxed out in the desired RPM range. For carbon issues, it will be the same. Unelss Aerocharger invented some special material or coating to prevent this sisutation. I am still waiting for a reply from them. Porsche 997 turbo, they have electronic diverter valve, and how did they solve carbon deposit problem? Does anyone know? The turbochargers are from BorgWarners.

 

[Warpspeed]

I have personally spent around eighteen months trying to get a VNT turbo to work, as have a great many others. It is a complete waste of time.

Garret know this only too well, they would be marketing their VNT turbos instead of their range of excellent ball bearing turbos if they had any potential advantage on a gasoline engine.

Nissan have used VNTs on their diesels for decades, but never on any of their range of sporty turbo cars.

Honda used VNT on thier race winning Formula one engine, but never in their passenger car range. And they spent a vast fortune trying to make it work on the Honda Legend before completely giving up the idea.

http://dwolsten.tripod.com/articles/jan89a.html

Perhaps you can do better than the engineers at Garrett, Nissan, and Honda?

 

[R34ztune]

Warpspeed,

I am not saying I can do better. I am still focusing on the technical issues of VNT setup in gasoline. I know many people tried it. Even some videos in youtube demonstrate some VNT in gasoline applications. What are the reasons behind it is not widely used? Nissan and Garrett don't do VNT on gasoline, Porsche+BorgWarner did.. If it is technically impossible, then why there are so many success stories out there? Price of Porsche cannot compare with Nissan, it looks to me its a cost reason more than technical. Complexity means cost, we have not yet come down to a point to talk about cost. Thanks for your input on the Honda page, but if you can point out why Honda didn't continue to produce these turbos, it will be nice.

 

[Warpspeed]

O/k, so you are driving part throttle at 1,800 rpm, and floor the throttle.
The vanes instantly slam almost completely shut, exhaust back pressure suddenly spikes up from 5psi to 85 psi.
How do you think the engine is going to respond to that sort of back pressure while under load?

Boost may actually rise fairly quickly, but not as fast or as far as the exhaust back pressure rises when you close the vanes up. Instead of the massive surge of torque you were probably expecting, the engine just completely dies in the bum.

Explain to me your proposed control strategy to control both the variable vanes and an exhaust turbine wastegate over all modes of operation.
I would really be interested to know.

Until you actually try to make a VNT work on a real gasoline engine, it all looks so terribly simple. It is not simple.

It is far easier to get both response and power from a properly matched ball bearing turbo. That is why Garrett and the other turbo manufacturers still sell vastly more fixed geometry ball bearing turbos than VNT turbos.

 

[R34ztune]

I never mention it is simple. If it was, then I don't have to post this out and do this on my own, or spending so much time and effort to find related material.

I am from a Mechatronics engineering background, where computer controlled machinary is my main expertise . Vane control is not an ON/Off mode. Garrett VNT3 actuators have vane position feedback and a PWM input for vane actuation. The actuation power comes from engine oil pressure. Intake pressure, rpm, throttle position, vane position feedback, atmospheric pressure are all input variables to the controller. As I already said before, implementing these complex control by using pure mechanical/neumatic actuators is likely to fail.

I will not explain any control theory here. But to gain the best control over the vanes, it is desirable to read the ex-manifold pressure and take it into account so that we can control the pressure ratio of ex-back pressure. Turbine theory is well known, it is a matter of pressure ratio, and you will end up with a simple transfer function that describes the system's model. As soon as we know the mechanical limits of all variables, then it should be able to implement properly. The system is a microprocessor based control, it is not an electronic control base on passive components.

There exists an external wastegate, but we should not rely on this device to control. It exists in the experiment only for safety issues. If this device end up become a must, then it will add to the cost of the setup. So far, its still unknown until we run the system.

By the way, how much experience do you have in microcontroller? The situation that you mention is just a back pressure limit control, and this number should be a known preset value . So the controller is able to handle this situation. MAP+RPM will tell you the gas flow with a fixed VE engine, even you have a variable intake camshaft system, the required flow rate can be mapped.

The guy who did his project a few years ago also implement his own controller. He is an electrical engineer . The difficult part he mentioned is the adaptive of vane movement resistance due to carbon deposits (as this is an unknown variable). We are still in conversation about this matter and hopefully can come down a feasible solution.

Thanks for input to make this thread more interesting. I do think we should start another VNT turbo thread though.

 

[patprimmer]

R34ztune

Are you an engineer. Is this in anyway work related.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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for site rules