Jaycar Boost and Fuel Control

[Sydneykid]

What about those of us without boost??

Does retarding the CAS compromise anything in the NA cars. I've got a CA18DE in my little Nissan Exa, and I'd love to see if anyone has some mapping exmaples for the DE. Other than using a wide band O2 sensor, how do you tell if you're mapping is too rich or too lean. I know it adjusts it over 128 points, but is the adjustment relative to load for example 5% at any load point anywhere across the rev range, or is it a + x.xx voltage at any loading in the rev range. If its absolute and not relative, how would you ensure you are mapping correctly for light load and not too lean or rich for heavy load?

I've read the stuff on the jaycar website. Perhaps you should put me down for the book as well, I'm told its a good read. Can anyone help clear this up for me? Also, can anyone (who knows what they are doing) put up a map for a CA18DE (I know that different cars will need different maps, ie FWD vs RWD, but it'll give me a starting point)

Jase....

Hi Jase, retarded ignition kills power and response in any engine.

You need an A/F meter to tell if it's too rich or too lean.

The DFA load points are relative to the AFM voltage output, the adjustment (+ or -) changes that voltage as sent to the ECU. Lower the voltage and the ECU thinks there is less airflow (than there really is) so it squirts in less fuel. This obviously leans out the A/F ratios. Increase the voltage and the ECU thinks there is more airflow (than there really is) so it squirts in more fuel. This obviously richens up the A/F ratios.

I wouldn't be expecting a great power increase from optimising the A/F ratios on an N/A engine. Turbos are always tuned rich standard, and when you turn up the boost they just get richer. The manufacturers do this for engine protection and it is simply not necessary to do on an N/A engine.

[Niroth]

So is there any real benefit from using the DFA on an NA engine? I'm not running especially high compression or anything, its just had a standard rebuild. It's been run on a dyno (long story on a an apauling dyno) and I noticed the tell tale brown smoke under load showing it was running rich. If there is no power gain to be had, and no other obvious benefits such as better fuel economy or the possibility of keeping the engine running better for longer, than I have to consider if its really worth it. I don't plan on going turbo at this point....

Jase

[Sydneykid]

So is there any real benefit from using the DFA on an NA engine? I'm not running especially high compression or anything, its just had a standard rebuild. It's been run on a dyno (long story on a an apauling dyno) and I noticed the tell tale brown smoke under load showing it was running rich. If there is no power gain to be had, and no other obvious benefits such as better fuel economy or the possibility of keeping the engine running better for longer, than I have to consider if its really worth it. I don't plan on going turbo at this point....

Jase

Hi Jase, the DFA costs ~$70 and I bet you could sell it for three or four times that if it doesn't do much for your engine. I assume you have a larger exhaust and maybe an airfilter, they generally make an AFM controlled ECU run a bit rich. So you will get something out of it. What I was saying was, don't expect 30 rwkw like I got from the Stagea.

[benl1981]

I just fitted a gauge. Around 0.55 bar (8psi) with a constant earth on the soenoid (r33 rb25det). I'm really only wanting about 10 psi, I'm wondering whether the Jaycar boost controller will be worthwhile. I can get a needle valve for $13 to replace where the solenoid is currently. WIll the anti creep of the jaycar setup reduce lag in 1st and 2nd gear much? To only squezze a few exta psi I'm wondering whether the hassle and cost of the jaycar is warranted>..

I find in 4th and 5th gear you can get the boost very early and by small throttle openings due to the higher load, yet in 1st and 2nd it takes quite a throttle opening and more revs to get boost.

Also the engine has a fuel cut at certain boost pressure and a knock sensor. Is it unlikely that you will blow your engine if you run too much boost or run it too lean or advanced?

[Sydneykid]

I just fitted a gauge. Around 0.55 bar (8psi) with a constant earth on the soenoid (r33 rb25det).  I'm really only wanting about 10 psi, I'm wondering whether the Jaycar boost controller will be worthwhile.  I can get a needle valve for $13 to replace where the solenoid is currently.

1. WIll the anti creep of the jaycar setup reduce lag in 1st and 2nd gear much?

2. To only squezze a few exta psi I'm wondering whether the hassle and cost of the jaycar is warranted>..

3. I find in 4th and 5th gear you can get the boost very early and by small throttle openings due to the higher load, yet in 1st and 2nd it takes quite a throttle opening and more revs to get boost.

4. Also the engine has a fuel cut at certain boost pressure and a knock sensor.  Is it unlikely that you will blow your engine if you run too much boost or run it too lean or advanced?

A few questions there benl1981, I have taken the liberty of numbering them and my suggestions follow;

1. It isn't "lag" as such, more slowed boost build because the wastegate is partially open. The IEBC ensures that the wastegate stays firmly closed until your mapping tells it to open. You can't do that with a needle valve.

2. A few PSI is a lot of kw, you will feel the difference. Plus, with the current set up, I bet you get a drop off in boost (1 or 2 psi) at higher rpms. The IEBC enables you to map that out and hold the target boost all the way to the rev limiter. You can't do that with a needle valve.

3. That is quite normal for a turbo car as the engine has more load on it in higher gears and therefore produces more exhaust flow, hence the turbine is more active.

4. The ECU has no idea what the boost is, there is no map sensor. The often called "boost cut" is actually "excessive airflow cut" as determined by the voltage output of the AFM. When the ECU sees excessive AFM voltage it goes to its "rich and retard" strategy to protect the engine. This is not gentle protection, it takes 20 degrees or so out of the timing and dumps a bucket load of fuel in. You loose 30 hp or more, instantly.

More 4. The dashboard warning light will tell you if there is excessive knock.

Even more 4. There is nothing that will help you if it is too lean, the answer is don't tune it too lean. If you have no tuning capacity then the standard ECU runs very rich standard, when you turn the boost up, it just gets richer.

Hope that answered your questions:cheers:

[Panikin]

So SK if I use the dfa, iebc, LM-1 a/f meter & Nissan data scan with laptop, will I be able to read knock, is it accurate enough for safe tuning.

CHEERS!

[Sydneykid]

So SK if I use the dfa, iebc, LM-1 a/f meter & Nissan data scan with laptop, will I be able to read knock, is it accurate enough for safe tuning.

                       CHEERS!

Sounds perfect to me:cheers:

[benl1981]

Thanks for answering my questions SK. I see - it doesn't reduce the turbo lag, just the way the boost actually builds, makes sense. I think you've sold me on the jaycar one. SOunds like a worthy investment.

Why do you lose boost as revs increase? Is it because the engine takes in more air up the higher rpm and the wastegate actuator can not respond quick enough?

Nice one. So at 10psi is there a significant pressure drop across the factory cooler. Would the R34 unit help this much?

[Sydneykid]

Thanks for answering my questions SK.  I see - it doesn't reduce the turbo lag, just the way the boost actually builds, makes sense.  I think you've sold me on the jaycar one.  SOunds like a worthy investment.

1. Why do you lose boost as revs increase?  Is it because the engine takes in more air up the higher rpm and the wastegate actuator can not respond quick enough?

Nice one.  

2. So at 10psi is there a significant pressure drop across the factory cooler.  

3.Would the R34 unit help this much?

Suggestion follow;

1. The turbo can't keep up with the engine's airflow requirement at higher rpm. Remember boost is simply a measure of resistance, by increasing the rpm you are effectively lowering the resistance. If the tubo can't keep up, then the boost has to decrease. The Jaycar design of IEBC is unique in that enables you to close the wastegate and get as much airflow out of the turbo as it will produce. All other boost controllers leave the wastegate partially open because some boost gets to the wastegate actuator. At high rpm (exhaust flow) it only takes a tiny wastegate opening to lower the airflow and let the boost drop.

2. At 10 psi and 5,500 rpm it is ~3 psi if I remember rightly. At 12 psi and 6,000 rpm it is ~5 psi, so the rate of climb is steep.

3. Is that R34 intercooler? Yep they are a bit better, flow slightly more with less restriction. It isn't dramatic though.

Going back to the "lag" question. If the wastegate is closed and you put the throttle down, the engine is going to respond faster than if the wastegate is slightly open and you put the throttle down. So you could argue that the "lag" will be reduced under those circumstances.

Hope that was of some help

[benl1981]

Thanks again.

1. So at what pressure does the wastegate open slightly? Assuming 5psi is stock, will it open a very small amount at say 2psi?

2. So with a standard needle valve that I set to 10psi the wastegate will still partially open at around 4 psi or some small value? Hence Jaycar is better!

[Tommyk]

SK

Ive been reading this thread with a fair bit of interest.

I think i'll be purchasing a boost control kit fairly soon. MY only question is - Can I use the factory GTR solenoid ? I dont think It would be any different really to the GTS-T one ?

Cheers

[LowRollaBoy]

So how does the jaycar EBC measure intial boost? Does it use an map sensor like an AVCR, then you can just type in say 1 bar, and the EBC goes to 1 bar?

Or is it like an Manual boost controller, in which you set an % for the solenoid to open, and you just have to test on road to set the required boost level?? Ie... start at the lowest jaycar EBC setting, then work your way up, watching your boost gauge until you hit the boost you want??

I dont understand how the Jaycar EBC would work as good as an ProfecB/AVCR if it has no MAP sensor to meter boost.

[resonance]

Hey LowRollaBoy,

The IEBC works kinda like as you said:

Or is it like an Manual boost controller, in which you set an % for the solenoid to open, and you just have to test on road to set the required boost level?? Ie...  start at the lowest jaycar EBC setting, then work your way up, watching your boost gauge until you hit the boost you want??

The difference is, the boost you set is not for the whole RPM/load range. You set the 'boost' (see next 2 paragraphs) for 128 different load points. These load 'points' are derived from the injectors - how much fuel they are putting into the engine. So it's not RPM, but load that you map the boost levels against. Imagine a 2-D graph, with load on the bottom axis and 'boost' (again, see next 2 paragraphs) on the side axis. You are making the graph line by driving and 'dialling in' the 'boost' for each load point.

The thing is, it's just a tuneable (variable) duty-cycle digital voltage source, and the duty cycle is set by you for each load point. It doesn't have to know what the boost is if you have tuned it using a gauge (or other means of measuring boost pressure). Once you do it, you just leave it and it'll keep the 'map' you have made.

In fact it has 2 maps, a 'wet' and 'dry' map, with a switch on the side so you can alternate between them.

I can understand your point, but when you really think about it, there is no need for it to be fed with the boost level if it already (blindly) knows what voltage to send to the solenoid to achieve a certain boost. I think it's elegantly simple

It's kind of like if I trained you to walk around a corner to a door by telling you to walk 5 steps, then turn and walk 10 steps and turn left, then you can do it again with your eyes closed. You don't really need your eyes feedback (other than to avoid people) to reach the door because you know how the steps to take. Get me?

It's more the way the mechanical part of things works that's the beauty with this EBC. Like what SK was going on about ages ago, you put the solenoid in 'series' with the wastegate actuator boost pressure line, and managing (blocking) what pressure the wastegate actuator sees, rather than just venting it out. This allows the wastegate to stay totally closed (thus causing exhaust to totally pass through the turbo compressor wheel and not through the wastegate, causing your turbo to generate maximum boost it can at that RPM/load), until you reach desired boost level, then make the solenoid gradually open to keep the boost at a given level. This means boost coming on harder (apparently much harder) and earlier than other EBCs or stock. This is all done by reading a boost gauge, holding on, and tuning in the level with the hand controller as someone drives the car through the load range.

I have pretty much just reproduced what SK has been explaining

But let me just say, everyone who isn't 100% sure on how this whole IEBC thing works, have a slow read of the above, and what SK said back in his first few posts as it is pretty much what I just said. I've quoted it here because it's a great explanation:

Well, the theory is;

It can't not hold boost (as long as the turbo is up to it of course) because it can completely stop any boost (airflow) reaching the wastegate actuator. This is because the boost control solenoid (pnuematically) sits in between the plenum and the wastegate actuator. Unlike most boost controllers (EBC of not) that bleed off air and lower the pressure that way. Put another way, Sillycoon Chump's design is in series with the wastegate actuator whereas most other EBC's are in parrallel.

Spiking, is pretty much a factor of the electro mechanical response of the solenoid. Plus how fast the processor can interpret the results and send instructions to the solenoid. Once again Sillycoon Chump's design has an interesting advantage, it doesn't use boost to give feed back, it uses injector duration. This means the boost control processor is not waiting while airlfow is buffered though pipework to a MAP sensor. As soon as the injector cycle changes, it knows the airflow has changed. And that happens once for every two engine revolutions, that's 50 times per second at 6,000 rpm. That sort of response is physically impossible using airflow to drive a MAP sensor.

What is really interesting is the ability to have 2 completely different boost maps with up to 128 load points in each. That doesn't mean simply "high" and "low" boost settings. What it means is I can have the same max boost, but have one boost map (say for wet weather) that brings the boost on slower. I can have lower boost as well if I want, but I don't have to. Pretty cool huh?

I did a fair bit of research before I decided to give these a go, and they have some very interesting features. Looking forward to giving them a real world try out.

PS; The interpolation (smoothing) algorythm between the 128 load points looks to be quite effective as well.

As SK says, hope this helped (hehe) :headspin:

[Oosh]

The problem with using a MAP sensor is unless you have a very expensive one they react relatively slowly, whereas you can measure inj. duty-cycle in a fraction of a second, and that % figure correlates with boost pressure very well. But this method does require more tuning and has no self-learn mode.

[heartbrkr]

I',m interested in this.

But silly question is, running high boost all the time, is going to produce poor fuel economy?

or should i just set the mode to wet or whatever for driving sedate?

[heartbrkr]

Other question that comes to mind, if the car is boosting constantly, is it worth upgrading the stock intercooler?

I imagine it would heat up consistantly, or have i missed the point?

[Sydneykid]

I',m interested in this.  

But silly question is, running high boost all the time, is going to produce poor fuel economy?

or should  i just set the mode to wet or whatever for driving sedate?

Fuel economy is throttle position dependant, if you want better fuel economy don't push the pedal down so far.

Other question that comes to mind, if the car is boosting constantly, is it worth upgrading the stock intercooler?

It is always "worthwhile upgrading the stock intercooler" if you are using max power a lot of the time. Or if you simply want more power. The standard intercooler has a fair bit of capacity, but it does get restrictive at higher rpm and boost levels. There is no absolute number, but I would be quite comfortable at 0.6 bar and 150 rwkw using the standard intercooler for normal road driving. More boost than that or higher power output or track work and it's intercooler upgrade time.

[grepin]

So Sydneykid have you decided to chuck the PFC control kit for the Jaycar unit yet.

The reason I ask is that I am using a PFC control kit however my wastegate gets pushed open quiet early in the rev range. I have done everything possible to stop this. Running 20psi actuator (my boost aim) extra spring, tensioning, lengthening the control arm. My car has a HKS 2835pro making 290rwkw however loosing heaps of torque mid range due to actuator opening early.

I have all but given up short of going external gate and this kit might help a bit.

[Sydneykid]

So Sydneykid have you decided to chuck the PFC control kit for the Jaycar unit yet.

The reason I ask is that I am using a PFC control kit however my wastegate gets pushed open quiet early in the rev range. I have done everything possible to stop this. Running 20psi actuator (my boost aim) extra spring, tensioning, lengthening the control arm. My car has a HKS 2835pro making 290rwkw however loosing heaps of torque mid range due to actuator opening early.

I have all but given up short of going external gate and this kit might help a bit.

Hi grepin, nope, doing a gearbox service on the R32 GTST. The team race cars are demanding a lot of time, with 3 race meetings in 2 states in 4 weeks. So I have had no time for my car.

Before I get into your problem, a quick clarification on the IEBC boost control advantages might help. The IEBC is great when you want, say, 10 psi boost and have a 5 psi wastegate actuator (as in the Stagea). The 5 psi wastegate actuator opens quite a lot at 2 psi. If you have a bleed valve or a normal (parrallel) EBC, they will let 2 psi get to the wastegate actuator at around 6 psi of boost. This means the wastegate starts opening at 6 psi, not the 10 psi that you want. This is the big advantge of the IEBC, you can set it so that 0 psi gets to the wastegate actuator until the 10 psi is reached.

Moving on, I am not sure that I understand your problem, let's see if I have it right. You are running 20 psi boost and using a 20 psi wastegate actuator and you think the wastegate is opening at less than 20 psi. Have I got that correct?

If so, forgot about boost controllers for a minute. The real problem is you don't have 20 psi seat pressure on the wastegate. You really need to measure the seat pressure to make sure that you have the wastegage actuator adjusted to for 20 psi seat pressure.

Now let's add the PFC boost controller into the equation. Being a parrallel style of EBC, and having a 20 psi booost target, it is going to let 2 psi through at around 10 psi. A 20 psi wastegate actuator is not going to open, even a tiny bit, at 2 psi. At 15 psi boost it will be 3 or 4 psi, still not enough to overcome the seat pressure. Maybe at 18 or 19 psi you might get a bit of wastegate opening.

Now the IEBC will most certainly overcome this early opening, but it is nowhere near as dramatic an improvement as when you have, say, a 5 psi wastegate actuator. That's the big advantage of the IEBC, I no longer have to pay rediculous amounts of money for higher psi wastegate actuators for internal wastegates or "special" springs for external wastegates.

Hope that was of some help:cheers:

[grepin]

Hi grepin, nope, doing a gearbox service on the R32 GTST.  The team race cars are demanding a lot of time, with 3 race meetings in 2 states in 4 weeks.  So I have had no time for my car.  

Before I get into your problem, a quick clarification on the IEBC boost control advantages might help.  The IEBC is great when you want, say, 10 psi boost and have a 5 psi wastegate actuator (as in the Stagea).  The 5 psi wastegate actuator opens quite a lot at 2 psi.  If you have a bleed valve or a normal (parrallel) EBC, they will let 2 psi get to the wastegate actuator at around 6 psi of boost.  This means the wastegate starts opening at 6 psi, not the 10 psi that you want.   This is the big advantge of the IEBC, you can set it so that 0 psi gets to the wastegate actuator until the 10 psi is reached.

Moving on, I am not sure that I understand your problem, let's see if I have it right.  You are running 20 psi boost and using a 20 psi wastegate actuator and you think the wastegate is opening at less than 20 psi.  Have I got that correct?

If so, forgot about boost controllers for a minute.  The real problem is you don't have 20 psi seat pressure on the wastegate.  You really need to measure the seat pressure to make sure that you have the wastegage actuator adjusted to for 20 psi seat pressure.

Now let's add the PFC boost controller into the equation.  Being a parrallel style of EBC, and having a 20 psi booost target, it is going to let 2 psi through at around 10 psi.  A 20 psi wastegate actuator is not going to open, even a tiny bit, at 2 psi.  At 15 psi boost it will be 3 or 4 psi, still not enough to overcome the seat pressure.  Maybe at 18 or 19 psi you might get a bit of wastegate opening.

Now the IEBC will most certainly overcome this early opening, but it is nowhere near as dramatic an improvement as when you have, say, a 5 psi wastegate actuator.  That's the big advantage of the IEBC, I no longer have to pay rediculous amounts of money for higher psi wastegate actuators for internal wastegates or "special" springs for external wastegates.

Hope that was of some help:cheers:

Yes that is right. I have actually measured the exhaust housing pressure to be around 40psi. I have what is quoted actuator of 20psi however what I do know is with the PFC set to less than 1.4 bar it cuts, indicating as you know it would be around that as a base value.

What confuses me is that by just putting compressed air into the housing against the spring pressure it wont lift off until it reaches 20psi. However in normal operation I can physically see the actuator lift off at around 5000rpm. I have provided a pic of the boost curve with the standard 1 bar HKS actuator. One thing i know is if I held the actuator closed it ramps up nice and hard. Must be something to do with the physics of the wastegate flap being quite large compared to most providing a large surface area. As you can see the turbo is still holding power with boost dropping off so is not running out of puff I guess.

Cheers