Tuning boost with stock ECU + a rising rate reg

[Shifty]

Hey guys

Obviously when turboing an engine you need to run a 1:1 regulator to maintain the same base fuel pressure as boost increases (eg. another 1psi fuel pressure added for every 1psi of boost) and then you tune your aftermarket ECU to provide fuelling for the boost.

I know it's a slightly ghetto solution, but assuming you are putting together a budget low-boost setup on a previously non-turbo engine would an adjustable fuel pressure regulator run at a higher rate provide a workable solution instead of springing for an aftermarket ECU?

For example if you ran an adjustable rising rate regulator set at say 6:1 you would effectively be adding 1psi of fuel pressure per 1psi of boost to maintain the same fuel pressure, and then an additional 5psi of fuel pressure per 1psi of boost to provide the additional fuelling for boosted conditions.

Using the example of a base pressure of 45psi running 5psi boost and the reg set at 6:1 you are talking 45 + (5 x 6) = 75psi fuel pressure from a base of 45psi off boost. Obviously the exact rising rate would be set by using AFR probe (or on the dyno) and you would also need a more competent fuel pump to cope with higher base pressures.

Obviously this isn't going to provide optimal performance but I don't see why it wouldn't work especially for a low boost setup to make an extra 50hp, not chasing an extra 300hp.

Thoughts?

[Dieseltrain]

WHat engine is it on ?

[CrUZida]

Couple of points here.

• Stock regulators are 1:1
• RRFPR are the devils creation, and a very poor substitute for doing it properly.
• Very few fuel pumps will handle the pressure a RRFPR demands, which can (and will) lead to a dead pump and leaning out) - most pumps can only handle about 60psi.
• RRFPR's are 'designed' to be used when boosting an NA engine on a stock NA ecu, and if you are doing that, (for anything other than shit'n'giggles) its only a matter of time before things go bang.

[thechuckster]

a MSefi ECU would be a cheaper solution than a RRFPR and a new pump - and you'd then have an ECU that will happily cope with boosted motors.

[CHB]

first of all, what motor?
if you can dial in the A/F (only if), its not the AFR kills the engine but the ignition timing from NA ECU that does..
but i know couple of 4AGTE using AE92 MAP ECU with Turbo map sensor works great at 14psi without any piggy back or ECU mods....

[Shifty]

What engine is it on?
First of all, what motor?

That's really just superfluous information, but for those who are interested it's a 1402cc inline four cylinder twin cam air & oil-cooled Suzuki GSX1400 motor running 9.5:1 compression.

if you can dial in the A/F (only if), its not the AFR kills the engine but the ignition timing from NA ECU that does

That is why I am asking the question, as to whether this is a viable option on a budget. You can either get a fully adjustable rising rate regulator or make an educated guess on the correct fixed-rate rising rate regulator and bleed pressure from the reference line for slightly finer tuning. I have full access to a proper wideband setup so it's not just going to go bang the first time I start it.

As far as engine safety goes, moderate boost and standard ignition timing are more than fine due to the extremely low CR. You need to bear in mind the comparitively low load conditions seen by a bike & rider that weighs say 1/3 of even the lightest cars. It is also quite easy to knock a couple of degrees timing out of it by modifying the trigger wheel, of course this will impact slightly on low down performance but honestly the bike will wheelstand off idle so a loss of a tiny bit of low-down grunt in the interest of turbocharged midrange is a non-issue.

Back to fuelling, the factory ECU actually allows a very agricultural adjustment of up to 15% on the standard fuelling parameters, but of course can not cope with boosted situations and only runs off load (throttle position, actually). As far as I know it's only adjustable on three load points but that is a loading on the standard map which is already fantastic, and obviously that provides a completely smooth transition rather than just three different amounts of fuel going in.

Stock regulators are 1:1

As I understand it, stock fuel pressure regulators only work as far as coping with changes in manifold vacuum and do not allow for positive manifold pressure. Hence the need for a 1:1 rising rate regulator for turbocharged applications. Feel free to correct me if I'm wrong as I've never really dabbled with workarounds.

RRFPR are the devils creation, and a very poor substitute for doing it properly

I think I mentioned that a number of times in my post. In a perfect world I'd ship the bike in a crate to a workshop and it would come back with a motec, traction control, wheelie control, carbon fibre wheels, ohlins forks & ohlins rear shocks.... but it's not a perfect world and 'properly' actually equates to me not doing it at all. I have other priorities than throwing money at things for the sake of it, but am happy to dabble if a workable result is achievable with a little thinking outside the square.

Is upgrading a KE10 to a 4K with a 32/26 weber and a set of extractors a poor choice in comparison to fitting a 4AGTE? Hell yes! Is it still an improvement and give a pretty cool result? Hell yes! This is where I'm at....

[Shifty]

Another option I had considered was running an auxilary injector but as the bike runs individual throttle bodies and no manifold as such I'm not happy with a fuel-filled intake.

[Shifty]

a MSefi ECU would be a cheaper solution than a RRFPR and a new pump - and you'd then have an ECU that will happily cope with boosted motors.

Bear in mind it is going to need a new pump anyway, so the cost of the pump is not part of the equation... the only cost will be the RRFPR.

I have an aftermarket ECU sitting here that will do the job fine, but I have it earmarked for my 3SGTE. Perhaps I should just buy a second flying loom and switch between two maps but that's fairly impractical.

[Shifty]

I had a 60 second look at that MSEFI site.. it looks like some hardcore nerd DIY shit... you can keep that all for yourself

I can buy a plug-in fuel ECU (Power Commander - on like 80% of bikes) for about $450, and it is expandable with a multi function hub to reference boost for about another $450 but we're getting up around a grand and it's still not tuned.

I could go complete standalone as well, but then I'm cutting up the wiring loom on a four month old motorcycle with 3,500km on it... not likely!

[CrUZida]

1:1 is not rising rate, 1:1 is constant rate.
Generally a stock FPR between a turbo motor and an NA motor is the same.

However, given your engine and much complete lack of knowledge of it, its not something I'd rely on (that the stock FPR on your engine can handle boost)

[thechuckster]

the way to manage turbo-ing a high-comp, high-reving motorbike motor (that's only 3500k old) is to spend the time and resources on decent engine management not an arbitrary (and from experience non-linear and highly variable) addition of fuel via a RR FPR.

The more boost your engine is running, the more timing you pull out. Just knocking off a few degrees off static timing is not going to let you run more than a few pounds of boost and off boost, the motor will suffer.

A nerdy MSefi (and btw, there's a small-form version of MSefi specifically designed for bikes - Microsquirt) does not need you to spend $450 to enable a USD$12 MAP sensor that will cope with up to 21psi of boost.

You've already got the wideband O2 sensor which can feed straight into any of the MSefi ECUs. That lets you deal with AFRs leaving dyno time more focused on timing, fuel-map tweaking and peak power.

If you want less nerdy, go for an adaptronic or Motec clubman-level ECU.

If you've got a progammable ECU, then use it for the bike motor, and then load different configurations to suit its use if transplanted into another car.

saving money by relying on a RRFPR might end up destroying the motor which will cost you much more than an aftermarket ECU and dyno time.

[Shifty]

the way to manage turbo-ing a high-comp, high-reving motorbike motor (that's only 3500k old) is to spend the time and resources on decent engine management not an arbitrary (and from experience non-linear and highly variable) addition of fuel via a RR FPR.

The more boost your engine is running, the more timing you pull out. Just knocking off a few degrees off static timing is not going to let you run more than a few pounds of boost and off boost, the motor will suffer.

A nerdy MSefi (and btw, there's a small-form version of MSefi specifically designed for bikes - Microsquirt) does not need you to spend $450 to enable a USD$12 MAP sensor that will cope with up to 21psi of boost.

You've already got the wideband O2 sensor which can feed straight into any of the MSefi ECUs. That lets you deal with AFRs leaving dyno time more focused on timing, fuel-map tweaking and peak power.

If you want less nerdy, go for an adaptronic or Motec clubman-level ECU.

If you've got a progammable ECU, then use it for the bike motor, and then load different configurations to suit its use if transplanted into another car.

saving money by relying on a RRFPR might end up destroying the motor which will cost you much more than an aftermarket ECU and dyno time.

Fairly pissed as I just wrote a massive response which timed out, so ignore my brevity

• My bike is not high compression. It's 9.5:1 which is probably about as "high compression" as 7:1 in a car.
• My bike is not high revving. It's 9000rpm redline which is like 4500rpm in a car. Power also stops at 5500rpm which is actually more like 2750rpm in a car.
• That it has only done 3500k is an advantage, not a disadvantage. We know that everything is in perfect condition - oiling, etc all perfect so it's a good thing, not a bad thing.
• As mentioned the timing does not need to be touched at all. I know of half a dozen of these with boost, and no timing modifications.
• Even if it did need to be changed, the bike already gets to 100km/h in 2.6 seconds and I can take off in 4th gear.... so the loss of a few degrees down low is neither here nor there - it's a fricken car engine in a scooter and you couldn't make it "slow" or "gutless" if you tried.
• If it did become doughy down low for whatever reason, this could also be addressed by a change of gearing - on a bike this costs $25, is a 10 minute job, and you have infinite ratios available.

I understand this is not the ideal solution, the main thing I am frustrated with is that I am struggling to find anyone who understands the concept/intention of the project and who has worked with this type of thing in the past.

If I was able to have the bike run fine on the stock ECU off boost and with an FPR get the bike to run between 10.5:1 and 12:1 on boost then although it would not be ideal it would be workable. I am sure that with an aftermarket ECU I could run a brilliant & consistent AFR and get more power and more boost into it, but if I can end up with a bike that goes fuknwhoosh without needing to mess with ECUs etc then that is all I really want. Fitting an aftermarket ECU and farking around with a ground-up tune is not something I'm interested in. Obviously if the FPR route is going to generate wildly fluctuating AFRs from 9:1 to 14:1 then it's not going to work, but noone can really tell me categorically that it will not work within say 20% of ideal, other than that "it's bad mmkay?"

I don't know anything about megasquirt/microsquirt, something I *would* be interested in is something that I can run as an interceptor - essentially running the stock ECU signal until positive manifold pressure is reached at which point fuelling is amended by the ECU. Do you ahve a suggestion as to how I can do this?

I can run a Power Commander, Multi Function Hub and MAP sensor but by the time I do that I'm up around $1100 plus tuning which starts to become a little silly all over again. The advantage is though that it is (a) 99.9% plug in and (b) allows you to run the stock ECU off boost and have it trim fuel by up to 100% at regular load/boost intervals.

Is something like this achievable with any other products on the market? A microfueller would be a good solution but as mentioned I don't have anywhere to fit up an aux injector.

[CrUZida]

Try American websites, they are gods at doing things on the cheap.

[The Witzl]

Try American websites, they are gods at doing things on the cheap.

what he said.


The RR-FPR will definitely give you wildly fluctuation AFRs, probably much worse than 9:1-14:1. YOu could theoretically use something like an emanage.... have a look at them.

[Shifty]

The RR-FPR will definitely give you wildly fluctuation AFRs, probably much worse than 9:1-14:1.

Ok well I'll can the FPRidea then...

You could theoretically use something like an emanage.... have a look at them.

Looking at options now. All I really want is something to run the stock ecu down low, and tip in a fuckload of fuel on boost. i'd not have thought that hard, but apparently so!