LSOHOLIC

For all you guys running some sort of "by gear" management....like boost by gear.

My question is.......is there a way to build a timing and fuel table per gear and the OEM ECU recognize what gear its in ??

COS or maybe a Resistor base trick ?? Or piggy backed with a system like Leash ??

Of course with the OEM ECU ??

Or if I'm wanting this level of tuning I'll need an aftermarket ECU...like the Holley Dominator system.



Thanks.........

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stevieturbo

There is no way for the OEM ecu do control boost or boost by gear.

Just buy an aftermarket boost controller, or go full standalone ecu.

LSOHOLIC

Thanks for the response.

I'm aware that the OEM ECU can not do it on its own. My question was....is there a controller you can piggy back with the OEM ECU that will allow something like this ??

Didn't know if the boost leash (or similar controller) could be wired to allow access to the OEM ECU timing/ fuel tables per gear.

Or is this going to be strictly an aftermarket ECU territory ??




Thanks again.....


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stevieturbo

What exactly are you trying to achieve ?

LSOHOLIC

Well....the computer side of the tuning is where I have a lot to learn. Although I do use a very reputable tuner, I'm trying to learn what the OEM computer can and can not do.

But what I'm trying to achieve is the flexibility of tuning per gear/ per boost.

So my "1st gear" tables can be optimized for psi ramp, load, ratio, inertia, aero..etc. And the same for the remaining gears.

How much do you think "is on the table" per gear if you just tune in the 1:1 gear ??

Can the SD react fast enough to make adjustments going down the track ??


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stevieturbo

There are no issues with SD in terms of speed, period.

You seem to be wanting multiple differences.

First you asked about boost by gear, then different fuel/spark settings per gear, now adding other things which not really sure of their relevance like ratio ? inertia ? aero ?

SD essentially takes care of any fuel/spark in relation to any boost vs rpm cell, simply by design, although yes other factors can influence the overall outcome.

As for how much is on the table....a very open ended question. What is the actual problem you're trying to correct in the first place, is it hurting you for whatever type of racing you're actually doing ? Are you blaming one aspect of the car for anothers performance ?

Where/when/why are you needing these other adjustments to take place ? Do you need different fuel tables in different gears, likewise spark ? Do you always need boost per gear or boost vs speed ? Are you trying to use one against the other ?

If you're wanting an ecu that truly offers you various adjustments per gear, per boost and a variety of other factors, then you're into the more capable ecu's out there, and pretty sure the likes of now popular Holley wont be accommodating all that

Even the simple basic of gear recognition will depend what ecu you're using. Some will allow this to be calculated ( road speed vs rpm ) others will need some sort of positive ID of whatever gear you are in from the gearbox/selector mech itself.

there are a lot of ecu's that can do many things ( and few things ), you'd need to detail exactly what you want them to do under various circumstances, then you can start searching for one that meets those needs.

At a guess though you're more into top end stuff like Syvecs, Motec, ProEFI, Life Racing, Haltech Elite, AEM Infinity type of territory vs some of the other offerings for the sort of things you're talking about.

LSOHOLIC

Let me back up a bit......


Here is what prompted my question. We tend to tune in our cars in a final drive trans ratio, lets call it 1.0:1. Now lets compare whats happening in our final gear vs 1st gear with a turbo combo.
I'll use a m12 T-56 for an example.

In the beams, 2.97 1st gear, on the 2 step @ 5500rpm making 7lbs. So we have zero momentum, thus greatest initial load, the car will have the greatest mechanical advantage it will ever see, zero aero drag, as boost begins to rise quickly. (now picture what the ideal timing curve and fuel curve would look like in this scenario)

Does the optimal 1st gear fuel and timing curve look the same as the 4th gear pull, 25lbs of boost, full aero drag, the lowest mehcanical advantage the car will ever see.

This is just an extremely simplified example of what prompted my question.


"Load based fueling is superior to the traditional Throttle Position and RPM (Alpha-N) based tuning systems, because different gears place different loads on the engine and these Alpha-N systems cannot tell the difference between first or fifth gear. These runs, both made with 100% throttle and both moving through the same RPM range, show that although the Throttle Position and RPMs are identical, the load is not. Due to the obvious limitations of throttle position and RPM based mapping, they can optimize either second or fourth gear, but not both. You are forever compromising, trying to get the best of both worlds. But as you can see, due to torque multiplication, there is a different load placed on the engine in 2nd and 4th gears. " muzzys



And for the record....I could be completely misunderstanding the way the computer interprets the tune entirely.

Maybe the boost by gear reference was a confusing way for me to introduce a product that can differentiate between gears. My intentions were to find a product that could be piggy backed into the OEM computer to allow more tune-abilty per gear.


Thanks.....

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JoeyG

From your M12 example, I would say that the computer will be seeing different cells (timing and fuel maps) starting in first versus same rpm in say 4th because of the engine loading the pcm sees via rpm, iat, ect, map, maf. The computer can only calculate torque loads and limits via the way the values are scaled in the tuning session. 2 identical engine combos could have a 200#/ft difference in calculated loads at the same physical load.

Now to the original question. You could use the original pcm and having a couple of breadboards full of pots, rheostats, and timersyou could fool the stock pcm into a caveman approach to boost by gear manipulating the tach, iat, ect, and map signals. But if you dont want to go through the guinea pig steps that some have tried on ls1tech, a well versed standalone would be the best bet, imo

stevieturbo

For the most part the engine doesnt really care what gear you're in. load is load

7psi at 5500rpm will always be a different load site than 25psi at 5500rpm, so that aspect is a non issue.

And I'd say that in 1st gear that is the least load the engine sees because of mechanical gearing, the engine will see far more load in the higher gears and spend more time there again because of the gearing.

But that statement you're referring to sounds like n/a mapping or else the person commnenting is confused.. NO boosted setup ever would use only throttle position and rpm. It would have to be based around a huge number of assumptions to ever work...The ecu just needs more information to do it reliably.

Typically TPS vs RPM with MAP compensation, or you can simply do MAP vs RPM which is more common.
Sometimes setups with ITB's or big cams etc will prefer the TPS option because MAP signals at low loads can be unstable so they can choose to ignore the MAP reading until a certain level.

You could of course add other information in too, but those are pretty much the most basic and common methods.

As for determining what works best per gear, etc etc...really you'd need to find an appropriate dyno to do in gear and steady state load testing to find what may be optimal
I cant think of anything you'd be piggybacking onto a standard ecu that will let you do that....other than a full standalone ecu lol and leaving the OEM ecu to run car/trans functions if it needs to be there to do that

LSOHOLIC

Thank you guys.....

And yes you are correct Steve, that "quote" was from a probike (n/a) tech article.

As I said, this area is where I'm very deficient.

Thanks........

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stevieturbo

I'm not saying that an ecu that offers the ability to change the tune based on gear etc may not yield benefits in some cases ( after copious amounts of testing )...but you're overthinking something based on slightly misleading information.

But tuning a n/a engine with TPS vs RPM as the main load parameters is quite common and not a problem. You can of course add other information there too though and in almost all cases there will be other info whether barometric pressure, manifold pressure, various temperatures etc etc

But you dont need to make a simple setup complicated just for the sake of it.

Blackonblacksls

Use a lingenfelter mph to voltage box. And an ams1000 and it will do boost by gear.

LSOHOLIC

Just to recap...I'm wanting boost by gear but also want access to timing and fuel tables per gear also (to dial in each gear).


Thanks........

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stevieturbo

Then buy a suitable aftermarket ecu.

Ls240sx

Forget all this get an aftermarket ecu stuff. While it is a much better solution there are def ways to do what you are trying to do. Go get yourself an Apexi AVC-R. It is a boost controller that has been around for many many years. You can set up boost by gear based off gears/speed/rpm.

stevieturbo

And of course it doesnt do what he specifically asked for, nor will any boost controller.