ownor

iTrader: (5)

Hey guys,

i'm gathering as much infos and details as possible to decide on the engine i'm going to build for my formula.
anyways i'm not going to discuss this drivetrain or how high a particular engine needs to rev to make X amount of power, so just for theory and discussion, this is what i'm looking for:

is there any way to have a healthy revving engine running well on TBI? will the fuel distribution suffice? what about fueling and spark latency at those high rpms? we're talking 6,5 to 7krpm here, so imho that would make it necessary to reduce loop time to approx. 8.5ms at least.

i also noticed the EBL's tables end up with 6375rpms. asking RBob about this turned out the ECU will continue to use the last values in those tables when the engine is approaching higher rpms. is there any way the table mapping can be changed? or is there any other TBI-capable ECU that would be working with higher revs?

Thanks in advance, any input is appreciated!
greetz, ownor

bluers91

That is a great question, something I'd like to know too. I hope you aren't intending to use the stock L03 bottom end to rev to 7k.

Ronny

iTrader: (1)

Somewhere there is a thread on the available timing for an injector to function properly. It explains the calculation based upon RPM that gives the msec. I recall in that thread it was mentioned 7.0 msec is what is available. I recall as well that about caps it to 6000 rpms maybe 6200 rpms. I will search. Some TBI injectors function better than others in this regard.
TPI injectors may do a better job.

Ronny

iTrader: (1)

This was in sticky above "free tune"

From RBob:

Static is at 100% or greater. The '747/'8063/'8746 ECMs fire an injector every time a plug fires. There are two injectors. They alternate on plugs firings.

Before I go too much further this is in synchronous mode. Sync mode is sync'd to plug firings. This is the most common mode. I have seen a few cals that are always in async mode, but never an f-body cal.

So for each revolution (V8) there are four plug firings. It takes two revolutions to fire all eight cylinders/plugs. Alternating injectors, that means each injector fires twice on each engine revolution.

At 4,000 RPM (revolutions per minute), divide by 60 for revolutions per second: 4000 / 60 = 66.67 revolutions per second. Invert this value for the time of each revolution (or frequency thereof): 1 / 66.67 = 0.015 seconds. Or, 15 milli-seconds (msec) per revolution.

With each injector firing twice each revolution we need to divide the amount of time in half: 15 msec / 2 = 7.5 msec.

This 7.5 msec is the amount of time an injector has before it is fired again (at 4,000 RPM). The higher the engine speed, the less time there is for an injector to deliver the required amount of fuel.

This is why it is important to keep an eye on the injector PW. Once the PW value exceeds that given amount of time, no more fuel can be added. The darn injector is on ALL of the time.

At this point the only thing that can be done is to increase the delivery of fuel. Bigger injectors and/or higher fuel pressure is required.

As another data point at 6,000 RPM a TBI injector is static once it hits 5.0 msec of on time. For best results TBI injectors shouldn't be open for more then 85% duty cycle. At 6K RPM this is 4.25 msec's.

RBob.

Timinsk

iTrader: (9)

oh wow.

bluers91

So, after reading that info I guess this is theoretically possible as long as you a) increase fuel pressure and b) add bigger injectors or larger TBI unit and c) are able to map fuel to to higher rpms than the 6375 in the ecm.

Ronny

iTrader: (1)

Ok lets assume you use a larger injector. I was told 80 lbs responds better to higher RPM's and or higher FP. Now we better fuel the WOT. Now the idle is overfueled. Before I used a VAFPR I had 80 lbs at 20 lbs FP and asynch firing resulted and idle went to crap. So I locked synch idle went OL idle and a very rich idle occurred. But liveable. I think I was around 1.5 msec which may in fac t be the minimum time on. Now with VAFPR I am at 2.00msec at 12 lbs FP. Again TPI or port fuel may be a better idea.

thomas1976

Good point, by spray'n anough fuel for the high rpm's it will be pooring a hell load of fuel at low rpm's.

Ronny

iTrader: (1)

emishions would be excessive I would think.

va454ss

iTrader: (1)

Could use sync for low and mid rpm, and async for high load.

ericjon262

or use a 2 2bbl tbi's, or one 4bbl unit.

ownor

iTrader: (5)

lol, nope as stated i'm in the process of making plans for a new engine build.

thanks for posting some of RBob's considerations about high-rpm injector firing, i hadn't realized they were in here at some point.
so as said at 7krpm we have 8.5 msec per revolution, using RBob's calculations that make it a 4.25ms per injector firing and we don't want our injectors to be open more than 85% DC, so that's a max of 3.4ms where we need all the fuel delivered. that would definitely imply some big, cleaned and flow-matched injectors and high fuel pressure.
what i don't get is this line: "As another data point at 6,000 RPM a TBI injector is static once it hits 5.0 msec of on time." it's just a numeric example to explain we shouldn't go over 85% DC, right?

i do understand your concerns about consistent fueling from idle all the way up to 7krpm. i need to play some more with this whole idea and make some calculations but i do see the point Ronny made concerning idle fueling. let me think about that some more before i can ask any more questions

of course any port injection would be a better idea. as a matter of fact i would go PORT-EBL if it would support higher rpms.. big time bummer in my eyes. i went to buy a new 'aftermarket' or modded ecu and then find out it's not capable of engine control over 6375 rpm
i'm not ready to go with TPI or any proprietary PFI setup because it's pretty expensive afaik. i'd also prefer a single plane intake or something along the lines of an air gap intake and have it modded for port injection, rather than using the somewhat limited TPI system.

oh about async and sync fueling, if someone could fresh me up on these techniques that'd be great. i'm guessing the async fueling implies the injectors are not firing in the usual sequence pattern but rather asynchronous, well .. let me know how you would implement this theory of sync in idle and async at high rpm please.

thanks for your input guys

va454ss

iTrader: (1)

EBL has parameters where you can chose to go in and out of synch to async based on rpm and map.

RBob

iTrader: (1)

The other way to look at tables that end at 6400 RPM, is how much change in the tune is required for the additional 600 RPM? Will the PE SA change? TPS% required to enter PE? The main SA tables, will the SA need to change after 6400 RPM is reached?

On a 7,000 RPM engine the SA usually goes flat around 4,800 - 5,200 RPM. So a SA table that goes to 8200 RPM is not required. Even a 6,400 RPM table is overkill on most vehicles.

For VE, an argument can be made for a table that goes to a higher RPM. At the same time, how much will the VE change from the 6,400 RPM table end, to the 7,000 RPM shift point. It will drop off some, which will make the engine run a little on the rich side.

Running a little rich isn't a problem. It will also help prevent the lean spike on the upshift. This lean spike is apparent in data logs when running an auto trans.

Note that the rev-limiter can be set close to 10K RPM. So no issues with the engine just stopping.

RBob.

RBob

iTrader: (1)

Looked into extending the VE table(s) to a higher RPM. Using an RPM/31.25 variable the table can go to just under 8,000 RPM. This is with a VE data row every 500 RPM.

We can pick up at 6,375 RPM where the current table ends and have a row at:

6375, 6875, 7375, and 7875 RPM

Or, we can pickup at 6,000 RPM for more sensible RPM values:

6000, 6500, 7000, 7500, 7969 RPM

Although it would probably be best to use 6400 RPM as the switchover point and use:

6400, 6900, 7400, 7900 RPM

This is the same as the first set above increased by 25 RPM for each row.

Either way there is only 1 to 1-1/2 rows added from 6400 to 7000 RPM.

The LT5 engine's ECM uses VE tables to 7,000 RPM. But the resolution is less as they use every 500 RPM breakpoints at 4,000 RPM.

The questions then is: which other tables need to go to 7900 RPM? Maybe the boost multiplier table. Not sure if other tables need to go that high, such as: TPS% vs. RPM for PE mode, PE AFR vs RPM, PE SA vs. RPM, SA vs. RPM, open loop AFR vs. RPM.

Ideas?

RBob.

Fast355

iTrader: (2)

I for one have had a couple of different TBI engines up to 6,700ish RPM. A 305 and a 350, both with Vortec heads and an Edelbrock Victor Jr 2bbl intake. Both were running on Dimented's $OD MAF code and both were running the TBI unit in ASYNCH @ WOT and upper rpms. The one trouble spot I found had to do with the stock ignition control module and the dwell they run. With the stock coil the engine would flatten out above 5,000 or so. With a good coil and MSD6a it would pull strong until the PCM shut the fuel off at 6,700 rpm.

RBob

iTrader: (1)

It may be that you do not realize it, but the EBL Flash code is field update-able. Let me know what areas that you feel require a higher RPM table. I've posted some ideas and other items regarding this. Higher RPM tables are easy. And we have methods of handling the WUD regarding different version of ECM code.

One item that has helped is that laptops are much faster then the ones of even a few years ago. That allows more things to be done in the WUD. The EBL Flash system is being updated on a regular basis.

Let me know, and it will be taken into consideration.

RBob.

Fast355

iTrader: (2)

I guess they do not realize they are running a code that was written by you. I for one completely understand why you felt that 6,400ish was enough for the 99 percentile. Most people just don't need tables that run over 6,500 rpm. I run my daily drivers up to 6,500 thats about it.

Its like the guys that I am writing SCT programs for in the Mopar world. They do not realize I can extend their fuel tables and spark tables as high as they could want (16,000+ rpm) and re-arrange the tables for 2 or 3 bar MAP sensors for boost (they do loose resolution though because I cannot change the PCM code).

I briefly ran Superchips and they flat refused to give me the option to raise my Rev-Limit over 6,000 on the 4.7s, LMAO...They felt WOT closed loop was a good thing until the catalyst overheat protection kicked in. They alse refused to turn off the transmission torque management. Thats why I don't run them today and do SCT Tuning for others that want to actually run.

ownor

iTrader: (5)

oh i do realize that the code author Robert R. is RBob.. i wasn't that sure the tables could be field shifted like that though. also let me say i was not trying to offend anyone in person, don't get me wrong, the EBL is great as we all know!

well i don't know how the actual code other than the calibration scalar and table data is stored, so can it be changed by means of modified bin and xdf files, or would the EBL device be sent to you, Bob, in order to have it updated? in my case this wouldn't be too bad since mine doesn't have the PORT mod installed anyways

you also posted some good hints and ideas on what can be done which i do very much appreciate. i'd guess and say it's not easy to get personal support like that with any aftermarket engine managements.

I like this suggestion for set of data points best so far.
as for the other tables needed to have RPM resolution updated, i'll have to take a look at an EBL bin since it's been some months i've worked on one. put the bird into storage in september and haven't played with the EBL some time before that because my headers were leaking, so not much sense in tuning it any further at this point. but i think the tables you suggested for updates are the most important already anyways.

edit: i've been advised that it might be not okay with RBob to post his real name on here so i edited it. i for myself wouldn't mind people on here know my real name but maybe that's just me.

RBob

iTrader: (1)

The ECM code can be updated right in the car. Just like flashing a new calibration.

There would be a newer XDF with the additional tables added in. The way the table(s) is added won't affect the current calibration. So the layout remains and you can use a current calibration and just update the new table(s).

The WUD would also be changed for the VE Learn. Along with the tachometer range being extended.

And of course the code/XDF/WUD update would be available to current EBL Flash users at no charge. And also be released with newly purchased EBL Flash systems. Which also means that the 30-some included calibrations would also be updated with the new table(s).

RBob.

ownor

iTrader: (5)

Thanks for the clarification and your offer and cooperation in general.

So i take it this would be implemented in all future EBL devices and also an optional update for people who already have EBL and decide they need the wider rpm range? Or will it be included in the next EBL/WUD patch anyways, so that all devices will be on the same stand?

Btw, i'm guessing the ECM code is also being stored in the .bin, any input on that?

RBob

iTrader: (1)

Once the changes are finalized and tested they will be what is included with the EBL Flash from then on. It doesn't make sense to try to support two different versions.

Then for current EBL Flash users the updated code (firmware) will be available. Along with WUD, doc, and ECU/XDF updates. This is just a continuation of the way is has been handled.

RBob.

graebz28

iTrader: (5)

May be off topic, but what about ability to add code for incorporating a sensor for flex fuel. My next build is going to be e85 - e98. I saw there are sensors out now that can measure ethanol content. I am really familiar with EBL and want to keep it and continue to support. Otherwise I'm building my own with a PLC.

Also, my WUD display request is that you have a display that shows the calculations for SA, PW and IAC. By seeing how each attribute is contributing to the 3 main calculations that a ECM control, it would make it easier to troubleshoot (i.e. How you show how AE is made up from map and tps. I need more for SA especially if I am going to blend IAT/CTS). Plus, it's a great learning tool for newbies to learn. If it is too much for the datastream, then maybe have options for standard, SA, VE and IAC logging.

Thanks again RBob for an affordable TBI option and all your support.

RBob

iTrader: (1)

Can you provide a link to the ethanol sensor? I've looked into the one that GM had been using and found them to be on the expensive side. About $600 each. And they were not reliable.

If there is something cheaper then I can probably do something with it. The other way to go is to use the NB & closed loop to calculate an E percentage. That may be better.

As for the additional display items. Would this be in the dump log file? I'll have to check to see what is available for inclusion for SA and IAC. VE is VE, not modified.

RBob.

Fast355

iTrader: (2)

My 4.7s E85 is done in the programming alone....With the 02 sensors. I believe the newest GMs are done the same way.

ownor

iTrader: (5)

The O2-based calculation might be a good idea. Alternatively, i know Zeitronix is also offering a sensor for their ethanol content analyzer, the sensor alone is 350$ according to their website.

Not flaming you guys at all for suggesting new features for an EBL upgrade in my thread, but maybe this would be a good point for starting a separate thread with a more suitable title? Probably would do a good thing in catching people's attention and see if there are any other feature requests and also to publish information about this future release?

ownor

iTrader: (5)

did i miss a new thread about this EBL update or what? i didn't intend to stop people from giving their input.

Ronny

iTrader: (1)

Quote:I guess they do not realize they are running a code that was written by you. I for one completely understand why you felt that 6,400ish was enough for the 99 percentile. Most people just don't need tables that run over 6,500 rpm. I run my daily drivers up to 6,500 thats about it.

That pretty much sums it up. Most of us that modded engines most likely will look at more CID rather than spin to stratosphere. Dart now offers a GM replacement block that is not to costly (?) and will deliver the HP and TQ to excess and stay <6300rpms.

RBob

iTrader: (1)

Just to let everyone know, things are moving along. Test drove the new code today with good results. This is the VE and Boost Multiplier tables to 8K RPM, single fire mode for Port, and some other odds and ends. Some of the odds & ends are being able to data-log/see cranking RPM. And having the data-logged/seen RPM return to zero at key-off.

Along with those code changes are ECU/XDF file changes to match. And WUD changes too.

I am contemplating adding 3-bar MAP support. With single fire mode injectors sized for high boost are supported.

RBob.

ownor

iTrader: (5)

NICE progress! that's some good news there.

Also, the addition of 3-bar MAP support is imho a great idea! Makes the EBL even more attractive, even for boost addicts Maybe there's also a possibility of using some GPIO for adding boost control/wastegate solenoid support?

Btw i have another question, can i do the PORT module install myself? Otherwise i'd have to send you my EBL and have it done, right? So, I was wondering how much that would come out at?

Thanks for your effort

RBob

iTrader: (1)

Port Mod install needs to be done here. The cost is as what is listed on the site along with return shipping.

RBob.