I agree with all of that. My 396 used a ported LT4 intake and really good flowing heads, and I still had a cam with 110 LSA (and a good bit more duration and way more lift). And it pulled hard in the midrange. People who drove it or rode in it always thought it had more power than it really did. But of course, it didn't fall on its face after 5000rpm either, because the intake wasn't a restriction and the heads flowed well.

Yariv, I definitely understand the limitations of trying to build an American car project half way around the world. I have serious respect for anyone who even attempts it!

 

Yariv,

That is a simulation of an engine with the specifications you provided.

There is a lot of information in there.

The difference between the Intake Port pressure and the Cylinder Pressure (Green arrows) isn't large, so the intake system isn't a major restriction.

One of the main characteristics of any engine comes from the inertia in the intake runner ... Intake Ramming.

After the piston reaches BTC it no longer contributes to cylinder filling.

The inertia of the air moving in the runner creates pressure (boost) at the valve and continues filling the cylinder until the intake valve closes IC.

You can watch this pressure wave (Red arrow) build and peak at around 4750 rpm in the GIF I posted earlier.




Also included a graph of your intake tuning pressure showing the peak at 4700 rpm.

This is why your engine should be making power up until 4800 rpm or so.

At higher rpm, the wave moves to the right past the intake closing IC point and you no longer get the benefit of this boost.

That's why the Intake Tuning Pressure curve (and horsepower) drops so quickly after 4800 rpm.




You can also see that if you delayed the cam intake closing IC point, you would capture more of this boost.

I look at Intake Ramming as a narrow band (rpm) supercharger.

That is just some of what is in these wave graphs.

 

Thank you for your detailed response
I think you asked earlier, Yes the torque convertor was locked during the pull. 3rd gear + TCC

 

Hi,
I made a second run today. same dyno as a month ago.
Ambient temperature was 70F (dyno room) and @ sea level.
The changes I made are: SA tables, reduces a bit. PE - target AFR, was 3000 RPM and above about 14.1 changed it to 12.6.
I made two runs, the first 3rd gear (700R4) and TCC on and the second 3rd gear no TCC. theere was a minor change (2-3HP) for the TCC on (better with lockup).
attached the graph from today with a comprasion to the 1st (a month ago).

njoy

 

I'd say it liked the changes... what does the current tune out look like now?

 

I'll update during the weekend.

Also a CSV of the pull from the Dynamic EFI/EBL

BTW, if the Mv of the O2 sensor is not stable flipping in non WOT condition within 400mv range, can it points to an exhaust leak in the driver side where the WB sensor and O2 sensor are?

 

Looks like you’re running too rich based on EBL video/logs? Your target AFR is not matching with reported WB. Your A/F is between 10-11.x. Pay attention to fueling. I would shoot for 12.5-12.8 AFR during WOT.

 

Yeah its not perfect but better then the pull last month. WOT ~13.5 to 14

I still have lots of work to do. but I think there isn't much to gain. I have tiny cam.

I also attach the BIN and XDF if someone interested.


* change EBL_V40a.txt to EBL_V40a.XDF

 

Something I noticed, your TPS doesn't indicate 100% until about half way into the pull.

 

yeah you are right. it seems the dyno operator wet WOT after 3800 RPM

 

I think, and this is just speculation, that your commanded AFR would tighten up a bit if he had gone wide open from the start. It appears that your PE AFR richer was kicking in due to how long you were in PE.

 

I just verified, switch ON engine OFF. TPS goes from 0 to 100. TPS is a sensor and not a calculated parameter.

 

Yes, it should be based on only the movement (in volts then converted to % by the ECM) of the TPS sensor.

 

So, can we say the dyno operator hasn’t went WOT till ~4000 rpm?

 

Correct! You can verify this also by looking your MAP values.

 

It seems the dyno operator did this on your first run as well. What I would take from this second run is that you have made positive changes in your tuning and you are on the right path. I think tuning off datalogs of street driving and some WOT pulls (in a safe and responsible manner) will be enough to dial things in without having to pay for more dyno time. This second run also shows that your engine is performing as expected based on the work done to it and parts installed, which many of us were unsure of when you posted that first dyno pull.

This is an awesome thread, it is really helping me learn how to go about tuning my own ebl swapped car.

 

I so wish I could dyno tune my 85 and 89