So I am getting a rebuilt streetported motor from rotaryrebuildstore.com and I am wondering what kind of tuning adjustments will be needed if any compared to the tuning with a stock port motor? And what about the idle, will it be richer now? My idle has always been too rich, around 11.0 afr with 850 primarys and I could not get it any leaner, so I was thinking about going back to the stock 550s and I have seen many others run these with the 1680s which I have also. Please let me know, thanks!

 

porting the engine will reduce the amount of vacuum it generates at idle and low load. This will make the engine fall into different cells in the fuel map and run richer, as the speed density system assumes less vacuum = more load. How much richer it will run during normal driving just depends.

Under high load, there may be a need for more fuel, or a change in the shape of the fuel curve. Good logs (Datalogit with accurate wideband input) will be able to tell you.

 

Thanks for the info. I do my tuning with logs from my PLX r-500 wideband, logs showing AFR and RPM. I'd also like to hear from anyone else who has tuned their car after a streetport.

 

Here's one method you can try that I have used successfully for figuring out how engine volumetric efficiency has changed. I recently opened up the exhaust ports further on my single turbo engine. Previously they were matched to the sleeve, now they are ported beyond that. Normally, fuel delivery peaks at a given rpm and then drops off as the engine loses efficiency up top due to port design and turbo efficiency:



This is the Base map tab, in base x INJ view. That shows you your final injector pulsewidth value after INJ corrections (if you have not used recalc). You can see after the 6000 rpm column that fuel delivery drops off in the PFC basemap that I am showing.

What I will do is flatten out the fuel curve up top.



Injector pulsewidth is the same instead of dropping pretty hard. Then do a recalc. Observe AFR through your logs. If after 6000 rpm it starts getting very rich, trim fuel back progressively using the INJ map:



the result is a less drastic increase in injector pulsewidth which reflects increased engine efficiency up top:



Here I am just working with two P rows but remember that the PFC interpolates between cells. You can fiddle with it from there. You may have to richen up a small matrix of cells and then lean out the rest. Here is that same group of cells in the fuel map for my single turbo T04R setup. Note that I have a large street port and decent sized single turbo. I would think your engine with nonsequential twins would need less fuel in those higher rpms. Don't look at the actual numbers themselves too much (different fuel pressure etc), just look at how the fuel curve is tapered. This gives me a pretty steady AFR in the mid 11's up top at about 16psi or PIM of 21000

 

Thanks alot for all that. Does anyone else have experience going to a streetported motor and the idle being richer than a stock ported motor?, can you still use the 850s for primarys with a PowerFC?, all else staying the same. Right now I am trying to figure out if I need to go back to the 550 injectors if the idle will be too rich with the 850s with a powerFC, it was always rich before and cant get any leaner, so I can get that all taken care of when I put everything back on the motor. Thanks

 

you will have to use negative primary injector lag values to lean out the idle. that will require retuning the rest of the fuel map

 

damn that doesnt sound so easy just cause I will have to do so much tuning. Thanks

 

I found my new 550 injectors so Im gonna put those back in there, that will be better, I will run those and the 1680s.

 

on stock turbos that should be fine

 

cool thx

 

How about timing adjustments now that I have a mild streetport, do I need to retard the timing in the boost areas in the maps and by how much? I was thinking zero or very little change for low boost and a little more retarded timing for high boost. The car is running great and time for tuning. thanks

 

you still have the default Apex'i timing map in there?

 

yes. i have been told before that it is pretty conservative under high boost, and I was also going to add more split to the last few rows where the split is not very much.

 

bump. How about timing adjustments now that I have a newly rebuilt mild streetport, do I need to retard the timing in the boost areas in the maps and by how much? I was thinking zero or very little change for low boost and a little more retarded timing for high boost. The car is running great and time for tuning. thanks

 

On the leading you can pull a little timing in the higher rpms if you're not comfortable with what's in there. N18 - N20 , P15 - P20. 2 or 3 degrees maybe, just make sure you smooth out each row and then adjust the trailing split again. Set all the split from P16 - P20 to 12 degrees for now. You can adjust it later if you want to.

Also, are you changing your MAP sensor calibration? The default one usually makes the PFC read 1 - 1.5psi low depending on your boost level.

 

thanks alot! I really dont know alot about timing, but I know that what ever timing comes with the power fc worked good even at high boost up to the last row. I also just wanted to make sure it was not too advanced for a mild streetport but I didnt think it was unsafe especially where it is really conservative around max torque. I use the apexi 3 bar map sensor and did not do any recalibration.

 

sounds good. by "smooth out" I mean make sure that the cells blend so that timing isn't oscillating up and down too much.

 

right. I got 600 miles on my rebuild, just started letting it boost to 5 psi but have not revved past 5k yet, wanted to make some timing adjustments first. should be good to go now, and tune the afr. only problem now is the snow haha.

 

yeah the break in thing just depends... depends on what you reused and how it was clearanced. I started part throttle boosting by about 150 miles, then WOT at 14psi at 500 miles, then by 800 I was at 16psi.

the default PFC timing map is really pretty safe on the leading side, nobody really disputes that. In my experience you may find you need more fuel up top from the street port, but the stock twins will still restrict you up top. If you go to the basemap tab and click "base x INJ" view, you will see that the default map falls off hard in terms of fuel delivery after 6000. with a street port you may have to taper it more gradually because of increased volumetric efficiency.

After you make adjustments, make sure you look at your cells carefully in the INJ vs basemap view. In the boost areas, as you go down the P rows the fuel should continue to increase. As you look to the right (N rows) the fuel should continue to increase until you reach peak volumetric efficiency for that boost level, at which point the fuel will drop off (injector pulsewidth will fall). The whole goal here is keep from just randomly adjusting a few cells here and there without blending. That will result in a fuel curve that oscillates heavily as the PFC interpolates between cells.

 

The rotor housings were in real good shape, low miles from japan, a rebuild kit with ALS 2mm seals. I've just been doing part throttle boost and no full throttle or above 5500 rpms, but I'm ready for more as soon as I make the timing adjustments, which I will try to do tonight or tomorrow and I will also post on here my timing maps after I do it.

Thanks again for the great info.

 

Break in period depends on engine builder.

We build alot of engines that go straight on the dyno to make 500rwhp+ straight off the bat.

Generally only very strict with run in period when engine has new bearings etc.

 

Okay so I just did all the changes to my timing maps, using datalogit and excell. See the excell attachment for details and exactly what I did. I saved the datalogit files, but now they are not anywhere to be found on my computer, they not in the maps folder anymore after I saved them, I don't know how they disappeared so now I have to redo it on datalogit.

I did it all using excell and then just copied the cells from excel and pasted them into the maps on datalogit. I made changes to the leading map from N13 - N20 and P14 - P20, many cells were retarded 2-3 degrees, some cells 1 degrees to help smooth it out.

I then added those changes to the trailing map to keep the split the same as before, then I changed the split to 12 from N13-N20 and P14-P20, then I changed the split in a few more cells to smooth it out from N10 - N13 and P17 - P20, you can see all these changes clearly in the excel file attached.

 

Attached are my datalogit .dat before and after timing maps. I still have to tune for AFR so don't pay attention to my "Inj Adjust" PIM values and base map.

 

i didn't look at the excel spreadsheet but i looked at your "after timing" datalogit map.

Your P16 IGL row is nice and smooth, with a gradual timing curve to fit the VE curve and no real oscillations. Check P15. otherwise it looks good considering it is a modification of the default map. Your split map is fine. It still has some of the random split curve of the default map (rows up to P14) but that's more of a "tuner aesthetic" than anything else, I don't think it will make a noticeable difference in the way the car runs.

Your fuel map needs a little work (I know the default map isn't perfect either). Go into the base map tab and select (base x INJ msec) view. Look horizontally across your P14 and higher boost rows. You'll see some oscillation there. And with the PFC interpolation it will make your AFR's fluctuate even more.

 

I just smoothed out the boost rows in the base map, and did some other little smooth out changes to the leading timing and the split. Next I have to add more fuel to the end of the boost rows as you talked about above, so the fuel doesn't drop off so much.