2015 GT Valve Overlap Tuning

[kris5597]

Hi Guys,

Have any of you had any experience increasing or decreasing valve overlap on the 2015 GT chassis to notice any gains in power from VCT adjustments? It seems most tuners are getting by with just ignition and fueling. From my tuning experience in the past, all aspects should be considered when tuning a vehicle for maximum usable power. So my current adventure is VCT tuning. Unfortunately I currently do not have access to a dyno being in between shops, just wanted to see if any others are having any luck.

Thank you,

Kris

[redline5.0]

Hi Guys,

Have any of you had any experience increasing or decreasing valve overlap on the 2015 GT chassis to notice any gains in power from VCT adjustments? It seems most tuners are getting by with just ignition and fueling. From my tuning experience in the past, all aspects should be considered when tuning a vehicle for maximum usable power. So my current adventure is VCT tuning. Unfortunately I currently do not have access to a dyno being in between shops, just wanted to see if any others are having any luck.

Thank you,

Kris

You could find a flat stretch of road and log some wot pulls after making changes and toss them into virtual dyno. While not as great as using a dyno you could still see if your making any/losing power.

[kris5597]

You could find a flat stretch of road and log some wot pulls after making changes and toss them into virtual dyno. While not as great as using a dyno you could still see if your making any/losing power.

I have used the virtual dyno for years and would love to do so, however, the VCM Scanner does not log time, so I cannot use the VD.

[CarsonTech]

The scanner does log time. Do an export to .csv format. The "s" column is seconds, which should be the first one.

[kris5597]

Hmmm... I'll have to check but every time I've checked the .csv, it never showed time.

[kris5597]

Have you guys used thr virtual dyno with hptuner before?

[FLtuner]

If you take the time and play with it some gains can be had, logs the cam timing and you'll figure out fast what is really going on with them.

[kris5597]

From what I can tell, there is something that is causing the 2015 coyote engine to not like much overlap at peak power. I'm a firm believer it's a flow issue. I've been playing with the intske VCT and have noticed an increase in MAF #/min, other than that, it's hard to tell if it's actually making more power without a dyno.

[txcharlie]

Run time won't work?



Screenshot (9).png

[CarsonTech]

I have with lots of my old GM cars. Work pretty well.

[kris5597]

Yea, engine run time won't work. It literally uses the time the engine started running since you turned the key, so by the time you do a log it's at some random number and minute. I tried it but virtual dyno won't accept it.

I think it's a log issue with the 2015 mustang gt. No time logged. I asked hptuner about it and they said they would consider it on their next update.

[redline5.0]

I don't have a 2015 but I will be trying it on my 13 to see if it works or if I can make it work.

[CarsonTech]

I have a 2015 Mustang GT, and HP Tuners exports a .csv of my log files with a column dedicated to time (seconds).

[kris5597]

I have a 2015 Mustang GT, and HP Tuners exports a .csv of my log files with a column dedicated to time (seconds).

Yes, I reviewed my log and saw the same thing. The issue with importing the .csv converted file from the VCM scanner were the labeling of each column. I had to delete a view lines, change a couple of names and I got the file to import into the virtual dyno. That being said, it seems to prove that my change in VCT actually lost top end power lol. Back to the drawing board.

Kris

[kris5597]

Also, I saw a log from a reputable tuner that changed VCT. It was a 2015 GT with intake, header, exhaust. My prediction is that with the increase in flow, they would have increased overlap by advancing the intake closer towards TDC for peak power rather than have it retard the intake cam for peak power like stock VCT. It was the exact opposite. The tuner retarded the exhaust cam and intake cam more over the stock VCT. That just flusters me as to why you would want to retard the intake valve opening even more after TDC.

Kris

[FLtuner]

Also, I saw a log from a reputable tuner that changed VCT. It was a 2015 GT with intake, header, exhaust. My prediction is that with the increase in flow, they would have increased overlap by advancing the intake closer towards TDC for peak power rather than have it retard the intake cam for peak power like stock VCT. It was the exact opposite. The tuner retarded the exhaust cam and intake cam more over the stock VCT. That just flusters me as to why you would want to retard the intake valve opening even more after TDC.

Kris

Like I mentioned earlier advance the intake cam, data log the cam timing and you'll figure out what is going on.

[kris5597]

Will do. I appreciate the advice. It's sad to say, but I think this tuner, is tuning the VCT incorrectly. :/

I made a change to intake VCT by creating some overlap and it seems to be going in the right direction. I will let you know how it goes.

Thank you,

Kris

[Russ K]

To gain power at higher RPM, the intake cam needs to be retarded & the exhaust cam needs to be advanced (reduced valve overlap). And to gain lower RPM power, the intake cam needs to be advanced & the exhaust cam needs to be retarded (increased valve overlap).

Russ Kemp

[kris5597]

Yes, that's exactly how it should go. However, on the 2015 GT engine, stock VCT is 0 overlap at peak power. I feel that retarding the cam more with 0 overlap to begin, will not do anything but cause issues. The intake cam retard at peak power is 14 degrees after TDC and the exhaust valve retard is also 14 degrees after TDC. Creating some overlap with an increase in airflow (intake, exhaust, etc) I feel the engine could possibly benefit from a little overlap. Considering torque and VCT both start decreasing immediately after 4500 together, gives me reason to believe the issue is a cork in airflow from both intake and exhaust side. I feel with a short runner and higher flowing intake manifold and long tube headers, valve overlap will show to be what is considered and expected as "normal" from a tuners eyes. I've never seen an engine have intake opening and exhaust closing after TDC, normally I've seen overlap with the intake cam always being advanced and the exhaust cam either being fixed at TDC or retard after TDC. New animal for me.

[Plimmer]

Yes, that's exactly how it should go. However, on the 2015 GT engine, stock VCT is 0 overlap at peak power. I feel that retarding the cam more with 0 overlap to begin, will not do anything but cause issues. The intake cam retard at peak power is 14 degrees after TDC and the exhaust valve retard is also 14 degrees after TDC. Creating some overlap with an increase in airflow (intake, exhaust, etc) I feel the engine could possibly benefit from a little overlap. Considering torque and VCT both start decreasing immediately after 4500 together, gives me reason to believe the issue is a cork in airflow from both intake and exhaust side. I feel with a short runner and higher flowing intake manifold and long tube headers, valve overlap will show to be what is considered and expected as "normal" from a tuners eyes. I've never seen an engine have intake opening and exhaust closing after TDC, normally I've seen overlap with the intake cam always being advanced and the exhaust cam either being fixed at TDC or retard after TDC. New animal for me.

Thanks for experimenting and sharing the results. Guys like you will help us all unlock the mysteries of 2015+ Coyote tuning.