Hello
I can hardly find information or examples of tuning the variable valve timing of the 1.4t
Is there room for optimization ? What must I change to optimize it more for power and what to change it towards efficiency ?
Thank you
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Hello
I can hardly find information or examples of tuning the variable valve timing of the 1.4t
Is there room for optimization ? What must I change to optimize it more for power and what to change it towards efficiency ?
Thank you
I made probably the most power off of tuning my cam timing. I do it all of the time, but the way GM and HPT have the tables laid out, the numbers don't make sense until you get how they work. My cruze SCREAMS from 2800 to redline, and does not quit. I can easily attribute my car to be as quick as it is because of my tuning of the cam timing.
Exactly, but can you shed any light on making sense of them? Are bigger number advancing and smaller retarding? Are those opposite on Intake vs Exhaust? Are they in crank degrees? Etc.
So from what I gather and have tested, at least on a 2015 with an e78, the intake cam at 0 is 8 degrees before top dead center, and as the numbers go up, they retard, so the higher the number on the intake came the more they are retarded. The kicker is they are not in degrees, but in fractions of a degree (I wanna say every 12 or 16 is a degree of retard based on the rotation of the crankshaft. I don't rember exactly is I have medicated for the night. Lol.) the exhaust cam is opposite, but the same scaling (download some gen v tunes from the tune repo and look at them. Iirc, intake starts low, exhaust will start high but it's not always the same. Don't ask me why. I've asked tech at gm and nobody seems to know.).
The key is to find where they are parked and what they idle at, and calculate overlap from there. Boosted applications tend not to agree with a lot of overlap, and I'm sure there are failsafe, but don't go crazy with the numbers otherwise you may have your piston give a smooch to a valve. Especially if you are revving high at high boost on stock valve springs. I spent months screwing with my vct and just tonight I got into a race with a base model v8 challenger... He was impressed. We locked and neither one of us pulled on the other, so I stand by my research on my particular ecu with my particular os. They are likely different and unfortunately there is little info about it unless you pay way too much dough.
Learn how advancing and retarding both or either cam can affect your power band and you will just have to experiment. I have been using only the wot tables to do it, as well as the "high" tables for part throttle but still wanting some more boom outside of wot.
Be aware that when you change this, you will have to more or less treat it like you swapped cams (your duration and whatnot will be the same because the cams aren't getting bigger or wider) for a different profile, because that is what it's doing, you will need to adjust vve tables, maf, spark, etc to accommodate. It will change how your engine flows air, as well as the cylinder pressure, cylinder temps, intake valve temp, and exhaust temps.
Basically, it's not for the faint of heart, so research a lot, and adjust in small amounts. :)
Leave VT alone.
dial in fueling all will follow
by any chance did u find out where the park exhaust cam angle is ? i have the 1.8L cruze and yes i know the cams are different but i did the spec look up on the cams and i have a 205 int. and a 196 exh. duration
centerline for:
intake is 102.5 degrees
exhaust is 98 degrees
lobe separation angle is 100.25 degrees
advancement is -2.25 degrees
intake opens at 0 degrees btdc
closes at 25 degrees abdc
exhaust opens 16 degrees bbdc
and closes 0 degrees atdc
have you found out a way to determine the parked angleQuote:
Originally Posted by RoninDusette
when i log both the cams angle and desired at idle my intake is at 7* and exhaust is at 0
So when the cams are parked they are at 8 degrees of cam rotation. Cams rotate 4 full rotations for every 2 rotations of the crank, and you have 32 degrees for each cam to move. So they start at 8 degrees advanced and retarded, which is 0 on the tables. That is parked. Each degree positive in the tables for the intake and exhaust advances and retards (respectively) the cams by 1 degree of cam rotation or 1/32 of a crankshaft rotation. If I remember correctly. They work the same across a of gms platforms, at least from what I have seen. If that doesn't make sense I can clarify further and show my tables from my car and one of my buddy's cars I tuned. I'm on my phone and nor typing in a steadfast manner. Lol
If you would that would be great. Seems my exhaust cam maxes out ~"23 degrees" and keeping intake at 0 degrees makes the car quicker.