Cylinder pressure at 1500rpm is high, especially with the vanos system on this car. In general, low RPM is harsh on a motor since you can get really good cylinder fill and the motor is moving so slow that it sits at high pressures much longer. Knock is more prevalent at low RPM for this reason, etc. If you want to apply this to coils bmwfixerguy and his observations are correct you'll generally see them struggle at low and mid rpm first, it gets easier for them after torque peak but often lower RPM is still worse for misfires since mixes are leaner before torque peak. Lean AFR, high pressures (present and lingering at low rpm), e85, all these things make it harder to ignite. I think the notmpwr guy was confusing dwell and duty cycle for how hard the ignition system is working. That's true to an extent, but the coils have full dwell (charge time) at low duty cycles until 8,000+rpm, so they are fine from that perspective everywhere. It's a common misconception for people who started with old dizzy ignitions, since as rpm increases you lose a ton of charge time and get more misfires with a dizzy. Modern computer controlled ignitions don't have this issue until really, really high RPM. Since the coils are at 100% output from idle to redline, you will instead see them struggle down low every time. Multispark helps mask this and keep emissions clean, etc.
VTT / Precision Raceworks Coil install / Results thread
- Thread starter Tony@VargasTurboTech
- Start date
Thanks v8 for unjumbling what I was attempting to kinda say but made a pot of alphabet soup instead lol
I don't want the fella questioning the results to feel like he's getting ganged up on.. Its not really like that.. I know when you have an argument it's really hard to go back on your original thought! My offer was instead of fighting it try and understand it because it might make him more power down the road
that's what we're all here for is more torques!!
I don't want the fella questioning the results to feel like he's getting ganged up on.. Its not really like that.. I know when you have an argument it's really hard to go back on your original thought! My offer was instead of fighting it try and understand it because it might make him more power down the road
that's what we're all here for is more torques!!Thanks v8 for unjumbling what I was attempting to kinda say but made a pot of alphabet soup instead lol
I don't want the fella questioning the results to feel like he's getting ganged up on.. Its not really like that.. I know when you have an argument it's really hard to go back on your original thought! My offer was instead of fighting it try and understand it because it might make him more power down the road
It's all good man, I don't feel like being ganged up on. I could be the only one that has a doubt and not feel like that.
Why didn't the coils produce more power above 5k rpm where cylinder pressure is higher?
Also has static timing been confirmed with these coils vs stock?
I think V8bait answered that question pretty damn well.. I couldn't have said it better myself.. Like literally I wasn't able to lol.
And the reason is super duper simple... Because he didn't need it then.. I know with have dual vanos we can alter cylinder pressure to any degree.. He is running higher lift cams, larger plenum and the ability to run near zero over lap if he wants which he probably was at that rpm.. That is a perfect storm for increased cylinder pressure then to throw nothing but E85 at it and all of a sudden I'm disappointed he didn't make more lmaooooo
I really wanna know the exact answers too and I'm inviting you to join us for the week on the optimistic team and with the knowledge you have and give a detailed explanation of gains
This business needs a pessimistic crowd if not we would buy all our mods off of QVC or an infomercial lol
I deff think your a smart dude with tons of experience and I surrender to the fact that you absolutely with out a doubt have more experience with high horse power cars, dyno time and base engine.. So I'm willing to bet if you put your mind to the optimistic side of this you will find an application you could apply this too as well
Where do you get the idea it's higher at 5k? The torque is pretty flat so highest pressure will be at 3k and decrease after that most likely. After 5,000-5,500 pressures are way on the down slope as airflow increases, exhaust back pressure isn't even that high up there. As for timing the logs are public and he didn't change timing. Just regapped plugs and flashed the PR dwell table.
I was talking about actually timing, not table timing or anything.
I have switched coils before or wires and have found discrepancys in timing due to latency and other factors.
The dme assumes we are still running stock coils when it looks up a ignition angle, but just because the table says 15* doesn't mean you get 15* if there are some other factors going on.
The stronger spark creates a better burn, which causes the peak cylinder pressure to happen sooner in the rotation (effectively advancing the timing) at higher rpm the turbulence in the cylinder creates a quicker burn also, so the stronger spark has much less of an effect.
You'd have to go back to the electrical bench tests done by PR, V8bait, and a few others before these were released. They provided all the actual results and did show the impact to latency and response times and how that would impact timing. If I remember right they were playing with a bunch of variables to keep latency, and response times as close to stock as possible. In the end they were not the same as stock, but so close it was negligible.
These coils don't have latency, they are triggered by the DME and fire instantly just like OEM. The smart coils that Alex uses in his kit have a little latency but it's negligible and would only lower advance if anything.
Some smart coils will fire premature if dwell is too long as a safety. These coils will not, they will melt before they fire early. And the DME has thermal and current limits if you exceed the IGBT rating (which is like 40amps or something). We hit it a few times in testing on purpose to see what happens using multispark and 0.1ohm coils. Hope that helps.
Some smart coils will fire premature if dwell is too long as a safety. These coils will not, they will melt before they fire early. And the DME has thermal and current limits if you exceed the IGBT rating (which is like 40amps or something). We hit it a few times in testing on purpose to see what happens using multispark and 0.1ohm coils. Hope that helps.
@boosty, just so I'm clear - I see you're plotting power (Leistung) and torque (Dreh moment) v rpm, but what's the difference between the red, green and blue data lines?
This was not the final calibration but we didn`t faced any ignition problems with the stock coils at this point. after we moved to PR Ignition we finished the calibration by advancing the ignition timing a bit. at the end it was about 660whp (+ ~40whp) but the ignition timing was not much more advanced than other similar setups with stock coils.
We did not increase or decrease the gap as I don`t like playing with gaps on used plugs
We did not increase or decrease the gap as I don`t like playing with gaps on used plugs
So you didn't gain anything much just swapping coils/etc but were able to advance timing more and gained some via that mechanism. Right?
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