You know who else blew at least one motor? Every car company ever. Do something enough and a mistake happens.
I’m running Revo 1+ and it Mustang dyno’s 370 at the wheels (290 stock on same dyno same day). I keep trying to get over to Sonoma Raceway on a Wednesday afternoon but I always have another meeting in SF.
West west, don’t you have the record for the slowest tuned B8S4 ever?
We don’t race dynos here either, so save the long winded dyno breakdowns too.
Finding the limit of a shop cars motor is completely understandable.
Releasing a tune that blows a customer’s engine is not.
Gents, I’m on hang fire until I hear from Revo. The closest GIAC dealer is a 6 hour ride from me. In my opinion I’m done with APR, worked closely with them and I’ve been stone walled. Below is a video from Audizine, on this site too. 330-150 mph run. Again when I cruise I see 25 degrees advancement on my P3 and when accelerating it drops to 14 degrees! This video shows the man’s car getting 29 degrees advancement, me 14. Oh APR…where are thou? They say my tune is normal. I’ll write again, I’ve spent hundreds on VCDS, logging, driving and hotel rooms working with APR to resolve this.
use your google and read about ignition timing. It’s complicated enough that I’m not going to screw it up with an explanation that has already been written enough. The pistons travel up and down in their cylinders, and fuel and spark and o2 create an explosion in that cylinder. Think of top dead centre as when the piston is at the peak of it’s travel at the top of the cylinder. Your tuner (Audi originally, APR now, REVO next week, GIAC in September) will tell the car when to ignite that cumbustive mixture by giving it a spark, and the exposion drives the piston down, turning the crank, propelling the car. Remember this is happening 6000 times a second times 6 cylinders at 6k RPM…it’s manic in there.
Anyway, there are gains to be made by igniting earlier than TDC (to a point…ignite too early and you lose power…ignite way too early and the piston is still travelling up while the explosion is at it’s full force pushing it down, and you now have two forces fighting with the connecting rod as the thing absorbing this force. Bent rod equals piston that is all wonky and not perfectly aligned, and then…grenaded engine. At these speeds, that often means the piston travels not up and down…but through the side of your aluminium engine block and out on to the road at 100 MPH. Anyway leave it too late, and you are leaving TONS of power on the table with the timing values your car is making vs. say primetime or anyone with a well sorted 2010-2012 tune. On a forced induction car running a decent amount of boost on decent octane, the ignition timing that you are running vs. say primetime or someone with a well sorted 2010 car is a big gap . It can be 50-60 hp that gap. Your car is effectively requesting ignition 8-10 degrees before top dead centre. Then your knock sensors are picking up knock and telling the ECU to retard that timing even further…another 1-2 degrees. So it’s net igniting 6-8 degrees before top dead centre. The other guys are in the 18-20 degrees range I believe. My stock tune NA Audi RS4 sees ignition timing of about 31 degrees at its peak. NA is different, but you get the idea.
Hopefully that helps a little. Now the smart people will tell you me where I was wrong.
p.s. how old are you…you keep mentioning it. Are you ‘I don’t even buy green bananas anymore’ old? Or just not 28 old.
Sakimano, understand all you wrote and thanks. Old enough to have been drag racing flat head Mercury engines in an “altered class” during the 60’s. Wow, we turned in the 14’s and 95 mph?!?! On Medicare too. I’m retired and some may think too much time on my hands. I’ve run the gambit of toys, cars, boats and even an airplane. Aircraft are far too expensive now to operate. Hope this helps explain my insanities?
I think it would be nice to start a “noob guide on engine control and performance”, I know there’s a lot I don’t understand.
When I was first trying to understand concepts of engine performance and controls, this thesis came up which has some really interesting stuff: http://www.diva-portal.org/smash/get/diva2:23960/FULLTEXT01.pdf
Also provides a nice introduction of the 4-stroke cycle for those not familiar with the details.
I copied this figure as an example, where you can see the influence of spark timing on engine torque:
https://farm4.staticflickr.com/3895/14739676190_8cd510a059_b.jpg
PM count vohn and maybe he will share. He likes writing short essays on various topics. He has plenty of experience to colour the explanations with anecdotes, always entertaining.
How do you not follow that he is on
1 a race tun
2 has race gas and E85 in the tank
3 has water/meth
Looking at your cruising timing is pointless because it can be all over the map based on load.
Instead of shouting how much experience and intelligence you think you have step back and read or just listen to the guys who know what they are talking about like Primetime.
hahaha
Euroswager, thanks much.
So a larger timing degree is closer to the danger zone described earlier in the post (the piston is 6-8 degrees before or after tdc?). Where he is seeing 6-8 before tdc, others are at 18-20 meaning there is more volume in the “explosion chamber”, wouldn’t that make less power? I thought the smaller the box the explosion gets to happen in, the stronger it is?
This is the part I get confused on, why wouldn’t tdc be the best time to ignite the spark, unless we are calculating for the time it takes for all the stuff to go bang and thus you light the spark earlier that tdc?
Thanks for the help.
I do have the slowest one. I revert to stock when I need to tap some real speed.
Do you fly on airlines that have had crashes in their history? Completely unacceptable to kill customers.
I need Count Vohn to answer to help better…but the biggest reason is because spark isn’t instant. The combustion/explosion doesn’t happen on command. You need to time it. It also happens longer for better fuels (which is good) so there are a few things upon which you need to understand to get the timing (no pun intended) right. This is why when customers buy a 93 tune, and then run 91…it’s tough on the tuner. He has to build in protection for stuff like this. Conversely, when the customer has AWESOME fuel, the tuner can give you a little more than their standard calibration (if you want it). APR and GIAC responded to some of the guys showing great logs who were running 110 and released their respective ‘104’ tunes, which were more aggressive than the 100 tunes and relied on EXCELLENT race fuel. Aggressive is a tough word…it implies bad. How about we say ‘stronger’, not more aggressive.
My understanding from the lesson CV gave me in Detroit one fall evening was that these actions were BEFORE top dead centre, not after. After wouldn’t make much sense. This is to drive the piston down, and drive the crank, and knowing spark and explosion isn’t instant, after makes no sense. I saw that Jones misunderstood this in another thread and said ignition timing refers to timing spark AFTER top dead centre, but that’s wrong. I’m sure it was a typo, as I don’t think he’d start threads about how much ignition timing his car is seeing without understanding it 
From that thesis I linked, spark advance is defined as a negative angle since it occurs before TDC. To truly understand the physics you’d need a PhD in fluid mechanics. The pushing a swing analogy doesn’t really work lol
Hey west you should go to Sacramento with JHM. They’re having an audi dragstrip day in November. Or just find out another time they’re going and go along.
I’m probably wrong, but I always envisioned the angle as applying to the position of a distributor cap. I can rotate it clockwise or counter clockwise to adjust the timing of the spark relative to TDC. Whether it’s accurate or not, it works in my mind to some degree (pun intended).
-Skid
In response to a request. Here are some thoughts.
Timing
TDC = Top Dead Center, or the piston is at the very top part of its travel.
BDC= Bottom Dead Center, or where the piston is at the very bottom of its travel.
The ideal “event” as its called
Event= the point where the spark ignites the fuel and the burn “event” starts
The ideal “event” would be at TDC, so why would you want the ignition cycle to start before TDC? Before we get into that let’s backtrack a little.
+timing and - timing.
Think of it like this; if you start something before DTC it would be +, if you started something after DTC it would be after or -
So, when you see +14 deg this is 14 deg before DTC. You wouldn’t want to do it after TDC because the piston is already traveling down away from the “optimal event” point
To just recap +is before - is after. For the best results we want to start everything before our DTC window comes, this way we will be ready.
Why before?
To better understand, lets get an idea on how fast things are happening in your motor. let’s take a snap shot at 6000rpm. At 6000rpm your piston is coming up to TDC 100x a second. Think about how fast that is. When we are looking time wise, 100x a second is incredibly fast. When you are calculating the ignition window, you’re looking at not seconds, but milliseconds. Very small increments of time.
Ok, so here comes a little sports analogy to help us out. For those of you who know me know how big of a sports nut I am. With baseball getting ready to end, lets use that.
We look at the “optimal event” in baseball, that’s having the batter hit the ball right at his best power point, and for this example that’s directly over the plate. So in baseball DTC is directly over the plate.
When a pitcher throws a 100 mph fast ball, the batter can’t start swinging when the ball is over the plate, even tho in theory the best place to have the “event” or contact, take place is over the plate. If the batter started to swing the bat when the ball was directly over the plate, he couldn’t move the bat fast enough to hit the ball and the “event” window would be missed. So, when the pitcher throws the pitch the batter starts his swing before the ball is over the plate. The faster the ball is thrown, or the faster the motor is spinning, the sooner you need to swing your bat or start the ignition.
You need to start before (+) the “event” happens. So, to further the example lets say that the pitcher is throwing 100 mph and the optimal time for the batter to start swing the bat is when the ball is 15 feet away from the plate. So, here is what happens. The ball is pitched the batter starts his swing when the ball is 15 feet away and the “optimal event” takes place right as it should. The bat hits the ball right over home plate and, home run, the ball gets smashed out of the park.
So, why is it such a big deal then when you see people saying that the ignition timing is too low. Well, now lets look at what happens when the batter swings later then the optimal window. If the batter swings when the ball is at say 12 feet away from the plate, its after the optimal window so, now some of the energy getting transferred in the “event” is lowered and the ball won’t travel as far. This is the same thing that happens in the motor.
As the motor accelerates there is a calculated optimal ignition window for each RPM. Depending on how far in or out of that window you are you will not be able to accelerate faster then you did your last “event” One of the things the Audi computer will do is reduce ignition timing, to slow the acceleration rate of the motor. So, when you see one guy that is hitting the optimal ignition timing of say 22deg (if that is the actual optimal figure) and then you see in a log another guy with 15 deg there is going to be a big difference in acceleration rate of the motor. (this considering same car mods etc.)
Each RPM point depending on load, CFM, fuel, temperature and several other factors, will have it’s own optimal ignition point. Knowing how to calculate that point and knowing where the perfect “event” window is for part throttle, WOT, low load, high load etc etc etc. is part of making safe productive power. At WOT you would be shocked to find out just how many times the car actually misses its “event”. Check out a stock RS4 and tell me how many misfires you have. You want to reduce the amount of missed “event” cycles, so getting this right will effect how the car accelerates. If you don’t get the curve right, the car won’t accelerate as fast as it could. Or if the car is protecting itself the acceleration rate will be greatly reduced.
Hope this helps. This was just the quickest thing I could think of to help those that might not know how this worked. This was far from an in depth explanation.
Very nice analogy.
Haha great explanation
Damn good stuff CV. Thanks for the explanation and great analogy.