Thanks sir. I didnt get a chance to have someone at the event make any change since I couldn't even get the password. I just gave up when I hit 110 db on day2

 

Oof, thats rough. The back firing rev limits are so terrible, I dont know why they're the default settings for all these base files Ive seen.

Playing with the Motec enough, this is where Im at for launch limiter which sounds pretty much the same as rev limit. (Go to about 41 sec for the 2nd run to hear it)


Once I get the TBW setup finished I'll also use throttle to control things a bit as well. Id love to get it to that smooth brrrrrrr you here porsches do.

 

nice.
scca is now measuring sound on local events here. I think theyre lowering the limit next year

 

grrr

 

Can you trophy in sound? Might be time for a turn down.

 

Yes, in Take Over meets.
Not sure a turn down-left-right would work in our HPA venue where we have buildings near the track. I would prefer to go back to stock ecu where the tuner cant play too much with the tuning. somehow the tune got my wastegate stuck open and had no power in 1st gear in my last run. I also think this revlimiter destroyed my sensor for my AFR gauge. I really dont want racecar problems

 

ugh

 

Ignition cut limiter. Ironically, its probably easier on the engine than the factory rev limiter.

 

I'm curious why you think that?

 

are you recommending that, or thats what i have? i think this thing killed my AFR sensor in just a few pulls. i also had to remove my highflow cat to avoid destroying it

 

You can hear how fast it is, almost sounds like a bunch of rapid succession misfires vs a rev limiter. The stock rev limiter hard fuel cuts, causing rapid accel/decel of the engine from the limiter, down 200-300rpm, fully reintroduces all the fuel, and then back to the limiter. That is very hard on parts. You can hear it as braapbraapbraap where the haltech is more brrrrrrrrr. The haltech keeps the engine in a much tighter rpm range. Also if its setup correctly, the ECU should be slowly introducing the limiter about 2-300rpm before hard limit. To somewhat reduce the engines acceleration rate before slamming the hard limiter.

The way this car looks to be setup, the fireball definitely isn't helping the exhaust valves or turbine though. Which is why you should introduce some fuel cut in this as well. Ultimately a properly setup rev limiter with a stand alone is easier on the engine than the factory fuel cut limiter.

I'm not sure why you had a cat on a racecar to begin with. But if this can't pass sound thats going to be up to you.

 

I can confirm this was mentioned in the conversation. I just didnt know how loud is too loud. I will try to see if he can get it to a sweet spot

It's a street car. if the performance with highflow cat was about the same as a straight pipe then i'd run with the cat...so not to be called "cheater" or someone reporting me for driving without a cat.. ya just dont know how people are in BMW/Porsche/snubby clubs. we also use the Police academy test track

 

I guess I don't see the change in RPM as a stressing condition. the loads in the valve train, rods/pistons, and crank are driven by RPM alone as there are reversing and pulsing loads in every cycle. I suppose you get some low order harmonics happening in the crank from the engine torque turning on and off but I view the higher frequency cutting of the limiter as more dangerous (closer to the resonant freq of the crank) than the lower frequency hard cuts. For sure the huge spike in EGT's from the ignition cut is not good for anything in the exhaust.

 

I'm using these numbers because I just mathed them out the other week for an engine build. My typical 2.2L piston/pin/rings/circlips/recip rod weight... they weight roughly 3600lbs at 9800 due to the gforce of accelerating from 0-113mph in 1.6", in 3.5miliseconds.

And then you go and instantly load the assembly, unload it, load it, unload, load it.

Rev limiters cause false knock because they make the engine make a bunch of noise.

Motorsports ECU manufacturers all have their logic for a soft limiter.

It's a thing, because hard limiters can hurt ****.

@viscousLSD, if your map isn't locked send it over. I can fix the limiter. It'll be quite, and feel like a stock mazda3 hitting the limiter

 

in normal engine conditions (no rev limiter) the engine is instantly loaded and unloaded, as you described above, 2 times per revolution. Skipping ~20 (soft limit) or ~100 (hard limit) cylinder firing events doesn't make the loads go up. *edit* changing the frequency of the firing events definitely changes how the crankshaft responds and operating closer to a resonant mode of the crank can cause issues. I haven't done any math on evo crankshafts to know if we better or worse (or don't care) with different rev limit strategies.

I wouldn't over estimate the aftermarket ECU manufacturers motivations for having different rev limiter options. the fact that it sounds cool and shoots fireballs is not an unlikely reason they support the soft cut/ignition cut modes.