Datsun Roadster Forum-311s.org

How do you know if it's detonating ?
You won't hear it

redroadster wrote: Sun May 01, 2022 10:21 pm How do you know if it's detonating ?
You won't hear it

You can hear it, and if you look at the plugs, they may look like this... (hopefully not this bad.)



Will

It is hard to hear, especially for this drummer who has lost some high frequency Ability! But the dyno operator can and did last time, which helped me create a much better and safer map. But the motor has changed since then too... new intake valves, recut seats, new rings, lower compression, 40mm Jenvey Heritage EFI... Now comes the final work, where you run her at 2500 and put a load on it while monitoring torque and advancing or reducing timing until you get your best "safe" (not detonating and pulled back a couple degrees of max torque for safety) advance, then moving up 500 rpm and doing the same thing until you reach say 5000-5500 rpm, then adding a couple degrees above that just to keep in front of the burn. Then a WOT pull for numbers and the torque curve to see how the cam is working and where, and if it looks good I'll be happy. From there, it will be tuning for fuel economy at cruise with a little timing advance and a leaner mixture in the zone.
This will be the most control I have ever had over all of this stuff. No matter what, it's been and continues to be a fun experience! What fun this car has always been for me. I feel very lucky and appreciative of all it has brought to me. I know you guys/gals get it.

You can't hear it on quiet exhaust rides
OBD 3 systems show the times the knock sender operates in last run , ya you can hear extreme knock ( that's eng killing ) but the lite times add up per manuf. Trainers

I was working on a knock sender system to bolt to a head to detect detonation to set timing have to get back toit

Very excited for this Greg!!

redroadster wrote: Tue May 03, 2022 8:48 am You can't hear it on quiet exhaust rides
OBD 3 systems show the times the knock sender operates in last run , ya you can hear extreme knock ( that's eng killing ) but the lite times add up per manuf. Trainers

I was working on a knock sender system to bolt to a head to detect detonation to set timing have to get back toit

Agreed, that's why the dyno is really needed here. Max torque at a given rpm should be occurring before detonation, but it's often quite close. Thus, we will find that number and then pull a couple degrees of advance off that to create a safety margin. Some engines don't detonate very easily, and since max torque might actually occur with a lot less advance, using detonation only as a guide to set timing is problematic. One write up I saw had a Porsche engine making best torque a full 8-10 degrees before it would barely start to detonate. They continued to advance the timing but the torque would go down steadily even though it wasn't detonating. It's really what the engine wants given the fuel it has that matters... more isn't always better eh?

I briefly looked into what it would take to add a knock sensor (the Microsquirt can accommodate), and unfortunately there are no easy, plug and play answers there as the frequency is very engine specific, so determining what it's listening for and then creating a system myself was beyond my capabilities and knowledge.

Thanks Simon, I always appreciate your cheerleading!

Error entry! No new updates yet, still prepping for the dyno...

Hey Greg how are things ? Did you ever dyno the setup?

Mind sharing more details on the surge tank setup? Parts used etc , I’m embarking in a few “upgrade” to Scarlett this winter and I feel this could be a good setup to emulate
Thanks

Ha! I just posted to your fuel line thread... at some point I will update this thread, likely after I FINALLY get on the rollers. I had ignition problems this summer that required a coil and systems change, but its good now. Unfortunately dyno time was scheduled way out and I never got scheduled. I know its making more power, and I've seen as high as 29mpg on my last trip around Mt Rainier, often at warp speed. It also runs the same whether I'm in the mountains or sea level. For now, review the thread and PM me and we can discuss. I'm very happy with the system. It's not plug and play, but the engine is the best it's ever been and I think I've worked out most of the bugs while learning a lot.

Thanks i'll go trough the thread and see if I have questions for you
My project seems to have some key differences so I'll update my Ongoing build thread instead so as not to clutter yours