Hello all,

I am searching for information on SR20DE timing curves. I have searched and found Calum's very old post wherein he compared the stock SR20DE timing curve to one he was using in his ECUs. My question would be: Is there anything new in the SR20DE world that would affect what is the most usable performance-oriented timing curve?

I have an S13 SR20DE. I have it running carbs and a Nissan EI distributor from a '80 200SX. I have the ability to control static (initial) timing as well as the mechanical advance (when and how much). Currently I have things set at 20° initial with 12° of mechanical advance, but the rpm in which the mechanical starts and is all-in by is currently unknown. I want to set up the ignition side of things properly.

Thanks for any help or direction to the appropriate threads.

It would be hard to say follow a fuel injected timing curve. I know nothing about nissans with the set up you have. But I do build/set up v8s for performance marine and nascar short track cars. And most of the race cars have the mech advanced locked out and use a retard box to start the car then its locked at 38 or so all pending on the build. But other carb v8's the best way to do it is on a dyno. For what your running you wanna get a good base line timing and find your max advance. Then adjust when it kicks on by swaping the springs in the distributor. The total timing should not be unknown???? you need a light with a built in advance or put timing tape on your balancer. Keep bringing the timing up untill it starts to ping then back it off 4-deg if you cant do a dyno. And have your mech advanced pull up @like 5k would prob be a good place to start.

Thanks. I could copy Calum's earlier timing curve relatively easily, as it seemed to be ~22° straight until about 5700 where it started to ramp up to an all-in of 30° at redline. The graph was cut off below 3000, but my car already runs well with 20° initial from idle.

I don't like the "advance-until-you-detonate" method because detonation is happening before you can hear it.

A timing curve for a fuel injected car is way different!!!! its a waste of time to fallow some random timing curve you find online but it sounds like you already know everything good luck:biggthump

A timing curve for a fuel injected car is way different!!!!

Why?


its a waste of time to fallow some random timing curve you find online

Which is precisely why I'm here asking.

You are pulling way more cfm and fuel than a basic F/I sr20. Are your carbs all jetted and adjusted the same? using a sync gauge or cyl temps after you run the car hard? A/F for each cylinder should be perfect before you advance timing. There is many fancy ways to tune the car perfect on the carbs before you work on the timing. You can get a a/f ratio gauge and get 4 bungs with caps a cheapo ebay header!!!! weld them on and tune away......There is also ways to time each cyl by altering the tabs on a hall effect wheel..........anyway there is way too many combos of things to be like yeah run your timing like this with out a ton of info about your motor set up....... even with all the info on for motor and car its hard to just say run this timing for best power. It sounds like you have a 1 off set up, and you got as far as to get it running so keep playing with it 1 adjustment at a time and write down and keep track of what you did. And the dyno will be your best friend

You are pulling way more cfm and fuel than a basic F/I sr20.

I think the potential is there to do that, but I don't think it's set up to do that yet. I had it on the dyno for a baseline and it's about stock power figures for an SR, but with a fat top end. The top-end is still way rich and I'm dealing with that separately. Even when it's done and the fuel is dialed, it won't be significantly different from stock WRT power. It's not my intention to even open this SR for cams or any other internal work, so it'll essentially just be an SR uncorked.

Are your carbs all jetted and adjusted the same? using a sync gauge or cyl temps after you run the car hard? A/F for each cylinder should be perfect before you advance timing.

It's the ol' chicken/egg thing. I dial in the A/F before adjusting timing and once I get timing where it wants to be the A/F will be wrong. Carbs are synced at idle and at high (throttle plates engaged) so they're set. As mentioned A/F tuning is in process. Innovate WBO2 has and will be used, plumbed into the header collector.

anyway there is way too many combos of things to be like yeah run your timing like this with out a ton of info about your motor set up....... even with all the info on for motor and car its hard to just say run this timing for best power.

Sure, but I'm not looking for perfection. Just looking for a more applicable starting point than what I've got. With all the dissection of SR ECUs I figured there would be some acceptable ranges for timing. IME timing is more directed by combustion chamber shape and such (provided you have the fuel required, etc.). If so, that won't change no matter how the engine is fueled. It's just a big air pump.