Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum - View Single Post - SR20det ignition timing issues/engine getting hot

Kingtal0n · 08-10-2021, 09:09 AM

Now to the issue of timing

The rom-tuned ecu isn't going to impact cooling temps
there is very little if any difference in tuning for any sr20det with respect to ignition timing and camshaft changes, for most changes this is true.

That is because the engine uses a cruise timing which is similar no matter what the compression ratio of a turbo engine can encompass.

In other words, a typical turbo engine is already using a very low static compression ratio (8.5:1 or 9:1 is typical) therefore while cruising the alterations to engine VE due to camshaft and other mods is negligible with respect to gasoline ignition timing tuning.

So, there is nothing in your ECU causing your temp related issues unless it was some kind of mistake or bad part involved, or bad wiring I guess (its not tuning related).

If anything, as camshaft "size" increases, engine VE increases, which would call for LESS ignition timing at wide open throttle (MORE EGT = less timing)

---

Now the timing itself, could be an issue. most timing light have a directional pickup. The critical issue with sr20det timing is the position of the CAS. Take a careful look at where it is positioned between the lockdown bolts. It should be just slightly off-set (the bolt is not quite centered in the slot).
Next, check the timing, then FLIP the pickup on the coil pack wires. In other words, flip the clamp around 180* so the wire goes from left to right instead of right to left (or whatever). Then re-check the timing.

The timing which yields 15* BTDC while the cas is nearly centered (bolt in the center of the slot adjustment) is the correct timing. When flipped incorrectly it should push the CAS off to one side (FULLY moved to the edge of the slot).

08-10-2021, 09:09 AM	#17
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 41 Posts: 4,828 Trader Rating: (17)	Now to the issue of timing The rom-tuned ecu isn't going to impact cooling temps there is very little if any difference in tuning for any sr20det with respect to ignition timing and camshaft changes, for most changes this is true. That is because the engine uses a cruise timing which is similar no matter what the compression ratio of a turbo engine can encompass. In other words, a typical turbo engine is already using a very low static compression ratio (8.5:1 or 9:1 is typical) therefore while cruising the alterations to engine VE due to camshaft and other mods is negligible with respect to gasoline ignition timing tuning. So, there is nothing in your ECU causing your temp related issues unless it was some kind of mistake or bad part involved, or bad wiring I guess (its not tuning related). If anything, as camshaft "size" increases, engine VE increases, which would call for LESS ignition timing at wide open throttle (MORE EGT = less timing) --- Now the timing itself, could be an issue. most timing light have a directional pickup. The critical issue with sr20det timing is the position of the CAS. Take a careful look at where it is positioned between the lockdown bolts. It should be just slightly off-set (the bolt is not quite centered in the slot). Next, check the timing, then FLIP the pickup on the coil pack wires. In other words, flip the clamp around 180* so the wire goes from left to right instead of right to left (or whatever). Then re-check the timing. The timing which yields 15* BTDC while the cas is nearly centered (bolt in the center of the slot adjustment) is the correct timing. When flipped incorrectly it should push the CAS off to one side (FULLY moved to the edge of the slot).